Power rateing for an 8 3/4

shaq787 · Post by **shaq787** » Wed Apr 19, 2006 4:39 pm

A two part question, first how much horse power can a stock 8 3/4 hold and how much power can it hold useing aftermarket internals in the stock houseing?

Also i am unsure about lockers vs spools vs sure grip/posi units. The truck is not going to be a daily driver any more and sometime next year it will have a 550-600 hp shortblock 400 in it. Right now it has about 300 hp in it and i want to get a unit strong enough for the new engine.

~Alex

JJ · Post by JJ » Wed Apr 19, 2006 9:45 pm

I've heard 8.75s are good to about 600 ponies. The 741 casings in our trucks are the weakest of the 8.75 housings and I think they're pretty stout. At least the one behind my 440 is still living

Post by **cowboy** » Thu Apr 20, 2006 6:39 am

I agree with jj , I have put them through the pace with alot of pones , & have seen them behind a Hemi or two , Knew a guy once who put A truck 8/34 behind a full house 427 Ford , because he said he liked it better then the 9in ford

mopar400 · Post by **mopar400** » Thu Apr 20, 2006 8:35 am

It's a good rear and fairly inexpensive. One of the week links I have found personally is cracking the driver side bearing cap (with 500 HP). When this happens it distroys the ring, pinion and usually the case. This can be remedied by installing a billet cap. mopar400

Here is a example:
http://www.markwilliams.com/detail.aspx?ID=609

Post by **Seabee** » Thu Apr 20, 2006 4:35 pm

Very, very strong. Good innards as posted above and with high HP, bracing welded from the pumpkin down to the tubes - you will be hard pressed to build something that could break it.

shaq787 · Post by **shaq787** » Thu Apr 20, 2006 4:43 pm

Thanks for the help guys. now that i know the 8 3/4 will hold the power i need to diecide between a posi/sure grip, lockers or a spool. I'm not worried about it being a daily driver, just don't want a one tire fire.

~Alex

and nice avatar Mopar400

Post by **CSS-Registry** » Thu Apr 20, 2006 6:18 pm

a sure grip is a great way to hold traction and not loose drive-ability... with the HP you're planning a SG will hold up just fine. all the miles on my HPP 426 truck we never broke a SG. back in the late sixties the old man bolted a dual quad set up with 3.91's in the pig and it would hold strong.

put a spool in it and it is really just a track beastie then - not much street-ablility with them.