Bmr4life

Man, 3k at 80mph isn't an option for me. If only my drive was shorter.

Bmr4life

What? Auto with 3.31 is fine from the factory. 4.10's is overkill IMHO. 3.73 is the perfect mix for Auto.

bolivianpimp

With a 275-35-20 tire out back with 4.10's on a manual, would that be like 3.90's? Also, what gear oil is good to use?

Bmr4life

No, those tires are barely larger than stock.

East87

Picking up my car with the newly-installed 4.10's tomorrow...man am I gonna have fun breaking those babies in...

08droptop

How long is the break-in period?

stealth_GT

Ditto.. I really didn't like the 4.10s at first because of how aggressive they were, but once I knew how to launch with them I wouldn't have it any other way! Around town it's great as well.

The RPMs are ridiculous though with the O/D off after 90 or so..

East87

My installer told me that as soon as I get the car, I need to get the gears good and hot so that a compound on the gears themselves can break down into the oil to aid the wearing process. His estimate is about 20-40 miles of driving. WOT or normal throttle makes no difference apparently. He's done at least a few dozen or so installs and has reported no problems. I think if you're just not stupid about driving the car too hard with new rear gears, it shouldn't be much of an issue.

Then he told me it's about 200-250 miles of driving before I take it to the track or anything...on top of the 20-40 miles of "getting the gears hot"

chris09

man i would love 4.10s. will my 3.31s in 5th at 3,000 im doing 110mph with no *****.

macomacus

I just dropped the 09 off at the Ford dealership for my 4.10's. It came to $669 for gear and installation and tuning. I will be retuning after I get the gear broke in Can't wait to get it back!

The waiting is almost as bad as the first kid - lol.