sbp rotor shims

[r3dplanet]

Hey gang,

I'm putting together rear disc brakes on my '65 Barracuda that has an 8-3/4" rear end with a small bolt pattern for wheels.

The rotors sit right up against the inboard side of the caliper and it looks like only way to push them outward is to use a wheel shim or spacer. When I look at Summit or Rock Auto there are many rotor shims, but nobody lists them by dimensions.

I doubt anyone makes one for an early A-body. Does anyone know anything about this?

Cheers.

[qkcuda]

5 by 4 inch bolt pattern spacers will be tough to find now. Try searching for 5 by 100 mm. it is virtually the same. At worst you may have to open the bolt holes a tad.

[r3dplanet]

Agreed. I reached out to a couple of places who make custom spacers who also agreed that 5x100mm is the easiest approach, but I need only 0.100" thickness. Apparently the minimum thickness they sell is 3/16". Looks like I'll have to find a way to fabricate my own.

[qkcuda]

Can you space the caliper back instead?

[r3dplanet]

That would certainly be the better way to go. I can see how to shim the caliper on the bracket to move the caliper outboard, but that only makes the problem worse. It doesn't seem possible to shim the caliper inboard.

I'll get some photos.

[r3dplanet]

Okay, here are some photos that show the problem probably better than I can explain it. In the first photo you can see how the rotor rubs right against the right side of the caliper.

rotor_rub_caliper.jpg


This photo shows how the caliper mounts to the bracket (Scarebird). You could add some spacers between the caliper and bracket, but it would only make the problem worse. The caliper needs to move the other way.

caliper1.jpg


Here's a view from the rear without the rotor installed.

caliper_rear.jpg

[qkcuda]

Yes the bracket is on the wrong side of the adapter to be able to space it back. You could use washers on the wheel studs to temporarily align the caliper. It looks like you will need more than .100 of a spacer to center it.

[r3dplanet]

I ended up sending the brackets back to the manufacturer to be re-made with the correct offset. That way I won't need shims at all. I don't know what the axle hub differences are year-by-year but I'm guessing that I have an early 8-3/4.

cheerio

[my64dart]

Hi,
Have you tried to put the wheels on the car yet? I've heard you need 15'' rims to clear the calipers. Small bolt pattern is 14'' rim I think. I'm not sure if this is correct or not.

[r3dplanet]

Yes. My 14" rally rims do clear by 1/4". Not much, but enough. Just to be on the safe side I'll report back when the new brackets arrive. If anything I suspect they'll provide a bit more clearance.

[my64dart]

OK, Good Luck. We spend to much money on all these parts and end up having to modify them in the end.

[r3dplanet]

Oh, totally. But I went into this project knowing it wasn't a kit. It was destined to be a project. I've been taking photos and notes along the way so once my setup is done I'll write up a how-to complete with part numbers and measurements. That will make it much easier for others to get into this setup.

[r3dplanet]

Peeps,

Mark at Scarebird made a new set of brackets for me. Neither he nor I knew that early 8-3/4" rear diffs have shorter axles. I found some illuminating literature on that subject that says Mopar made the early -741 rear ends 0.125" shorter on each side. I measured 0.100" but my axle housing was custom cut long ago.

I welded on a couple of holds onto the housing for the soft brake line adapters since one of the ones on the new brackets was clocked wrong. That's fine, I like my way better. Anyway, it's all together now and I have four wheel disc brakes. While I was in there I took the opportunity to make all new hard lines front and rear, and then top it off with a new vacuum booster and master cylinder. The car stops great. Predictable and smooth with off-the-shelf wear items. For me it's a great setup.

Good times.

[r3dplanet]

The calipers do clear the 14" Rallye rims by a good 1/4". No worries there. But I've ordered 15" x 6" small bolt pattern Rallyes just to have better tire selection. Not much in the way of 14" tires these days.