Stephen

iTrader: (12)

Is it possible to put a set of iron calipers & rotors, from a '87 9-bolt, onto a '90 10 bolt rear?

And, I assume the center section & housing, are the same, between a '87 9-bolt & a '89 9-bolt? Making everything else interchangeable. I know both of the rears I have are the same gear ratio.

Apeiron

There are no "9 bolt" and "10 bolt" brakes, only "brakes". They're all the same regardless of what rear they were mounted on. The only difference is in the backing plates to mount the brakes to the axle flanges.

Stephen

iTrader: (12)

You get my point, geez....Disc brakes from a 9-bolt rear, onto a drum brake 10-bolt rear? And no, they WEREN'T all the same. 88 & later 9-bolts, got the PBR calipers. Before that, they were iron calipers.

Apeiron

89 (not 88) and later 9 bolts got PBR calipers, and so did 10 bolts. The brakes are exactly the same on any 9 bolt and 10 bolt of the same year.

Stephen

iTrader: (12)

So, the axle flanges are the same, between 9 & 10 bolts? Meaning, just swap the backing plates, and your good?

Apeiron

The bolt patterns on the axle flanges are different between the 9 and 10 bolt, which is why the backing plates are different, but if you swap the backing plates out then everything else works fine.

The axle flanges are also different between disc and drum rears, but i think ebmiller88 is offering a backing plate now that will let you bolt the disc setup directly into an unmodified drum backing plate.

Stephen

iTrader: (12)

Maybe he'll chime in here, if he has those.

ebmiller88

iTrader: (7)

To answer your question, the backing plates from the 9 and 10 bolt "old style" disc rears will be different due to the flange bolt pattern but the brakes are the same. I would assume you could redrill the 10 bolt plate to fit the 9 or elongate the holes. If you can just upgrade to the PBRs and be done with it, the old style calipers will give you trouble unless you rebuild them with the recall kit.

Ed

Stephen

iTrader: (12)

I understand all the stuff about the PBRs being better, etc., etc.

I just want to know...

Will early 9-bolt rear end disc brakes ('87), fit on a '90 10-bolt drum rear?

Forget all the other semantics. Can it be done?





I didn't know that a straight forward question, was so hard to answer...

ebmiller88

iTrader: (7)

Ok then...yes. But it won't be a bolt on thing. How's that?

But here's some info you NEED to know. The 10 bolt drum rear will have a center section where the axle goes thru that is SMALLER than the center hole on the 9 bolt backing plate, you will need to perfectly center the plate so that the rotor will be centered on the caliper. You will also need to trim the top of the drum flange off to get the disc plate to sit flush on it as well.

Ed

Stephen

iTrader: (12)

It's just that you referenced putting 10-bolt disc brakes on a 9-bolt. Totally opposite of my question. 10 to 9, instead of 9 to 10.

The goal was convert a '90 10 bolt drum, into discs, by using the brakes from a '87 9-bolt.

scooter

iTrader: (11)

Yes it is possible, I would not recommend it, lol. You will need a different backing plate for the drum brake rear though, and the way you are going you will need to fab a backing plate.

Stephen

iTrader: (12)

And, why would you not recommend swapping from drums to discs? Because of the work involved? It sounds the backing plate, is the only real issue. True, the master cylinders should be swapped too, but that would be a simple R&R.

ebmiller88

iTrader: (7)

Yes.
----------
No.

scooter

iTrader: (11)

I personally would not go to the older style calipers. I think you would be better off with the drums, at least we know them to be fairly reliable compared to the iron calipers