I just swapped my 98 z from an a4 to an m6, and I still have the stock 3.23 gears in the rear and it feels real sluggish I now this effects the low end but would it pull harder at higher speeds or what??
I was thinking of either gettive some 3.90's or 3.73's, wut do you think will be best for my mods, also would I feel a big difference in power by changing the gears


My mods are all in my signature

thanks

 

Do a search on this, a lot has been said. You need to do some work on figuring out first what tire size you want, that will dictate the gears in the rear. Rule of thumb and your research will show it, 4.10's for the M6.

 

I'm doing the same swap, I just did the gears while I wait for my clutch kit. This way I can drive it to be sure the rear is quiet first.

I went with a low mileage 3.73 set.
The rpm will be slightly lower than with the automatic still.

Gear ratios for the M6 are 2.66, 1.78, 1.30, 1.00, .74, .50.
For the automatic. 3.06, 1.63, 1.00, .70.

If you figure the math like this: rear gear x trans gear x 336 (manual, or 355 auto with stock converter) x mph / tire diameter = RPM.

Heres an example using a 25 inch tire and 30 mph in first gear.

M6 3.73 x 2.66 x 336 x 30 / 25 = 4000 rpm.
A4 3.23 x 3.06 x 355 x 30 / 25 = 4210 rpm.

If you get used to using this you can figure out which gear ratio you'd like better.

 

well I have 315/35 r17 on the back , I'm thinking I want the 3.90 motive gears but just wondering what your' s guys point of view was on this..btw it's a 10 bolt