drivetrain abuse

[rebelx]

ok. just how much power/torque can the stock 7.5" rear end handle?

im planning out my 80MC and im either swapping in a 6.2L GM Diesel or the BBC 427 my dad just traded for.

what all will i have to do to keep either of these motors from twisting my monte into a pretzel?

[twomanymontes]

Ben, the 7.5" rear end has always been the weakest link in these cars. Putting a diesel in one would be OK since there is no real heavy torque right of the line, Even the Turbo ones need to spool up a bit first, once your moving, it's not a big deal. A stock big block has the power to make the ring gear look like the one in your Durrango, If it didn't shear the axle splines off first.

My thoughts, would be, a Currie 9", they will bolt right up and will be a lot stronger [and cheaper too] than trying to get a 12 bolt A-body rear end into the G-body. Plus once that is done, you will nee dto be sure all body mounts are in goos shape and are tight and then get your self a set of those rear bracings that mount behind the rear seat. Otherwise there is a good chance ot twisting the body also. Hope this helps

[bigrepp]

so your not cuting the moon roof out of it huh?? hahaha finally

[rebelx]

Feb 18, 2009 20:27:25 GMT -5 bigrepp said:

so your not cuting the moon roof out of it huh?? hahaha finally

nah. its growin on me. gonna cut it out and have newer better one installed instead, lol.

[rj]

Dave, the stock posi rear won't handle abuse from a big block?

[rebelx]

Feb 20, 2009 12:36:05 GMT -5 rj said:

Dave, the stock posi rear won't handle abuse from a big block?

in my case it prolly wont. the engines gonna be pumpin around or slightly over 500hp at the tires is my dads n my goal. its goin in his black 79 or my 80. were still fightin over it, lol.

[twomanymontes]

RJ, the 7.5" rear end is the weakest link of the G-body drivetrain. That's why the 8.8 rearend in the GN and the olds 442 are so much in demand. They are stronger and bolt right in, only mod would be the driveshft length. Not 100% sure, But I was once told they will hold up to 450 HP.

[rj]

Thanks. I wasn't sure if the posi rear used a different size ring/pinion versus the open end rears?

[twomanymontes]

Nope, Same rear end, just different guts.

[bigrepp]

ill tell ya what... if you go cuttin that out let me know... if you can keep the internals together ill buy that off of you....

[85t5mcss]

The 7.5 is weak yes, but with street tires and a good driver it will still last. My last one handled 400 HP/Tq. But I didn't run it at the strip either. Build the engine and see what happens but it will end up letting loose. And how u drive it prob wouldn't take long. Not sure why, but the 7.5 that was in my diesel Monte held up to the abuse better.

If u can find the GN 8.5, great. Just gotta shorten the driveshaft an inch. I threw alot of abuse to one of those with better axles and had no issues. That was 400HP also with a 4.10 gear. It was fun until the frame got unhappy and I ripped a rear control arm.

[rebelx]

my dad won the arguement/contest for the motor. he's got a solid black 79 that he's gonna stuff it it. he told he he's aimin for the 600hp mark and has a 9" allready for it.....lucky.


so im back to my possible diesel swap, 4.3 build or my 355....which one to pick, lol.

[twomanymontes]

355!!!! Thats what I would do! Unless you build a turbo set up like Mike's, then the 4.3

[rebelx]

i was thinkin supercharged like superchevy did. they got 500hp outta a 4.3L supercharged engine.

[twomanymontes]

Ok that works too! LOL!

[85t5mcss]

Keep the diesel.

Propane injection and whatever else they do with Turbo Diesel stuff to make them fast.

That would be different and a whole lot of fun. Too bad it would also be pricey.

[rebelx]

i thought about that also. twin turbo setup with propane injection....fun stuff.