Stock Axle/Rear End Good to ??? HP/TQ

Hi All -

In reading a more recent thread about 8.5 rear end setup for 550 hp, it got me thinking about your stock rear end. I am curious to know your experience with stock rear ends and upgraded power plants - at what power level do you become concerned with failures warranting upgrades?

I have a stock 1970 OO 3.42 rear end, but will be getting an upgraded power plant via Jim W at TSP with a 482 and TA SE Stg 1 heads, headers, like to think I'd be in a similar ~550 hp ballpark. Being a street car the majority of the time, do you think the stock rear end can hold up? Or should I consider upgraded axles/posi?

Thanks for the insight!
Andrew

 

I ran stock 28 spline axles until 10.90. Then went 30 spline and spool.
The 28s were soft in the spline area and would try to roll the splines. Only broke one once....drivers side....seems to plant that tire harder.
I would replace the drivers side every few years with a fresh junkyard one back then but these days good luck finding them.....
On the street you won't have a problem....I'm talking racing.

BTW the 8.5 71-up is a lot stronger than 70 and earlier....IME

 

I ran stk axles in my 8.5 to that same 10.90s on slicks......I never broke one only major twist. I tried when I was going that fast to rotate axles every 25-30 passes side to side.....seemed to help.

I dont think with street tires this would ever be an issue

 

I would park the OO-code 8.2” and build an 8.5”. It’s difficult to find replacement parts for that 8.2”,if you would break something. The shafts are pretty good,but not quite what the 71-72 shafts are. The posi unit is the cone style and there are zero replacement parts to fix it if you break something in it. That built 482 might be a little more than what it can handle,plus the fact that it’s 50 years old used condition.

 

Street car, street tires - don’t worry about it.

 

How about 60 ft time for stock 8.5 1971-72, since this should indicate the amount of maximum force being applied.

 

I ran 1.53s on my stk axle.....I wouldn't tell anyone else to do this.

 

A 3900lb A-body running 11:70’s or slower,with a footbrake automatic can run on a stock shaft. If you increase the blunt force with a trans-brake,slicks,clutch,etc.,you will find the limit sooner.

 

Very good info. Thanks