I just got 4.11 gears installed with the stock 10 bolt rear, and the shop told me to go easy on them for about 500 miles, then come back and change the oil. They said the gears need to break in for the first 500 before I really get on it. Also a lot of people have told me that with a lower gear ratio, f-bodies tend to blow out their rears. My questions are; do the gears really need to be broken in? Also, have you guys ever blown out your stock rears, do I really have to be carefull or can I just punch and shift it as if it were stock gears?

Thanks to all

02 WS6
-slp loudmouth, MAF sensor, JBA headers, K&N FIPK, Hypertech power programming, 160 deg. thermo, 4.11 gm gears, BBK throttle body, MSD wires, Double Adj. PHB, Anti-squat kit, Eibach sportline.

 

Yes, the 4.10 is a weaker gear because the gear teeth are much smaller and can't hold as much strength. You need to break them in carefully otherwise you may snap some gear teeth and trash your new rearend.

The most important thing to remember when breaking in gears is that it's not only the gears you're breaking in. It's the new rearend fluid as well. If fresh rearend fluid is brought to too high a temperature before breaking in it will spoil its protective factors and you'll thusly have a weaker fluid protecting your gears.

Here is what I recommend for breaking in your new rearend. It's a bit overkill but it's better than having to buy new gears.

- For the first 100 to 150 mniles don't drive for more than 20 or 30 miles at a time. Let the rearend cool for a good 20 to 30 minutes between runs so the fluid has time to cool. No highway driving. Stay below 40 MPH if possible.

- After reaching about 200 miles you can drive pretty normally but don't romp on your gears yet and avoid highway driving. Try not to drive more than 50 or 60 miles at a time. Remain off highways.

- After 500 miles take it on the highway. Get a good 100 or so miles at highway speeds. Romp on them a little. This will make sure they're nice and broken in.

- Get your rearend fluid changed. Follow the first two procedures. Gotta remember that you're breaking in new fluid again.

After hitting about 200 miles or so drive however you want.

 

When I had my 4.10s installed recently, the mech. said to drive it like I stole it.

On the other hand, my bottom end went out with only 8K on the odom, so maybe listening to my mech. might not be the best course of action.

I've never seen instructions with a new car that say "take it easy with the rear end".

Seems to me that if they are good gears and set up correctly, that breaking in more than 100 miles with a couple of cool off periods would be all that is necessary.

As far as 4.10s breaking. Seems anytime you pop the clutch (esp. with power) that you jeopardize the integrity of the rear end with a stock 10 bolt system. JMHO