What is the accepted practice for breaking in a new ring and pinion. Also, should this be done with dino oil rather than synthetic.

Dyno oil yes. You'll want to change it after about 500 miles, Break in. Was told to be easy on it for the first 500 miles, short trips but enough to heat up the complete assembly and allowed to cool completely (30 miles run, 3hrs cool down) Bet Freddie will be in to give you the low down.

I'm moving this to the trans/rear end section so the experts will see it.

Jody

BGH will give you the best answer, but here's my $0.02:

Break in has to do with work hardening the gears. If the differential gets too hot, they may get softened instead of hardened.

The most critical part is the first drive. Keeping it under highway speeds, go 15-20 miles and then allow the diff to cool down all the way.

According to Randy's R&P you can use synthetic oil.

HH,
What does the manufacturer of your gears suggest ?? That is what I would do.

I usually run it in both directions for a few minutes with jack stands under the housing to get the oil circulated well before putting a load on it. Then I drive it about 5 miles and let it cool completely. Then I drive it about 10 miles and let it cool again. Then I call the customer and tell them to come get the car and drive it home and let it cool. Then I tell them to drive it easy for about 500 miles and then do what they want with it. I use Amsoil from the beginning.

BGH,

For future reference, how long do you need to let the rear cool to "cool completely" in between drives?

Victor

I believe he will answer "Let it cool back to ambient temperature." As in let it cool overnight.

I would say an hour or two. I don't think that the break in period should be as complicated as some people try to make it. If you look at a new ring & pinion you will see a dark gray finish on the teeth. This has a slightly rough finish to it. As long as you take it easy long enough to wear this finish smooth I don't think that you will have any problems. It shouldn't take more than a few miles to wear the finish smooth on a new set of gears. You just don't want to over heat the oil in the beginning, so drive it a little and let it set for a few hours and drive it again. If the gears are in a truck that will be used for towing then you need to put a few more miles on it before you hook a trailer to it. I use Amsoil 75W90 Series 2000 in a car and Amsoil 75W140 Series 2000 in a truck.

BGH,

Thanks for the info!


Everett, I am still laughing from yesterday! (do it again, do it again!)


Victor