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      10-03-2019, 09:04 AM   #6
3002 tii
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Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT

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Quote:
Originally Posted by eggman51 View Post
D'oh yeah... I realize I confused that site with a different marketplace site which is predominantly E46 stuff. Thanks for pointing it out.

WRT the type of diff and the final drive ratio, these would seem to be totally independent.

Are you saying that the M diff is better than a Quaife or Wavetrac style diff for track use?

WRT the drive ratio, on all the tracks I have run I never use 1st, rarely use 2nd, and have never needed 6th. One of those tracks - Area 27 - has a very long straight that leads me to believe that pretty much any track I am going to run at would benefit from a 4.10 drive ratio.

Effectively on a track day, I have a 4 spd box from 2nd thru 5th.

It seems like a 4.10 drive ratio would make it into a 4 spd box from 3rd to 6th, but allow much greater acceleration out of corners. Not to mention rarely needing the 2nd gear downshift which is the worst shift in this transmission imo.

Cheers and thanks for all your patience and wisdom!

Eamonn
Yes they're independent, which is why I was saying I personally wouldn't care for (or pay up for) a Wavetrac unless I wanted 4.10s that badly (and it was being sold as a package). But I guess its personal preference, and you're the one buying so what do you find compelling about the Wavetrac? Or were you indifferent and more focused on getting 4.10s?

In any case, safe to say none of us really use 1st or 6th on a road course neither but I don't see why that means shorter gearing is the answer. Not saying that it isn't but that statement alone of not using 1st and 6th doesn't say much.

I don't want to come off as someone lecturing so I won't tell you how to spend your money. But I would just do more research on gearing and look at your data (e.g. shift points, tire sizing, etc) to see if it'll actually result in shorter lap times. You may find yourself bouncing off the rev limiter more and needing to short shift to 5th only to find yourself in hard braking moments later on certain corners.

People here knock the 3.91 saying it's not all that much different than 4.10s and so you may as well go for that extra jolt of torque but most times those folks are talking about for everyday use. On a road course, I'm not sure if 4.10s is the obvious choice over 3.91....
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