8.5 in rearend

[spidereyes455]

Makes you wonder if it might be at all profitable or worthwhile for someone who is good at welding and fabrication to build a jig to correctly position the lower control arm mounts, housing ends ect and cut down the tubes from say B body 8.5 and make your own "G body" 8.5's.

 

[doood]

G-bodies had their own C4L set-up that required GM/G-body spec'd mounting points for the housing 'ears'. The arrangement was the same for any rear GM housing intended for a G-body.

GM A-body & B-body cars used a similar rear suspension layout but the actual housings were different vs a G-body. The mount positions for the upper links on the housing pumpkin were probably the same as GM wouldn't invest all that $$ into one design for one line of vehicles (excluding the vette). Since the housing widths were different (wider), the lower link positions would be different (farther apart).

Swapping to a similar set-up converging 4-link & similar width (like what's under a Fox body Mustang) is where there are differences in the housing mount locations/orientation.

I understand the older A-body and B-body 8.5 housings were different vs. a g-body. I thought the mount positions on the housing pumpkin were different based on my readings and needing special UCA (example link for 12-bolt): https://www.umiperformance.com/home...y-12-bolt-swap-adjustable-upper-control-arms/

 

[scoti]

I understand the older A-body and B-body 8.5 housings were different vs. a g-body. I thought the mount positions on the housing pumpkin were different based on my readings and needing special UCA (example link for 12-bolt): https://www.umiperformance.com/home...y-12-bolt-swap-adjustable-upper-control-arms/

A/B housings were different but adaptable w/the aftermarket arms.

 

[81cutlass]

My (shameless) plug product development project that never went anywhere was

Buy your choice of $100 crusty 8.5 leaf spring rear (I prefer zr2 s10 but gmt400 works fine too) because it has the disk brakes that are easy to convert to G body and came 3.73
Remove zr2 disk brake calipers and backing plates, save
Cut off axle tubes and throw axle tubes and shafts in dumpster
Cut off g body axle tubes and sleeve/weld into 8.5 center section
Buy 2wd blazer backing plates and rotors $75
Buy moser 30 spline drop in axles $300
Buy Yukon 30 spline posi $300
Buy my UCA adapter sandwich plate $150
Buy Hummer H3 1350 forged yoke $40
$150 of brake lines, paint and seals

If you are OK with drums you can reuse your OEM G body stuff and save some money/drilling the flange from G body 3 bolt to S10 blazer 4 bolt disk

But my buddy sold his CNC I was using and I have the attention span of a squirrel and the interest level on dealing with customers of a grumpy old guy so the CAD and CNC files sit on my desktop waiting for my motivation to kick in.

 

[Pc3]

Know what your buying
best bet have one that meets your needs
dont look back

 

[doood]

A friend had THM400 come apart in a 10-second drag car. He didn't have the transmission shield to prevent it coming through the floor when the transmission detonated, and he nearly lost his foot. From what I've read, when my 7.5" rear goes, it should fail related to the c-clips; the axel will no longer be retained, and the axel/wheel will leave the car. What I am really worried about though, is for the rear to come apart and come through the back seat maiming my passengers. I'd like a little bit more margin to safety in the rear end. I'm late to the game, and there aren't any 442 rears left.

My (shameless) plug product development project that never went anywhere was

Buy your choice of $100 crusty 8.5 leaf spring rear (I prefer zr2 s10 but gmt400 works fine too) because it has the disk brakes that are easy to convert to G body and came 3.73
Remove zr2 disk brake calipers and backing plates, save
Cut off axle tubes and throw axle tubes and shafts in dumpster
Cut off g body axle tubes and sleeve/weld into 8.5 center section
Buy 2wd blazer backing plates and rotors $75
Buy moser 30 spline drop in axles $300
Buy Yukon 30 spline posi $300
Buy my UCA adapter sandwich plate $150
Buy Hummer H3 1350 forged yoke $40
$150 of brake lines, paint and seals

If you are OK with drums you can reuse your OEM G body stuff and save some money/drilling the flange from G body 3 bolt to S10 blazer 4 bolt disk

But my buddy sold his CNC I was using and I have the attention span of a squirrel and the interest level on dealing with customers of a grumpy old guy so the CAD and CNC files sit on my desktop waiting for my motivation to kick in.

You said in a previous post that you blew this rear up with track use. I would like to see your UCA plate better. Being leaf spring rear, it didn't have UCA mounts to begin with, right? And you're welding plate to a casting, right? That isn't amateur stuff...

I was talking to another guy that told me the 8.5 g-body used the same tubes as the 7.5. Mind you I've never had my hands on an 8.5 to make the comparisons...

 

[86LK]

you're almost better off buying everything new from Strange/Moser/Summit and building yourself a new 9" rear or sumpin' . get all new parts for the same amount of money and not nearly the cuttin' and measurin' and inevitable cussing when you're off by 0.1"

 

[81cutlass]

A friend had THM400 come apart in a 10-second drag car. He didn't have the transmission shield to prevent it coming through the floor when the transmission detonated, and he nearly lost his foot. From what I've read, when my 7.5" rear goes, it should fail related to the c-clips; the axel will no longer be retained, and the axel/wheel will leave the car. What I am really worried about though, is for the rear to come apart and come through the back seat maiming my passengers. I'd like a little bit more margin to safety in the rear end. I'm late to the game, and there aren't any 442 rears left.



You said in a previous post that you blew this rear up with track use. I would like to see your UCA plate better. Being leaf spring rear, it didn't have UCA mounts to begin with, right? And you're welding plate to a casting, right? That isn't amateur stuff...

I was talking to another guy that told me the 8.5 g-body used the same tubes as the 7.5. Mind you I've never had my hands on an 8.5 to make the comparisons...

I blew up a stock GM axle which are known as glass
I blew up a gov lock which are known as glass
I split a Yukon posi case

But I have had issues with wheel hop and my car is heavy, a stick, and I'm mean to it at drag and drive tracks. I'd estimate most of my issues are around a really aggressive setup and chassis tuning issues I self created.

And that's kinda why I never put effort into building the kit for sale. It's probably strong enough for 95% of people, I'm in that 5% that it's not. We will see what my control arm bracing does this summer.

Correct, a leaf rear does not have the uca mount ears.
That plate I designed is bolted into the 10 rear cover bolts with grade 8 hardware. It requires no exotic welding, just axle tube mild steel to mild steel.

I'd agree a new D60 from strange is the most cost effective method if you can't find a G body 8.5, fab something goofy like me, get lucky and find a fox 8.8 or 12 bolt A body which are hard to find for a good price, or fab a 8.8 brace like Jim (nailhead64)

 

[Rt Jam]

While I'd agree with a D60 is the strongest rear. It's a pretty heavy unit so do not waste it on a car unless it's making 700 or more ft/lbs of torque. They do give you the option of the best differential, a Power Lock. The only diff that has more holding power as you add torque. Not a factor if you chose spool which I don't advise for the street.

For spool, a 9" is a good choice but the extra pocket bearing forces you to run a tiny differential.

For street, a D60, S60 or a GM 12 bolt is you best option for the sole reason they have big differentials.

 

[gnvair]

Moser makes a bolt in 12 bolt for 78-88 A/G bodies that includes bolt in axles.
No one mentioned the fact that the G body specific 8.5 housings have small axle tubes which is also a detriment. Most non G body rears and all of the Ford 8.8 rears have 3" or large tubes.