View Full Version : switching rear end gears

new cobra guy
11-28-2011, 11:11 AM
I have an '01 Cobra. I hear about upgrading to 4:11 or 3:73 in the forums. What exactly would I gain? I do almost exclusively daily driving. Would my car run at higher rpm all the time?

I'd like to get a quicker launch, but don't want to sacrifice too many mpg's.

Please help me out with some info!!!

New Cobra Guy.

11-28-2011, 11:25 PM
I like the 4.10. Had it and went back to 3.27 and now changed to 3.90. Is nice to have the gear.

11-30-2011, 11:24 PM
go 4.10's, you wont lose that much more mpg from the 3.73's. I have 4.10's in my 97, and love them. They really wake the car up

12-05-2011, 01:43 AM
The gears will make the revs climb quicker and make the car accelerate quicker. If you do a lot of highway driving at 70 mph or above you will probably lose a little mpg. But for all of the low to moderate speeds it will just mean you shift up to the higher gears sooner. You will love how quick the car is after switching. 4.10 seems to be the most popular for mild street cars. Go for it! Best bang for the buck on these cars.

12-05-2011, 08:04 PM
the mpg loss is so minimal, don't fear the gear:D

new cobra guy
12-30-2011, 04:07 PM
Ok! I'm ordering the 4:10's!!!! Car is in storage now for the winter. I'll be ready to put them in right away in spring. How long of a job is this? Anything special
I should know about the install process?

12-30-2011, 09:14 PM
If you have never done this before I would suggest you take it to someone who has.If you don't get the clearences right you'll either tear the rearend up or have noise issues.


new cobra guy
01-03-2012, 01:52 PM
Thanks for the advice. I do plan to have someone do this for me. I'm planning the gears and Tune package from American Muscle.

02-03-2012, 11:09 PM
I was down that road once. Have all the parts for the install, just never got around getting the parts installed on the 04. I went with 3.73 which is not much of a step from the 3.55. Not sure what to expect since the parts are in boxes. Had a shop lined up for the install before moving but they were booked so it never happend.

For the 01, 4.10's or 3.90 would definately wake up the car. You will have more torque at the low end. Depending on the milage, you may want to invest in a clutch pak for the differential. Do not forget to replace the side bearings and seals, shim kit with differential bearings, bolts, and pinion bearing with bearings, etc...You may want to replace the pinion flang as well. I would also consider replacing the differential cover with one that is stronger than the factory. And then there are busings that could be replaces to stiffen up the IRS cradle. :eek: There is only a slight difference between the 01 IRS cradle and the 03/04. The odd thing, I had more wheel hop on my 01 than I ever did with the 04.