I didn't have a backlash problem when I pulled my diff. It was the torsens. They just get loose and sloppy over time. Before I pulled the diff, I got lucky and bought an S4 turbo II diff on ebay for $60.00. No more play! I also replaced the solid diff bushings with the Powerflex units. Sooo much better now.

 

When I broke my stock differential I pulled it and the backlash was pretty loose, I put in an s2 and tightened up the backlash. Felt like a brand new car, I had no idea how much slop I had until it was fixed. My ring and pinion looked fine aside from just feeling loose.

 

so are the torsens not rebuild-able? ive got a little slop on my project car diff that id like to eliminate... i just happen to like the torsen (when working properly). Did they change the torsen type for 99+ FD's or its all the same stuff? At least a used japanese unit would have lower miles

 

You can't rebuild the torsions, not realistically anyways. Usually the slop is between the ring and pinion. That's where most of it was for me anyways. Some people will say you have to replace the ring and pinion if there's slack there, I don't think that's always or even usually required. The bearings wearing also have an effect on the backlash. The fd uses shims for adjusting the backlash, it's not necessarily difficult to adjust but it takes trial and error and the shims are rather costly. I think you can reduce a lot of slack by tightening the backlash. You won't know for sure until you're in there.

 

If there is too much backlash after replacing the bearings the cause is gear wear in the ring and pinion. You can adjust the backlash and probably get good results but technically the gear wear causes lost efficiency and it will wear again faster than if it were new gears.

David

 

I am very happy to hear this! not to be messed up but now I am 99% sure its my torsen. Looks like its time to buy a new lsd.

 

Surprised no one has mentioned using the 8.8" IRS diff out of Ford Cobras, Explorers, Lincolns....

 

That's because that swap requires a ton of work. Your also talking new drive shaft and axels. Eventually I will turbo my NA 20b to around 600RWHP. My $60.00 turbo II clutch style diff will more than support my needs!

 

and repeatedly replacing blown differentials isn't? Do it right, do it once.

The Ford unit is a popular swap for those making 600 RWTQ. After you've swapped the rest of the drivetrain the differential isn't that much more work.