Okay i know that the 10 bolts are no good for high powered applications and that the 9 bolts are okay but will also go at a certain point. Why is this? What is it about the 2 that are different compared to each other and compared to aftermarket heavy duty rear ends.

 

size and strength of the parts, nothing really worng with them as far as how they're made or the design.

 

"Aftermarket" is a fairly loose term, since there are very few true aftermarket companies making axles. Most of the major names are OEM suppliers to the auto and truck companies. Dana/Spicer, Eaton, Auburn, Saginaw (now called AAM for "American Axle and Manufacturing" division), ZF-Friedrichshafen, Borg-Warner, and others make axles for OEM suppliers. The "aftermarket" usually simply alters the mountings and brackets to adapt to other vehicles' springs, driveshafts, shocks, and brakes. There are some companies that make actual housings specifically for the aftermarket (like Winters and Frankland), and many companies that make replacement parts for the aftermanrket, but unless you're using a Quick-Change or something more specialized, you are basically using an axle that was stock in something that came off an assemblty line. Install better parts in your axle housing, and you can overcome many of the weaknesses that the factory accountants specified in the original design. A Richmond carrier and Moser axles are a good start to beefing a 10-bolt.

 

i know you can put better gears and what is the carrier i thougt that was the housing for it all. And yeah you can "beef up a 10 bolt" but where is the actual weekness that makes it different from something like a ford 9 bolt or a moser 12. Is the difference in the casing? Assuming you replaced everything internally with bullet proof parts the only thing left is the housing?

 

The weak link is mainly in the size of the ring gear, 3rd-gen 10-bolts have a 7 1/2- 7 5/8" dia. ring gear, the bigger the ring gear the stronger it is, a 12-bolt has like a 8 7/8" gear or something like that, A 9" Ford of course has a 9" ring gear and I think the strongest one would be the Dana 60 with like a 9 3/4" ring gear. Check out this chart:
Ring gear chart

 

GM designed and installed the 10-bolt Rear for the Power Combinations available STOCK from the Factory and not for for afermarket build ups.

 

You could say that about a 12-bolt or a 9", for that matter.

This week's National Dragster had an article about strengthening rears. They used 12-bolts & 9"s as examples. The 12-bolt is closer to the 10-bolt, and their recommendations for it were cast cover with cap support load bolts, weld around the tubes, and good gears (along with good bearings and careful set-up).

Last month the local Bandimere magazine had an article focusing on axles. More splines is better, because the spline pitch is the same, so more splines means larger diameter.

Hmmm, that kind of stuff is about what this says https://www.thirdgen.org/newdesign/t...nguprear.shtml .

You can beef up what the factory gave you, which will handle most street cars, but as Dart said, there will be a limit. That's when the modified 12-bolt starts looking pretty good.