New rear gears... is there a break in period?

I’d think the heat cycle part might be more important than the “500 mile” stipulation. However, I’m not really aware of any instructions when you take delivery of a brand new car that says to limit trips to 20-30 mile intervals to set the wear pattern on the ring and pinion - or run in the bearings.

I would do the break in procedure on the rear end clutch pack though. I believe it’s driving in a figure 8 pattern at lower speeds to wear them in.

With that being said if the rear was set up properly, there really shouldn’t be any problems regardless. I’ve never given my junk a “proper” break in, and never had any issue.

If you’ve got the time, do the break in procedure. A couple heat cycles can’t hurt before flogging it.

We never broke any in at the dealer
The cars and trucks went right the hell back into service
They (new gears) come lapped in and the Ford service parts are supposed to, be a 7 on a scale of 1-10 for noise
The ones that come down the line to assemble cars with can be 1-5 and noisy as hell
Similar to the class of fit with bolts (remember the old inch and a steenth lug nuts for the F250's that took 90 lbs. just to screw them on?)

I drove my car conservatively for the first few trips after I installed the 3.55s in it...then had some fun. No issues to date and the rear is quiet.

The shop that put 3.55s in my ‘86 told me to take it easy for 500 miles.

Bill

500 miles is what I’ve been told. I’ll find out once I pull the cover and see where I’m at! Just did a rebuild myself.

There's always been a lot of debate on this topic. Many people take them out immediately and do burnouts. Many follow the 500 mile breaking procedure. It seems that the gears that are set up correctly work well no matter which method you follow.

It will be interesting to learn which procedure you follow and how it works out for you.

If you are going drag racing what cha gonna do?
Run what cha brung. Paint a stripe down both axles
Make sure it is set up correctly and run it

Some gears are more sensitive than others. Depends on who makes the gears.
Personally I never got a set of Richmond gears to be quiet. Every other manufacturer of gears I have had no problem with, Ford, Ford Performance, Yukon, Strange, Eaton ect, ect.
On my racecar, I put the new gears is, car on jackstands, trans in high gears and let it run for 15-20 min.
After that it is off to the race track and have at it.

Exactly Bullitt, do that before every race to warm up the gear lube