[EkS]

Hey guys, well I might be swapping my 12bolt rearend with a posi rearend. I was wondering if the rearend needs to be broken-in, in anyway? I've got the gear and posi lube already. Any suggestions are greatly appreciated.

 

[sinned]

NO-that is what guys who didn't build it right tell their customers with problems to buy themselves some breathing room. Think about it-do brand new trucks have a "break-in" time.

 

[EkS]

Originally posted by dennis68:
NO-that is what guys who didn't build it right tell their customers with problems to buy themselves some breathing room. Think about it-do brand new trucks have a "break-in" time.

OK thanx, my is built right, just making sure.

 

[LeoP]

Originally posted by dennis68:
NO-that is what guys who didn't build it right tell their customers with problems to buy themselves some breathing room. Think about it-do brand new trucks have a "break-in" time. [/QUOT

brand new trucks have some mileage on them when they are purchased, don't they?

 

[77 cruiser]

If you get gears from Richmond they have a breakin procedure they want you to follow. Besides what can it hurt?

 

[engineguy]

EkS,
Yes, the ring and pinion should be broken in following the gear manufacturers instructions. Differentials (and other major parts) in brand new vehicles are assembled in very controlled environment, usually by robots, therefore break-in procedure is not normally necessary. But, in a situation where the part is installed in a used case along with other used parts such as carrier, spider gears, etc., then break-in is very necessary.

 

[bulb122]

When I had my axle rebuild, they told me no long trips, and let it cool between drives over 20-30 miles. They also told me not to hammer on it for at least 500 miles.

Definately check with the gear company or the shop that rebuilt it (that is if you don't do it yourself!)

 

[big gear head]

Yes it does need a break in. Drive it one time for about 15 minutes and let it completely cool. Drive it again for about 30 minutes and let it cool. Drive it normal for a while and them it should be all right. The break in is different, depending on who you ask, but it does need a easy break in before you get on it hard. The surface of new gears is a little rough from the heat treat process and needs to be smoothed out a little before you abuse it.

 

[Pat Kelley]

BGH, what about a car not driven on the street? My guy said to run the car on stands for about 30 minutes, cool and do it again, that is what I did. I hammered on it at the strip after that.

 

[JWagner]

What Pat Kelley has suggested is pretty much how Dana used to break in their axles in the test lab. They were put on a test "dyno" and run no-load for some time to polish the gear teeth prior to doing oil evaluations.

 

[big gear head]

A drag car doesn't run long enough for the gears to get too hot. Breaking it in on stands should be fine.

 

[sinned]

I don't know about aftermarket parts but when I build a Dana or Chrysler corp. it is ready to beat when you pick it up, no factory diffs have no break in and are not run prior to customer delivery. If you are lucky they have 10 miles on them and it wasn't nice and easy miles. I have heard some folks heta cylcle their new gears, I never have and have never had a gear failure either.

 

[vettefinderjim]

On my old road race CORVETTE, we did easy but steady laps on test day when we had a new diff.

Then drove it hard on race day. We changed all the fluids after the first race weekend. Lots of fine metal shavings are not uncommon. For gear oil, we used CHEVRON Ultra 80-90. Redline is also very good. Always ask for the premium top grade diff fluid. Cheap insurance. And the GM additive works well also.

 

[michaelem]

had my diff rebuilt a few years back and after driving it home from the shop about 15 miles the housing was very very HOT!