8.5" in '84 Cutlass Supreme?

[FE3X CLONE]

I don't think the standard Cutlass could even be ordered with an 8.5.

But I also thought 8.5's came out in G-Bodies starting in 1985.

I don't know when they were available in the Buicks, but for the Olds, they were available in '84 on the Hurst Olds.

You could order an 8.5 in Monte Carlo SS's I know.

Monte's came with 7.5" rears, never the 8.5.

 

[88hurstolds]

TOTAL MYTH
Go with a Ford 9" if your serious about a rear upgrade.
Your wasting your time and money with the 8.5, unless you have 450+hp AT THE REAR WHEELS, an 8.5" does you no good, and even then those rears are only good up to 600 hp.
7.5" rears are fully capable of handling 400hp, I have one behind a 400hp 500ftlbs 455 in TWO different cars an have had no problems hooking up.
90% of these asshats that part out a 442 or 84 Hurst for the rear don't even need it and should be beaten for ruining a VERY RARE car. Save a Hurst, kill a Turbo T :lol:
I know of one douchebag who raped an 8.5 out of a numbers matching 1986 442 for his gay *ss Salon with a stock 350.

YOU DO NOT NEED AN 8.5 REAR UNLESS YOU ARE INSTALLING A MOTOR THAT IS CAPABLE OF RUNNING 500+HP 500+FT-LBSTQ

 

[tdvick]

Well, it was misrepresented as expected. Just another 7.5"...

 

[1badbu]

Well, it was misrepresented as expected. Just another 7.5"...

That's too bad .

Man those 7.5's pop like ballons and needles :lol:

Before my Dad put the 8.5 under his wagon he changed spider gears all the time.He finally just give up on the 7.5's when he started breaking teeth off the ring gears.

You can beef up a 7.5,but why :?: Just spend the extra money and time finding and buying a better rearend.

The 7.5 was not GM's best idea at all

7.5" rears are fully capable of handling 400hp, I have one behind a 400hp 500ftlbs 455 in TWO different cars an have had no problems hooking up.

Must be a really good 7.5 you got there.My Dad's motor was based on 300hp,350 chevy.

I've busted a factory SS rearend with 3:73's on street tires at the track once.Sounded like a cannon going off !
I took the cover off and just closed it back up 😢 It had more pieces that fell out than I thought could have ever been in it :shock: .

 

[joelbert62]

TOTAL MYTH
Go with a Ford 9" if your serious about a rear upgrade.
Your wasting your time and money with the 8.5, unless you have 450+hp AT THE REAR WHEELS, an 8.5" does you no good, and even then those rears are only good up to 600 hp.
7.5" rears are fully capable of handling 400hp, I have one behind a 400hp 500ftlbs 455 in TWO different cars an have had no problems hooking up.
90% of these asshats that part out a 442 or 84 Hurst for the rear don't even need it and should be beaten for ruining a VERY RARE car. Save a Hurst, kill a Turbo T :lol:
I know of one douchebag who raped an 8.5 out of a numbers matching 1986 442 for his gay *ss Salon with a stock 350.

YOU DO NOT NEED AN 8.5 REAR UNLESS YOU ARE INSTALLING A MOTOR THAT IS CAPABLE OF RUNNING 500+HP 500+FT-LBSTQ

I saw a 283 scatter a 7.5 monza rear in a vega v-8 swap there are diferences I know between that and a G body I am wondering as I put a 383 in my Elcamino though There is a fip side Have seen meany 80's camero's w 7.5 's at the track not meany scater?

 

[Chris Van]

There will always be one in every crowd that has a story of some guy running a 7.5 and a posi unit in a 900 hp pro mod. BUT from my personal experience..... don't WASTE your time or money. At one time, I probably could have started my own junk yard with all the 7.5 parts I've broke until I found a willing 442 to donate the 8.5. Over the years I upgraded that rear as well with c-clip eliminators, spool and axles. By now the car was more of a drag car than a street car and over the years of breaking a gear every couple of years to breaking one every couple of months, I then decided to part with my trusty old 10 bolt and upgrade once again to a 9".
With that being said the 8.5 10 bolt will live behind almost any street/strip application and take almost anything you plan to throw at it. The 7.5..... well, you would probably be better off playing the lottery. The odds of it surviving are about the same as your chances of winning the lottery.
Yes I know, the lottery does have winners too..... Just not me.

 

[FE3X CLONE]

There will always be one in every crowd that has a story of some guy running a 7.5 and a posi unit in a 900 hp pro mod.

I'll be one of those guys. 😉

The key with the 7.5" is you need aftermarket parts. The problem with that is if your spending money on aftermarket parts, you might as well go with something bigger.

When I built my 7.5" years and years ago (before the internet became what it is now) an 8.5" rear was almost impossible to find locally. So I spent roughly a $1000 on parts and labor to have mine rebuilt. Auburn limited slip and Richmond 3.73 gears. Reused the stock axles and replaced all the bearings and seals.

It lasted years of abuse behind my 455 both daily driving and running at the track. Now I never put slicks or drag radials on it because I didn't want to push my luck but I did let a friend drive the car once and on a back country road he came to a dead stop and romped on the car. He's only comment besides the smile on his face was "I have a new respect for the 7.5" rear".

My brother bought a 7.5" rear that a friend of ours had built for his drag car and then decied to go with a Ford 9". So for $500 he bought a newly built 7.5" with Auburn limited slip, Auburn 3.73 gears, brand new axles, bearings, seals, everything. I bought him a rear support girdle for Christmas and this 7.5" has been behind his 403 for over 10 years. Runs low 13's with 1.7-1.8 60's on drag radials without so much of a wimper.

If your starting a new build, then yes, I would look into a stronger rear. It just makes sense, however if your stuck and can't find an 8.5" for a decent price then building a 7.5" for a mostly street driven car would be no problem in my opinion.

 

[stomis]

TOTAL MYTH
Go with a Ford 9" if your serious about a rear upgrade.
Your wasting your time and money with the 8.5, unless you have 450+hp AT THE REAR WHEELS, an 8.5" does you no good, and even then those rears are only good up to 600 hp.
7.5" rears are fully capable of handling 400hp, I have one behind a 400hp 500ftlbs 455 in TWO different cars an have had no problems hooking up.
90% of these asshats that part out a 442 or 84 Hurst for the rear don't even need it and should be beaten for ruining a VERY RARE car. Save a Hurst, kill a Turbo T :lol:
I know of one douchebag who raped an 8.5 out of a numbers matching 1986 442 for his gay *ss Salon with a stock 350.

YOU DO NOT NEED AN 8.5 REAR UNLESS YOU ARE INSTALLING A MOTOR THAT IS CAPABLE OF RUNNING 500+HP 500+FT-LBSTQ

I saw a 283 scatter a 7.5 monza rear in a vega v-8 swap there are diferences I know between that and a G body I am wondering as I put a 383 in my Elcamino though There is a fip side Have seen meany 80's camero's w 7.5 's at the track not meany scater?

Dont listen to this advice. Sure hes right about tearing apart decent cars for the rear but the advice that you dont need an 8.5 until 500ftlbs and 500hp is trash.

Ask any camaro or gbody guy. Once you hit that 375hp mark your 7.5 is in danger. Bolt drag radials on it and i dont care if you have 200hp, if you leave hard its only a matter of time. Dont confuse his getting lucky with the equipment holding up, theres a difference.

And for the record no one rates the strength of anything at what it puts at the wheels. Transmissions, clutches, driveshafts, axles, ring and pinions, rear ends, transfercases or ANYTHING else you put power through is all rated in INPUT torque.

 

[JBreu]

I agree with Stomis on this one here..........Think about ot for a second. The only G Body cars that the General put the 8.5 rear ends in were the high performance muscle cars.....YOu know the HUrst Olds, Grand National, T-Type and the 442....That being said, lets look at the rest of our G-Body cars......They were turtles from the factory and the 7.5 rears were adequate....Apparently the General forgot that these cars would be modified through the years....I think they shoulda put the 8.5 rears in all our G-Body cars in the first place. Anyways, when I decided to build my Monte up the first thing I did was replace the stock 7.5 rear with a '69 Chevelle 12 bolt 8)

 

[tc1959]

I agree with Stomis on this one here..........Think about ot for a second. The only G Body cars that the General put the 8.5 rear ends in were the high performance muscle cars.....YOu know the HUrst Olds, Grand National, T-Type and the 442....That being said, lets look at the rest of our G-Body cars......They were turtles from the factory and the 7.5 rears were adequate....Apparently the General forgot that these cars would be modified through the years....I think they shoulda put the 8.5 rears in all our G-Body cars in the first place. Anyways, when I decided to build my Monte up the first thing I did was replace the stock 7.5 rear with a '69 Chevelle 12 bolt 8)

I always wondered why GM put 7.5 rear ends in all the 90s F-Bodys ? Some of them where pretty good runners.