Checking Limited Slip

#1

Somewhere around here there is a thread that talks about checking the diff by putting a wheel in the air and putting a torque wrench on the axle nut. And a couple searches didn’t find that thread.

How much torque should you be able to put on a wheel before it turns?

Easy way to do this…Not having a socket to fit the axle nut I put my torque wrench on a lug nut such that it increased the size of the lever arm by ~2" or ~10%. Then I added 10% to the # on the torque wrench. Not perfect, depending on the design of the torque wrench, but pretty close and darn easy.

I got 55ft lbs (50 on the wrench).

#2

I think you’re good, my car was about 30 ft/lbs.

#3

That’s well within spec Scott.

Mine was good cold, but this past week at CMP it started slipping bad in right handers and then I started getting a bad vibration under load in right handers. On jackstands, the rear end felt pretty “skippy”, firm/loose/firm on rotation.

Anyway, I went ahead and ordered Chuck’s complete rebuild kit. I’ve already pulled it out and taken it apart, just waiting on the goods.

My diff clutch plates were worn completely out, by the way. Bearings all look and feel good.

There’s a GREAT pdf photo guide to doing this job on Chuck’s site too!

#4

Link to Chuck’s site for those of us who haven’t been around recently? Thx.

#5

Here’s a link to the clutches on the store site:
http://www.factory3performance.com/shop/shopdisplayproducts.asp?id=59&cat=Differential

And here is the writeup:
http://www.factory3performance.com/product_info/E30_Limited_Slip_Clutch_Disc_Replacement.pdf

The previous thread that talked about measuring diff resistance… I don’t know that there’s a scientific method behind this, but for consistency, most folks seem to be checking it with the car hot, in neutral, parking brake off, jack up RR wheel, put a 30MM socket on the center nut if you’ve got one, then dial in different amounts of torque until you see where it rotates instead of clicks.

We checked about 6-7 cars at the August RA. Several were down in the 25-30 range (all diffs of unknown condition) and the others were in the 55-63 or so range. These were mostly recent rebuilds.

For those who have only a 17mm socket, Ranger supplied a reasonable-sounding conversion/adjustment factor. But basically, I would say if it’s below 45 it’s bad, and higher than that is probably OK.