The Slowmobile

[64nailhead]

9 inch rears are overrated and over priced. But as Jack mentioned, if you have the money, then buy one. Most of the rear end choice comes down to what you do with the motor. A stock plus a little 455 will be handled by a well built 7.5 with slippery tires. An 8.5 will handle whatever you chuck at it with upgraded diff and axles - much cheaper than a 9". An 8.8 will keep up with the 8.5, but need some additional weld in parts to get it to work correctly.

By all means the best bet, IMHO, is to find a stock 8.5 and build it correctly with a set of Moser or Strange axles.

When most talk about or reference a 9", they aren't referencing a stock 9", but rather an upgraded 9" - and I hate seeing a Ford anything in a G-body.

 

[fleming442]

If you say so. Before I bought mine, I did some pricing, and it was $200 (all new) over rebuilding a 12 bolt.

 

[TURNA]

9 inch is the way to go.

Especially with all that nice torque the engine will have.

Even GM smartened up up and put a 9 inch in the new COPO Camaro

 

[pontiacgp]

the 9" is popular in circle track for the lower classes for the floating axles. If an axle breaks it stays in place which safer than a c clip axle. The 9" is easier to change the gears as well. In the Pro Late Model we built we used the Winters rear end but that in kind of expensive for a street car. I have no need to change the gears and I will never get close to 500 hp so the GM 8.2 rear end in my GP is perfect for my needs.

 

[Turbolq4]

Slap that 455 in there and clean up the broken junk as you go. I have big power in a total shitbox. 8.8 rear is capable of containing alot of go juice on the cheap with a few parts.

 

[64nailhead]

Even GM smartened up up and put a 9 inch in the new COPO Camaro

Come on man - what Ford ever had the same axle as found in the new COPO Camaro's? That may be a 9' platform, but it's no 9' other than by name.

If you say so. Before I bought mine, I did some pricing, and it was $200 (all new) over rebuilding a 12 bolt.

I agree that a 12 bolt would be better than a stock 8.5' IF you can fabricate the mounting or buy an aftermarket housing, then deal with parking brake cables and different wheel offsets due to different width.

I'm not saying a built 8.5" is the cheapest, nor can withstand more than a built 12 bolt or 9", but it's the easiest solution to withstand 800+ft/lbs. Seriously, it's a bolt in factory part that can be swapped in a weekend including upgrading the diff, gears and axles.

The next G-body I build will have an 8.8 direct from the junkyard modified for 2 explorer axles. It won't be the easy and quickest, but it will be the cheapest. If you couldn't tell I'm somewhat cheap - lol. But the 8.8's track record is better than good and I can fabricate/build a little, so it's no big deal.


Fleming what did your 12 bolt come from? And what's it width?

 

[pontiacgp]

When most talk about or reference a 9", they aren't referencing a stock 9", but rather an upgraded 9" - and I hate seeing a Ford anything in a G-body.

a GM 3rd member from a 55-64 passanger car rear end...

https://www.randysworldwide.com/differential-identification/gm-55-64-passenger-car/

 

[fleming442]

Fleming what did your 12 bolt come from? And what's it width?

Well, it's in my red car, so the width doesn't apply. I ordered it from a place called Driveline Solutions in WI(?). I don't think they're in business anymore, but I'm sure Quick or someone else would do the same. They drop shipped a Moser housing and axles fit for the car, and he built the center (Stange nodular, 3.70 gears on a Detroit TrueTrac, all set up). All I had to do was get the backing plates on, and press on the axle bearings. Granted, this was 12 or 13 years ago, but it was $2k shipped to my door. To do the 12 bolt, it was going to be 1800; an 8.5 would cost the same. My whole issue is with the c-clips; I much prefer bolt in axles. You have to put ends on a GM to get rid of them.

 

[pontiacgp]

I agree that a 12 bolt would be better than a stock 8.5' IF you can fabricate the mounting or buy an aftermarket housing, then deal with parking brake cables and different wheel offsets due to different width.

I'm not saying a built 8.5" is the cheapest, nor can withstand more than a built 12 bolt or 9", but it's the easiest solution to withstand 800+ft/lbs. Seriously, it's a bolt in factory part that can be swapped in a weekend including upgrading the diff, gears and axles.

The next G-body I build will have an 8.8 direct from the junkyard modified for 2 explorer axles. It won't be the easy and quickest, but it will be the cheapest. If you couldn't tell I'm somewhat cheap - lol. But the 8.8's track record is better than good and I can fabricate/build a little, so it's no big deal.


Fleming what did your 12 bolt come from? And what's it width?

The A body 12 bolt comes in 2 different widths, the 64-67 is 2.5" wider than the G body rear and the 68-72 is 4.5" wider. The conversion uppers works on both, the stock lowers work on the 68-72 version but on the 64-67 version I used a roto joint to pick up the misalignment. I have an 8.2 but the width matches the 12 bolt. The parking brake cables are the same on my 8.2 as the G body and I'm pretty sure the 12 bolt uses the same set up. JBrue is a member here and has the wider version on the 12 bolt in his Monte.

 

[lilbowtie]

Dito the spool - I wouldn't worry about running the 7.5 your not making enough HP. 9.0 1/8th mi very do-able