So I did a 6 speed swap and I want to dump my 308 drum rear . I found a gu6 g80 disc at the wrecking yard did some research on the VIN code I believe the car was a 1985 door tags were wore off. It's a iroc the rear end is a 342 disc from my research not real sure if it's a 9 bolt or 10 it was very low on the ground in the dirt . Salvage yard said they will pull it and check it out and I can have it for 250 would this be a good rear as long as it still works ok?

 

85 Camaro would have come with a 10-bolt.

If it has disc brakes, they're the crappy Saginaw system.

The posi would be an Auburn POS and most likely is worn out.

Axles would be 26 spline.

Leave it there.

 

If you are looking for a 9-Bolt; and the seller knows the gear ratio of the diff. for sale...

The 9-Bolt OEM ratios are 2.77:1, 3.08:1, 3.27:1, 3.45:1, and 3.70:1.

 

9-bolt didn't come in any 85 Camaros.

Which is NOT the same as saying that THIS REAR is not a 9-bolt, or that a 85 Camaro "can't have" a 9-bolt in it; only, one of those didn't come in that car.

I'm not a big believer in codes and tags and that sort of thing. Too many parts get swapped around. My car (83 L69 T-5, 3.73 non-posi drum brakes originally) has had at various times a 73 400 block with 69-70 350 heads, a 91 T-5 out of a 1LE car (2nd design obviously), a 96 T-56, a 91 or 92 10-bolt with PBR brakes and an Eaton posi and the original ratio, and so forth. At no time, to my knowledge, were any "codes" or "tags" changed to match.

Regardless, that junkyard rear will still have the crappy Saginaw disc brakes in all likelihood even if it is a 9-bolt (there being only ONE year of the 9-bolt in these cars that had the better brakes), and equally likely, the posi will be worn out. The 9-bolt posi system is the direct ancestor of the Auburn, since Auburn was formed by former B-W employees; and the reason the Auburn one is crap, is because the B-W design was, before it.

 

Hmm yeah it's probably a 10 bolt . Which year 9 bolt had the good brakes? I also have a 9 bolt disc from a 88 but it's a 277 and it be spendy to change the carrier and gears from 9 bolt.com

 

The brakes shouldn't be a deal breaker. You can strip the backing plates and bolt on discs from a 90-up car. 9 or 10 bolt, you're still going to need to do something to the carrier. Easier to get parts for the 10-bolt. Or just try to get a better rear to start with.

 

1989 had the better disc brakes.1990 10 bolt had 28 spline axles and revised webbing around the pinion bearing housing to maintain better alignment under load.

 

Problem is, the ONLY backing plates that bolt up to a 9-bolt and also accommodate the PBR brakes, are from 89. They are NOT the same as the 10-bolt version such as was more widely available from 89 up. Or perhaps I should say, instead of "more widely", the right phrase might be "less narrowly".

Yes I have a set.

No they're not for sale.

IMO the brakes are a deal breaker. After all, STOPPING is pretty important; especially when your SO and her/his offspring are depending on THEIR VERY LIFE for their function.

 

Where did the Saginaw brakes come from?

I only recall 2 different brake caliper manufacturers for the disk brakes... Delco-Moraine and PBR.

 

Delco-Moraine is the "brand".

The plant and design was in Saginaw.

Those are the cast iron ones, just to dodge a nitpicky argument.

Of all people, I don't think I should have to tell YOU that.

 

Sorry I did not intend to be rude or start an argument.

The reason that I said anything about this, is because you are the 3rd or 4th person that I have heard say this.
I did not work for GM in the 1980s and I did not work with brake systems until the end of my career when GM started using Brembo and Akebono.
I started as an engineer the the 1990s.

I asked one of my former co-workers about this.
He was an engineer in the Delphi steering and suspension program (formerly a part of Delco Moraine) , but worked at the Saginaw metal-casting plant earlier in his career.

From the documents he had; the 3rd-Gen F-body iron brake calipers were tested and assembled in the Delco-Moraine plants in Dayton and Moraine Ohio.
He did say that some of the brake calipers were cast at the Saginaw metal-casting plant when supply was short.

Into the 1990s GM was phasing-out the Delco Moraine brakes (at all 4 plants) and the Delco Moraine Division as a whole.
In the late 1980s the Moraine and Dayton plants were assigned government contracts by GM (as part of the Delphi steering and suspension division), to build Humvee and Grumman frames and do some vehicle assembly.

Two Saginaw plants also went over to Delphi.
As I am sure you know, PBR brakes came into a contract with GM to produce the majority of calipers and brake systems.

So as far as I can tell from researching private GM documents on this topic; none of our iron calipers/ brakes were produced by Saginaw

 

If it's what OP says it is, it's a 10-bolt. If so later brakes with 10-bolt backing plates will bolt up. Easy fix.

If it's a 9-bolt it's probably not worth messing with since brake upgrades are more difficult and service parts are harder to come by.