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8.5 ten bolt diff applications

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8.5 ten bolt diff applications

Postby rfoll » Sun Nov 13, 2016 5:48 pm

When and where did this rear axle first become available? I know second generation Camaro had them, but I am not sure about the year. I have one that was supposedly from a 70 nova, but was it an original installation? Were thy available on a 69 Camaro?
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Re: 8.5 ten bolt diff applications

Postby pdq67 » Sun Nov 13, 2016 9:14 pm

If I remember right, there is a, "Steve's Nova", site that has a big table of rear end info.

I might have the site name wrong, but it's out there.

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Re: 8.5 ten bolt diff applications

Postby rfoll » Mon Nov 14, 2016 9:17 am

http://www.novaresource.org/axle.htm. I had it on my favorites page. They show it as appearing in 1972, and the 7.5 shows up in 1976. But that's just a Nova. When did the others start using it? Logic would be same year, but that is not conclusive.
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Re: 8.5 ten bolt diff applications

Postby pdq67 » Mon Nov 14, 2016 8:37 pm

rfoll wrote:http://www.novaresource.org/axle.htm. I had it on my favorites page. They show it as appearing in 1972, and the 7.5 shows up in 1976. But that's just a Nova. When did the others start using it? Logic would be same year, but that is not conclusive.


This site has a good list of year and vehicle type in it.

https://www.hemmings.com/magazine/hmn/2 ... 81844.html

Sorry, I thought the Nova site listed all of them, my bad.

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Re: 8.5 ten bolt diff applications

Postby rfoll » Tue Nov 15, 2016 11:30 am

I went to Steve's site, pretty cumbersome to look for info. The 70 and later Camaro spring perches are wider, not sure of length, but they will not fit an X body or first gen F body. Of those that do fit, there appears to be at least 2 different widths. I have one from a 75 Skylark that has 1/2" longer axles with a smaller diameter brake hub than the earlier units. It also has to be different at the brake flange or the tube length to make up for the drum location. on another thread, someone assured me that a 73-77 A body 10 bolt will bolt right in my 79 Impala. The B body 8.5 axles came with the huge brakes and a 5 on 5 bolt circle, making them a nuisance to put in my car. This subject can burn up a lot of time just to satisfy my curiosity.
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Re: 8.5 ten bolt diff applications

Postby dave brode » Tue Nov 15, 2016 5:12 pm

rfoll said,

I have one from a 75 Skylark that has 1/2" longer axles with a smaller diameter brake hub than the earlier units.
---

That car an A body?

Aren't '68 up Novas and cousins the same width as '67-'69 F body?

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Re: 8.5 ten bolt diff applications

Postby dave brode » Tue Nov 15, 2016 5:32 pm

Fwiw: There are '71/72 A body 10 bolt 8.5s that came in non chevy cars that used bolt in axles in Olds, buick, not sure about Pontiac. The posi looked same as the chevy S spring unit. Same width as '68-'70 A body 12 bolt.

Also fwiw, I had a '73 A body [455 4 speed Cutlass "S"] with a 8.5 with bolt In axles.

On the '73-'77 A body rears, those will work in a "G" body, [and I assume '78-'81 A body]. They are MUCH wider, but the upper mounts work fine. You can narrow them easily, reusing the outer end and use "G" body axles from GN/442 [$250 ish a pair, summit], or, '62-'67 chevy II 28 spline axles from an 8.2".

You can also use 28 spline '88 up 2wd S-10 axles to make a narrower rear, about the same width as a stock vega rear.


Dave
p.s. - axle bearing is same for 7.5" 8.2", 8.5", 12 bolt car [some impala etc and trucks have a bigger wheel bearing]
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Re: 8.5 ten bolt diff applications

Postby rfoll » Tue Nov 15, 2016 6:55 pm

The B body 8.5 axles are larger at the bearing surface. All of this would be easier if you could still find them in the wrecking yards. In the Portland OR metro area, all of the old yards became housing complexes when the building boom was on in the early 2000s. Then LKQ bought the U Pullit yards and crushed all of the older cars.
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Re: 8.5 ten bolt diff applications

Postby pdq67 » Sat Nov 19, 2016 3:20 pm

Off Topic, but....

Somebody posted how to put 12-bolt car gears in a 12-bolt truck rear end or the other way around!!

And there is a shit-pot full a 12-bolt truck rear ends still around!

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Re: 8.5 ten bolt diff applications

Postby rfoll » Sun Nov 20, 2016 9:57 am

The truck 12 bolt has a smaller diameter pinion shaft, it is a weaker diff.
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Re: 8.5 ten bolt diff applications

Postby pdq67 » Mon Nov 21, 2016 12:56 am

rfoll wrote:The truck 12 bolt has a smaller diameter pinion shaft, it is a weaker diff.


I know that!

The '80 C10 P/U I sold to M Brekke had a 3.50 Sag 1st gear 4-speed along with a 2.76 rear end gear PU 12-bolt!

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