transmission or rear-end?

[85montess]

so im putting a 350 with about 375 hp and about 380 torque in my 85 monte ss and i was wandering what i should replace after? the rear-end or the transmission? what are good transmission's and/or rears?

wow, thats a noob question...sry. thanks in advance

 

[455OLDSMAN]

TH-350 transmission is one of the best. If you want overdrive you can go with a 200r4 but i believe those usually need to be built up a little. Your rearend will be ok IF you dont drag it at the strip alot. Almost everyone is going to tell you to put in an 8.5, ford 8.8 or ford 9". Ive been running a 7.5 with moser internals for a while now. I dont live at the track so thats not a huge issue for me personally. If I were you and didnt have to worry about cash i would go with the 9".

 

[Silent viewer]

a 85 ss should already have a 8.5" and 200r4 transmission right?? thats about the most ideal combo to have and i think you already have it, stick with it if you do!

 

[85 Cutlass Brougham]

No, the Monte never had an 8.5, just the 7.5 with 3.73 gears. It will last unless you hook up then it will fail fairly quickly.

 

[megaladon6]

if you're not going to be at the strip, get a 200-r4 trans if you don't already have one. bowtie overdrives builds a good stage 2 for under 2k. unless the rear is a non-posi. nothing sucks more than 1 wheel drive.

 

[85 Cutlass Brougham]

Tell me about it...

 

[Silent viewer]

a ss monte does have a 8.5.......

 

[82355supreme]

No regalman, the Monte SS never had an 8.5" just as others stated above. It had the 7.5/7.625 all the way thru its production run.

The only G-Bodies of the 80's to get the 8.5 were the '84 Hurst/Olds, all the 442's & the Grand Nationals.

Now, back to the original question, I wouldn't worry about either the trans or the rearend with sub 400 numbers. The friend of mine who helped be build my engine has a Monte with a 500+ horse 377, & still uses the 7.5 with Auburn internals. He runs it at the strip 2-4 times a year 11.30's on spray, with no issues.

Heck, look at my signature, my numbers are pretty close to what you're looking to get & I have the 7.5 in my car still. Auburn internals though.

 

[clean8485]

No mid '80s Monte SS ever came from the factory with an 8.5" rear axle in it. In '83 & '84, they had a 7.5" with 3.42 gears and a TH350C, and from '85 to '88, they had the 7.625" with 3.73 gears and the 200R4 trans. The only mid '80s G body cars to get the 8.5" axle were the Buick Turbo T types & GNs and the Olds 442 & Hurst cars.

 

[Vern]

The 85 MCSS had as noted the 200-4R and a factory shift kit which worked well behind the stock 305. For transmisson longevity and better shifting under greater power upgrade to a MUCH better shift kit such as the $99 unit by CKPerformance. Also add a large cheap transmission cooler. Transmission issued solved for you.

If you don't plan to own a pair of slicks the 7.5 (7.625) rear will be fine. It won't rob you of power and fuel mileage like the Ford 9 either. No its not as strong but you don't need it for your application. If it does not have a posi add one. The Eaton is the best or sometimes you can get a factory posi at a salvage yard for cheap and just add clutches. I am not a fan of the Auburn stuff. Some of the 7.5 rear/posi units that came out of an S-10 pick up had 28 spline axels instead of the 26 spline that came in your car. If you find this you get both for a nice cheap upgrade. If you want spring for a support cover and you are good to go.