I have an '85 IROC with a 305 TPI. I'm looking to make a serious torque and HP jump, to a stroker 383. I've been told that the stock posi unit and gears will handle up to 450 HP. Is that true? What torque are we talking about? HP isn't what breaks things, torque is, so I'd be more comfortable knowing how much torque I can push through it. Also, I may need to replace the gears. There has been damage due to lack of lube. I know the pinon bearing is locked, but I beleive the posi itself may be okay, how can I tell? I have to look closer at the gears to see if they are damaged, I may need to change them if the ratio isn't at least 3.73:1 anyways. If I change the gears to good aftermarket units, will that increase the torque rating of the whole assembly? Or will it just cause something else to break first?

Thanks

David

 

you aren't going to be able to build the entire unit to with stand xxx amount of torque, some will alway be the weak link and break before something else will, there's no getting around that ,as you've already figured out. if you ran the rear low on oil enought to seize the pinion bearing there's a very good chance other parts are damaged as well. reduceing flex i nthe houseing is more important to long life than the strength of the parts you use. how you apply the load has as much to do with longetivitey as anything.

 

So, what do you suggest to reduce the flex? A heavy duty diff cover? Welding braces to the shaft tubes?

David

 

yeah that and weld the tubes to the center section

 

Welding to the center section? Isn't it cast iron? I'd have to have a specialist do that to get a good weld wouldn't I? I doubt I can weld steel to cast iron with my little wire feed.

I just got through pulling the assembly out. Now I gotta take a closer look at it as see if I can figure out what gears are in it and if they are any good anymore.

David

 

I got lucky, the numbers on the ring gear were facing out. I saw 13/42, I assume that means 13 tooth pinion and 42 ring which works out to 3.23:1, so even though the gears look to have normal wear I'm probably going to upgrade to a 3:73:1. I beleive the posi unit is still okay, It took all my effort to turn a wheel and I'm a big guy. How can I be sure the posi is okay though?

David