looked in the archives but didn't find anything for this. Need to replace my stock non posi small 7+" rear end soon, starting to clunk and make noise and want to upgrade to posi disk or drum. What is a good rear end for a fairly straight swap, with 8.5' gear. Will be running between 300 to 400 hp.eventually and need something that will take it. Any and all replies welcome. Thanks Merv

 

The only 8.5 that will fit into a third gen is a Dana44. Good luck finding one.

I ran a 3.27 geared 7.75" 9 bolt in my race car for 2 years. I now have a 4.10 geared 7 5/8" 10 bolt because there are no performance parts easily available for the 9 bolt.

The 9 bolt had a best pass of 11.8 in the 1/4 and the 10 bolt is still surviving with the results below.

The only diif that will fit directly in a third gen is from another third gen. Although you may find other diffs that are the same width and you could move all the mounting hardware over to the new diff, you'll never be able to fabricate a mount strong enough for the torque arm unless you go to ladder bars or a 4-link system.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

[This message has been edited by Stephen 87 IROC (edited June 25, 2001).]

 

Merv, i just finished up a rear swap on my '82, original 10 posi bolt went BOOM. The best i could find locally was a 9-bolt posi w/disk. It was at a yard where the owner owed me one so it did'nt cost me, but retail was $450. Be prepared for sticker shock at every turn when dealing with rear ends. My car was a late '82 WS6 when they ran out of rear disk parts so mine has drums. To change over from drum to disk can be costly. I would'nt have any part of using the junkyard calipers because, who knows? Plus new cables, hoses, prop valve, and possiby a master, and the bill for just brakes is $500, and thats for the pre 89 rear brakes. No thanks.

I put my original drum brake system on the 9-bolt. Easy really but i have a lot of tools to make it easy. The whole job cost me a bottle of posi lube and a diff cover gasket.

Pick your rear by brakes first. If you have drum, try to get a drum rear. If your going to swap to disk, get an '89 up. Any bolt. 9 or 10.

Another option is to buy a posi rear end out of an S-10 and swap internals. I believe mail trucks used this rear too and they usually have posi.

With the HP your looking at you should probably get a 9-bolt or a 4th gen rear, both are roughly 7.5 however. If you want to put your rear end to bed for life, get a Ford 9 inch ready to roll, minus brakes for $2100.

Good luck

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Kenney
82 Trans Am WS7 notchback
83 Trans Am WS6 T-tops
Painter @ Chevy dealer
GM junkie

 

Stephen, good to hear from a fellow third generation Canuck. Nice looking race car, sorry to hear about your motor troubles. Looking to replace the rear this winter so am starting to look now for parts. If your ten bolt 7 5/8 is running high 10's at sea level and is standing up to the abuse, maybe that's the way to go. I'll only run at two or three meets a year at Mission. Want a street/mild strip setup for cruzin. Will keep eyes open for a Dana 44 and a 9". Do you ever make it to Mission. Was there on sunday to see the Austins (Bucky and Pat)perform,pretty impressive. Thanks Merv

 

Kenney, I agree about the costs for the drum to discs and will stay with drums. Just finishing up a front drum to disc swap on my 67 Firebird and costs were way more than I thought they would be. It looks like I will be looking for a 9 or10 bolt 7 5/8 posi with drums, a 9" would be nice but to good(read expensive) for a mild streeter? Anybody tried or know anyone who has tried the 12 bolts that Strange and Moser are making for our third Generation Camaros,(read expensive again). Thanks for the info guys, keep it coming, as I don't know as much as I would like about this subject. Merv

 

One minor point, your '82 has SAE fittings, later ('85 I believe, perhaps '84) have metric.

Not a big deal, you can get adapters. What I did was put new '82-type wheel cylinders in the later rear and used the '82 lines. All disc rears will have metric, though.

Currie and others make custom 12-bolt and 9" rears for 3rd gen. No brakes, made for disc. But, bullet-proof.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. 0.030 over 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlock header mufflers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, LT MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1/95.5 @ 5800' Bandimere.

 

I've never been to Mission yet and I don't know if the rear end would hold up to a high 10 second pass at sea level. I wasn't expecting the 10 bolt to survive this season but since I can't keep an engine together I haven't had a chance to destroy the 10 bolt. Once it does explode, a Moser 9" housing will be purchased and installed. I already have a center section with 4.56 gears and a 31 spline spool.

The trick to making a 10 bolt survive is to build it up as per the "ultimate 10 bolt" article. The weakest part is still the small gears but the buildup will let them survive longer than a factory diff. Buy some good gears, good carrier, rear solid cover with pinion supports and some aftermarket 28 spline axles. Weld the axle tubes and that's it. There's not much else you can do to strengthen the diff.

 

Looks like a 7 5/8 will be o.k for want I want to do. Will try to bullet proof it as best I can so I can make a few runs every year. I'll spend the money for a bullet proof rear for my other projects, 67 firebird 455 or 63 Impalla SS with a 454. Either a 9" or 12 bolt reworked for these two projects. Thanks guys for the help, much appreciated.