Soul Crusher

Just finished fabing one up. Pictures and details to follow. It's too late and too beer now.

HCI2000SS

iTrader: (2)

Is this an 8.5 10 bolt?

Darth_V8r

iTrader: (4)

if it is, it's how they should have shipped from GM

HCI2000SS

iTrader: (2)

My thoughts exactly!

farmington

iTrader: (14)

GM could have probably put 12 bolts in our cars for less than $100 extra back then.

MY_2K_Z

iTrader: (1)

Hurry up and post some pics!!

01ssreda4

iTrader: (96)

Anything can be fabbed. Any rear end can be put in any car. Its a matter of is the work worth the effort and is it (tools, skills) accessible to each person.

HCI2000SS

iTrader: (2)

I'd love to know how hard it is to fab and the end cost. Hopefully the OP will tell us

AnotherWs6

iTrader: (17)

I'd like to see this as well, dude was still drinking at 6am yesterday lol, he might take a while to recover.

How much HP was a 83 model putting out? A 7.5 was plenty back then. But yeah, an 8.5 should have been factory by the time 4th gens came out. They had em so wtf.

01ssreda4

iTrader: (96)

The obvious issues to me is the brackets are wrong, no torque arm mount, and its too wide. Well if youre gonna fix all that **** why not just go with a 12 bolt or 8.8? Seems like if this was a viable it would have already been done.

AnotherWs6

iTrader: (17)

Is the tube size the same?

RPM WS6

iTrader: (3)

The 8.5" had already been a factory rear for the F-bodies in the 2nd gen cars, even the late ones with less power than the TPI 3rd gens. A late 2nd gen Z28 made half the power of a LS1 4th gen, yet it got an 8.5 because the underpinnings were already compatible with that rear from earlier in the '70s.

Launch

GM really counted their freakin beans when fitting these 10 bolts to LS powered cars. It looks more like it should be behind some 1980's asthmatic 4 cylinder.

I need to ditch my 10 bolt before I kill myself and i was having thoughts of getting a mopar '8 3/4' done for mine, because I believe it could be 1 tenth faster than a 9".

The dodge 8 3/4 is huge infront of our 10 bolt. Ive riden in big block cars that couldn't kill one on sticky tires. S60 is better but the 8 3/4 has 2.73 gears available for the street and has a removable center section like a 9" so you can swap out centers.

Or maybe it wont be any quicker than a 9" and it'll just eventually break easier and I just do all that for nothing

Some guys seem to get good gains with using lighter driveline components, others nothing. I guess there's too many variables in car setups.

RPM WS6

iTrader: (3)

The same is true of the GM 8.5" 10-bolt. It also looks huge next to the 7.5" and can be made to handle tons of power. Even stock it's almost as strong as the 8.875" 12-bolt. I've known many Grand Nationals (they came stock with the 8.5") to run some crazy times on this rear.

It doesn't have the center section benefit that you mentioned about the Mopar rear, but I assume it's lighter than the 12-bolt or other typical options for the 4th gen. If there is a cost effective way to make the 8.5" work, it's a very solid rear with lots of potential and gear options.

Darth_V8r

iTrader: (4)

I went round and round on this too. In the end went with a fabbed nine. For the money and the effort, it was the only way to get lighter than the stock ten bolt, handle plenty of power, and have the available parts from many sources.

But had GM simply used the 8.5 in the first place like in lots of S10's, that would have been great.

Launch

S60 or M9 it is for me also. I don't trust the 8 3/4 will eventually hold up as well. Braking driveline parts isn't fun.

Funny on the weight some guys say they hooked better and et quicker with S60 due to the extra weight pushing down on the tires.

ramairetransam

iTrader: (18)

my grandfather made 3 Chrysler 8 3/4 rear ends for f bodies , one for my dad 77 trans am , one for an 82 camaro and one for my 85 trans am . So it can be done . Only thing that sucks is the drum brakes or you have to spend money on aftermarket disc brakes.

Darth_V8r

iTrader: (4)

I actually thought very hard about it for that exact reason. But it's unsprung weight on a street car. Not the best for handling. Plus the easier ratio changes if needed and the number of ratio options. Hard to beat a nine inch

SparkyJJO

iTrader: (11)

I had an 8.5 (well 8.6, technically) in my Trailblazer and always thought that rear end should have been under the 4th gen. I think it is the same 8.5 guts in my Silverado too. Did they ever even use the 7.5 on any other platform? You'd think it would have been cheaper to use the otherwise ubiquitous 8.5 in the fbody like they used the 4L60E in almost everything RWD aside from the HD trucks.

murphinator

iTrader: (2)

the 7.5 was in all the s10 variants , it was in a lot of g bodies too including rwd monte ss's .

I think Monza/vega etc... and variants of those basically low hp 70's and 80's stuff got them while higher perf 72-81 chevelles , Camaros , firebirds , novas ,venturas etc... got 8.5's and a couple g bodies gn ,t type , 442 and cant recall if the grand prix 2+2 got it also.

I had a couple monte ss's 87 and 88 and felt ripped off that the slower 442's got the beefy rear lol