Besides everywhere? Do the axles go first? Or the ring gear? What about the internals in the differential?

I was thinking about building my 7.5. If I stiffen the case with a girdle/cover and get a solid bearing pinion spacer I think it'll solve the problem of the case flexing and causing the ring gear to chew up. I can get stronger axles. But I'm not sure of what the internals inside my posi can handle. If they're a problem I'll get a mini-spool and lock the axles. I'm figuring I'll be pushing about 325 hp and 340 ft-lbs torque.

Any advice??

 

Well. First off let me admit that I don't know the answer to your question, but this is what I've kind of figured out so far. I'm about to start on an axle rebuild myself, so I've been listening some.

Seems that the axle girdle is a good idea as the whole housing apparently tends to flex, and any extra rigidity is a help. Also, I guess, the girdle helps stabilize the two large straps which hold the ring gear/posi assembly in place.

Most guys are advising welding the tubes all the way 'round where they insert into the center section. The factory spot welded the tubes in place. Another rigidity adder.

Seems like everyone agrees that stock gears are strong enough to outlive the rest of the assembly, so not much emphasis is being put on aftermarket gears. (except when a ratio change is desired)

The later model axles (after 88, I think) have more splines and seem to be the preference from what I've been hearing. All this stuff is pretty cheap, so I'd at least try to scrounge up a later axle. My project axle is from a '91.

I've never really heard of a posi breaking, some just work better than others, and they wear out.

Seems like the point of diminishing return on stock or near stock TPI motors is about 3.50 to 1. Guys going deeper, to 3.73s or 4.11s don't seem to be gaining much over the common 3.42 or 3.45 ratios while drivability begins to suffer a bit. Of course a more modded motor will probably like the deeper gears.

I think both the 10 bolt and 9 bolt use C-clip axle retention. I would (and will) get a c-clip eliminator kit, especially on a drum brake rear. This will keep the axle/wheel from coming completely off the car in the event an axle does break.

General concensus it that the 9 bolt axle is superior as to the 10 bolt in just about every area. A little harder to find. Like most GM driveline parts, neither are really worth a crap, though, so it's just a matter of putting enough band-aids on them to get them to live.

Just my .02

 

Oh yeah, and unless this is a strip only car, don't mess with the spool. You'll get tired of it in everyday traffic, and it will adversly affect the good handling of your IROC.

Also. The biggest enemy of any axle is traction. Cheapest way to get your axle to live forever is to put a nice pair of BF Goodrich Radial T/As on the back. 0 traction = 0 stress.

.02

 

Thanks for the advice.

Speaking of traction, a few years ago I had BF Goodrich Comp TA's on the car. They were absolutely the worst handling, worst grabbing pieces of crap ever produced. In about 20,000 miles they were practically bald - and I was babying them after having to shell out almost $800 for 'em. I went back to Goodyear Eagles.

 

THe 7.5 part...that`s what weak- the ring gear size.

 

My old turd has Kumho Ecstas on it. I really like them. I had one develop a bubble on the sidewall though, and had to replace it, but overall I've been really happy with them. They bite pretty good in the twisties, but with power (something my iroc has very little of) you can get the the car to oversteer and 'impress' other commuters. Cool looking tread, like a tractor. Not real expensive either. I would definitely buy another set.