old 8.5" 10 bolt rear fit in 4th gen?

[camaroguy26]

I've heard that you can get a 8.5" 10 bolt to handle plenty of horsepower, up to the thousands if it's built right. But the 4th gens have 7.5" I'm not sure what all came with the 8.5" but I think it's all the older cars or bigger trucks, but nothing later than the mid 80's? anyways, can these be modified easily to fit into a 4th Gen? Or is it not even worth trying? It would be a lot cheaper than buying a Moser 12 bolt or go to strange or something of that sort. You probably have to weld a few brackets onto it but will it withstand the heat and not mess up the internal diameters or surfaces? Maybe if I have it professionally done with a Tig (or is it Migs that burn cooler?) Any ideas would be great, or even if you could point me to a company or shop or phone number that could give me advice. My 10 bolt now is holding up fine especially with the little bit that I've done to the car but something about it just worries me, It's like a bad nightmare waiting to explode.

[curtis73]

You can find 8.5" in the following cars:

-almost all 1/2 ton trucks
-optional on most "muscley" rwd cars from 65-97
-standard on HD cars like taxi, police, wagon
-standard on Olds 442 G-bodies 78-87
-standard on Buick GN/GNx
-optioned on a rare few Monte Carlo SS 82-88
-all Impala SS 94-96

That's all I really have to say. I'm not an F-body expert, I had just done the axle research for another project. I think your problem will be that none of the above 8.5" examples offer the same suspension configuration. The 7.625 (which is what your 4th gen should have... same case as the 7.5 but the ring gear is 1/8" bigger) is more capable than you think in that car. The light tail, solid axle, and gearing of the car make getting traction the limiting factor. The tires will break loose long before that axle will blow. Of course if you punish it with traction-adding goodies and lots of sidestepping the clutch, it won't like it. But if you're driving a vaguely stock F-body, don't fret.

[camaroguy26]

yeah the rear seems to be holding up extremely well. I changed the fluid in it and it was very clean, the gears looked great. But eventually I will want to put a stronger rear in there. I want to build the engine up for at least 6-700 horses which can easily be done. But I want to know that my rearend can handle it instead of just wait for that fatal day. So just doing my research before I get too far ahead of myself. But will I be able to cut the original brackets off those rearends and weld new ones on there to fit my suspension? If so what kind of welding process should I use? I can only weld with sticks and I know it burns really hot. I burn holes in my exhaust all the time so I'd have to take it in for someone else to do it for me. But is it possible to do it? Thanks for all the help

[curtis73]

Its possible to do, but probably not with an arc welder... unless you're good at it. The problem is that sticks (like flux core wire) have so many inclusions and the weld isn't as strong. The other problem you may encounter is alignment. Unless you have a jig set up, you might have binding and some serious handling issues crop up from misalignment. I think that overall you'll have much more money in modifying an 8.5 to put under an F-body that you would just calling Currie or Moser for a pre-built 8.5" or Ford 9" that will be a bolt in.

Check with a local race fabrication shop. I had a 14-bolt truck axle modified to bolt in under a 66 GM full-size car for a very reasonable price. They had the jigs, the access to the parts, and the expertise to weld what I needed.

[demon9766]

Moser is the way 2 go thats where i ended up having to go to get me a bullet proof rearend. A nd they only cost about $1300 thats not bad.

[camaroguy26]

yeah but I don't have 1300 lol, but I guess by the time I'll need the bullet proof rear I'll be better on money