7.5 to 8.5 rear

[LukeZ]

ok so I found a guy selling a rebuilt 8.5 posi rear from a GN, and before I buy it I was wondering if someone could tell me EVERYTHING I need before I buy it. It doesn't come with brakes or control arms or any of that, just the actual axle. The gears, and the posi (plus a housing cover). Will this bolt DIRECTLY up to my car? It's an 86 El camino with a 7.5in rear, no posi, 2.56 gears and stock drum brakes.

Will my brakes bolt up to this axle? Will my driveshaft fit? Will my control arms work? I appreciate any help that you can offer. I don't want to buy this and then not be able to use it. Thanks

 

[v2vera]

It should be a direct bolt on, Control Arms and Brakes that you have should swap over. I believe the driveshaft should also swap over, not 100% on that though. I just swapped my 7.5 for an 8.5 from a GN and everything swapped right over.

 

[L92 OLDS]

It should be a direct bolt on, Control Arms and Brakes that you have should swap over. I believe the driveshaft should also swap over, not 100% on that though. I just swapped my 7.5 for an 8.5 from a GN and everything swapped right over.

Everything bolts up. The drive shaft is different. No biggy though....it just gives you a reason to buy a new shiny drive shaft with new universal joints.

 

[MC96]

Good time to upgrade to disks in the rear.
Allstar parts
ALL42095 x 2 Rotors
ALL42180 and ALL42181 Brackets
L & R Front calipers / Pads
ALL41021 disc/disc combo valve.

Best way to do it on the cheap

 

[LukeZ]

Everything bolts over. The drive shaft is different. No biggy though....it just gives you a reason to buy a new shiny drive shaft with new universal joints.

What kind of driveshaft do I get? I dont want to drop big money on a really nice lightweight one or anything... Just looking for a relatively cheap one that fits

 

[wonderboy24]

i install a 8.5 in my cutlass.but i did replace control arms. everything will swap to the 8.5.
i had to get a different drive shaft. lucky for me the guy i got the rear from had one. it is inch shorter. than the original that was hooked to my stock 7.5.

 

[el corvino]

wait wait wait what? A new drive shaft? Have a shop shorten your current drive shaft and balance it.

 

[LukeZ]

i install a 8.5 in my cutlass.but i did replace control arms. everything will swap to the 8.5.
i had to get a different drive shaft. lucky for me the guy i got the rear from had one. it is inch shorter. than the original that was hooked to my stock 7.5.

Is that w expensive? My car is a daily driver so it can't take long either

 

[el corvino]

Also, what is he trying to charge you for an 8.5" with no brakes? I presume there are drive axles...? I'd make the guy prove it's a posi carrier and that it spin's smoothly so you know he didn't crack an auburn and just wants to ditch it.

I'm most curious of price. Unless you watch him unbolt it from a Grand National like I did way back in the day for my first one (The GN was totaled), it could have come from a Olds 442, T-Type, or 84 Hurst Olds and most people just say GN rear for more money / recognition.

 

[el corvino]

If I went back in time, I would have went with a strange or even a 9".... but I put down big numbers in my El Camino. I don't see any need for an 8.5" in a daily driver unless you daily drive on radials and plan on putting 500+ with good suspension to the rear... unless you are getting it for stupidly cheap.

I did a full frame off my first elco. Here is the 8.5" directly bolted on with stock suspension.

Disc's and suspension parts aren't cheap either my friend.