Okay Ive read that its really not worth doing a 4.10 over a 3.73 in an A4, but why? The 4.10s are the same price as 3.73 in Summit racing Parts Magazine. How much more strain can a 4.10 cause on the rear end. They are both pretty high ratios. Quite simply why is known as overkill? I really dont understand this stuff so please enlighten me.

 

I have an A4 Z28, and most recently changed my gears to 3.73's.

At one point I was strongly considering 4.10's, and after alot of research here are the reasons I decided against them.

1. (main reason) At freeway speeds, of 60 MPH or above, when you accelerate, (depending on how much pressure you put on the throttle) your PCM may decide to downshift into 2nd gear, that will put you over the RPM redline everytime. Run this gear calculater yourself, and you will see what I mean:

http://www.f-body.org/gears/

2. With an already fragile rearend (i.e. 7.6" ring & pinion, C clips), the 4.10 gear ring itself is too thin. The more teeth the thinner the gear.

3. The lower the ratio (i.e. 4.10 vs 2.73) the more noise the ring and pinion will make.

4. Your gas mileage will suffer.

Alot of people will tell you about going to a Torque Converter instead, however that also carries alot of extra baggage (i.e. increased trans temp (need oil cooler), and increased line pressure(need transgo kit), and increased torque slamming into already fragile rearend (i.e. 2.5 and above STR)

Get the 3.73's, you will be very happy with them, they sure put a smile accross my face.

SteveC

 

how about that u already have a very weak stock rear-end. i know for a fact if ur tires stick with those 4 10 gears ur gonna snap the rear-end in half. not to sure about this....i dont think u have enough gears for 4 10s' either. go 3 73 u will be more happy and u will keep some money in ur pocket for a different upgrade other then a spare rear-end.

 

Thanks this really helped, i ordered a set of 3.73s and cant wait to put them in.