My E90 M3 Dedicated Track build (with pix!)

[warp10]

Originally Posted by dogbone

The bumper was pulling away from the fender due to the downforce. At Auto Club Speedway in 2016, the bumper pulled that flat metal hanger between the bumper and fender so far down that the sharp tip of the hanger was poking into the edge of the tire and grinding it like a cheese grater. Yuck. So we took all that stuff out and put the latches in. Problem solved. I drove at Auto Club this weekend and last weekend going 156mph (GPS) on the Oval and no issues.

Any pics of what you did. Does it make it easier to take bumper off?

[dogbone]

Originally Posted by warp10

Any pics of what you did. Does it make it easier to take bumper off?

I don't have any in-process pix of the project. But here is the beginnings of that metal hanger being pulled away. That tip on the left just kept getting pulled lower and lower. At Auto Club, with the high speeds and the long banked Oval super-compressing the wheel into the wheel well, the tip of the hanger was able to touch the edge of the 285 R1S tire and grind it. I discovered it before the grinding was too much. (A narrower tire was able to sneak below it without touching.)



The latch basically removed some metal pieces on the inside of the fender and bumper. There's more room under there as a result. I'm very happy with the results.

I haven't removed the bumper since the latches went on, but since it removed some connecting pieces, I have to imagine these latches are easier to deal with.

Racewerkz Engineering installed the latches. I suggest contacting them if you have specific questions because I just don't have the answers...I'm a total end-user on this one.

[Datka]

Originally Posted by dogbone

I don't have any in-process pix of the project. But here is the beginnings of that metal hanger being pulled away. That tip on the left just kept getting pulled lower and lower. At Auto Club, with the high speeds and the long banked Oval super-compressing the wheel into the wheel well, the tip of the hanger was able to touch the edge of the 285 R1S tire and grind it. I discovered it before the grinding was too much. (A narrower tire was able to sneak below it without touching.)



The latch basically removed some metal pieces on the inside of the fender and bumper. There's more room under there as a result. I'm very happy with the results.

I haven't removed the bumper since the latches went on, but since it removed some connecting pieces, I have to imagine these latches are easier to deal with.

Racewerkz Engineering installed the latches. I suggest contacting them if you have specific questions because I just don't have the answers...I'm a total end-user on this one.

How did you fit 285 R1S in front?
I hear these tires run very wide for the size.

[dogbone]

Originally Posted by Datka

How did you fit 285 R1S in front?
I hear these tires run very wide for the size.

Yeah, 285/30/18 R1S run wide---wider than both 295/30/18 Hoosier A7 and Hankook TD. I've had them all side by side.

Fitting the 285 in the front required some setup changes. Gutting the car and losing a lot of weight added to the list of issues.

Losing weight caused the car to sit higher, so the suspension had to be lowered to get the car to sit the same height as when it was full weight. This was a problem because now the lowered spring perches were too low and hitting the tire.

So, we had to get rid of the helper spring. This allowed us to raise the spring perch around an inch up. That helped a lot. But the fat R1S was still too close to the spring perch, so I added a 3mm spacer. This finally was the last piece of the puzzle.

On an Apex ARC-8 10.5" ET27 with a 3mm spacer and no spring perch on a JRZ RS Pro, I can run the 285 R1S. It's pretty tight in there, but I've been running this setup for two years with no issues. And i don't miss the helper springs in the front. The car drives completely fine without them.

Lowering the car for the lost weight caused the rear toe arms to not be able to give us the toe we wanted. So I switched to adjustable toe arms so we could get the desired rear toe settings.

hehe---things always lead to other things with this stuff.

[slicer]

I'm sorry if I missed it but where did you place the temperature sensor for your DCT temperature gauge?? I have a Stack oil temp gauge that I believe is currently delivering engine oil temp (installed by PO). DCT temp would be far more useful. Thanks in advance!

[dogbone]

Originally Posted by slicer

I'm sorry if I missed it but where did you place the temperature sensor for your DCT temperature gauge?? I have a Stack oil temp gauge that I believe is currently delivering engine oil temp (installed by PO). DCT temp would be far more useful. Thanks in advance!

I have two Stack gauges dedicated to DCT oil temps--one for hot oil leaving the trans and one for cooled oil entering the trans. Racewerkz decided to put the gauge boss down at the trans exit and entrance. They thought it would be best to compare the entire cooling chain when were comparing the OEM DCT cooler to the do88 cooler. You could also put the gauge boss at the inlet/outlet of the cooler itself.

If I only had one gauge, I'd probably put it at the exit of the trans or the inlet of the cooler to get the hot oil temps. The cooled oil temp is not that useful on it's own. Obviously, the most important thing is to build your own data set from the gauge, wherever it is, so that the data is useful to you.

[slicer]

Originally Posted by dogbone

I have two Stack gauges dedicated to DCT oil temps--one for hot oil leaving the trans and one for cooled oil entering the trans. Racewerkz decided to put the gauge boss down at the trans exit and entrance. They thought it would be best to compare the entire cooling chain when were comparing the OEM DCT cooler to the do88 cooler. You could also put the gauge boss at the inlet/outlet of the cooler itself.

If I only had one gauge, I'd probably put it at the exit of the trans or the inlet of the cooler to get the hot oil temps. The cooled oil temp is not that useful on it's own. Obviously, the most important thing is to build your own data set from the gauge, wherever it is, so that the data is useful to you.

Thank you sir

[burnrbr]

Originally Posted by dogbone

Several years ago, I was given advice from someone who races a lot: try Cobalt Friction pads---great stopping power and easier on rotors than some others. I decided to try a set. The set I received ended up having some mixup. So, I contacted Cobalt Friction. And immediately, the owner of Cobalt responded and he jumped on it to take of care of the error. He let me keep what I had mistakenly gotten and fixed it and sent me hats and a t-shirt. GREAT service. And nice guy. As a result of this error, we ended up talking on the phone and I started asking questions. The owner of Cobalt is actually the one mixing the compounds, so he's super knowledgable. And he was now giving me direct advice based on my car and my setup. He is the one who recommended the XR2/XR3 combo.

So, as far as I can tell, I'm getting the best advice anyone could ask for when it comes to brake pads.

If you're curious about Cobalt Friction, PM me and I can send you details on how to contact them.

I have also spoke with the owner of Cobalt Friction. He's super knowledgeable and nice. He recommends using two different brake compounds when using high friction/torque brake pads. All of the additional braking force when using high torque brake pads in our cars results in more weight transfer to the front and a lighter rear. The lower, relative to the front, friction/torque brake pad in the rear helps prevent premature rear abs engagement. Interestingly, he recommends higher torque brake pads for the rear of race spec 911s.

[///Mobbin]

dogbone Curious if you run helper/assist springs and what rates if so? Seems the helper springs BW sent me are zero-rate but I'm curious to see what actual rate springs would feel like. I've been told this could be useful in keeping your dampers pre-loaded when transitioning on and off curbing. Then I've also read that it can help maintain grip when going over dips/bumps.

[dogbone]

Originally Posted by ///Mobbin

dogbone Curious if you run helper/assist springs and what rates if so? Seems the helper springs BW sent me are zero-rate but I'm curious to see what actual rate springs would feel like. I've been told this could be useful in keeping your dampers pre-loaded when transitioning on and off curbing. Then I've also read that it can help maintain grip when going over dips/bumps.

No helper/tender springs anymore. And I don't miss them AT ALL. I never had them on the rear.

I did have them on front--150lbs Eibach. They spec'd by JRZ. But when the car was gutted, it raised up on the suspension. So we had to lower the suspension to get the car back to the desired ride height. This meant the lower spring perch was too low and hitting my fat front tires. So we ditched the helper spring and were able to raise the spring perch up and out of the way.

If you have ever watched a car get lowered onto the helper springs, it's a joke. Even my 150lbs tender springs just collapsed under the massive weight of the car. You realize they're only there to fill space and don't do anything. I haven't noticed even 1% difference with them gone. And I never hear weird noises if the car fully unweights, like in the cork screw at Laguna, or when hopping off berms.

As far as doing anything on small bumps, again, the helper springs will always stay fully compressed under load, so what can it really do? And as far as jumping off berms, a tiny helper springs can't do anything against that car landing. Think about it---the front corner of the car has to be static 900+lbs. If it comes crashing down from a 5" inch hop of a berm, how much instant weight is that? Who knows but it's well over 1000 lbs. Again, any helper spring is going to get crushed.

Ultimately, fitting fatter tires is WAYYY more useful than having a helper spring.

I'm not a scientist on this topic, but all my observations on this topic point to the fact that helper springs fill gaps and hold the main springs in place when the car unweights. Since I've driven without them, I've never had any issues.

[///Mobbin]

Originally Posted by dogbone

No helper/tender springs anymore. And I don't miss them AT ALL. I never had them on the rear.

I did have them on front--150lbs Eibach. They spec'd by JRZ. But when the car was gutted, it raised up on the suspension. So we had to lower the suspension to get the car back to the desired ride height. This meant the lower spring perch was too low and hitting my fat front tires. So we ditched the helper spring and were able to raise the spring perch up and out of the way.

If you have ever watched a car get lowered onto the helper springs, it's a joke. Even my 150lbs tender springs just collapsed under the massive weight of the car. You realize they're only there to fill space and don't do anything. I haven't noticed even 1% difference with them gone. And I never hear weird noises if the car fully unweights, like in the cork screw at Laguna, or when hopping off berms.

As far as doing anything on small bumps, again, the helper springs will always stay fully compressed under load, so what can it really do? And as far as jumping off berms, a tiny helper springs can't do anything against that car landing. Think about it---the front corner of the car has to be static 900+lbs. If it comes crashing down from a 5" inch hop of a berm, how much instant weight is that? Who knows but it's well over 1000 lbs. Again, any helper spring is going to get crushed.

Ultimately, fitting fatter tires is WAYYY more useful than having a helper spring.

I'm not a scientist on this topic, but all my observations on this topic point to the fact that helper springs fill gaps and hold the main springs in place when the car unweights. Since I've driven without them, I've never had any issues.

All good observations and thank you for sharing. I wonder if a higher rate spring like the swift "assist" series would be more noticeable? They come in 223/279/335 lbs/inch ratings. I've also heard that they have a benefit in that they pre-load the damper before the weight transition occurs (perhaps just another way of describing "the" benefit). I get your point though that you have the massive weight of the car coming down on them and any subtle difference in grip/performance at that particular moment would be far outweighed by the ability to fit wider tires, which provide a benefit much more of the time. Will continue studying this but perhaps my focus should be on fitting wider tires for now.

[dogbone]

Originally Posted by ///Mobbin

All good observations and thank you for sharing. I wonder if a higher rate spring like the swift "assist" series would be more noticeable? They come in 223/279/335 lbs/inch ratings. I've also heard that they have a benefit in that they pre-load the damper before the weight transition occurs (perhaps just another way of describing "the" benefit). I get your point though that you have the massive weight of the car coming down on them and any subtle difference in grip/performance at that particular moment would be far outweighed by the ability to fit wider tires, which provide a benefit much more of the time. Will continue studying this but perhaps my focus should be on fitting wider tires for now.

Yeah, ultimately our cars are not 1200lbs. Given that our cars approach 4000lbs with us in them, I think the reality of the situation is that there are subtleties like this that get lost at these weights.

I decided to try the car with no helper spring at all because I was in a situation where I had to do something. For me, it worked. If it made funky noises because the spring was slamming back into position after unweighting, I guess I would have gotten those zero rate thin slinkies and tried to make that work. But it hasn't been an issue for me. And if Bimmerworld is sending you those zero rate helpers, I think that says a lot. Those guys are very knowledgeable.

As far as suspension options and choices, you know what I think does help, is remote reservoirs. I believe that all that extra oil makes a damper move more smoothly in all circumstances. Plus, all that extra oil can deal with heat better. I think that's a rubber-meets-the-road option that has tangible benefits.

What brand/model of suspension are you running? The more mature/high-end damper you have, the less you have to worry about this.

As a side effect: Since I don't have a pre-loaded damper that's under high tension, I can change springs easily at the track. We've done it. I've run a session, come in, changed front springs and run back out there. No special tools needed. That's awesome. You can't do that with a damper that's under high tension. You need a shop with those special compression devices.....

[Richbot]

Piggyback dampers can do the same job as remotes, if they're designed right, but yeah, agree

Agree on helpers.

[///Mobbin]

Originally Posted by dogbone

Yeah, ultimately our cars are not 1200lbs. Given that our cars approach 4000lbs with us in them, I think the reality of the situation is that there are subtleties like this that get lost at these weights.

I decided to try the car with no helper spring at all because I was in a situation where I had to do something. For me, it worked. If it made funky noises because the spring was slamming back into position after unweighting, I guess I would have gotten those zero rate thin slinkies and tried to make that work. But it hasn't been an issue for me. And if Bimmerworld is sending you those zero rate helpers, I think that says a lot. Those guys are very knowledgeable.

As far as suspension options and choices, you know what I think does help, is remote reservoirs. I believe that all that extra oil makes a damper move more smoothly in all circumstances. Plus, all that extra oil can deal with heat better. I think that's a rubber-meets-the-road option that has tangible benefits.

What brand/model of suspension are you running? The more mature/high-end damper you have, the less you have to worry about this.

As a side effect: Since I don't have a pre-loaded damper that's under high tension, I can change springs easily at the track. We've done it. I've run a session, come in, changed front springs and run back out there. No special tools needed. That's awesome. You can't do that with a damper that's under high tension. You need a shop with those special compression devices.....

I'm running MCS 2WNR's. It sounds like one issue with going into higher tender/assist territory is that you start getting into the complexities of a dual spring type of setup and that can be time consuming to test, tune, and get right. That said, I do like experimenting and I already have the helper perches so I thought I'd try something out, though more on the helper/tender side of things. I went ahead and ordered some real-rate helpers/tenders in 168 lbs/in, Swift Helper Springs. I will likely pull these back out when I go for 10.5" front wheels later this year but wanted to give them a try and see if I can feel the difference. At COTA I like to drive over the curbing, so hoping to test these out there.

[YoitsTmac]

Absolutely fantastic thread. Great read and inspiring build

[dogbone]

Originally Posted by YoitsTmac

Absolutely fantastic thread. Great read and inspiring build

Thanks! I've been posting all this with the hope that my experiences can help other people in their decision making processes.

[FrostyAZ]

Your detailed build info and technical knowledge has been very helpful, keep up the detailed posting. Seeing what works for others has been really helpful throughout my build.

[dogbone]

Originally Posted by FrostyAZ

Your detailed build info and technical knowledge has been very helpful, keep up the detailed posting. Seeing what works for others has been really helpful throughout my build.

Thanks. Looking forward to seeing your build in person. That is a serious ground-up build.

Do you have a final weight on the car?

[FrostyAZ]

Thanks. I was hoping it was going to be delivered last week but no luck. I am now being promised it will be at my home track on July 28th. Should have a weight in a few weeks. Hoping for <2,900 pounds.

[rhyary]

>>I am finding that when I push the car very hard for a couple laps in a row, I get some unpredictability in the gear shifts. I don't know whether to blame the VF tune on the supercharger, or blame the GTS-DCT software......whatever it is, it's damned annoying. Does this happen to anyone else?


Yes, exactly what happened to me at NYST
I have the ESS 650 kit and the DCT-GTS

Originally Posted by dogbone

hehe let's file this latest installment under Analysis, but really, we should put it in the crying-in-my-spilled-milk folder.....

I hate to be the guy blaming the hardware, buuuuut.......I gotta blame the hardware on this one.......

On Friday, I was driving with Speed District at Buttonwillow 13CW, and I exited Sweeper 0.5 seconds faster than my fastest 1:48.07 lap from February. I was on a 1:47.6 pace with less than 3000 feet left. I exited Sweeper, started heading up the Esses in 3rd gear, shifted to 4th----and the DCT double upshifted to 5th. Argh! The acceleration was killed off. I battled the car back into 4th gear and kept going as quick as I could, but it was a mess. In all that stupidness, I lost about 0.6 seconds. The lap ended up as a 1:48.3. Up until that shift, I was on the fastest single lap of my life.

I took a screenshot from the AIM software to illustrate the mess. In the picture below, the lap in question is colored Red. For comparison, I included 5 other laps, colored Black. Some of the laps were done on slower tires just to illustrate how lame this moment was. The AIM software cursor is set at the exit of Sweeper at 11100 feet down the track.

The reference lap in this picture is a 1:48.07. The first thing to note is the Yellow circle in the bottom right corner. You can see that where the cursor is, the Red lap is 0.499 seconds faster than the 1:48.07. So, it would be fair to say that I am on a 1:47.58 at this point.

The next thing to look at is the small Yellow circle in the middle of the picture. This chart shows the gear that the car is in. To the left of the yellow circle, you can see that ALL laps are in 3rd gear as I finish Sweeper. Then at slightly different times on all the laps in the Yellow circle, I shift to 4th gear. But then on the Red lap, you can see the DCT shifts again to 5th gear. ARGH! It does this on it's own sometimes. I am QUITE certain that I am not pulling the shifter twice. You just never know when it will happen. It is quite maddening. So then you see I try to get it back into 4th, and then I finally go up to 5th.

The last thing to look at is how the speed was affected. The large Yellow oval at the top of the picture shows the comparison of the speeds going up the Esses. You can see that at the moment of the double upshift, the speed line flattens out and doesn't keep up at all with any of the other lines----even the speed profiles of 1:50 and 1:53 laps on slower tires......



This lap was the second 1:48 lap in a row, so the car had been under a fair amount of stress already. The DCT double upshifted earlier in this same lap while exiting Off-Ramp. I was able to get it back into 3rd gear quickly. I definitely lost a little time there too, but not like after Sweeper. I am finding that when I push the car very hard for a couple laps in a row, I get some unpredictability in the gear shifts. I don't know whether to blame the VF tune on the supercharger, or blame the GTS-DCT software......whatever it is, it's damned annoying. Does this happen to anyone else?

I actually really enjoyed the afternoon time with Speed District on Friday. They went to an Open Track format (with point-by required) at 3PM and I ran a ton of laps (on slower tires). I think I stayed out there for almost 40 minutes during one of my open track sessions. I don't think I've ever stayed out there that long before. The weather made it possible for the engine to keep going, so I stayed out there. I learned quite a few things by doing so many laps at one time. I like how you get into a flow lap after lap. This is the one thing that bums me out about my car---it's really good for a couple hot laps and that's it. Sometimes I wish I had a car that could do 10 full-on hot laps in a row at any air temp.

[dogbone]

I wanted to give an update on some suspension tuning I've been doing over the last number of months.

The whole process started as a result of bracing straps I had installed on the canards to stiffen them up. I've mentioned before that I was concerned that the canards were pretty flexible and perhaps could benefit from being stiffened up. The straps are a thin inconel brace that attach to the splitter.

The original design had the strap going to the underside of the splitter and being held via a screw. There was a bolt head that sat on the underside of the splitter to screw the strap into the splitter. (see pic)



The brace worked very nicely and the canards are nice and solid. However, a new issue cropped up: The head of the bolt holding the strap in place was getting sheared off because it was rubbing the ground in turns.

The question was: is the car leaning too much? And should we put in stiffer springs?

I had been wanting to experiment with stiffer springs for quite awhile. I wondered if I could benefit from less nose dive during braking, less squatting on acceleration, less leaning on long fast corners, quicker weight transition on quick back-and-forth turns, etc. The idea of stiffer springs seemed like something worth trying.

I talked to Bryan at JRZ to see if the RS Pro dampers could handle more spring rate. He said they could. He recommended going up 25%. 600front/800rear was on the car, so I purchased 750/1000. When I asked him if I should try it, his answer was very noncommittal. He basically said, "springs are cheap. There's no harm in trying." (Back in 2012, when I first bought the JRZ, he said that stiff springs on race cars was a myth.)

Let me tell you----I hated the stiffer springs. The car's ability to turn was severely reduced. The car was just SCRAPING across the ground in corners compared to the softer springs. It just WOULD NOT hold. And it became really edgy. I experimented with suspension settings quite a bit. I could reduce the edginess but then the suspension felt floaty and disconnected and still didn't turn as well. And it would bounce off berms instead of absorbing them. ugh....it was a disaster. I lost around 8 mph at the apex of Riverside at Buttonwillow.

I tried re-aligning and softening the front sway bar. Nope. No better.

Two days on track with the 750/1000 setup and I was done.

However, instead of changing springs at the shop, we decided to do it at the track. So, the next track day, I drove the first session with 750/1000---hated it, and then we put just the 600 back on the front for session 2. Holy cow, my turn in was back! Crazy! I was glad I could do back-to-back sessions with the different front springs. It really highlighted the change in feel.

And the car felt pretty good with the 1000 lbs still in back. So I drove it for awhile like that. I drove my 1:48.07 at Buttonwillow with 600/1000.

But I still felt that the rear had too much spring. So, I bought 900lbs for the rear.

I really like the 600/900 lbs combo on my car that weighs 3250lbs (no fuel, no driver). The car feels great. Turn-in grip and grip throughout the turn is solid. My suspension settings are back to more "normal" settings in the middle of the damper range, so the connected feel is back. The rear feels responsive but not overly edgy. I'm happy to have a little more rate on the rear of the car than before.

I'm glad I went through this exercise. Now I don't wonder about stiffer springs anymore. I honestly don't know why people setup race cars with super stiff springs....

And now the canard straps have been re-made to sit on top of the splitter, instead of going to the underside. I believe the 900 lbs springs give the car a bit more support, so the head of the bolt doesn't seem to rub the ground as much. I'm wondering if we can attach them without even having anything on the underside. I asked about riveting, but that didn't seem to be the answer. We'll see.

[Richbot]

What settings did you play with? Ride height? Camber?

Stiff springs are overrated generally I agree, it's just a different way to get to the same place