BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > Track / Autocross / Dragstrip / Driving Techniques
 
EXXEL Distributions
Post Reply
 
Thread Tools Search this Thread
      03-08-2016, 08:16 AM   #155
///Mobbin
Colonel
///Mobbin's Avatar
1475
Rep
2,672
Posts

Drives: m3
Join Date: Jul 2011
Location: Houston

iTrader: (3)

Quote:
Originally Posted by dogbone View Post
But you know what is rearing it's ugly head now----the DCT overheating after just a couple top-speed laps. I am going to have to do something about that. Basically, now that the car has full aero, sticky R1S and DSC-off, the transmission is quickly overheating from the stress. To be fair, I could probably do lots of laps at 1:55 and be fine. But when trying to go 1:48…… the car only gives me a few cracks at that before the gear icon flashes up on the dash and the car only shifts in even numbered gears due to overheating. I may have what I think is a plan to attack it. I'll write more about that later if I implement it.
I'm curious if you are running stock or some form of the GTS DCT programming?
__________________
2021 Alfa Romeo Stelvio Quadrifoglio | 2.9L | Trofeo White Tri-Coat | 8-spd
Appreciate 0
      03-08-2016, 08:36 AM   #156
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Quote:
Originally Posted by ///Mobbin View Post
I'm curious if you are running stock or some form of the GTS DCT programming?
I do not have stock DCT programming anymore. I believe it is GTS DCT.

It is MUCH smoother on downshifts than the stock software. I can basically downshift ANYWHERE at anytime and not upset the car.

Why do you ask?
Appreciate 0
      03-08-2016, 10:11 AM   #157
///Mobbin
Colonel
///Mobbin's Avatar
1475
Rep
2,672
Posts

Drives: m3
Join Date: Jul 2011
Location: Houston

iTrader: (3)

Quote:
Originally Posted by dogbone View Post
I do not have stock DCT programming anymore. I believe it is GTS DCT.

It is MUCH smoother on downshifts than the stock software. I can basically downshift ANYWHERE at anytime and not upset the car.

Why do you ask?
I'm considering the modified (more conservative) GTS DCT programming myself, mainly for the smoothness of downshifts as you've indicated. I've heard this is a nice benefit on the streets as well as at the track.

I've also read in a few threads that there were concerns the programming would cause the transmission to heat up faster at the track. If this is truly the case I might put off the programming until I'm closer to installing an aftermarket DCT oil cooler, like this one:
DO88 DCT Oil Cooler Install Thread

Though it sounds like you can still get some good lapping in without it. There is also another brand that is popular but I haven't seen a thread on it recently. Either way, good to have some well sorted solutions already available if this becomes an issue.
__________________
2021 Alfa Romeo Stelvio Quadrifoglio | 2.9L | Trofeo White Tri-Coat | 8-spd
Appreciate 0
      03-08-2016, 11:19 AM   #158
Jive
Lieutenant
Jive's Avatar
156
Rep
580
Posts

Drives: 2013 E92 M3
Join Date: Dec 2010
Location: Bay Area

iTrader: (0)

Along with the upgraded DCT radiator, you should look into the upgraded transmission pan. Significantly larger heat capacity will help with tracking for longer periods. Gintani sells just the larger pan and SSP sells an entire package (larger DCT radiator + pan): http://sspperformance.shopgate.com/item/333435
__________________
2013 E92 M3 Mineral White Fox Red / Black
Appreciate 0
      03-08-2016, 12:44 PM   #159
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
The overheating of the transmission is a relatively new thing for me. I've had the DCT software in there for years. The combo of full aero, stickier tires and DSC-off clearly upped the stress on that system.

I was aware of the Do88 DCT cooler. But I hadn't seen the SSP offering. With the SSP setup, I wonder where I would put that cooler though, since I already have a supercharger cooler in that spot….hmmm
Appreciate 0
      03-08-2016, 08:24 PM   #160
roastbeef
Lieutenant General
roastbeef's Avatar
United_States
11575
Rep
12,714
Posts

Drives: E92 M3
Join Date: Nov 2010
Location: Orange County, CA

iTrader: (4)

i know jordan yost is using the full csf cooler package, but he is 6mt. in speaking with him at a few track events, he had nothing but great things to say about those coolers, and they didn't have any cooling issues in their 25 hour races. do you think that keeping everything else cooler (overall reduction in temps) would help reduce transmission temperatures?
in another thread, okusa stated that he didn't see any significant difference in engine oil cooler temps when looking at AIM data- and went on to say the same was true for other coolers (dct, water).
i'm not at that level of expertise yet, but maybe coolers just keep the temperatures about the same for a longer period of time?
__________________
Instagram; @roastbeefmike
Appreciate 0
      03-09-2016, 01:48 AM   #161
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Quote:
Originally Posted by roastbeef View Post
i know jordan yost is using the full csf cooler package, but he is 6mt. in speaking with him at a few track events, he had nothing but great things to say about those coolers, and they didn't have any cooling issues in their 25 hour races. do you think that keeping everything else cooler (overall reduction in temps) would help reduce transmission temperatures?
in another thread, okusa stated that he didn't see any significant difference in engine oil cooler temps when looking at AIM data- and went on to say the same was true for other coolers (dct, water).
i'm not at that level of expertise yet, but maybe coolers just keep the temperatures about the same for a longer period of time?
Yeah, the issue of overheating in an E9x M3 is definitely a challenging one. It seems that CSF has made some bold claims of having solutions that deal with the issue, but as you pointed out, okusa---who I know very well---hasn't seen any of the results he hoped for. That's a bummer…..so I am looking at other solutions than CSF.

The Yost car was built as an endurance car. That is quite a different approach than a time attack car that needs to be fast for one lap. I would say my car is setup with the idea of doing time attack. The Yost car is very light (400-500 lbs lighter than my car), it has a manual transmission (I have DCT) and the power of the car was purposefully kept within a certain range to keep heat down---meaning no S/C or stroker, etc. (I have S/C.)

The fact is that the stock M3 wasn't made at the factory for this kind of high stress hammering with a ton of aftermarket go-fast parts. The cooling it has is perfectly fine for the street and occasional track. Remember, my DCT didn't give me hardly any warnings in the last 4 years-----until I slapped full aero, super sticky R1S tires and started hammering with DSC-off. That's just a whole new level of stress on the car. Can any of us really say it's a surprise that a heavy car with a high revving 8-cylinder engine, with a supercharger, with full aero and almost-slick tires is overheating? I'm not surprised that it overheats. What I am surprised by though, is that no company has proven that they have an effective---and mostly importantly-----CLEARLY DOCUMENTED solution for it. This M3 is not the first car to be heavy and make a lot of heat. Isn't that pretty much the story for all American cars? I have been hoping that some company who has a long history of dealing with this in American cars like Mustangs or Camaros could provide us BMW guys with a solution. I have to assume that the E9x M3 platform will become a common racing platform someday. Somebody is going to have to come up with a workable solution for the overheating. Can you imagine a whole field of E9x M3's racing wheel-to-wheel taking cool down laps in the middle of a race because the cars can't handle it? "Ok fellas, laps 4, 8, 12 and 16 are cool-off laps. We'll put up Yellow flags for those laps. We'll hammer the rest!" I mean c'mon…….

The Swedish Do88 cooler looks interesting simply from the fact that it's so much larger than the stock cooler (almost double) and it sits in the stock spot. The SSP thing looks crazy. At $2200, that's just frightening. And like I said before, since I have a supercharger intercooler, where would I put the SSP one? And again, I'd like to see some documentation. Companies seem so quick to SAY it works……I want to SEE it working. This stuff is easy to document if you want to. SSP claims that their cooler keeps DCT temps down for 40 minute sessions, but I don't see any data…...Do88 shows some charts based on 11 minutes of hard driving. Plus, a forum member has talked about how the Do88 seems to be working and he has a temp gauge tapped into his DCT system. Perhaps, the Do88 might be a place to start……it costs more than the CSF cooler, but is half the price of the SSP. We'll see.
Appreciate 2
      03-09-2016, 02:36 AM   #162
redpriest
Colonel
redpriest's Avatar
2146
Rep
2,527
Posts

Drives: 2011 M3/Porsche 992 GT3RS
Join Date: Apr 2014
Location: Bay Area, CA

iTrader: (0)

Garage List
Quote:
Originally Posted by dogbone View Post
Yeah, the issue of overheating in an E9x M3 is definitely a challenging one. It seems that CSF has made some bold claims of having solutions that deal with the issue, but as you pointed out, okusa---who I know very well---hasn't seen any of the results he hoped for. That's a bummer…..so I am looking at other solutions than CSF.

The Yost car was built as an endurance car. That is quite a different approach than a time attack car that needs to be fast for one lap. I would say my car is setup with the idea of doing time attack. The Yost car is very light (400-500 lbs lighter than my car), it has a manual transmission (I have DCT) and the power of the car was purposefully kept within a certain range to keep heat down---meaning no S/C or stroker, etc. (I have S/C.)

The fact is that the stock M3 wasn't made at the factory for this kind of high stress hammering with a ton of aftermarket go-fast parts. The cooling it has is perfectly fine for the street and occasional track. Remember, my DCT didn't give me hardly any warnings in the last 4 years-----until I slapped full aero, super sticky R1S tires and started hammering with DSC-off. That's just a whole new level of stress on the car. Can any of us really say it's a surprise that a heavy car with a high revving 8-cylinder engine, with a supercharger, with full aero and almost-slick tires is overheating? I'm not surprised that it overheats. What I am surprised by though, is that no company has proven that they have an effective---and mostly importantly-----CLEARLY DOCUMENTED solution for it. This M3 is not the first car to be heavy and make a lot of heat. Isn't that pretty much the story for all American cars? I have been hoping that some company who has a long history of dealing with this in American cars like Mustangs or Camaros could provide us BMW guys with a solution. I have to assume that the E9x M3 platform will become a common racing platform someday. Somebody is going to have to come up with a workable solution for the overheating. Can you imagine a whole field of E9x M3's racing wheel-to-wheel taking cool down laps in the middle of a race because the cars can't handle it? "Ok fellas, laps 4, 8, 12 and 16 are cool-off laps. We'll put up Yellow flags for those laps. We'll hammer the rest!" I mean c'mon…….

The Swedish Do88 cooler looks interesting simply from the fact that it's so much larger than the stock cooler (almost double) and it sits in the stock spot. The SSP thing looks crazy. At $2200, that's just frightening. And like I said before, since I have a supercharger intercooler, where would I put the SSP one? And again, I'd like to see some documentation. Companies seem so quick to SAY it works……I want to SEE it working. This stuff is easy to document if you want to. SSP claims that their cooler keeps DCT temps down for 40 minute sessions, but I don't see any data…...Do88 shows some charts based on 11 minutes of hard driving. Plus, a forum member has talked about how the Do88 seems to be working and he has a temp gauge tapped into his DCT system. Perhaps, the Do88 might be a place to start……it costs more than the CSF cooler, but is half the price of the SSP. We'll see.
The Do88 is what I'm looking at too, I'm hoping you will Guinea pig it for us . I actually have felt sluggish shifts on certain tracks, so I know you can encounter it without too many heroic mods.
Appreciate 0
      03-09-2016, 06:14 AM   #163
roastbeef
Lieutenant General
roastbeef's Avatar
United_States
11575
Rep
12,714
Posts

Drives: E92 M3
Join Date: Nov 2010
Location: Orange County, CA

iTrader: (4)

it all makes sense, thanks for taking the time to share your thoughts. i'd rather get the Do88 cooler over the $2k cooler as well. you have space issues with your intercooler, but $2k for a cooler is pretty ridiculous. the Do88 cooler is at least custom and doesn't interfere with other coolers. the SSP cooler looks like any other cooler you could get from JEGS or Summit for $100.
i have about $600 total into the three "custom" coolers with custom braided lines/fittings for my junk truck (pieced together from coolers on jeg's and a local hose shop). so when i see the prices for m3 coolers that look similar, i sort of shake my head. the Do88 is the first one that really looks custom for our cars, plus it comes with the ducting so you don't have to mickey-mouse anything.
i'm not at this stage with my car yet, but i do like reading about it.
__________________
Instagram; @roastbeefmike
Appreciate 0
      03-09-2016, 08:07 AM   #164
///Mobbin
Colonel
///Mobbin's Avatar
1475
Rep
2,672
Posts

Drives: m3
Join Date: Jul 2011
Location: Houston

iTrader: (3)

Quote:
Originally Posted by dogbone View Post
The overheating of the transmission is a relatively new thing for me. I've had the DCT software in there for years. The combo of full aero, stickier tires and DSC-off clearly upped the stress on that system.
Good info here, thanks. In fact, I went ahead and had Alex program the GTS DCT tune last night, shifts are lightning fast in S5 and I'm getting some new and interesting rev match noises from the exhaust, good times. Can't wait to try S6 at the track! The D modes seem a bit smoother as well, more testing today.
__________________
2021 Alfa Romeo Stelvio Quadrifoglio | 2.9L | Trofeo White Tri-Coat | 8-spd
Appreciate 0
      03-09-2016, 12:11 PM   #165
PrimeBMW
Major
PrimeBMW's Avatar
No_Country
662
Rep
1,424
Posts

Drives: E46 M3+S62, E92 M3
Join Date: May 2009
Location: Portland, OR

iTrader: (0)

OP, I am good track buddies with the guy that installed the Do88 coolers. That car and driver is VERY fast! I mean the fastest car that shows up to the track. With the diffs on line lower gears it (plus every go fast mod you can think of) it is putting a lot of stress on the DCT. Given that he has demonstrated/documented temp reductions I would personally go with the Do88 without question. When considering other options running a 25 hour sounds impressive.....right? Well consider that it is so cold during that race that teams sometimes have to place cardboard in front of the coolers just to get the engine up to operating temperature (2014). In 2015 i think the high temp was in the 40 degrees F so the cardboard was not needed.
Appreciate 1
      03-09-2016, 01:57 PM   #166
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Quote:
Originally Posted by PrimeBMW View Post
OP, I am good track buddies with the guy that installed the Do88 coolers. That car and driver is VERY fast! I mean the fastest car that shows up to the track. With the diffs on line lower gears it (plus every go fast mod you can think of) it is putting a lot of stress on the DCT. Given that he has demonstrated/documented temp reductions I would personally go with the Do88 without question. When considering other options running a 25 hour sounds impressive.....right? Well consider that it is so cold during that race that teams sometimes have to place cardboard in front of the coolers just to get the engine up to operating temperature (2014). In 2015 i think the high temp was in the 40 degrees F so the cardboard was not needed.
Thanks for the confirmation of NRBRNG's results. I appreciate it. And his DCT results do seem QUITE impressive---he's talking about a 30-40º drop in temps. The fact that he has a temp gauge dedicated to the DCT is great. THAT'S the kind of data I want to see from manufacturers. If I do act on this topic, I will put in a dedicated gauge too. The way I would approach it is to put the gauge setup in first and get some baseline temps from the current setup. Then, I'd add the cooler to see what we netted.

And if NRBRNG is showing up at all his events running Yoko A005's, MCS, full aero and 3100 lbs, he better be flying out there!!
Appreciate 0
      03-09-2016, 06:10 PM   #167
dapopa9
Captain
dapopa9's Avatar
68
Rep
653
Posts

Drives: F80 M3
Join Date: Apr 2008
Location: San Diego

iTrader: (0)

How much quicker are the R1S vs the TD's?
Appreciate 0
      03-09-2016, 06:25 PM   #168
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Quote:
Originally Posted by dapopa9 View Post
How much quicker are the R1S vs the TD's?
I can't tell you with 100% certainty yet because I haven't been at Buttonwillow with new TD's since I have had full aero and DSC-off, so I haven't really made a true top speed attempt with fresh TD's. But I'm approximating that R1S gives you around 2 seconds over TD's.

There's a chance I may have an answer for you later this month.

As a side note, I have been able to weigh brand new unmounted 295/30/18 TD's versus brand new unmounted 285/30/18 R1S [on my unofficial scale at home back-to-back]. It's worth noting that a 285 R1S is slightly WIDER than a 295 TD. The R1S weighs approximately 3.5 lbs less than a TD. That's 14 lbs lighter for a full set. That's pretty good!

I still like the TD. It's a solid tire and you can time attack in the Limited class with them at 80 tread wear rating. The R1S with it's 40 tread wear rating dumps you into Unlimited. If I have to go Unlimited, I'm showing up with SLICKS!!!!!
Appreciate 0
      03-09-2016, 06:28 PM   #169
dapopa9
Captain
dapopa9's Avatar
68
Rep
653
Posts

Drives: F80 M3
Join Date: Apr 2008
Location: San Diego

iTrader: (0)

Quote:
Originally Posted by dogbone View Post
I can't tell you with 100% certainty yet because I haven't been at Buttonwillow with new TD's since I have had full aero and DSC-off, so I haven't really made a true top speed attempt with fresh TD's. But I'm approximating that R1S gives you around 2 seconds over TD's.

There's a chance I may have an answer for you later this month.

As a side note, I have been able to weigh brand new unmounted 295/30/18 TD's versus brand new unmounted 285/30/18 R1S [on my unofficial scale at home back-to-back]. It's worth noting that a 285 R1S is slightly WIDER than a 295 TD. The R1S weighs approximately 3.5 lbs less than a TD. That's 14 lbs lighter for a full set. That's pretty good!

I still like the TD. It's a solid tire and you can time attack in the Limited class with them at 80 tread wear rating. The R1S with it's 40 tread wear rating dumps you into Unlimited. If I have to go Unlimited, I'm showing up with SLICKS!!!!!
Nice! Good info here

Have you ran the Hoosier A6/A7 tire at all? It seems like those were similar to the TD speeds.
Appreciate 0
      03-09-2016, 08:02 PM   #170
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Quote:
Originally Posted by dapopa9 View Post
Nice! Good info here

Have you ran the Hoosier A6/A7 tire at all? It seems like those were similar to the TD speeds.
I have only run R6, not A6. The TD was 2.5 seconds faster than R6 of the same size. TD's had noticeably better braking grip than R6. R6 glides nicer. When past the grip limit, TD's fights for grip very hard which can be unpleasant. I was always mildly curious to see what A6 felt like but never felt like dumping the cash on tires with such a short life span. As it is, R6's had a pretty short life in the high grip zone----after 6 heat cycles, you could feel them dropping off.

I have to say the R1S is an impressive tire. Even 15 heat cycles in, it still delivers solid grip and very good lap times. I was rolling 1:50.x at Buttonwillow 14 heat cycles in. At 15 heat cycles, the R6 has fallen way off if you can even get to 15 heat cycles at all without cording. The TD are drivable up to 25 heat cycles, but the grip has seriously fallen off by that point. The first 10 heat cycles of TD's are really nice. They're decent at 15. After that, they're just fun scrubs to go mess around with. (I'm running square so I am able to rotate around the car and get more life out of the rubber. I'm also a fan of flipping the rubber on the rims so that we can use those less abused inside edges on the outside.)

I really would like to try some fresh slicks. That would be fun. But I'm going to wait until after the summer and the weather cools down again to do that. I could use more time in the seat learning the new diff and driving DSC-off. I'm never in a hurry with these kinds of things. It's my hobby!

And hopefully by then, I'll have sorted out some solution to the DCT overheating so quickly, because slicks will just make that even worse.
Appreciate 0
      03-09-2016, 11:58 PM   #171
dapopa9
Captain
dapopa9's Avatar
68
Rep
653
Posts

Drives: F80 M3
Join Date: Apr 2008
Location: San Diego

iTrader: (0)

Quote:
Originally Posted by dogbone View Post
I have only run R6, not A6. The TD was 2.5 seconds faster than R6 of the same size. TD's had noticeably better braking grip than R6. R6 glides nicer. When past the grip limit, TD's fights for grip very hard which can be unpleasant. I was always mildly curious to see what A6 felt like but never felt like dumping the cash on tires with such a short life span. As it is, R6's had a pretty short life in the high grip zone----after 6 heat cycles, you could feel them dropping off.

I have to say the R1S is an impressive tire. Even 15 heat cycles in, it still delivers solid grip and very good lap times. I was rolling 1:50.x at Buttonwillow 14 heat cycles in. At 15 heat cycles, the R6 has fallen way off if you can even get to 15 heat cycles at all without cording. The TD are drivable up to 25 heat cycles, but the grip has seriously fallen off by that point. The first 10 heat cycles of TD's are really nice. They're decent at 15. After that, they're just fun scrubs to go mess around with. (I'm running square so I am able to rotate around the car and get more life out of the rubber. I'm also a fan of flipping the rubber on the rims so that we can use those less abused inside edges on the outside.)

I really would like to try some fresh slicks. That would be fun. But I'm going to wait until after the summer and the weather cools down again to do that. I could use more time in the seat learning the new diff and driving DSC-off. I'm never in a hurry with these kinds of things. It's my hobby!

And hopefully by then, I'll have sorted out some solution to the DCT overheating so quickly, because slicks will just make that even worse.
That's good to hear about the heat cycle endurance. With the A7's I'm 4 seconds slower after about 10 heat cycles and they are completely shot after 12-15. Looks like I might have to pick up a set of these R1S's
Appreciate 0
      03-10-2016, 08:46 AM   #172
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Quote:
Originally Posted by dapopa9 View Post
That's good to hear about the heat cycle endurance. With the A7's I'm 4 seconds slower after about 10 heat cycles and they are completely shot after 12-15. Looks like I might have to pick up a set of these R1S's
I'm assuming you don't run square on the Corvette right? I'll be curious to hear how they hold up in a staggered setup. The only people I know who have R1S ran them square.
Appreciate 0
      03-10-2016, 08:59 AM   #173
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Originally, I was going to just post a couple pix of data about my new OS Giken diff and add a couple notes. But then I got into the typing and I thought people might be able to learn from the research I had to do.

PART 1: GENERAL INTRO TO DIFFERENTIALS

Unfortunately, there is not much empirical data available to the general public when it comes to differentials---at least none that I could find. Most conversations about diffs end up using general terms and catch phrases. When it comes to analyzing what is actually going on with a specific setup in a specific car, the info seems to dry up. I find this strange because that little hunk of metal can drastically change how the car drives. I ended up doing a ton of research on this topic and with this posting, I'm trying to remove some of the mystery surrounding diffs. (I was forced into this topic because my stock differential seemed to be making some odd noises, so I had to figure out what direction to go.) As I mentioned in a previous post, the AIM Solo DL can log the individual wheel spins provided by CAN bus data. Watching these charts can shed some light on how differentials perform.

First, so as not to be a tease, I'll jump to the end of the story and say that, according to AIM data collected from my car, the OS Giken Superlock (OSG) unit that was custom setup for my car by the OSG techs is doing everything that was promised and expected, and quite well. Has this translated to instantly new lightning quicker times? No. But, it feels good on acceleration and braking, makes the car feel very predicable as it begins to slide, and as I grow into it more, I believe it will be a contributing factor to lap times decreasing. Anyone who knows me knows that I like to build up speed and confidence gradually. (In my AIM Solo setup, I have split Buttonwillow into 4 sectors. According to the AIM, I have run faster times in all 4 sectors now with the new diff. I just haven't been able to do it all in one lap.)

Ok, back to the beginning. So, what do we want from a diff? People always generically say, that a performance oriented diff allows you to "put the power down." It sounds very impressive. But what does that mean? And how can you quantify that? Literally NO ONE had an answer to this last question.

In it's most basic task, a rear differential simply allows two wheels on the same axle to spin at different rates as you go around a corner. In a turn, the outside wheel needs to spin faster than the inside wheel. The differential allows that to happen. Differentials on the majority of regular street-going vehicles are open differentials---meaning they always allow the two wheels to spin at different rates regardless of anything else going on, and they always apply the engine's power to the wheel with the least resistance. The classic example is the car stuck in snow----one wheel is on concrete, the other is on the snow. The snow wheel spins as you press the gas, and the concrete wheel sits there like a spectator. If you don't know what an open differential is, youtube has a bunch of good videos. An open diff is great for street driving but not as great for high performance track driving. Applying all the power to the less-weighted/inside wheel during a turn on the track is a waste---you end up spinning up the inside/unweighted wheel while the outside/weighted wheel gets very little power. On the track, you would like the engine's power to be applied to the weighted/outside wheel as you exit a corner because that wheel has a ton of grip due to the vehicle's weight leaning and pressing on it. All that grip along with power on that rear wheel can propel the car forward very effectively. The quicker you can apply power to the correct wheel, the faster you can go and sooner. So for track driving, a Limited-Slip Differential is preferred because it can apply differing amounts of locking to the axle which then sends power to both rear wheels more equally. The M3 comes from the factory with a GKN Visco Lok LSD, which is a speed sensing differential---meaning it senses one wheel spinning up faster than the other and then provides some degree of locking. ( http://www.gkn.com/driveline/our-sol...coLok-engl.pdf ) In the aftermarket, a clutch-type LSD seems quite popular in M3's. The OSG unit that I purchased is a clutch-type LSD. This video is excellent at introducing the topic of clutch-type LSD's:



M3 Stock GKN Visco Lok diff vs OS Giken Superlock:
The stock M3 Visco Lok diff stays open most of the time, except for when you really get on the gas and stay on it, but it takes a bit of time for the diff to lock. When you get on the gas and stay on it, initially the unweighted/inside wheel will get more power and spin up faster than the weighted wheel. The stock unit can sense the spin up and then it starts applying a certain degree of locking to the axle so that some of the power goes to the outside/weighted wheel. But this process takes a bit of time. And the predicability of the car's movements is not as high as other solutions because you're in a dynamic situation in a corner applying a lot of power from the engine but it starts by applying the power to the inside wheel, and then gradually it starts shifting some of the power to the other wheel. And this is happening while there's a bunch of wheel spin going on with the inside wheel. So, you have funky wheel spin happening and you're waiting for the power to transfer to the "correct" wheel. It works but it's not ideal. And the stock diff does not provide any locking on deceleration.

The OS Giken Superlock has 5 sets of clutch plates on each side (noted in Green below). (I took the case off my OSG to take a peek inside. It's a piece of art in there!) In general, more clutch plates make for more smooth locking and unlocking than less plates. The point of the plates is that they spin somewhat freely past each other and keep the diff open until a large acceleration or deceleration force is applied to the differential. As the pressing force is applied by the spindle that holds the spider gear, the two Pressure Rings around the spider gears (Marked in Yellow) start to spread apart. This spreading is controlled by the angle/shape of ramps cut into the pressure rings (Marked in Red). The diff manufacturer can make these angles in many different degrees which affects when, how fast and with how much force the pressure rings spread apart.



When the Pressure Rings spread apart, they press harder against the clutch plates. This spreading pressure creates enough friction between the plates that they start to lock or bind together. As the plates lock together, the axle locks and the two wheels move in unison. When the force being applied to the diff unit is reduced, the Pressure Rings relax inward back to their natural state and the pressure inside the diff is reduced and the plates are able to slide past each other again, and the differential opens again and the wheels can move at different rates around the corner. A unit like the OSG is able to lock and unlock very quickly if you want, depending on how it's setup. And while the stock M3 unit can only lock on acceleration, the clutch-type OSG can provide locking on both acceleration and deceleration if you set it up that way. Locking both rear wheels on decel provides very nice stability during braking----it feels like a parachute is slowing the car.

In general, people say a more performance-oriented diff makes your gas pedal feel more "connected" to the rear wheels. This is because a clutch-type LSD can lock and unlock quickly transferring power where you want it, which reduces the lag you may feel in a speed sensing diff, where first it needs to spin up, then it has to realize that it did, then it takes a few moments to start sending power to the other wheel.

What I was afraid of was a performance-oriented differential that would lock too fast and too hard when getting on the gas. The problem with a super fast or super touchy diff is that it can send a car sideways very quickly---especially if your car has a lot of power, so I didn't want it to be too touchy. With a supercharger in my car, I was concerned about a lot of power coming on very quickly and making the car unpleasant to drive if too much locking happens too fast. Plus, if you don't like how it feels, making physical changes to a diff is expensive because of how involved pulling it out is, sending the unit back to OSG and paying them change it, and then putting that all back together again…..Obviously, it would be great if the first assembly was something that I liked, but it's impossible to know. You just have to try it and see. It turns out this can be a very subjective topic.

My OSG diff could have been setup a bunch of ways. I chose what is called a "1.5 way" setup. A 1-way only locks on acceleration. A 2-way locks equally on acceleration and deceleration. A 1.5-way locks on acceleration and deceleration, but it can lock less on deceleration and usually for a shorter period of time. In the picture above, you can see the 2 ramps outlined by the Red lines have different angles. The left ramps (decel) are steeper than the right ones. The steep Decel ramps make it harder for the spindle to separate Pressure rings, and the shallower Accel ramps make it easier for the Rings to spread. 1.5-way diffs seem generally popular with road course tracking because you want the locking on accel, but you only want some lock on initial decel. And you want to MAKE SURE that the diff is open as you start turning that steering wheel to enter a corner. If a diff is still locked as you enter a corner, you will get unwanted understeer. When two rear wheels are locked together and spin at the same rate, they tend to want to go straight----even if the front wheels are turned. Again, this is great for initial braking, but terrible for corner entry. So, a 1.5-way diff gives you some initial lock when the brakes are applied but as the decel force is reduced and you're thinking about getting into that corner, you want the thing to be open as much as possible.

At this point, you may say to yourself: the theory is fine, but how practical is all of this? The answer is: It is quite practical. The diff has a LOT to do with the character and feel of a car.

In the next Part, I'll show data from the AIM that shows what was going on in the car with the stock diff, and what is happening now.

Last edited by dogbone; 03-21-2016 at 12:29 PM..
Appreciate 10
CSBM52695.50
M3MPH1S592.00
kyoo340.50
      03-10-2016, 12:04 PM   #174
dapopa9
Captain
dapopa9's Avatar
68
Rep
653
Posts

Drives: F80 M3
Join Date: Apr 2008
Location: San Diego

iTrader: (0)

Quote:
Originally Posted by dogbone View Post
I'm assuming you don't run square on the Corvette right? I'll be curious to hear how they hold up in a staggered setup. The only people I know who have R1S ran them square.
Yeah it's staggered on the Z06 - typically run a 315/345 setup
Appreciate 0
      03-10-2016, 01:44 PM   #175
Jive
Lieutenant
Jive's Avatar
156
Rep
580
Posts

Drives: 2013 E92 M3
Join Date: Dec 2010
Location: Bay Area

iTrader: (0)

Very informative post and thread. Thanks for all of your detective work!
__________________
2013 E92 M3 Mineral White Fox Red / Black
Appreciate 0
      03-14-2016, 12:03 PM   #176
dogbone
Colonel
dogbone's Avatar
5303
Rep
2,799
Posts

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

iTrader: (1)

Garage List
2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
PART 2: OS GIKEN SUPERLOCK VS. STOCK M3 DIFFERENTIAL - CHARTS AND ANALYSIS

In Part 2, we'll look at some charts I've captured from AIM's Race Studio 2 software to compare the behavior of the OS Giken Super Lock versus the Stock M3 differential. As I mentioned before, finding data on differentials is virtually impossible---especially finding data that's specific to our E9x M3, so I'm doing my best to shed some light on the topic with the tools I have----an AIM Solo DL. I'm not an expert, but I've learned quite a bit over the last couple months.

Most of the following charts show data from 2 laps at Buttonwillow 13CW.

-The fastest lap I've ever run with the Stock diff. 1:49.02. This is my current PR.
-The fastest lap I've run so far with the OS Giken Super Lock diff (OSG). 1:49.21

Buttonwillow is a good place for this kind of analysis because it has a little of everything---tight turns, wide rounders, blind turns, top-of-hill turns, dog legs, decreasing radius sweepers, tall berms, short berms, berm hopping, elevation change, mild Esses, good pavement, bad pavement…..you name it, it's pretty much there at Buttonwillow.

Obviously, it's important to use similar lap times because we're trying to see how the diffs are reacting under similar driver input. A diff would react quite different if you were snoozing your way around a track versus hammering on it.

It's worth noting that the 1:49.2 lap has a glaring driving mistake in it---I did not take the Off-Ramp corner correctly and it cost me a 1:48….ah well…. We'll look at that mistake below. Since that is a very important corner---perhaps the toughest on the track---I will be showing two other examples of that corner later.

For setup, it's also worth mentioning that the 1:49.02 with Stock diff was done at 55º F. The 1:49.2 with OSG was done at 68º F. My opinion is that 52-58ºF are the perfect conditions for setting new personal bests. The engine pulls like crazy and the track surface is warm enough to allow the tires good grip. When it's a little warmer, the track might be even better for the tires, but as you cross 60º F, the engine doesn't pull as hard. And when it's below 50º, the engine loves it and pulls like a superhero, but the pavement gets a bit sketchy.

The questions we'll be trying to answer are:

-Does the OSG lock on acceleration as promised?
-Does the OSG lock quickly on acceleration?
-Does the OSG lock on initial braking?
-Is the OSG open when entering a corner?
-Can you actually see the performance characteristic of the OSG looking any different than the Stock unit?
-Does the stock unit lock on acceleration?
-Does the stock unit lock quickly?

Things to look for in the charts:

-Looking at the speeds of the rear wheels, we can get a sense of how a differential is acting under driver input.
-Looking at the gas pedal position along with the spinning wheels can tell us how quickly or slowly the rear wheels are responding to the driver's gas pedal input. The diff controls that behavior.
-Looking at the brake pedal position along with the spinning wheels can shed light on if there's any locking on deceleration.
-Spikes in the wheel speed of one wheel over another usually means the differential is staying open. When you see a spike, it's important to look at the gas pedal position. There are times you want the wheel to be free to spin it's own speed. Other times, you don't. But in general, with a performance oriented diff, you would like to see less spiking when on the gas because that means the diff is reacting quickly to your gas pedal press and transferring power where you want it. If you're on the gas and you see spiking on the inside wheel, it means power is being wasted, and having one wheel spinning up over another tends to give the car a destabilized feeling. Remember, the ultimate goal is to have a predictable car----a car that responds in a predictable way to all your inputs every time. That's how you build confidence.

Each Data Set is presented in 3 charts:

Chart 1: Both OSG and Stock Diffs overlaid on top of each other for comparison.
Chart 2: Stock diff by itself for an isolated view.
Chart 3: OSG diff by itself for an isolated view.

Each picture has a legend on it, so you know what all the colored lines are. The data will be the MPH of each rear wheel, along with the gas pedal and brake pedal positions. The numbers at the bottom of the pictures show how many feet down the track we are from the Start line.

The first Data Set will look at a zoom-out of the entire track with both laps. Looking at an entire lap all at once doesn't offer much detail, but you'll see from the overview if one diff looks smoother than the other. Then, we'll zoom in and look in closer detail at the whole track to see what's going on. After that, we'll look at a couple examples of the Off Ramp corner to see the OSG's behavior.

For people not familiar with Buttonwillow, I've created a track profile map that has some numerical markings indicating the number of feet down the track the corners are. This is so you can get a sense of what the corners look like, which direction they go, etc. The track profile comes from my AIM Solo DL. I wanted to show the line driven instead of a map of the track. If you're on a computer, I suggest dragging the track profile to your desktop and opening it separately from your browser so you can see where you are on the track based on the number of feet at the bottom of each chart.



Data Set #1: Full Lap: Again, it's hard to see much detail here, but if you look at the overall lines, most the time you can barely see the Dark Blue line under the Red line because the OSG wheels are working together in a more controlled way. The Pink and Gray lines of the Stock diff are frequently spiking and seem to be doing their own things often times. The OSG wheels are much smoother/less spiky and less jagged than the Stock unit. A spike on the wheel spin is generally not a good attribute. This means the power is being applied to the inner wheel and is generally being wasted. On Chart 2, the Gray line in particular seems to really spike away from the Pink line many times. On Chart 3, there's quite a bit less spiking. Ok, no need to dwell here. Let's start zooming in on the next data sets.







Data Set #2: From 0 ft to 3600 ft: - Sunrise and Off Ramp - At 800 ft, we have entered Turn 1 - Sunrise, a Left turn. On the stock diff, you can see a spin up of the inside Left Wheel on the Gray line. And it lasts for around 100 ft. The right wheel (the loaded wheel) spins up a little bit and then reduces. I'm going to guess that I felt the outside wheel because I completely let off the gas. Let's talk about predictability here. You have one wheel that has significantly spun up over the other. The car is probably wanting to tend sideways in this moment. It's a little tough to say because I get on the berm on this corner and the berm makes things a little funky. As I mentioned before, corners are very dynamic. When things start spinning their own speeds separately, it's harder to gauge what the car is going to do. Looking at Chart 3, the OSG shows no such spin up while achieving the same speeds. You can see I get on the gas and the Left wheel spins up just a little and then the diff locks and the wheels move in unison until I get off the gas for Off Ramp. I would say that the OSG is giving a more predictable result in this corner.

At 1800 ft, I enter Off Ramp, a very sharp right turn that goes up hill and as you go up, it's a little bit off camber. The pavement is not in great condition on this corner. Because it's such a sharp turn that goes up hill, cars REALLY load up in that corner and the pavement gets hammered something awful. The track owner has temporarily patched it with concrete and some odd top coat that's getting destroyed and it's not fantastic. From Chart 2 with the Stock unit, we can see that there are two Pink (right wheel) spin ups--one of them fairly long. The car is leaning hard on the left side. I get on the gas, the unweighted right wheel starts spinning, and it spins for 150+ ft. I'm not sure the stock diff ever really locked much here because I backed off the gas pedal a bit, and that's probably what brought the spinning wheel under control. But then under full throttle, the right wheel spun up again as I crested the hill. It doesn't seem like a lot of lock was happening here. And if it did, it was taking a while for it to catch up.

Looking at Chart 3, Off Ramp is the spot in the lap where I mess up with the OSG. I got on the gas a bit too much too quickly. The Red line (Right wheel) starts rising, but the Blue Line (Left wheel) follows very quickly. The OSG diff is locking quickly here, and it was a bit too much gas, so the car started sliding. I've gone beyond the tire's grip limit. You can see I completely let off the gas, got the car back, and then I got back on it. Ugh, I lost quite a bit of time here---and it was still a 1:49.2. Basically, this demonstrates that I have not fully re-learned how to modulate the gas pedal with the new diff. When I'm pushing hard, the new diff is transferring power to the loaded wheel more quickly than I'm used to. I need to continue to learn to use less gas pedal on initial gas press so as not to overwhelm the tires. The OSG tech I spoke to mentioned this would be the case. A positive side effect of this is that I can get to the grip limit of the tire with less gas pedal press, which is easier on the engine. People say that you're driving less "ham fisted" like this----not having to mash the gas and really push the car around to get what you want is considered better.

Another question to look at is: Is the OSG diff remaining open on corner entry? The answer is Yes. In Chart 3, we have three opportunities to look at. At 750 ft, we can see the Dark Blue Line of the Left Wheel slows down more than the Right as we're entering the corner. The diff is open. At 1750, the Red Line of the Right Wheel slows down more than the left as we enter the right turn. The Diff is open. At 3250, the Red Line RIght Wheel slows more than the left on the right turn entry to Cotton Corners. The diff is open. So, the OSG diff has remained open on each corner entry on the first three turns after significant brake presses.

And we can ask, is the OSG locking on initial brake press? The answer looks to be yes on Turns 1 and 3. Off Ramp is a bad place to ask that question. The track is so wavy, and there's a berm and there's a dip in the pavement right where you want to brake. That spot is just a super challenging spot. You probably don't want the wheels blindly locked going into Off Ramp because you're not really braking in a perfectly straight line. Off Ramp is just a tough corner. I'm not sure there's any perfect single way through there. You just make the best of it and get the heck out of there as fast as you can.







Data Set #3: 3400 ft to 7400 ft - Cotton Corners and Bus Stop - We've entered Cotton Corners and now at 3400 ft, I press the gas as I'm taking a left turn to go up a short hill. With the Stock unit, as I press the gas, the left wheel spins up. The OSG locks quickly and the wheels move in unison. At 3700 ft, I crest the hill and both the Stock unit and the OSG spin up because I jump off the berm on the right side.

Around 4400 feet, we have an interesting moment. The track is straight at this point, but there's a mild hump in the track. In both laps, I'm 100% on throttle. As I go over the hump, the Stock unit spins up the Left wheel dramatically. With the OSG, BOTH wheels spin up very similarly. The OSG is locked and keeps the wheels together. This is good for stability.

At 5300, the OSG has a spike on the left wheel. I am rounding left and I'm not very hard on the gas, so the diff is not locked here, and I'm in 5th gear not making a ton of torque. There is a berm on the left side as you round this bend. It's interesting to see how easily the wheel can still spin up when the diff is open..

At 5900 ft, I'm going around Bus Stop. The Stock unit spins up the inside wheel. I hesitated with the gas and the wheels sorted themselves out. With the OSG, I pressed the gas quite dramatically after Bus Stop and the diff locked very quickly. Looking at the comparison, I'd say I over-braked for Bus Stop on my OSG lap……..blah…..

I want to take a moment and look at a couple driving techniques on this part of the track. On the Stock diff, I did this section from Cotton Corners to the entrance of Riverside (3400 - 6600 ft) pretty well----EXCEPT for one tiny mistake that cost me 0.2 seconds and probably cost me a 1:48. At 3600 ft, I've turned left to go up the hill of Cotton Corners. I get on the gas quickly. And again at 4000 ft, I get on the gas early. Those two gas presses really setup the next 1000 ft. You can see the Pink and Gray lines stay consistently above the Red and Dark blue lines from 4000 to 5200 ft. That's a pretty long stretch of the track to have such an advantage. It all comes from getting on the gas early. However at 5500 ft, I lightly tapped the brake pedal earlier than I should have. You can see that little yellow tap right at 5500 ft. That silly little tap cost me 0.2 seconds. It's an earlier tap than any other fast lap I've ever driven there…….In fact, that whole brake press going into Bus Stop was not so great. Compare that to the brake press of the OSG that was much better form. Although, like I said earlier, I believe I am over-braking with the OSG. In fact, I think I've been over-braking a lot at most corners since the aero went on the car. Ah----so many things to learn!!!

Another thing to look at is the speeds going towards the apex of Riverside at 6800 ft. Lately, I have been trying to keep as much speed up as possible as I'm rounding Riverside. On Chart 1, comparing the OSG lap to the Stock lap, you can see the two laps are driven differently. My gas press at 5900 ft is much more confident on the OSG lap---you can see the light green line of the gas pedal is much more aggressive. And the net result is that I am able to achieve noticeably higher speeds from 6800-7200 ft. Anyway, the OSG looks pretty composed through this Riverside section and clearly I'm pushing fairly hard here.







Data Set #4: 7500 to 11000 ft - Exit of Riverside, Phil Hill and Sweeper. The Exit of Riverside goes towards a dog-leg left and then up to Phil Hill. This is a very dynamic time for the Stock unit. Between 7500 and 8400 ft, one wheel or the other is looking jagged and uneven compared to the other as I'm going from a right bend to a left bend. The OSG wheels look controlled through the same section, and it's worth noting with the OSG that I'm full throttle from the exit of Riverside to the braking point of Phil Hill. So there was plenty of opportunity for the OSG to look bad here, but it looks very composed. Both laps have spikes as I crest Phil Hill. No surprises there.

And again at 9100, the left wheel on the Stock unit seems to be doing it's own thing for about 700 ft, whereas the OSG seems more predictable all the way into Sweeper.

As far as braking with the OSG, at 8400 ft, I press the brake. Right before this moment, the Red and Dark Blue lines were separating as I wasn't on the gas and the unit was not locked. But then I press the brake and you can see at the max point of the brake press, the wheels quickly start moving in unison. The diff is locking here on brake press. But then as the brake pressure reduces, the Red and Blue lines separate again as I turn right into Phil Hill. So, the diff was open as I let off the gas, then I hit the brake it locked the axle for a bit, and then it opened again as the brake pressure reduced and I turned right to go over the blind hilltop of Phil Hill. It's also worth noting that the locking force on braking isn't blindly strong because at 10000 ft when I brake to go into Sweeper, the axle doesn't really stay locked. This is good because I need to get into the right turn of Sweeper and the OSG is not getting in my way. I will tell you from a "feel" standpoint, the braking feels GREAT now going into Sweeper. Very noticeable change in feel.







Data Set #5: 11000 to 14400 Finish line - Exit Sweeper, Esses and Sunset - The Stock unit is continuing to look a bit like the Wild West here. As I go up the Esses at 11000 ft, mild steering movements left and right are required. You can see the Stock diff responding by allowing each wheel to spin up a bit as I steer left and right. The OSG hammers through there without any drama. And I stayed on the gas quite confidently through the end of the Esses. You can see from the stock diff that I let off the gas much earlier. For some reason, I'm feeling more comfortable through this section on the OSG. Is it the diff? You decide!

At 12700 ft, going into Sunset, the braking looks very nice with the OSG on a VERY hard brake press. The rear wheels seem very much together until I enter the final corner and they drift apart. So the diff locked on braking but was open for turn in, and then locked again quickly as I got on the gas for the final run up to the line.

Sunset is a spot where I think we can see the effect of the cooler temperatures. I slowed down less with OSG, got on the gas sooner with the OSG, accelerated cleanly with the OSG, got to full throttle sooner with the OSG, but you can see by the finish line, the wheels from both laps were going the same speed. The cooler air definitely has an effect.







Data Set #6: Another Off Ramp - Different OSG lap to see a better comparison. I found another lap with the OSG where I didn't mess up the corner. The speeds from both laps are very similar. In this comparison, you can see with the OSG, as soon as I press the gas, the red line rises to meet the blue and then they basically stay together the whole way to Cotton Corners. Here again on the straight section of 2300-2800 ft, you can see the cooler air temperatures allowing the Stock unit lap to out accelerate the warmer temp lap with the OSG. They start with the same acceleration curve, but at 2300 ft the cooler lap starts to walk away.







Data Set #7: One more example in Off Ramp

So we're looking at Off Ramp again. This time it's just the OSG---and we're looking at what happens when the steering wheel is turned and the gas pedal is pressed and how the wheels react to all that. This chart will add the front wheels MPH and steering wheel position.

As I enter Off Ramp, all the wheels are spinning about the same. We can see all 4 wheel lines bunched up together at the left of the chart. The steering angle at the left of the chart is very near 0º. At 1700 ft, I turn the wheel to the right (dark green line moves downward). As I do that, we can see the Red and Yellow lines (both right wheels) fall away from the Blue and Green lines (left wheels), and they fall away more as I turn the wheel more. This makes sense because Off Ramp is a sharp right turn and if the diff is open in this moment, which it seems to be, then the right wheels will move slower than the left wheels as you go around the corner. Everything seems good so far. The diff is open, which allows the rear right wheel to slow, and this allows me to dive into that corner.

Then just after 1800 feet, the Blue line at the bottom shows that I get on the gas. Immediately, you can see the Red Line (Rear Right Wheel) begin to rise. But it doesn't spike. It rises to the level of the dark Blue line (Rear Left Wheel) and then for the most part, the Red and Blue Lines basically match each other, except for when I give one more jab at the gas at 1900 feet where the right wheel jumps a little bit and then settles back in with the left wheel immediately.

With that little extra touch of the gas at 1900 feet, it starts to get a bit more interesting. The Rear wheels (Red and Blue) start to both rise significantly above the Front Wheels (Yellow and Green). The rear wheels are spinning at up to 8 MPH faster than the front wheels. The car is now starting to go sideways because the uphill is a bit off camber there. You can see at 1950 feet, I had already been straightening the steering wheel, but then you can see the steering angle line move upwards (left). This is me counter steering the slide that is starting. You can see I stayed on the gas during this moment (Light Blue line at the bottom stays fairly consistent). At 2050 feet, the rear wheels are no longer spinning faster than the fronts. I return the steering angle back to straight and I continue down the track.

So, this was a relatively aggressive Off Ramp turn and hill climb. I pressed enough gas to break traction and counter steered appropriately to be able to stay on the gas and keep the car going forward. What's nice to see here is that there were no weird speed spikes---even with breaking traction. The locking was quick and the car was predictable.



In Part 3, I'll wrap up with my conclusions and some final thoughts.

Last edited by dogbone; 03-21-2016 at 01:30 PM..
Appreciate 9
chamba002238.50
M3MPH1S592.00
kyoo340.50
Scharbag2617.50
BIGMIG24.00
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 06:36 AM.




m3post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST