dinan 4.10 diff installed and broken in

[Trip3's]

Originally Posted by sterile stork

I haven't heard much about other people's experience, but I'm lining up a bunch of work on the rear-end for me E92, turner bushings, uprated sway bar, etc. I also figured I might as well go for broke and ordered a 4.44. Currently waiting for it's arrival from Germany.

I'm now torn on LSD units, whether or not to change out the M variable for a ramping setup...

I'm not sure if you saw this, but here is a LSD comparo

http://www.m3post.com/forums/showthr...highlight=diff

[regular guy]

Originally Posted by Mr.Metak2you

There used to be some awesome discussion in some threads from back in the day with PencilGeek, not sure if it can be dug up somehow. I think DCT guys should stay away from the 3.62 by all means. The 3.45 works well with the DCT and most 6MT guys that went with the 4.1 seem to love it.

Those were the days.

It seems we repeat many topics, but to new audiences.

Originally Posted by sterile stork

Wow! Thank you very much. I most certainly didn't expect for such extensive research as that, but sincerely appreciate the thought and would be delighted to see the comparisons!

Here's a simulation of different performance based on final drive and keeping everything else the same.

The dyno chart used in this test should be pretty similar to you (give or take).

• 371whp, 271wtq
• BPM Stage-1 ECU
• RD Sport Underdrive Pulley
• Macht Schnell Stage 2 Intake
• Both CAT Delete
• Akrapovic Evolution Exhaust System (Titanium)
• 91 Octane (US), 95 Octane (RON)
• 6-Speed Manual Transmission

[klammer]

Fwiw, have the 3.45 and do love it. Was primarily added for road course work and have never launched or raced in any top speed events, nor plan on it. Live downtown Chicago and in gear acceleration really comes in handy around here, and "value" can always be debated. It's not cheap and agree with all the simulations, but for my application do think it has merit. As you were...

[swamp2]

Originally Posted by regular guy

Again, although accurate absolute performance levels are not a prerequisite for accurate A to B comparisons for things such as a FD mod, I'm still curious about the overall low levels of performance here. 0-60 in 5 seconds and 13.3-13.6 1/4 mi times. These are substantially lower than most magazine times and lower than my CarTest results using crank power and 12% or so total losses. Any idea why these sims show such underperformance?

[Soorena]

Originally Posted by yoelev

yeah and it sounds AMAZING

Is the gears' helix angle changed?

[regular guy]

Originally Posted by swamp2

Again, although accurate absolute performance levels are not a prerequisite for accurate A to B comparisons for things such as a FD mod, I'm still curious about the overall low levels of performance here. 0-60 in 5 seconds and 13.3-13.6 1/4 mi times. These are substantially lower than most magazine times and lower than my CarTest results using crank power and 12% or so total losses. Any idea why these sims show such underperformance?

Yeah, I based these results on my slow shift speeds and my fat ass in the cockpit with a half tank of gas. I'm sure the magazines shift substantially faster than I do, and that could easily be 0.4 second difference right there on a 0-60. There's also weather conditions which affect power output; but not sure how much difference that would make because I didn't model it. Tire size was heavier 19's in this simulation. What do your simulations show for these same results?

[driftflo]

Originally Posted by sterile stork

I haven't heard much about other people's experience, but I'm lining up a bunch of work on the rear-end for me E92, turner bushings, uprated sway bar, etc. I also figured I might as well go for broke and ordered a 4.44. Currently waiting for it's arrival from Germany.

I'm now torn on LSD units, whether or not to change out the M variable for a ramping setup...

4.44 will be quite short, not sure if it is really better compared to the 4.10. you need to shift a lot.

if performance and handling should become noticably better, you need to switch the lsd to a ramped one.
as i wrote in my lsd shootout thread, forget the osgiken. the titan is better but needs to be set up quite different than it comes in stock setup. drexler gt4 is quite good out of the box but expensive. i have made some drexler "replikas" for not even half the money but i am located in germany.

[swamp2]

Originally Posted by regular guy

Yeah, I based these results on my slow shift speeds and my fat ass in the cockpit with a half tank of gas. I'm sure the magazines shift substantially faster than I do, and that could easily be 0.4 second difference right there on a 0-60. There's also weather conditions which affect power output; but not sure how much difference that would make because I didn't model it. Tire size was heavier 19's in this simulation. What do your simulations show for these same results?

I use a 0.3 second shift time for MT, 0.05 for M-DCT. My weights are 3581 for MT and 3626 for the M-DCT (less 165 for driver). Losses are 12% total. CarTest does not do a wheel weight calculation based on wheel size. Here are my MT and M-DCT results which correlate well with the best (or near best) magazine times.

I don't really see a need to run the changes to the FD as the delta's will be pretty well identical to yours.

[sterile stork]

Originally Posted by driftflo

4.44 will be quite short, not sure if it is really better compared to the 4.10. you need to shift a lot.

if performance and handling should become noticably better, you need to switch the lsd to a ramped one.
as i wrote in my lsd shootout thread, forget the osgiken. the titan is better but needs to be set up quite different than it comes in stock setup. drexler gt4 is quite good out of the box but expensive. i have made some drexler "replikas" for not even half the money but i am located in germany.

Thank you for chiming in. When looking into the drexler units, I'm curious about the differences between pre-load and not. The car is slowly approaching the line of track-rat, but will be used on the street for the next 18 months or so (10 miles per day/5 days per week or so.)

[driftflo]

Originally Posted by sterile stork

Thank you for chiming in. When looking into the drexler units, I'm curious about the differences between pre-load and not. The car is slowly approaching the line of track-rat, but will be used on the street for the next 18 months or so (10 miles per day/5 days per week or so.)

it is not only whether or not you have preload. it has a lot more aspects. the value of preload is the one thing. the way it is realised is the more important one. there are preloaded setups with and without bellevue washers, and there are non preloaded setups. each one has its own advantages. titan i.e, sets the preload completely wrong. drexler does a better job here. if you go without preload, you need to rebuild the lsd regularly if you want a good response. if assembly clearance gets bigger and there is no bellevue washer installed you get a really aggressive rear end on load changes.

so if you go for a drexler in a funtool, get one with preload. it is set quite ok. take the drexler without preload if you need the maximum performance with a minimum of understeer for a skilled racedriver that wants to win races.
but even top racecars are setup with preloaded lsd units. take the z4 gt3 for example. until 2012 they used a drexler with nearly no preload. afterwards they used a xtrac which was preloaded again. so it depends pretty much on what the lsd manufacturer suggests the customer to use. drexler likes non preloaded setups for track cars. but they also want you to rebuild it twice a season.

if you dont want to change anything inside the lsd before installation, i would recommend to get a preloaded drexler.
if you want an individual setup that exactly fits your special needs (i.e. the drexler standard setup is not ideal for street use and auto-x), i can setup a unit individually.

[shakywarrior]

Originally Posted by dcstep

Here's my real world experience with the 4.10 FD installed in my 2009 E92 M3 6MT. I've got around 14,000 miles on the 4.10 and well over 100 autocross laps. Other mods include the Active Autowerks exhaust, oiled air filter, Dinan springs, Dinan chip with 8600-rpm redline, UUC SSK and Dinan throttle bodies.

I don't do 1/4-mile races at tracks, I do occasional rolling start street races (but usually only up to around 100-mph) and I run BMWCCA sanctioned AX. AX is my main performance interest. It should be noted that I live at 5400-ft above sea level, so non-forced induction power adders are not near as effective as at sea level.

Around town the negatives of the 4.10 are poorer fuel economy and slight noise from the gears on the overrun. I expected these things going in and was only worried about the noise level. I can report that it's not bad at all and doesn't bother me, but I DO know it's there. My riders don't say, "What's that noise?", but it is more than stock. The advantages for street driving are in-gear responsiveness and acceleration in-gear. When I street race I hope to start at around 4000 rpm on the rolling start and use the full 8600 rpm redline and only shift once up to 100-mph. Squirting through traffic in 3d, 4th and 5th is clearly more responsive than stock.

If you look at those scientific charts, they're right. The gear ratios were not selected with this FD in mind, such that 1/4-mile time is actually worse, DUE TO THE TIME REQUIRED TO SHIFT. However, the in-gear acceleration can be better with the higher numerical ratio. Also, I'm able to space out my shifts a little more with the extra 200-rpm of redline that my car has.

AX is where the FD really pays off because, other than the 1-2 shift, the entire course is typically run in 2d gear. The 6MT has better acceleration than the DCT in 2d. The DCT will be faster on a road course, but the 6MT will be faster on an AX course.

Top priorities for AX speed are tires, then lightweight and wide wheels that reduce inertia and increase the contact patch and tracking width. Gearing and power come in distant thirds. I lean toward gearing, partly because my high altitude makes power VERY expensive to gain. Gearing is a known that won't be sapped by low oxygen density (my loss is around 16% vs. sea level). With my current setup (awaiting new, lighter 18" wheels and a switch to Dunlop Direzza tires) my car will spin its wheels anywhere on the course.

Anyway, I think that my case demonstrates there's no one absolute fastest answer. The answer is more like, "It depends on what you're doing." If you do standing start 1/4-mile races and that's important to you, then listen to the techno data. That is really, really true. Shifting time DOES cost speed. However, if you run events where shifitng is limited, you'll still want to minimize shifting time by either strategy or higher redline, or both, but it will not be as important to you as in a 1/4-mile event. A higher numeric gear ratio can be an advantage in events where there is little or no shifting.

I like the feel of the gearing with a 4.10 FD and I think it's quicker for AX.

Dave

Would you say it helps during rolling start street races? Imagine both cars have the same power, but one w 4.10 and one stock FD. Say from a rollin start at 40, the 4.10 would be at a higher RPM which would give it a nice leap ahead of the stock FD car? And then it would just be a chase from there on assuming both drivers were on par with shifting.

[dcstep]

Originally Posted by shakywarrior

Would you say it helps during rolling start street races? Imagine both cars have the same power, but one w 4.10 and one stock FD. Say from a rollin start at 40, the 4.10 would be at a higher RPM which would give it a nice leap ahead of the stock FD car? And then it would just be a chase from there on assuming both drivers were on par with shifting.

Rolling start at 40-mph is too high. With the 4.10, you're better off at like 20-mph, where you've got more gear left. At 20, you get a good jump and lots of room before the 8600-rpm redline (chipped).

[Scharbag]

Originally Posted by regular guy

Those were the days.

It seems we repeat many topics, but to new audiences.



Here's a simulation of different performance based on final drive and keeping everything else the same.

The dyno chart used in this test should be pretty similar to you (give or take).

• 371whp, 271wtq
• BPM Stage-1 ECU
• RD Sport Underdrive Pulley
• Macht Schnell Stage 2 Intake
• Both CAT Delete
• Akrapovic Evolution Exhaust System (Titanium)
• 91 Octane (US), 95 Octane (RON)
• 6-Speed Manual Transmission

Sorry if I am absolutely blind (I swear I have looked at the entire post, but I have my moments), but could you specify what FD each of the columns of data represents?

Cheers,

[shakywarrior]

Originally Posted by dcstep

Rolling start at 40-mph is too high. With the 4.10, you're better off at like 20-mph, where you've got more gear left. At 20, you get a good jump and lots of room before the 8600-rpm redline (chipped).

I meant starting in 2nd gear. With the stock diff at 40 in 2nd rpms are about 4500 so with 4.10 I'm assuming I'd get a better jump being at a higher rpm at the same speed. I also have an 8600 rpm redline.

[dcstep]

Originally Posted by shakywarrior

I meant starting in 2nd gear. With the stock diff at 40 in 2nd rpms are about 4500 so with 4.10 I'm assuming I'd get a better jump being at a higher rpm at the same speed. I also have an 8600 rpm redline.

I meant 2d gear also, at 20-mph. At forty, you're too near the redline and you'll need to shift soon. The 4:10s advantage is 0-80-mph. At 40, you've given up most of your advantage.

[srmast1]

Is it still possible to find an OEM 4.1 diff for a 6mt? Is there a part number for it? Or is it all just aftermarket now?

[nycplumber]

Originally Posted by srmast1

Is it still possible to find an OEM 4.1 diff for a 6mt? Is there a part number for it? Or is it all just aftermarket now?

https://www.turnermotorsport.com/p-21503-ring-pinion-gear-set-rp-only-410-e46-m3-e60-m5/

[srmast1]

Originally Posted by nycplumber

https://www.turnermotorsport.com/p-21503-ring-pinion-gear-set-rp-only-410-e46-m3-e60-m5/

I know of this product through Turner, but isn't there an OEM 4.1 gear set as well?

[SAMM3Y]

I'm 90% positive the turner one comes from diffsonline.com. Having said that I have a turner 4.10 diff from one of their GT cars which is sweet and sounds awesome on deceleration with an os giken LSD. I'm not aware of a stock 4.10 gearset but there could be.

[srmast1]

Originally Posted by SAMM3Y

I'm 90% positive the turner one comes from diffsonline.com. Having said that I have a turner 4.10 diff from one of their GT cars which is sweet and sounds awesome on deceleration with an os giken LSD. I'm not aware of a stock 4.10 gearset but there could be.

Are you currently running it? Does it make 1st gear noticeably shorter?

[dcstep]

Originally Posted by srmast1

I know of this product through Turner, but isn't there an OEM 4.1 gear set as well?

Ten-years ago, I installed the Dinan 4.10 in my E-92. It's wonderful through the gears, not making 1st too short, but adding oomph, particularly in 2d and 3d. I used to autocross a lot and it's the perfect setup for that. There is noticeable noise on the overrun, but not too much for most. My wife never complained about it, so it passed one critical test in that regard. It's still going strong, ten-years and 85,000-miles later.

Dave

[Richbot]

I've always wanted to do this and every time I cruise on the highway for any extended period I am cured of it and start wishing for a tall 7th gear with a shorter 3-6 gearset, but that's called a DCT and I don't like the downsides that come with that, soooo oh well