built67

^hahahaa...i have quality parts in the rear...motive 3.70 gears (motive is owned by Strange), Ford Racing Trac-Lok, Currie Axles. It's all 31 spline. Im going to wait a little to break it in just to be cautious but what is annoying me is the fact that the rear is built and painted and to change the fluid i have to rip the entire rear apart again! the 9inch im using is out of a 69 mach1 and i didnt think to put a drain plug in it while i had it apart the first time.

chris66dad

I was given the following instructions from my builder:
Break in procedure:
1) Do not use synthetic oil with a torque sensing differential. Be sure to add a friction modifier to the oil.

2) If you have new gears, then run the car in drive on jackstands for 15 minutes and let it cool for 1 hour. Repeat. The heat up/cool down procedure is for the gears, not the limited slip.

3) If you have new gears, take it easy for the first 150 miles. For extended life change out the oil after the 150 mile break in.

4) Do a few figure 8's or circles in both directions to get oil to all the clutches.


I bought a oil transfer pump from harbor Freight for $5 that got almost all of the oil out in less than 5 minutes. It is inserted in the oil fill hole. Best 5 dollar investment I made in awhile
http://www.harborfreight.com/multi-u...ump-66418.html

MustangBradley

Does anyone know how Ford breaks-in the rears on new Mustangs? Do they even do it? Is the fluid changed out during first service?

KMatch

Factory cars are assembled in a manner knowing they will leave the car hauler and be driven like hell. Warranty sorts it out. This is what I based my earlier response to - going easy on it for 500 miles is nice (factory preferred) but romping on it a few times is expected. Your gearset and bearings are extremely hard metal and to "see" wear is a hint of damage, so breakin really has little meaning here. The only reason for the oil change, and that's still not a hard core requirement, is due to clutch material floating around during breakin. Yep, the clutches have some breakin time but that's not affected by load, that's affected by making turns - more so turning under load. So, to baby it is nice and makes us all sleep better, but to light the tires up for a city block will make no difference in the rear, new or old. Any parts hanging out the side afterwards wouldn't make any difference whether it was broke in or not.

And again, to cover my ***, "with a properly setup unit with quality parts" as a disclaimer.

KMatch

2010 Mustang Gt shows synthetic axle lube, friction modifier required, and only changed after 150000 miles in the 7.5 and 8.8. Not applicable to the one posted here, but an example of how Ford ships it and forgets it for 150000 miles and THEY have to warranty during the normal coverage period.

JMD

Jim's 66 Grab-A-Trac 5s and nothing else, no wheel hop at all...

And we thrashed the 9" Currie right from the get go, because we are just no damn good that way....

putz54143

i did one just for you tonight on the way home

Norm Peterson

Patience, grasshopper. Patience.

New gears still need to do a little micropolishing of each other in their actual installed positions, and this process generates heat. Quite a lot of heat, which is not good for the fluid or the gears themselves if it runs too hot.

After a gear change in one of my cars it took a couple of 25 - 50 mile easy drives for the diff cover to get down to the point where you could stand to even touch it. And a couple more before you could do more than just touch it and have to yank your hand away.


Norm

MonsterBilly

I say light those babies up! SmOKEM IF YOU GOT EM!!!!!!!!!

chris66dad

I wimped and followed the builders advice for break in of the pumpkin. But now all bets are off and I am finding I need new tires. And only on the rear.... strange, can not figure out why.