Originally Posted by Panoz
I'm impressed you remember my comment so long ago...
Well, the prespective of using an /M diff in a non-M car is really interesting but using a shorter final drive ratio is mistaken (in my opinion ,of course).
There is no need to use a shorter final drive when you have a car that performs the +50% of its maximum torque from 1200revs ,like 335i.
A shorter diff would be ideal for the naturaly aspirated //M cars that needs to reach their beneficial rev range fast (which is pretty high at 5500revs+).
Again, I find impressive your whole experiment from a technical view, but in your place i would roll back to your quaife one
I remembered your comment as you said traction was a issue.
I think at this stage the diff is much to short, when bigger turbos come it will be beneficial in my case. I am not sure if you have driven a automatic car with lag. The first few rpms seem like a lifetime. Then there will be a benefit. Further than that I think I can pull away in second and still maintain the same rate of acceleration as using both gears with OEM final drive. Then 3, 4, 5 and 6th are crazy because the car has to pull through a much shorter gear.
Another advantage is that at the moment I have a choice of eight final drive ratios available after market with a zip of my credit card. With the OEM diff I have none or maybe 1 if I can find a manual diff which isn't welded.