I am putting a 450-500 hp BB w/ M22 4spd into a 79 Z28 with stock posi rearend 10 Bolt 8.5" 3.73. Traction Bars and Drag shocks. I will replace the stock gears and axles with better ones later, How much Abuse can this rearend take now and will it be able to take it later when it gets upgraded ? Can I run a quarter mile without worring about loosing the gears axles now and later?

From what I've been told the 8.5 10-bolt is nearly as strong as a 12-bolt. I run one in my 72; I did install c-clip eliminators and re-built everything (new gears and posi). My car currently runs mid 12's and is heading to low to mid 11's with a supercharger; I'm not concerned with the rear end. I've seen guys running 9's and 10's with them in basically the same pieces as mine has.

The difference would be if you're going to run slicks and launch at 5000 rpm; that would change things considerably. You would at least need some aftermarket axles, gears, c-clip eliminators, wheel studs, and a good race-type rear end guy to set the thing up.

Jody

Thanks for the help Jody!

Dave

The bearing caps are a weak spot in the GM rear ends. A good rear end girdle like the one T/A makes is a good investment. Ring & pinion set up is very important! I also like to use good bearings like
timken. Do NOT use any China bearings! If the car is to be raced only, then a full spool should be used. If it is going to be street driven, DON'T use a spool. A Detroit Locker is stronger than a posi for street use. Good axles with c-clip eliminators should be used. This should take all your abuse.

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'69 RS/SS396 pro street
427/4spd/9"

Thanks Big Gear Head,
I appreciate the help!

Dave

An option that I found interesting was an article I read in Car Craft magazine ( I think it was Car Craft). Anyway, they took a 12 bolt rear-end and weld the Ford large axle bearing end housing onto it. This eliminated the small bearing, leaking all the time, nightmares associated with the c-clip eliminators. The article was more or less a foot note to a much larger article, so the specifics were very minimum. I have just picked up the idea and right now I am researching bearing specifications to see what can be pressed on to the 10 bolt axle and have the proper outside diameter for the housing ends. Of course, backing plates are also necessary. This seems to be the perfect option for a rear disc brake setup also.

The Ford housing ends requier aftermarket axles. If you are considering welding on new housing ends, Mark Williams and Moser Engineering make housing ends that use the Ford bearings and still use the original Chevy brake backing plates. You still need aftermarket axles, but this makes a very neat installation and eliminates the c-clips. This should only be done by someone who has a housing fixture and is a very good welder.

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'69 RS/SS396 pro street
427/4spd/9"

Here's another thought. Sence you will probably be putting in new axles and a posi/spool, why not go ahead and upgrade them to 30 splines instead of the stock 28? All the 8.5s made sence '90 have been 30 spline and there are a lot of good parts to choose from.

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'69 RS/SS396 pro street
427/4spd/9"