Hey guys,

I'm looking at building a 350 for my Trans Am to replace my leaky 305. The desk top dyno at the machine shop showed that my build was going to run right about 400ft-lbs of torque, maybe a little more. Will my stock rear-end hold up to that or am I dreaming? I'll post the build in the Tech forum for comments.

 

its really a crap-shoot, some break with nothing, others take a beating and are still alive. I just pulled out my 10bolt, I'm putting over 400ft/lbs to the ground and it didn't break, but it was an open rear which helps keep it alive.

 

I would either beef up the rear or toss it. I have a similar 355 in my car and my stock posi rear lasted about 2 weeks behind the T5

 

I'm no expert but I'll throw in my 2 cents.

I have seen two completely stock 10 bolts that lost the preload on the pinion bearings when I first started making decent power in my car. One finally broke teeth on the pinion gear and the other I fixxed before it was destroyed. I'm not real sure why it happens, but I believe it has something to do with the crush sleeve.

When I installed the 4.10 gears in my car I used a solid spacer in place of the crush sleeve and the preload on the pinion bearings is no different 5 years later. Also the higher the gear ratio the weaker the pinion gear is since it is smaller. A 2.73 rear should be stronger than a 4.10 ratio. Once again, I have 5 years on this set of 4.10 gears and I beat on this car regularly.

The carrier is another area to look at. When I first set mine up I had an Auburn that funtioned perfectly, always spun both tires. About a year later it just exploded one day, springs and internal pieces everywhere. Something like an Eaton should be alot stronger. I have a friend that had a beefed up 10 bolt in his Camaro that did fine until he put slicks on it, he broke two axles back to back. The posi I have in my car now was a 28 spline so I bought a set of 28 spline axles from Moser. Definately stronger than the 26 spline. Also add that if you have an open carrier and spin one tire alot it is really hard on the spider gears and the cross pin.

So now I have a solid bearing spacer, welded the tubes, 28 spline axles, and 4.10 gears. Made one hail mary pass last year with a set of slicks and dumped the clutch at 3500 -4000 rpm and nothing broke.

I think you can build a 10 bolt to be reliable for street/some strip action, with some pretty stout power. If you drag race alot then it isn't a real good option. Also it seems to be better behind an auto than a stick.

If your starting with a stock crap ratio open differential you should stop and figure out what a beefed up 10 bolt will cost if you have to pay a shop to set it up. Gears, good posi, better axles, plus a shop labor for set up could end up pretty close to a bolt in 9 inch or 12 bolt, and a $1200 - $1500 10 bolt is a dumb investment. If you can learn to do the set up yourself and invest in some tools to do it, then the 10 bolt isn't a bad choice. I'm cheap and still haven't spent the money on a good posi, plus I bought my gears on Ebay for $50, so I have only spent about $300 on this rear end. I also had to buy a press and an in/lbs torque wrench, but I needed that stuff anyway.

 

I'm currently running a 700R4 and the original 3.73 gears and the stock posi carrier. I replaced the bearings in it about a year ago...the shop pulled the ring and pinion, showed it to me along side a "new one" and said it looks good to them, and I agreed. So while the bearings have been replaced it's basically the original rear-end. I don't ever plan on putting slicks on it and while I might finally get the nerve to put it on a track just to see what it can do, it's not going to be much of a drag car...just something that'll really get up and go when I get on it.