I'm considering putting a limited-slip differential in the 901 transmission in my 914/6. How hard is this to do? Is this just a slip-in, or are there some tricky procedures here - like setting the pinion backlash?

I looked into doing this myself...

I asked alot of tranny experts and got the same answer...and I asked the guys the were not looking for my business.

Each case is different...therefore you need to put in thrust washers to align the ring and pinion and get the correct backlash.

This requires a special tool. The tool cost quite a bit.
This process is best left to a pro.

There are a few guys in the states, one here on the east coast, one in colorado, and probably more than one inCA.

Send it to them, its an assemble, measure, dissassemble...new shims,,do it again..

So, send it to a pro.

Rich

I think the special tool is only a dial indicator.

I've set up ring and pinions before and don't think it's that hard to do.

But, I haven't read up on the procedure for the 901 to determine if it's a particular pain.

Last time I looked into getting a LSD installed, it was gonna run around $600 to do it right. That did NOT inculde the cost of the differential, just the labor...

-Josh2

It does take special tools to do it right on a 901. You can get real close by transferring all the shims and the ring gear from your current differental. It will work fine, but it may make a small amount of noise.


I would recommend doing it right, for longevity purposes.

QUOTE (groot @ Jan 30 2006, 01:26 PM)

I think the special tool is only a dial indicator. I've set up ring and pinions before and don't think it's that hard to do. But, I haven't read up on the procedure for the 901 to determine if it's a particular pain.

I agree.

It seems like a properly set up dial indicator will do the trick.

Please post the specs...I could not find them.

Rich

QUOTE (groot @ Jan 30 2006, 10:26 AM)

I think the special tool is only a dial indicator. I've set up ring and pinions before and don't think it's that hard to do. But, I haven't read up on the procedure for the 901 to determine if it's a particular pain.

It's a dial indicator, a fixture, and possibly a turning torque wrench. The fixture's been effectively NLA for decades. When it WAS available, it was a couple thousand bucks, in 1970 dollars. The Cap'n

I know a guy. He's got all the factory tools for it. I can ask if he wants to do it. He's in colorado.

QUOTE (Cap'n Krusty @ Jan 30 2006, 12:34 PM)

QUOTE (groot @ Jan 30 2006, 10:26 AM) I think the special tool is only a dial indicator. I've set up ring and pinions before and don't think it's that hard to do. But, I haven't read up on the procedure for the 901 to determine if it's a particular pain. It's a dial indicator, a fixture, and possibly a turning torque wrench. The fixture's been effectively NLA for decades. When it WAS available, it was a couple thousand bucks, in 1970 dollars. The Cap'n

I have a small beam type torque wrench in inch-pounds to set the bearing preload.


I bought the dial indicator fixture off E-bay for about 50 bucks. If it was a couple thousand, I got one hell of a bargain.

Ok. It's Al LAger. I almost forgot that I had a banner with his name on it.

I can't see why anything more than a dial indicator would be needed. For guys that setup gears on a regular basis, it's more an issue of feel than a given measurement. Some guys like it a little loose, some a little tight. You can actually get a pretty good sense of it by rocking the ring gear back and forth on the pinion. You can always take a measurement before pulling the stock diff and set it to the same with the LSD, shouldn't be too difficult. It's not the black art that everyone makes it out to be.

If your only installing a limited slip, and not messing with the gear stack, the pinion depth wont change. You can set the ring gear by using some white grease or prussian blue, and looking at the wear pattern.

If your using an after market LSD, be aware that some need substantially more shim than the stock open diff. Measure the width of the stock diff assemblies with the shims in place, then measure the width of the new assy. and calculate how many additional shims you need. Apply the dye or grease to the ring gear, install the diff. bolt up the side cover, put the tranny in gear, rotate the input shaft in order to spin the ring gear once or twice. Unbolt side cover, remove diff and look at pattern in the dye. the pinions should wipe in the center of the ring gear. If the pattern is off you need to add or remove shims

I installed a Quaife early 915 diff in a 901 box, this is where I found out about the drastic differences in width between the stock and aftermarket units.

I have thefactory manual also if anyone wants a scan

QUOTE

For guys that setup gears on a regular basis, it's more an issue of feel than a given measurement.

werd

We used to set up our g50/50 all by the book, but we kept breaking pinions (this is on the 935) so after the third failure, the ring and pinion were set by feel and the dye test

I looked over the manual's discription of setting up the R & P.....which is essentially what you have to do being as the ring gear carrier is new with an LSD. It's confusing enuff that I wouldn't try it without some adult supervision.


There's a local guy that can do it. I hope to watch him do mine. Since I'm prolly overloading the R & P, I'd be smart to have him do it righ and give the poor things a fighting chance.

Just did one - call me @ 408-842-0616.

Not hard but there are some tricks.

Ken