Jim bailey - 928 International

The matching pinion gear (it was an automatic) had been misplaced so the orphan ring gear has no value or usefulness. And yes we do have a lot of ring and pinions along with lots of other bits and pieces !

PorKen

I have an LSD waiting to go in, too. I hope you take lots of pics!

Backlash adjustment is side-to-side shims?

Garth S

I recently installed a Trac-Loc diff in my F150 4x4 - and as Imo000 and FBIII indicated, measure the backlash first. then xfer the ring gear, and left-right shim to get the same backlash.
Do note however that the carrier bearing preload is/can be sensitive to the total l + r shim stack, and is independant of the lash adjustment; however, I don't know if bearing preload is a big deal with this unit .

PorKen

Garth,

Did you use a dial indicator, or paste to check the backlash?
...

Bill,

You might want to disassemble that unit, and check that the spider gear axles are in one piece. I sold Brendan my spare (eBay) LSD, and one of the axles was broken. (Parts are still available.)

Bill Ball

I plan on using a dial indicator. I think the bearing preload is dependent on the total shim amount, whereas as backlash is left to right, but I need to review this. Also, the WSM says the bearing preload should be done WITHOUT the pinion installed. I'm hoping to skip that. :-)

Garth S

Ken,
I used a dial indicator for backlash: I skipped the 'paste' step for that is more useful in establishing the power/coasting contact pattern of the ring & pinion - and is established by shimming the pinion depth. Generally not ( as ) essential when thansferring the same ring gear.

Garth S

Bill, if that is what the WSM says regarding carrier bearing(s) preload, I'm guessing that you could get the correct total shim stack to set preload without the ring gear: then knowing the correct total, install the ring gear and divide the stack so as to restore the previous lash.
Yes indeed - you do not want to touch the pinion gear ....

Imo000

Well, yes and no, backlash is commonly called “free play” but it is adjusted by the side shims. When changing the differential gear set, there are only 3 things to check for. Pinion depth, backlash and bearing preload. The pinion depth will not change cause you are using the same gear set. Setting the backlash is pretty simple. You will need to buy a shim set that contains a variety shims with different thicknesses. You’ll have to use them to make a combination that will give you the required backlash and the required amount of preload. If you haven’t done this in the past, this is best left to a pro. There are a couple of specialty tools that are required for a gear setup. A dial indicator with a magnetic base, gear compound. I’ve done several rear end changes in the past but none were on a 928. However, the theory behind the installation of a new gear set is pretty much the same regardless of vehicle type. There are tons of write up on the net and the best would be to research the procedure for a rear wheel drive car that has an independent rear suspension (Corvette, Supra, RX7/8, etc).

I hope this helps!

Bill Ball

Thanks, Garth and Imo000. CS Mo told me his diff switch did not require shim changes. I've heard the same from a few others. If it's the same case and gear set and the diff dimensions are the same, this may happen. Obviously, when you swap gear sets, the it's a whole new ballgame. Here's hoping.

BC

Yes, I was just doing to say t his Bill. Please take it apart carefully and inspect what I would call the "planetary" gears in there behind the clutch plates. Maybe buy new clutch plates as well. I bought a new shaft, and the sticker said '96. I'm not sure how many are left, but its something to pay attention too. It could cause serious "implosion" issues if one of those tuny shafts (with cutouts like lincoln logs btw) were to crack. The one I had from Ken was broken for a LOONG time. It couldn't have worked very well when in "slip" mode. FYI.

Bill Ball

Brendan and Porken:

Thanks for the inspection advice. The LSD I got previosuly from 928 Intl was in good shape, and they do warranty their used parts to be in good working order. Externally this one looks very nice, but I will look at the innards.

BC

Be carefull. They seem to be kind of.... Sprung. Like there is pressure pushing the two halves apart. You'll need a press to put it back together or some helpers with clamps.

Bill Ball

Thanks again, Brendan. I've had open diffs apart, but not limited.

borland

Bill,

I have a MS Excel spreadsheet that I created and used to setup the backlash on my car. If your interested, send me a PM with your e-mail address.

Like they said, the only adjustment you'll be able to do with the transaxle in the car, is backlash. The WSM procedure calls for torquing to spec, the side transmission cover bolts. If you don't, the preload and thus backlash adjustment won't be correct.

borland
90' S4, Slate Metallic

IcemanG17

Bill
When you gonna install it? Sounds like fun!