Utah Boatail
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Postby Utah Boatail » Mon Feb 27, 2017 3:24 pm

Looking for some advice/recommendations. I have a 1972 Rivera with the stock 2:93 rearend. I was able to purchase a posi rearend from a 1973 that has the same gear ratio, last year on craigslist. So, I have two rear ends, the stock "open" carrier and a posi, both with the same gears. My first thing I would like some opinions on is, is this worth the effort of changing them out, just to obtain a posi?
To help with your opinion, the car has 70,000 original miles. It is completely stock currently. My restoration is a very "slow as I go" process. When I get to the point to pull out the engine and do a "refresh", I won't be looking for anything crazy. I will end up with around 450 to 500 HP when I am done. Normal driving for this car, is just to local car shows, charitys, etc.. I am not looking to race it and the 2:93 gears, at least for me, seems good for the better cruising mileage. The beast will easily break the tire loose from a hard start currently. So, my hope was to just be able to put more power to the ground (less spin) out of the hole, but yet still maintain reasonable rpm's on a cruise. I know how difficult it is to find the "unobtainium" 3:42 rear end from these years. And, even if I could find one, I would probably consider eventually installing a Gear Vendors unit to get the best of both worlds. Besides maintaining cruise rpm's, the other advantage I have is that, with both units being the same gear ratio, I would have a spare set, in the unlikely event of damaging one set, at some point.
With all this, any thoughts or ideas are welcome and appreciated in advance. If I do go ahead and switch these out, I would like to obtain a complete rebuild kit, if possible. I have seen on this site, all of the bearings and races for the diff and pinion. But, what about the wear components inside the carrier? Clutches, s-spring, etc... I have recently replaced the axle bearings and seals, so those wouldn't be needed.
Again, any opinions and advice are appreciated. Thank you!

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Re: Opinions/Parts

Postby monzaz » Tue Feb 28, 2017 10:31 am

First of welcome... Glad your using the site and hope it will help other in the search engine.

First off most choices on a rear differential are mostly WANT.... What do you want your car to do? where are you going with your car? etc.

So you have answered most of these questions and do know where your going and what your doing which is a BIG help.

2 tires will always give you more grip on the road or track... So if that is what you want the posi will help.... it will be minimal on the street but non the less looks cooler and 2 times the smoke. :)

If both housings, and or gears are in equally good condition always leave the original set-up. so rebuild the posi rear. IF you are looking to blast the rear and clean it DO THIS FIRST and send the whole rear out intact and complete. just remove the drum brake shoes and hardware leave the backing plates in place. send the drums too if you want them descaled.

Rebuild kit - yes we have all the parts to completely and fully rebuild your 1972 or 1973 riv rear. 9.3 or 8.875 (we do need to know which one you have and a picture of the rear cover will help if you do not know)
Posi unit- Again yes we have the parts to rebuild this unit IF it needs it. Most only need a re-shim and cleaning and away you go
Prices can be given with a PM to us and will get you a list ASAP.

Thank you, Jim Mitschke
J D RAce
J D Race

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