Quote:
Originally Posted by bNks334
You do quiet a bit of speculating here that I don't think is accurate.
E-diff's goal is to maintain a <5% wheel speed differential (Per Bosch documentation). If you run different aspect ratio ties in the rear all you will do is allow that wheel to spin at a maximum of 9.99% difference between the others wheels (granted the other 3 are all spinning at the same exact speed). I got that numbers by assuming your taller aspect tires are seen by the wheel speed sensors as spinning -4.99% slower than the front tires. This won't cause any intervention as is, but as soon as it starts to spin freely upon cornering the e-diff won't brake the wheel until it starts spinning 5% faster than the other wheels (-4.99 to +5% = 9.99% wheel speed difference).
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exactly what I experience, e-diff program now has a margin of ~10% vs. ~5%. I do not experience the ediff program intervening anymore because I keep wheel slip well under 10%. In autocross on the lots we use, with my alignment, and my dumb right foot I was often getting into the ediff program. Both of my coaches, one with several Solo national championships were also getting into the ediff on some corner exits in the 135is.
Quote:
Originally Posted by bNks334
Allowing the inside wheel to spin freely is not a good thing so not sure why you see this as a benefit. You won't be "losing the back end" in corners, you'll simply be spinning the inside tire more. Straight line acceleration is a mute point... E-diff will allow burnouts so long as both rears tires spin freely within 5% of each-other (Burnouts are hard to do since axel shafts are different lengths and more power always gets delivered to one wheel). Raising the ceiling to 10% differential, as seen above, will just allow you to smoke your tires for a bit longer. Once again, not exactly a benefit to spin tires in a timed event  |
I'm running SCCA Solo. So It's not straight line tire-smoking slip.
Here's where ediff is a problem:
on the 128 at speeds of 25-40mph in tight dual hairpin/chicane type elements the inside wheel may slip due to throttle or a bump, the ediff program takes a moment to come in, by the time it comes in the car is already turning the opposite direction and is loaded on the opposite side, so the ediff is now braking the unloaded wheel inside wheel. the power goes to that wheel, and the ediff program come in again. this braking creates an icey - unable to accelerate state.
Over the prior two season, running same size tires I encountered the ediff intervention slowing the car almost every event, and experienced the long (1 second+) intervention in a tight chicane 3 or 4 times.
So far this season in the 128, I've done 9 events with the taller rears I have only gotten into the ediff program once.. 1st run and a corner exit was on a slippery patch, and I lit up the tire. the ediff slowed the axel the program hung around after the car was hooked up. I took it easier on the following runs.
on the 135is the power and boost lag made it a poor choice for autocross, everyone that drove my car got into the ediff , we found that when the ediff came in it was best to stay on the throttle and let the program do its thing.
Quote:
Originally Posted by bNks334
E-diff is not a traction control system, so I don't see why the regulation you quoted would have any bearing on eliminating the e-diff with coding. I can tell you right now, disabling the e-diff without a mechanical LSD is not fun. You will be much slower as you will constantly be spinning the inside wheel and throwing up clouds of smoke lol.
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The ABS unit has ABS, brake biasing, and a lot of programs, including the e-diff program, for SCCA they are all traction control programs or ABS. I see it as traction control, inputs are wheel speed sensors, corrective action is braking.
The e90 and e82have Continental Teves MK6...v5.. ABS/DSC, though It probably does work about the same as the Bosch systems.
SCCA solo street rules are pretty strict on electronics & coding. It only allows unplugging or sending modified signals to a sensor.
Quote:
Originally Posted by bNks334
If you want to be able to run a bit of slip angle, then simply single click the traction control button... it won't allow you to swing the tail out as much as "track mode" on an M-series car, but you'll still be able to swing it out a bit while maintaining SOME level of traction control. personally, I always keep DSC 100% off...
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the 2013 128i and 2013 135is maintain some of the traction control modes after you hold the button down for 5 seconds. CBC is one of that stays on. in "DSC off mode" the oversteer correction amount is too severe for a car that is already on edge at an autocross. With DSC held down and "off" I had several spins that were caused by Traction control. They occurred in the direction opposite the way I was loading the car in a steady state drift.
Quote:
Originally Posted by bNks334
You do quiet a bit of speculating here that I don't think is accurate.
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yes, a lot of development on the car is started with speculation and trial and error.
I'm speaking from my experience with the car.
I appreciate the skepticism.
I'm getting a CAN data logger so I can confirm some things with data.