Finally got the differential fixed on my pickup today It all went well, the howling was from a broken possi circle thingy that allows for slipping so pieces of metal were all over and destroyed my right axle bearing. Nice and quiet ride now. Haven't put my foot on it because the "Warranty" says they will be able to tell if it's been abused or whatever the first 500 miles or something. I'm very happy with having a quiet ride though

But I wanna know, is it true when they say it has a break-in period and I have to stop driving it every 20 miles to let it cool down for a couple days and also that there should be no moderate acceleration or anything for the first 500?!

 

You really shouldn't romp on it for the first 1000 or so. You need to get a good uniform wear pattern on the gears to make sure they don't make noise or cause other issues down the line. I kept mine under 2500 for the first 1k miles. The gears do go thru a few heat cycles

 

That's BS. It should be no different than when the truck was new. Could you imagine telling a new buyer that BS?

 

It is actually true that you should break them in through a period of driving and cooling phases. However, this is easily accomplished through normal daily driving habits. So basically, the break period consist just not driving them hard and not driving for long distances within the first 500-1000 miles or so. In other words, your first trip after installing gears shouldn't be a 8 hour drive across the state with no stops. Otherwise, if you just drive around town or whatever like you probably normally do, they will be fine.

Definitely change the gear oil after 1000-2000 miles though. The gears will generate a lot of metal shavings as the teeth pattern emerges, and that needs to be drained out. I've had gears installed twice on my truck (4.10', then 4.56), and it is amazing how bad that gear oil looks after you've driven on new gears 1000 miles or so. I'm not talking just a drain and fill either, you need to get all those shavings out. Both times I did my first fluid service, I removed the cover, and let all the fluid drain. I jack up each side of the truck for a few minutes to let any fluid in the tubes drain into the housing and out. Then I sprayed out the differential housing with brake cleaner till it was shiney inside, not a spot of the old fluid left. This is how the shop that installed my gears does it, and they do thousands of gears every year.

 

I wasn't arguing the break-in part. It's the "20 miles and let it cool for a couple days" part that is ridiculous.

 

just romp it im curious 1 time wont hurt

 

I'll save his gears.

I have 4.10s on 265X70X16's.

it's the *****. I'm seriously thinking about going back to stock tire size and slamming this 2wd to the ground.