Dubious Torsen diff rebuild, risk of running with unknown backlash/preload?
 

I picked up a Torsen diff for $250 that was rebuilt (bearings replaced) and I'm told it was torqued within spec, but the backlash and pre-load were not set. Since I've already got it, I'm tempted to go ahead and install it and see how bad it could be. But I don't want to damage it, nor do I want to waste my time if it's going to immediately need to be removed and come apart to have the backlash and pre-load set.

What would you do in my situation? Is there a chance I get lucky and it doesn't make any noise?

Thanks!!
Dylan

Setting pre-load/backlash is pretty easy on these. Also, grab some gear marking compound. Not worth it to have it fail, imo

3 potentials here:

1: lash is set ok - result, perfectly fine

2: lash is a little bit off - result, diff works but crown/pinion wear faster

3: lash is way off - result, crown/pinion wear very fast, teeth break off and potentially get into the side gears and grenade the whole thing


If it's been pulled apart and put back together again, it's pretty unlikely the lash is corrrect.


I'd just check it, or if you dont have a dial gauge etc, take to to a diff shop for them to check it.

Last time I had a diff assembled it cost me au$150 for them to acid dip the casing, install the centre and check/adjust/set the lash, then seal it all up.
You should be able to get a pro to check it for relatively cheap, since it's assembled, and just needs a check over.

If you're concerned and aren't sure what to look for, take it to a pro or someone trusted. Ask them if you can look over their shoulder to see what to look for in the future.

Make sure when you take it to a "pro" he gives you the before and after measurements. A lot of these guys in shops are actually brain dead and do not know how to set things up properly.

As long as the shims that came with that diff housing are still on the pinion the depth is probably just fine. I'd double check the pre-load. Back lash is super easy to do on these with the side adjusters. I don't like the spec to check case spread, takes a big set of mics to do right. Anyone know how many "holes" it takes to get the carrier bearings pre-loaded correctly? Ford 9" use a spec like that.

I bought a giant mic off eBay for dirt cheap. It doesn't need to be extremely accurate or calibrated. Just repeatable.

As others have said. It is pretty easy to do yourself.

Check the backlash with a dial indicator. Then check the pattern using some white lithium grease or prussian blue compound. If the pinion bearings have been replaced then it needed a new crush sleeve or spacer made to set the preload. It would also have needed the shims changed to set the pinion height correctly. The side bearings are preloaded with the side collars which also adjust the backlash.