I'm using a T type case from another LSD swap but I have to change the ratio. I sourced a 3.90 R&P to match my front final drive ratio and have a question about the pinion depth. I don't have the dummy shaft or the special gauge to measure the depth and I'm pretty sure I'm not the only one to do this without the special tools. Can anyone tell me what the depth should be from the machined end of the case? The special gauge looks to reference from there.

 

I kept the pinion bearing and washers from the new pinion on the new shaft, with the adjusting washer in place and used the preload washer from that pinion as well. Would I be better off using the washers and sleeve from the pinion I pulled out? I have the preload correct but I can't verify the depth being correct to allow the carrier to go inplace with minimal shim relocation.

 

Any insight is helpful!

 

Jay Storm

I've changed a few 3.7s to 4.11s.. I've never removed the pinion shaft from the 4.11 case..

I put the new ring gear on the 3.7 chunk, put that in the new case with the pinion assembly left completely alone, then put the races for the 3.7 on the new case, bring all the shims with it to a driveline shop, and plunk down $50 and get that all done for me... hope that helps...

 

BTW a shop could adjust the front-back for you, as well as the side-side like I have done, at the same time.

Or you can use some bright red grease and do a pattern test on the gear teeth. You are simply looking for the best ring & pinion alignment. Special guages are handy, but trial and error with some grease patterns gets you there too.

 

GD

Thanks for the replies. I checked the pattern with grease just to see if I could get an idea of where I was at. It's running more toward the tail of the drive side and just about centered on the coast side. My backlash is too loose. I didn't put an indicator on it but it's probably in the neighborhood of 1.0mm instead of < 0.3mm....

 

I pulled the pinion bearing off both shafts I had, to measure both adjusting washers and pinion heights and they're both the same. Preload sleeves are the same but the washer for the sleeve is different by about .2-.3mm I'm getting good preload so I'm not worried about that right now. I'm going to bring one of the pinion adjustment washers to a local dealer and see if they have anything in stock. I've got a good enough rapport with the service manager that he'll work with me on this oddball stuff. Maybe I can talk him into a handful of washers and buying what I end up needing while renting me the dummy shaft and special gauge for an evening....

 

The kicker for me is....I'm doin this at work during breaks (generously loooong breaks;) ) and I wanna keep this stuff in my shop where it's warm and out of the lady's sight..... Once this is done and in...I have to figure out how to do the front LSD next!

 

 

Jay Storm

Got it setup finally. I shopped around the maintenance room and found shim washers that are perfect for setting bearings up. I added a shim under the pinion bearing and through trial and error, got my backlash down to .025". It's slightly on the tight side of FSM specs but feels fine. Mesh pattern is about spot on as well. I may break it down one more time to change the shim but I think I'll wait to see how it drives first. I've had this sucker apart and back together so many times this week it's almost as quick as changing my oil....

 

Hopefully I'll be able to get it into the car here soon and take advantage of some LSD action before this snow melts!

 

Jay Storm