Will g80 from 2013 fit my 1994

[Schurkey]

Don't you have to check the wear pattern with the paint?

Not really.

Isn't the pattern based on the the pinion depth?

Pinion depth, and backlash. And he's not changing pinion depth 'cause he's not dicking with the pinion at all. Which leaves...backlash.

Used gears are notoriously difficult to set-up properly when moving both the pinion and the ring gear. But he's using his original pinion, in the original housing, with the original depth and preload. And he's using the ring gear that's worn-in with that pinion, changing only the carrier and bearings. The only gear adjustment he's got to do is get the ring gear in the same position it was with the old carrier 'n' bearings; and that's done by getting the same backlash.

I doubt both carriers are exactly the same, but maybe you get lucky and get a good pattern if you swap them? Might be worthwhile to check though?

His difficulty will be getting carrier bearing preload, and backlash both correct. The new carrier may need different preload shims or adjustment to get the preload AND the backlash right.

 

[Erik the Awful]

I've never built a differential, but I have heard of an old trick for setting pinion depth. Take a 1"x6" strip of notebook paper and pass it through the gears. If should come out uncut. Take 1"x12" piece, fold it in half (1"x6"), and pass it through. It should have the tooth pattern, and every other tooth mark should be cut. If it cuts every tooth, it's too tight. If it doesn't cut, it's too loose.

If I ever get around to changing the bearings in my Mustang's diff, I'll shoot video.

 

[BulldogSS]

From my understanding the shims are mostly there for loose tolerances in the housing. The ring, pinion and carrier are much more precisely machined relative to the housing. If I were to put the same carrier in two different housings a good place to start would be using the original shims from that particular housing. I hope that makes sense. What I’m going to do is measure backlash on my current open diff set up. Then swap carriers using the shims from my original housing and adjust from there. Hopefully that will be a good starting point. I’m still not sure how much difference is acceptable from my current backlash.

 

[Schurkey]

Yup. Good starting point.

 

[BulldogSS]

Yup. Good starting point.

Any idea what amount of backlash deviation is acceptable? I’m thinking .002 either way??

 

[Schurkey]

Any idea what amount of backlash deviation is acceptable? I’m thinking .002 either way??

"New" gears would be set up with only .005--.009 backlash. As the gears wear-in, the backlash might increase a little. You'll see when you get the cover off and start measuring before you pull the carrier out.

I'd say .002 difference from what those gears wore-in with would be too generous. Try to get closer.

The service manual is saying that .003 difference in shim thickness would result in .002 change in backlash. In other words, if your backlash is "off" by .002, move .003 in shim thickness from one side to the other--this keeps the preload the same while loosening/tightening backlash.

 

[BulldogSS]

Thanks for that info. I’ll do my best to get it “dead nuts”. Knowing .003 shims change backlash .002 should be a big time saver. As far as bearing preload. I’m guessing it’s best measured by the rotational torque on the pinion yoke?

 

[Schurkey]

You need the service manual for this operation. It's all in there, except you'll have to make allowances for used gears rather than new.

Preload on the carrier bearings is going to be set with feeler gauges. Rotational torque on the yoke is for pinion bearing preload.

 

[BulldogSS]

Thank you

 

[Frank Enstein]

I feel that the tooth contact pattern is more critical than backlash. Please check both before disassembly. The Ratech brand shim kits are what I recommend.

https://www.summitracing.com/parts/rat-1105