diff ratio- 3.73 too much for SC ax/street

shark328 · #1 (**permalink**) 12-06-2003, 06:30 PM

I have 95 M3 with Vortec 7psi, and stock 3.15 LSD. I want to change diff to 3.38 lsd w/40% lockup, but do you think a 3.73 would be TOO much? What about a quaife 3.73? This car is daily driver, autox, & couple of driving schools. Main focus is autox.
NE1 running 3.73 in e36?
thanks
d

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sunir · #2 (**permalink**) 12-08-2003, 10:31 AM

a 3.73 for a street driven car is rediculous. Plus you have forced induction SC so the torque multiplication is not critical for your application.

jderry · #3 (**permalink**) 12-08-2003, 02:06 PM

No way ... 3.73 LSD w/40% lockup would be insane. Heck, a 3.46 w/40% lockup would REALLY REALLY be pushing it.

If your main focus is in auto-x, you would probably lose more time shifting than you would gain from the holeshot. i'm not sure about your courses; but, here, we RARELY see 3rd gear runs. Most of the time, you can do the course in 2nd gear (e.g., more technical). A 3.73 or even a 3.64 would cause you to upshift and then downshift.

You would have to H&T like the Holy Father himself to have a chance to not lose anytime. If you are mortal like 99% of us, you'll lose more time than it would help you.

Besides, you already have a LTW Fly I see.

shark328 · #4 (**permalink**) 12-08-2003, 02:52 PM

u r right. At BMWCCA, I don't think I ever get into third, but SCCA sees 3rd a lot. Shifting is a killer. It's not that it takes time, because you are still moving annyway, but I do lose fucus. I had picked up a nasty habit of shifting alot, before my FW. I finally was getting out of the habit at the end of the season. It is unbelieveablr how much it helped me to focus by not shifting. It somehoe seems to give you a tremendous amount of extra time just because I didn't shift. I'm dumping the idea of shorter gears but I would like to get 40% lockup. Maybe I should at least go to 3.23?