Limited Slip Differential Advice. . .

Tom Droze · 04-04-2015, 02:20 AM

As some of you may recall, my second trip to the dragstrip in January was after I installed the AA tune and while I picked up 2 MPH in trap speed, but my ET and 60’ foot times were all over the board because of increased wheel spin and wheel hop, which prompted me to invest in a limited slip differential, M3 differential bushings, Whiteline subframe inserts, performance trailing arms, and Michelin PSS. This evening I went back out to the dragstrip to see what effect these modification produced. The best way I can think of to illustrate this is to give you the average along with the best and worst result so you can see where the improvement lies. With the AA tune I made four runs and with the LSD and other mods I made six runs tonight.

With the AA tune my average 60’ time was 2.588 with a best of 2.388 and a worst of 2.687. As a comparison, with the LSD and the other mods my average 60’ time was 2.333 with a best of 2.262 and a worst of 2.372. The take away from this is that my 60’ times are much more consistent, as I had virtually no wheel spin and no wheel hop. I have an automatic and I was in sport mode, which launches the car in second gear. I would power brake to 2,000 RPM then launch. My average 60’ time improved by .255 seconds.

With the AA tune my average ET was 15.487 with a best of 15.102 and a worst of 15.638. As a comparison, with the LSD and the other mods my average ET was 15.170 with a best of 15.105 and a worst of 15.239. My average ET improved by .317 seconds with the best on best comparison being virtually the same. Again you can see much more consistency with the ET.

Now for the disappointing part of this analysis. With the AA tune my average MPH was 94.13 with a best of 94.87 and a worst of 93.01. As a comparison, with the LSD and the other mods my average MPH was 92.85 with a best of 93.18 and a worst of 92.04. My average MPH dropped by 1.28 MPH. The drop in MPH could be explained by three things, it was about 20 degrees warmer outside as compared to when I did the AA tune run, the LSD, because it is spinning two axles instead of one might be robbing a little horsepower, and the Michelin PSS might have a bit more drag as compared to the run flat tire I was running previously.

Honestly, I was hoping to crack the 15.0 barrier tonight, which I did not do; which means my only recourse, after I invest in an oil cooler, is to invest in a set of headers... damn, damn, damn!

Oh, it is now time for another Heineken Light… cheers!

DUI Elite · 04-04-2015, 03:18 AM

aww man there are a lot of factors that could affect that. Though on initial impression, that does sound disappointing :/

andrey_gta · 04-08-2015, 12:09 PM

Quote:

Originally Posted by MFactory

Our Helical LSD is Torsen type, so there are no ramp angles.

For diff bushes, the oem M3 are still quite soft (but stiffer than the 335i ones).

If you are going to change them, better to change them to the harder/solid type.

We have our own solid shifter bushings ready end of this month if you can wait, but if not, then the urethane type should suffice.

Hi
Any update on the solid subframe bushings development?

MFactory · 04-08-2015, 01:03 PM

Our diff bushings are scheduled for this month (was a delay at the factory)

04-04-2015, 02:20 AM	#89
Tom Droze Major 413 Rep 1,286 Posts Drives: 2012 BMW 328i (e92) Join Date: Jul 2014 Location: Scottsdale, Arizona iTrader: (0)	As some of you may recall, my second trip to the dragstrip in January was after I installed the AA tune and while I picked up 2 MPH in trap speed, but my ET and 60’ foot times were all over the board because of increased wheel spin and wheel hop, which prompted me to invest in a limited slip differential, M3 differential bushings, Whiteline subframe inserts, performance trailing arms, and Michelin PSS. This evening I went back out to the dragstrip to see what effect these modification produced. The best way I can think of to illustrate this is to give you the average along with the best and worst result so you can see where the improvement lies. With the AA tune I made four runs and with the LSD and other mods I made six runs tonight. With the AA tune my average 60’ time was 2.588 with a best of 2.388 and a worst of 2.687. As a comparison, with the LSD and the other mods my average 60’ time was 2.333 with a best of 2.262 and a worst of 2.372. The take away from this is that my 60’ times are much more consistent, as I had virtually no wheel spin and no wheel hop. I have an automatic and I was in sport mode, which launches the car in second gear. I would power brake to 2,000 RPM then launch. My average 60’ time improved by .255 seconds. With the AA tune my average ET was 15.487 with a best of 15.102 and a worst of 15.638. As a comparison, with the LSD and the other mods my average ET was 15.170 with a best of 15.105 and a worst of 15.239. My average ET improved by .317 seconds with the best on best comparison being virtually the same. Again you can see much more consistency with the ET. Now for the disappointing part of this analysis. With the AA tune my average MPH was 94.13 with a best of 94.87 and a worst of 93.01. As a comparison, with the LSD and the other mods my average MPH was 92.85 with a best of 93.18 and a worst of 92.04. My average MPH dropped by 1.28 MPH. The drop in MPH could be explained by three things, it was about 20 degrees warmer outside as compared to when I did the AA tune run, the LSD, because it is spinning two axles instead of one might be robbing a little horsepower, and the Michelin PSS might have a bit more drag as compared to the run flat tire I was running previously. Honestly, I was hoping to crack the 15.0 barrier tonight, which I did not do; which means my only recourse, after I invest in an oil cooler, is to invest in a set of headers... damn, damn, damn! Oh, it is now time for another Heineken Light… cheers! __________________ 2012 Jet Black 328i Coupe / ESS Tuning Gen. 2 Supercharger / Evolution Racewerks Oil Cooler / BMS Oil Catch Can / BMW Performance Exhaust with Dinan Y Pipe / Eibach Pro Kit Springs / Koni FSD Shocks / MFactory LSD & Differential Bushings / Performance Rear Trailing Arms / BMW Performance Strut Brace / Stop Tech Slotted Rotors / Hawk HPS 5.0 / SS Brake Lines / Brass Guide Pins / M3 Front Control Arms, 28 MM FSB, Engine Cowl, and DCT Paddle Shifters / Michelin PSS / APEX ARC-8
	Appreciate 0 Quote

04-04-2015, 03:18 AM	#90
DUI Elite ///M at Heart 90 Rep 1,954 Posts Drives: 06 SGM E90, 15 BSM E84 Join Date: Jan 2011 Location: Chicago, IL iTrader: (4)	aww man there are a lot of factors that could affect that. Though on initial impression, that does sound disappointing :/ __________________ \| 3-IM \| AA Headers \| Eurocharged Stage-3 \| BMW PI \|
	Appreciate 0 Quote

04-08-2015, 01:03 PM	#92
MFactory Major 581 Rep 1,421 Posts Drives: E92 M3 Join Date: Feb 2014 Location: San Dimas, CA iTrader: (2)	Our diff bushings are scheduled for this month (was a delay at the factory)
	Appreciate 0 Quote