A local Pontiac guy I know is selling an 8.5" posi 308 with disk brakes along with the master cylinder and proportioning valve. Since my car is 4-wheel drum brakes, I emailed him and asked about the front setup as well (A-arms, spindles, rotors and calipers). Still waiting to hear back on that one.

I don't think the 8.2" rear I have will handle the 455 and I don't want the expense of a 12-bolt. Happy medium.

Should I look into swapping the mono leaf for a 4 or 5 leaf setup?

My plans are to modify the new rear end to fit the car, not to modify the car to fit the rear end. I've read several articles about this swap and have decent welding skills.

I believe 2nd Gen rear axles are wider than FGF's.

2nd: I had a 80 Turbo T/A WS6 with the 4 discs. Those rear discs are a bit primitive and there are issues. You have to set the emergency brake lever after EVERY DRIVE because the setting the emergency brakes allows the wear adjusters to work properly on the rear discs. And frequently the ratcheting auto adjusters get cruddy and just quit working. Result - no rear brakes. There are is info out on the InterWeb about them.

3rd: Those late 2nd gen third members were behind some pretty weak motors. I'm not too sure you would gain a whole lotta strength with that swap.

1. Yes, it is wider, between 1/2" and 2", depending on which forum you read.
2. '98-'04 S-10 disks are a direct bolt-on and have integral drums for the parking brake.
3. I can't find anything stating one 8.5" is any different from any other 8.5" rear end as far as strength is concerned. If anyone knows of strength issues I'd like to know.

Thanks in advance!

I wouldn't go to the trouble to swap in the whole disk brake set-up. GOOD drum brakes are plenty good for the rear. Most of the weight is on the front of the car. Front disc brakes are a good idea. BUT, there are some upgrades that can be done to drum brakes that will make them adequate for most any reasonable street driving. Now if you're going to do a lot of high speed corner carving or road racing, that's different.

http://www.musclecarbrakes.com/stage16474nova.html

http://www.musclecarbrakes.com/bib6474nova.html


"...I can't find anything stating one 8.5" is any different from any other 8.5" rear end as far as strength is concerned. If anyone knows of strength issues I'd like to know..."

I've read that those with 30 spline axles, instead of 28 spline, are stronger. I think most trucks had 30 spline axles. You can buy 30 spline posi units and axles to replace the 28 spline units. . BUT, you can buy better 28 spline axles. And, unless you are going to do some serious drag racing, with sticky tires, the stock 28 spline axles will probably be plenty good enuff. Some of my drag cars have made lots of 12 sec runs, with stock 28 spline axles. Never broke one.

An 8.5 out of an X-body car will bolt right in, if you have multi-leaf springs. I think the driveshaft must be a little shorter. So, you should be able to buy an open X-body 8.5, a posi/gears/bearing kit, and have it properly set up, for somewhere around $1000 or just a little over, total.

For example: Here's an open 8.5 out of a '75 Nova, for $375. Of course, the shipping would make this not so good a deal. But, you may be able to find one, close enuff to pick it up.

http://www.ebay.com/itm/GM-X-BODY-1ST-GEN-CAMARO-8-5-INCH-REAR-END-2-73-OPEN-CARRIER-DRUM-TO-DRUM-OEM-/122121348365?hash=item1c6effe50d:g:Gw4AAOSw9IpX0LXt&vxp=mtr

OK, I don't understand why these Ebay links won't work, on this site. They work on every other Pontiac site I've ever posted one on. ???? But, you can type in a search item, and the link to the whole search will work.

http://www.ebay.com/sch/i.html?_odkw=8.5...amp;_sacat=6000

There are posi/gears/bearing kits, for around $500 or a little more. Ebay lists 'em in several different brands.

http://www.ebay.com/bhp/10-bolt-posi

http://www.quickperformance.com/GM-85-10-Bolt_c_52.html

But, the cheapest solution might be to find a complete drum brake 8.5 posi rear, with the gear ratio you want, from a 2nd gen Bird or Camaro. Then, move the spring perches. Depends on what you can find, and the price.

I wouldn't loose any sleep worrying that the 8.5 isn't strong enough. Aftermarket 28 spline axles are just fine. If your going the route to have a 8.5 built anyway have it built to the width of the rims and tires you will be using. That way you won't have to bend or cut the quarter panel wheel lip.

So I'm set on the idea of swapping out the rear end. My next question is whether to 1) Replace the mono leaf springs or 2) Change out the mono leafs for multiple springs.

Go with multi-leafs. I think there were probably good reasons for switching to multi-leafs after '67.

There are LOTS of conversion kits out there. Some have lower than stock ride height.

http://www.jegs.com/i/Hotchkis/515/2407C/10002/-1

Some kit's include the springs. Some don't. From what I've seen it may be cheaper to buy the hardware kit & springs separately.

https://www.summitracing.com/parts/bel-5975

Some hardware kits include more parts than others.

https://www.summitracing.com/parts/oer-r...BevEBoCWwbw_wcB

http://www.ebay.com/sch/i.html?_odkw=lea...amp;_sacat=6000

I've read that you can re-use your mono-leaf shock plates. But, will need longer shocks. I'm sure there are guys here, who have made this swap, who can give more details.

I have been running my 8.2 rear for a few years now behind my 455. I haven't broke it yet. Fingers crossed

THat said I have been working on getting a Nova 8.5 setup under there.

The second gen rear won't work as stated because of the spring perches are also too wide. You can cut the purches and make it work but IMO the wheel will be to far outward.

The nova rear are the way to go. A 28 or 30 spline Eaton unit and new axles and you should be good.

"... You can cut the purches and make it work but IMO the wheel will be to far outward..."

http://www.angelfire.com/on/geebjen/rearswap.html

Now it's time to clean it up.

I took the rear cover off while I was stripping it down for cleaning. All the teeth look in great condition. I'm still going to replace the seals, bearings, and oil while I have it out.

I did the 2nd gen differential swap and have had no issues. I found the rear with posi and the ratio I wanted (3.08) 20 minutes away for $250.00 so that made it a no-brainer. A friend of mine moved the perches for $100. The dimension from flange to flange was only 1/4" different. However the brake discs add another 1/2" for a total of 3/4" difference.
First set of calipers were junk but second set from NAPA are doing fine. Don't mount any caliper until you are sure that the parking brake lever ratchets the piston out as it should.
Good luck!

I also have a second gen 8.5 rearend and it is 1/8 of an inch wider on each side! Just as it said in the link posted by Oldshool You cant even tell by looking at it and yes, just move the spring pearches and shorten the drive shaft and your good.

Ditto, I did a second gen 8.5". Total length difference was 1/4" if I recall. I have drum brakes in the rear and no issues at all. I have a new drive shaft and the perches were moved also about 1" on each side. The 3.42 is a nice gear and the old tired 400 really woke up - that was before the rebuild and !00+ hp more. Haven't tested that yet...

New shaft bearings and seals are in. The calipers are ordered. Most all the pieces I could sand blast are rust free and shot with a coat of silver to keep the surface rust away. What are your recommendations for painting the rear end once it is finished? I saw some Eastwood products in a rattle can on one of the videos I watched. Thoughts?

The axles are pulled and I've started cutting the perches off. Not as easy as I imagined. Once the perches are gone I'll clean it end to end. Then I'll pull the rear end from the car and see what else I need to swap over.

I also plan on changing out the pinion seal; I watched a video on the internet today on how to do it.

I picked up the S10 rear disks today. I need to clean a lot of the parts up and apply paint. I'll attach pics once I have everything looking better.

Pay close attention to pinion angle when you position the perches . Somehow you need to have the weight of the car on the suspension when you locate them.

When I get to the point of welding on the new perches, can't i just measure the angle from the 8.2 rear end? This is what I had in mind from the start. I was going to set up the 8.2 rear end on a set of jack stands, lift the pinion end with a jack until it is parallel to the floor, then measure the angle of the existing perches in relation to the pinion. Copy that measurement over to the 8.5 and start welding.

I'm on my 3rd cutoff wheel and I still have a bit more work before the 1st perch is removed. Not as easy as I thought it was going to be

That's exactly how I would weld the perches on... put the old rear end on jack stands, put a level on a perch to make sure its level then measure from the pinion to the floor. Then put the replacement rear end on the jack stands, rotate until you have the measurement from pinon to floor from the old rear end, place the new perches on the rear end, rotate so they are level & in correct alignment with spring width... weld.

Put the 8.5 in the car sitting on the new perches with the U bolts clamped loose enough to rotate the housing. Center the housing in the car so that both tires are the same on both sides. Make sure you have jack stands under the shock plates to support the car with the weight of the car on the springs. Attach the drive shaft and measure the angles, shoot for 4-6 degrees with the car fully weighed down as it would be with a driver.

Bigchief, yes that would work too.

I have 1 side all cleaned/painted and mocked up with the S10 disks. I ordered the rotors from the internet (found them on sale 1/2 price of everywhere else) and they wont be in until next Monday. I sand blasted and painted the remaining parts. Once I have the new rotors I have to space out everything with shims to get the caliper to fit the hat properly.

When it is all said and done I will have replaced the brake shoes and the rotors.

I am already thinking how I am going to get the parking brake to work with the 67 pedal.

The rotors arrived today so I put one on. I had to space out the dust shield around 1/4" to get everything to line up.





Then the final test; I bolted on a wheel to check clearance. Between 1/2" and 5/8" from the caliper to the wheel with 15" rims.

While I was cleaning up the rear end for paint I had it resting on some saw horses. I flipped it around to clean the back side of it and oil started dripping quickly from the pinion seal. So I tore it down completely and ordered all new seals and bearings. I might as well do it right the first time. A buddy is coming over who has rebuilt rear ends before (and he has the tools) to set up the gears after replacing the bearings.