just wondering how much power theese rearends will handle. Im going to be running a 383 with around 400-425 horses and later on add a 100 shot nos this is in a 86 trans am i figuired new posi some 373s and that aftermarket diff cover. Im trying to keep from buying a 12 bolt or 9 inch moneys somewhat tight ya know does this seem like the right way to go about it

 

with 400-425 hp with an auto, you should be fine.

make sure when you rebuild it that you use a solid pinion spacer and the diff. cover with preload bolts. this will help keep things from flexing, which is what kills these rearends.

trust me, i know

 

i am about in the same boat. looking at same HP #'s aitha built 700r4. will i be able to run DR's with those same upgrades to the rear?

 

yes. There are several guys pounding these pretty hard. - As Matt said, run the aluminum cover with the bearing support bolts and a solid pinion spacer(...or end up with a pinion like his..uh...kustom multi-piece gear.....)

 

I know one
Still going strong - GM 3.73's, torsion diff, moser street axles and no other mods..

 

Mine does pretty good, but it's got Moser axles, a tru-trac, fully welded axle tubes, DTS cover, solid pinion spacer, 3.73 strange gear, etc.... 1.66-1.60 60fts with 5k clutch side-steps. - It's soon to be c-clip eliminated and fully braced...and either 4.10 or 4.56 geared....

 

how would a GM posi hold up with moser axles,3.42's, pinion spacer, and aluminum diff cover?

 

...which GM posi, and what intended use? The clutch type units are known for wearing out under moderate street use, so continous strip launching is probably gonna waste it pretty quick. If it's a gov-lock, don't even try. You'll have more parts than you know what to do with... - If it's a later clutch type, it probably won't break, but turn into an open rear... - The 4th-gen style torsionals work good and can be had for around $100.

 

when you put that little pinion gear in there, it's gonna end up like mine.

87 T/A has been 1.4x on his 7.5"

 

Probably. - I'm going to put the solid pinion spacer in, run full braces(off the diff cover to the housing ends) and c-clip elim. - Past that it's hope for the best. I should see low 11's/high 10's. I've been 11.72, and the car should be about 3000lbs when done, instead of 4001, plus motor set-back and a bunch of other weight shifting.
- I figure on giving the 10 a fighting chance, but if she goes, 9" time....

 

how do the B-W 9 bolts in the gtas hold up compared to stock gm 10 bolts?

 

compared to a stock gm 10 bolt, they are superior...but they are expensive to build up like a 10 bolt...you can completely build a 10 bolt with good axles, cover, etc. for right around $750 in parts...that is, if you set it up yourself. a 9 bolt will be around $1100 in parts...

personally, i'll be starting an 8.5" 10 bolt retro fit project when i get back into town in August.

 

the 9-bolts are stronger stock vs stock. Much more is available to strengthen a 10-bolt though, that's why I switched.(that and my 10 got dropped into my lap, Moser axles and all...)
- mw66nova - If you're gonna go through all that work, why not 9" or 12-bolt? - I've just see too many broken 8.5's. Built and broken.

 

thanks...do you think my car will hold up with a stock rear with the mods i have?

L98 350 10.5 compression, dual 450 holley w/ tunnel ram,Edelbrock 2204 roller cam, Edelbrock Alum heads, accel dist and coil, edelbrock headers, no cat, edelbrock cat back, M/T drag radials, energy suspension bushings, eibach sportline springs, Mad Dog Godfather 700r4 stage 3, 3500 9 inch stall converter, B&M Trans Super cooler

 

pmpnavt - as long as it's in good shape. If its got over 70k on it, I'd put new wheel bearings and some decent fluid in there just for cheap insurance.
mostly it depends on you suspension mods. You won't even bruise it until you get it to hook. Sticky tire's alone ain't gonna cut it.

 

cause they are lighter and more efficient than the 9" and 12 bolt. i'm also working closely with John Balinsky on this project. he's been 8.3x's @ 160+mph on a built 8.5" 10 bolt. i don't know if my car will ever be that quick, but i know that it *should* hold up just fine for what i'm doing...if you don't put cheap stuff in them, they live fine. i've also got 2 brand new sets of 4.10's at home already for it that i got for free.

and actually, traction is not normally the culprit of parts failure in drivetrain stuff. it's wheelhop, which would be a lack of traction. make sure if your going to put any kind of real power to these things, make absolutely sure your suspension is setup correctly and you have a good tire on the car. drag radials are my preference.

 

That's cool. If the 10'll take it have out. I haven't played with them much, just recently watched an almost new set of moser axles get scattered in one. I'm sure they make better pieces than what I've seen for them, personally, if I break something and go to improve, I go above and beyond so as to be able to forget about it.

- I agree on the wheel hop. Loading and unloading. The moment it breaks loose the motor gets up even further, then it tries to catch and...pow! Used-to blow my muncie "rock crushers" apart that way in my '69. ****** 2nd and hope it stays glued.....otherwise the trans tunnel dents in as the cluster rolls out...

 

when your trying to go fast on a budget...you live on the ragged edge of what might be considered sanity....lol!

also, the car has an "underdog" of a motor in her and i want to take advantage of every thing i can...and i know that the 8.5" is much lighter and more efficient than the 9" and 12 bolt so i'm gonna use that to my advantage...but it's still gotta hold good power cause i'm building a 383 to put in place of the little 305 once she blows.

 

Totally agree with that!!
It makes a huge difference in contact area - I have actually gone 1.38 best on the 10 bolt so far..

I also agree with a 8.5 or 8.8 build..
Not much more rotating mass and heft, but alot stronger!.

 

where is a good place to get parts for the B-W 9 bolt?

 

glad to have your support on this one sir, it means alot when more experienced people encourage us younger "innovators", lol!

anyhow, i thought long and hard about an 8.8, but i just couldn't justify running a ford product when i can find the 8.5's just as easily (out of a truck or something) and they are just as strong when built.

 

Sorry to bring this back from the dead but i have a question. i am having trouble finding a solid pinion spacer for my 10 bolt. is this what i need? and if not can some one show me a place to get one.

Ratech Pinion Bearing Spacer and Shim Kits: RAT-4111 - summitracing.com

 

Great thread. But I am moving this to "Trans and Drivetrain" where it rightfully belongs.

 

that should be the one, its the same one i have on my wish list

 

yep, that's the one!

 

(back from the dead...)
I'm thinking about doing an 8.5, but I can get an 8.8 w/ disc for a pretty decent price, and the mark 7 version might be wider. 4th gen wide I'd hope.
Is it hard to fabb up discs on thr 8.5?