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8.5

Questions, answers, tips and tech on drivetrain issues.

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Gitdowns
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8.5

Post by Gitdowns » Mon Mar 02, 2015 3:18 pm

I am going to get an 8.5 out of a B Body and cut it down to G Body width. Is there a preferable car to get one out of, one with posi, 3.42 or 3.73 gears, etc. I can narrow it myself, so won't be spending a bunch of money. Its for a daily driver. Will be running over drive auto trans.

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TexasT
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Re: 8.5

Post by TexasT » Fri Sep 14, 2018 8:59 am

I would hunt up one out of a wagon to get the big drum brakes. Doubt you will find a unit with those gear ratios. Lucky if you can get one with a 3.08
Rich

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LS6 Tommy
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Re: 8.5

Post by LS6 Tommy » Sat Sep 15, 2018 7:54 am

I hate to be a downer, but the control arm mounts aren't angled the same. I'd look for a G body axle.

Tommy
20k mile '80 Malibu, currently undergoing long term (aka no money) factory style install LS6 454, Cowl Induction, Legend LGT 700 5 speed. Full Global West suspension, 17" N90 wheels, 12" front/11" rear disc brakes, 9" 3.70 Auburn Pro posi.

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Doober
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Re: 8.5

Post by Doober » Wed May 15, 2019 10:10 pm

I was going to put a thread up for it but this is here so I'll put it here too, since I picked up a B-Body 8.5 for super cheap some years ago. SSM actually makes a set of swap arms to bolt it in, but I don't know how much misalignment there is... I'm guessing it's on the upper ears, correct? If they're the same angle (I'm guessing 90º between the ears), I imagine the swap arms will work fine, where they would not work very well with regular rubber/poly/etc. bushings if they were a different angle than a G-Body - i.e. 90º on the frame vs 80º on the housing ears, it would cause the suspension to bind.

I thought about having mine shortened, then I realized the overall difference on mine appears to be about 64-64.5" which seems to be in line with what I've been able to find about Caprice wagons (that they're wider than sedans), and almost exactly in line with having the proper length to run high offset GM wheels (C4+ Corvette, 4th gen F-Body, etc.). I have 3" adapters back when I thought I wanted to run some Camaro SS wheels on mine, but decided against the adapters and traded for some 16" Iroc wheels. Since I got this rearend I'm revisiting the idea. I found a place that makes control arms to extend the front track by 3" per side, getting rid of all wheel adapters... they're expensive, but I haven't found many other places to do a-arms in anything beside factory lengths.

https://southsidemachineperformance.com ... r-bushings" onclick="window.open(this.href);return false;

http://www.fatmanfab.com/product/1980-1 ... arms-gtech" onclick="window.open(this.href);return false;
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DOUG213XRJ
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Re: 8.5

Post by DOUG213XRJ » Sat May 18, 2019 3:37 pm

Hey Guys, What year B-body 8.5" am I looking for ?

Thanks Doug
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Doober
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Re: 8.5

Post by Doober » Sun May 19, 2019 12:00 am

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'94 was when they changed to the "bubble" from the "box" ('80s to the '90s style that looks like the Impala SS). I've read anything '77-'96 bolts up to each other, telling me the ears/mounts are the same on all the assemblies, but they will have different options. They also mount the shocks on the front side at the lower control arm instead of the rear like a G-Body. I don't know how far off the spring perches are (if they actually are). If you plan on shortening it to stock G-Body width, my suggestion is look for a '94+ with disc brakes. I got a deal on mine for $75 plus a spare engine stand I had. As far as I know, my rear is from a wagon (via the Craigslist seller), and from my rough tape measuring it's about 3" wider per side (6" total) than a stock G-Body rear. A sedan rear will likely be a little shorter, but if you plan to get custom wheels anyway this won't be a major issue. If I had my choice I'd have a disc brake '90s wagon rear, but I don't think they exist... pretty sure discs were only on sedans. There's also a police option for the '94+, I'm not sure what the differences are though.
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Re: 8.5

Post by prairiehotrodder » Wed May 22, 2019 11:36 am

seems like a waste to me and i've done it before. I put an 8.5 in out of a 77 cutlass many years ago. Simply chopped off the lower mounts and installed the stock 7.5 lower mounts on with a welder and a tape measure. Its a little wider but that can be corrected with the wheel offset as has been mentioned. The upper ears are farther apart but if you force them you can make them fit. Its a hillbilly swap. If you can narrow an axle then you can build a 9" and be proud of it and sleep at night when you are done. I've done about 10 of them.

https://www.youtube.com/watch?v=PaqdRoPxL4M&t=638s" onclick="window.open(this.href);return false;


If you want super cheap and easy, get the axles and posi unit out of a 2000 jimmy / blazer and stick it in. the axles are 28 instead of 26 spline. They are about 1/2" longer but still work fine. Most have 3.42 or 3.73 gears and a gov loc in the 4x4 ones.
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