Best ways to control traction

jchammond · 08-02-2018, 04:59 AM

Quote:

Originally Posted by bcfromfl

I appreciate the tips in this thread. I, too, am noticing traction problems, which I know are going to be a headache when I add the A2A kit later this year.

My biggest beef with my car is the gearbox. Gears are simply too short. I haven't done a lot of stoplight madness, but the times when I have, 7500 just comes WAY too quick in 2nd, and if I make the choice to pop into 3rd, at that speed, I'm already at 4500-5000 with not much room before 4th. 99% of the time I go from 2nd to 4th, and am getting quicker with it, but you just shouldn't have to play this kind of shifting game with a performance car.

I kept up with an older Audi TTS the other day, and while I know he has that (in)famous dual-clutch system, I was pushing the RPMs a bit too hard for comfort.

I had my car dynoed after the exhaust upgrade, and I'm at 312/269. I was hoping that the Michelins would reduce the traction control issues, and while I haven't noticed any fuel cutoff episodes like with the Potenzas, the light will still come on in 3rd accelerating out of corners. I don't want to be constantly replacing the rears...not only because of the cost...but because the owner of the speed shop who did it said he NEVER wants to change the tires again -- each rear took him three hours!

I suppose the best compromise is a diff upgrade, but I don't know enough about this sort of thing. Are there issues with speedometer accuracy? For those who have done this, what ratio is recommended? What speeds would the shift points move to?

Thanks!

Speedometer drives off of the 2 output sensors; mounted on the diff cover.
They read the toner rings on the output stub shafts,,,so 3.36 to 4.36 gear ratios will not affect speedometer- pending that you’re running a 27” tire (+ or - a tick)
Your 15’ Nismo has 3.92 axle ratio,,,pre 15’s had 3.69.
They make 3.54 & 3.36 if you want taller gears.

bcfromfl · 08-02-2018, 09:02 AM

Quote:

Originally Posted by jchammond

Speedometer drives off of the 2 output sensors; mounted on the diff cover.
They read the toner rings on the output stub shafts,,,so 3.36 to 4.36 gear ratios will not affect speedometer- pending that you’re running a 27” tire (+ or - a tick)
Your 15’ Nismo has 3.92 axle ratio,,,pre 15’s had 3.69.
They make 3.54 & 3.36 if you want taller gears.

Thanks so much for the info! With the numbers you provided, I was able to do a better search, and came up with this thread: 3.54 Final Drive Swap Review

One thing that was brought up in the linked thread was that with a taller diff, there is an approximately 4% hp/tq loss. Some members in the thread mentioned that they would rather go the other way to 4.08, for quicker acceleration...but they don't seem to realize the problem with the time required to shift more often (at speeds less than, say, 80mph) adding to overall acceleration times. If you could knock out one shift in an average acceleration run, the benefits would be huge...for example. The way my car is geared now, there's no point in using 3rd at all except for downshifting into corners. Accelerating in 4th at most speeds above 40mph or so is most efficient.

The OP in the thread never came back to explain whether the loss of cruise control was due to the new diff, or the cable malfunction he suggested. Any input here?

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