Ryan, picked up a posi unit for his 8 1/4 in his truck(85 D100) Is this something I can tackle, since the pinion does not have to come out? (He will be keeping the 3.91's) Can I just swap the ring gear and set backlash and change the fluid. Any insights are greatly appreciated.

Rick Covalt

Best to keep ring and pinion as a set. You can pull the carrier , remove the ring gear and swap it onto the Suregrip carrier.....

You will still have some setup to do.....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Rick,

Yes, that should work. No pinion diassembly required, and just put the old ring on the SG, drop in, and set backlash and check pattern. Will probably want new brgs on the carrier?

Lou

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Home of Slant6-powered fun machines since 1988

Ok, That is what I thought. I did forget about the bearings. I will have to check with Ryan and see if he has them or if they were already on the S.G. Probably not,

Thanks Rick

I would check the backlash on the old setup, before taking it apart. Then reset to the same amount when reinstalling. When installing the ring gear on the "new" carrier, make sure there are no burrs on either part, It takes very little to induce runout.
PS: check the backlash in several places, like about 90 degrees apart.

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Charrlie_S
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The backlash on the new installation must be greater than the old setup. The ring gear teeth have a step worn into the face. If the backlash is less on the new setup, the pinion teeth edges will be riding on top of the step. It will be noisy and gear teeth can break. Setting it the same is risky since the same can happen. The only way to guarantee face-to-face surface contact is to increase the backlash a small amount. 0.001" or 0.002" increase is enough. Note that the gears will likely make noise, since the mesh pattern will not be identical to the wear pattern. This happened on my Ramcharger when I installed a SureGrip.

Here's an illustrated "how-to":
http://slantsix.org/forum/viewtopic.php?t=36242

Ken