[Chris65LeMans]

Had an "I didn't even know that was a thing" failure on Friday night:

Was slowing for a stoplight and heard a "clunk," then the car acted like someone had replaced one of my wheels with a large rock. (Made the same sound, too.) It would hold it's place on a hill in neutral and was impossible to push. I fired it up again and pulled into a driveway. I suspected the issue was in the front, but the suspension up there looked fine. Tow truck guy arrives, I start backing the car up, and he notices a clanking sound from the driver's side rear. He pulls out the jack and:



"Well, there's your problem." Even with this blurry photo, you'll see that the caliper is centered at 3 o clock when it was originally mounted at 9 o'clock.



He simply pulled the caliper off, then zip-tied it to the suspension, and I drove home on three brakes.

The next morning, I jacked her up to take a look:





In this second picture, we're looking at the caliper upside down. (The longer part of the bracket mounts on the bottom.)

There is a second anodized bracket that goes between the bracket you see here and the rear end housing. I found half of it in the street, but discarded it before the tow truck arrived. (It was next to a motorcycle chain.)

So - the brake managed to rip itself free - much like my alternator did last year. (I was missing a bracket.)

Anyone else see this happen? The tow truck driver says he's seen it a few times: usually with Wilwood brakes and once with his own car.

I'll be calling the retailer that I bought the kit from on Monday to buy replacement brackets/ask for some tips. I had these brakes installed at a shop "because I don't want to screw up something as important as the brakes," but I may be tackling this one on my own.

My drivers side (the side with the broken caliper) axle has a few milimeters of in/out play. The passenger side does not. (Both sides used to have play, but the same shop that did the brakes worked on the rear end and improved (but didn't solve) the problem.

I'm interested in your thoughts - thanks!

[Scott Thelander]

wow !
you got lucky ,,, glad your safe
have em fix the tranny leak running down the exhaust
and
the lower control arm bushing looks blown out also ....

[694.1]

Loose or broken hardware? And I suspect that is a pinion leak...

[FrankieT/A]

There are spacers to go behind the backing plate to help dial in the spacing behind the backing plate and the housing if you need to go in that direction to maybe eliminate the washers. Again if that's the direction you need to go.

[Chris65LeMans]

First two pictures aren't showing up, for some reason.

[Chris65LeMans]

Yeah - Wilwood makes different thicknesses of the spacer between the backing plate and the bracket that the caliper attaches to. I ordered the two biggest sizes and will see if that works.

[FrankieT/A]

Originally Posted by Chris65LeMans

Yeah - Wilwood makes different thicknesses of the spacer between the backing plate and the bracket that the caliper attaches to. I ordered the two biggest sizes and will see if that works.

Gotcha but I was talking about between backing plate and rear end housing.

[Chris65LeMans]

Originally Posted by FrankieT/A

Gotcha but I was talking about between backing plate and rear end housing.

I see what you mean - that’ll move things in the wrong direction, though. Caliper mounting plate goes on the rear of the brake backing plate. When I put the rotor on, it contacts the caliper mounting bracket. That’s the bracket that I need to move inboard a bit.

[FrankieT/A]

Originally Posted by Chris65LeMans

I see what you mean - that’ll move things in the wrong direction, though. Caliper mounting plate goes on the rear of the brake backing plate. When I put the rotor on, it contacts the caliper mounting bracket. That’s the bracket that I need to move inboard a bit.

I see what you are talking about. On my car I has already converted my rear brakes to S10. Then I converted those to Wilwood. Those aluminum brackets you are using wouldn't work for me because the two bolt holes where the bracket mounts to the backing plate are a different dimension. What I did was design a similar bracket to yours but used 3/8 steel and had them water jetted. So far so good.

[ZeGermanHam]

So what actually happened? It looks like bracket hardware holding the caliper to the axle housing just snapped. Can you post a photo of the other side showing how it looks when mounted?

[Chris65LeMans]

What happened is the caliper clamped on the rotor, pulled itself free, and started rotating.

The “why” is more of a mystery. The witness mark on what was the top of the assembly is what has me confused- did the mounting bolts back themselves out? What snapped the (missing from the photos) spacing bracket? Did something get pulled up and stuck in there?

[ZeGermanHam]

What I'm curious about is whether your calipers use spacers to mount to the bracket which in turn fastens them to the axle flange. If so, and if the mounting hardware backed out a little bit, that would put a lot of lateral load on the hardware and could lead to the failure you experienced. Without knowing exactly how your rear brakes mount up, this is just a speculation on my part.

[Chris65LeMans]

I need to get back under there tomorrow to see if the threads on the flange are still good. I’ll take a pic of the other side when I’m there.

[Chris65LeMans]

Okay, I went and bought a propane torch in preparation to disassemble the as-delivered “assembled at the factory with Red Loctite” backing plates. I figured I first try it by hand and ... they came right apart.

The thicker backing plate looks like it works well with no rotor contact. I’ll mock up the caliper, take it all apart and torque/apply loctite, and we’ll be ready to go.

[Geoff]

My guess is the bolts were never fully tightened & loosened over time....

Maybe a few Hail Marys are in order!

[The Champ]

I was on a car cruise last on a Saturday last September to the Denny Albaugh car collection in Ankeny, IA and at the last stop sign before pulling into Denny's building one of the Corvette's lost a caliper just like you did.

The bolts had backed out - we were wondering if we'd be able to find replacements locally. Turned out the shop at Denny's collection was open and they had the bolt's and let us use a lift to make it an easy fix...

A few shots of Denny's collection:

[chrisp]

Common when no loctite used on the bolts they come loose & shear.

[694.1]

Pretty exciting when a GTP car at 180 mph shatters a rotor, tears off a caliper & tosses it up through the body work.
Ping Pong between the guardrails ensues, sometimes backwards or on a bad day, upside down.
That brings back some memories!

[Chris65LeMans]

There is a “spacer” bracket between the housing and the bracket attached to the caliper. The vendor I bought the brakes from (KORE3) in 2015 doesn’t carry them anymore, and this bracket doesn’t appear in the install instructions I have. I need to find out where I can buy just those two brackets without starting over.

[madokie]

soft brackets, soft spacers, soft washers,soft lock washers, all will be squished down and peened ,so to speak ,because they are soft and being tightened heavily and subject to much vibration,,because they are soft .not hardened,,and will lead to the bolts hold in it together becoming loose,, spend the time and money on high grade hardened hardware,,read carroll smiths book on race car hardware.he was a big advocator of safety wiring everything on a race car,i would suggest doing that on your calipers.DONT USE LOCK WASHERS , all useless..free down load on NASA fastener fabrication book. easy to find online..