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Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Suspension - Brakes - Steering> Beefing up G-Body 1986 Cutlass Suspension
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Topic Review (Newest First)
01-17-2010 08:30 PM
Originally Posted by SSedan64
I've used these before>> may find them for G-Body also. 14ga. or thicker steel.
alright thx again ssedan!!
01-16-2010 11:44 PM
SSedan64 I've used these before>> may find them for G-Body also. 14ga. or thicker steel.
01-16-2010 10:43 PM
zildjian4life218 Awesome thanks for all the replies everyone!! I think for now I am gonna just box in the control arms and leave the 7.5" rear end in the car. I am sure down the road I am going to swap in a 9" or maybe even the 8.8" to handle a little bit more power reliably. I will post before and after pics of the control arms when I can get all the snow out of my way to unbolt them.

What thickness steel should I use?
01-15-2010 10:36 PM
SSedan64 I keep forgetting about the 8.8" swap Eric.
Here's lots of Info/links on that swap>>

01-15-2010 08:05 PM
ericnova72 You might want to investigate the 8.8" Ford Fox Mustang rear swap, this is starting to get popular and supposedly is fairly easy to do, pretty much a bolt in with the right arms. The 8.8" is quite close in strength to a GM 12-bolt.
01-15-2010 07:25 PM
Originally Posted by zildjian4life218
Now what is the price difference in after market support from the ford 9" housing to the gm 12 bolt?
The 12-Bolts for G=Body are aftermarket only and aren't cheap. Check with Moser, Strange or Currie.
If you install a OEM GM 12-Bolt you'll need aftermarket Upper Control Arms as the mounting angle is different.

G-Body Rear Swaps >>
G-Body Tech>>
01-15-2010 05:46 PM
zildjian4life218 Now what is the price difference in after market support from the ford 9" housing to the gm 12 bolt?
01-15-2010 03:25 PM
M&M CUSTOM You can also buy prefabricated GM 12-bolt housings to fit right in there from several sources too.

The rear sway bar for my Malibu came with spacers to fit inside the original lower control arms, all factory original pieces. The most common cheap fix for the strength upgrade of the lowers is to tack-weld pieces of pipe inside the arm to prevent the arm from getting crushed by some torque happy person installing the swaybar bolts, then welding a piece of 1/8th inch flat steel to the open area of the control arms, and make sure you complete the job by making sure the bushing ends are welded to the added piece of steel.

Another commonly used strength add-on for the 7.5 inch axle is to drill and tap the ring gear bearing caps, and housing for larger/higher strength bolts, then you can also add to that modification by purchasing a cover with the bearing preload studs and nuts to assist in spreading the load to the housing better.

Another thing I have seen a lot is mark your axleshafts and prep them to paint a stripe the length of the shaft, Many racers do this to check how much their axleshafts have twisted, I have seen pics of up to nearly a full revolution of twist without them failing- and they were reported to be stock shafts.
01-15-2010 01:02 PM
zildjian4life218 My dad did urethane bushings a while ago. The car does have some wheel hop every now and then when you do burn outs.
01-15-2010 12:25 PM
Rickracer Yep, and the best part is that's pretty cheap to do. Urethane bushings are a good idea as well, if you can afford to do them at the same time. The boxed arms and bushings should give you considerably more decisive handling and traction, especially if you've got rear sway bar on there.
01-15-2010 11:42 AM
zildjian4life218 Alright sounds like I will just have to keep street tires on the back until I get a chance to put either an 8.5" GM rear end or a ford 9" in it. But for now it seems like pulling out the control arms and boxing them in will be the best to do.
01-15-2010 10:22 AM
Rickracer You really need a jig for narrowing the housing, to make sure it's straight. I know guys running as much as 450 fwhp on S10 (7.625", 28 spline) rear axles, but they cross their fingers a lot,
Up to about 350 rwhp, no trans brake and no slicks, you're fairly safe.
01-15-2010 10:07 AM
zildjian4life218 I will def consider getting a hold of a prefabbed 9". How hard is it to cut, chop, and weld the rear end to fit. My neighbor is one hell of a machinist and makes all sorts of crazy stuff for his race car. If I could buy a 9" housing and then give him a couple hundred bucks. We would have to cut the axle housing to the correct length. And then weld on 4 places for the control arms to hook up to. Doesn't seem like it would be crazy hard to do just have to make sure everything is straight. What is the approx hp limit for the gm 7.5" axle?
01-15-2010 05:41 AM
Originally Posted by zildjian4life218
I can get a 9" ford housing with axles for like $700 I would just have to get gears and a center section. Will the rearend hold. Im only gonna be making like 325hp at the wheels.
With decent axles and center section, it should hold up to a lot more than that. You could probably beef up your stock rear to stand up to that much power. Upgrade the axles, weld the tubes to the center section and add a girdle cover and you're there, but it would be pretty much maxed out at that point. A 9" will give you "room to grow", so to speak.
01-15-2010 05:25 AM
1ownerT It depends on how well it hooks up.
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