Hello,
I was comming home from work today when my right (passenger) side rear brake failed. After I pulled off the side of the road the cailiper was in peices and at the bottom on the rotor. I had the car inspected at the end of the month in May, two weeks ago. I had previously changed the rotors and brake pads. Everything seemed ok when I changed them (maybe a month ago). I had the car towed to the same place where it was inspected. I havent contacted them yet but they have always been fair with me. Any ideas what I should request??? What could have caused this? I appreciate any and all advice.

Thanks
Martin

 

I haven't actually looked for a while, but I'm pretty sure that the PA inspection sticker has a place for the mechanic to indicate which wheel was pulled to check the wheels. If this wheel was pulled by the mechanic, you may need to have a "chat". Read on.

However, I don't think that the inspection procedure requires the caliper bolts to be removed, just the pads to be checked. So, the finger may well point back to you since you changed the brakes.

Check the sticker first.

 

The above post was somewhat incomplete.

There are only two possible ways for the caliper to separate from the mount:

1) Failure of the hole where the caliper bolt runs through the "fixed" part of the car (the part that doesn't come off when the caliper bolts are removed).

2) The bolts backed out.

Go look at the car and see if the bolts are still there. They probably aren't. Then check to see if all of the circular openings that the caliper bolts are intact. If they are, the bolts backed out. If they aren't, something broke.

I personally consider it very unlikely that ALL of the caliper mounting points would break simultaneously.

 

Thats what I thought, that the brake system would be designed to stay together against almost anything. What would cause the bolts to back out I know I tightend them. Theres not even that much room for the bolts to back out underneath there is there?

Thanks,

Martin

 

I did use a high temp anti seize on the bolts, but it says on it for brake assemblies, it was a type 13(copper mix). I know the bolts were on there tight because I rember using the half inch ratchet to break them loose, and tighten them. Also they were changed at the beginning of May but I know it can take any amount of time for something like that to work loose.

Thanks again,
Martin

 

I really couldn't say how the bolts could work their way loose. While it's possible, I'd say it's unlikely that they would both come out at the same time without you noticing. Once the first one failed, it's make one heck of a noise I would think.

The more realistic possibilities are that the caliper simply broke in two or the mounts broke off. In the case of the mounts, once the first one broke, the additional load on the remaining once may have cause it to fail, too.

The only way to home in on the solution would be to take a long hard look at the state of the car.

Report back. I'd be interested to see what you learn.

 

ok KeithO. That seems like sound advice. This is strange because the car now has 77k miles on it. I've done the regular maintaneance and like I said I didn't see anything peculiar when I changed the rotors. The front brakes needed a new hose, and I let the mechanic handle that. The car did sit last winter but I did not notice any extensive rust etc etc. I do not have a lot of experience but I'm trying to learn as I go along.

Thanks Again for the help
Martin

 

Verdicts in. Fn bolt came loose, seems like it hit the rim pretty hard, mechanic said its about an 1/8 inch grove. Ahh nothing I can do now, I'm gonna have to talk to him and figure out what I did wrong, so atleast I can get a lesson out of this. Now I have to find the flange behind the axlehousing and the anchor plate, they are apparently discontinuted and will take anything from an 89-92 rear disc setup. Any ideas where I might find one.

THanks
Martin

 

First, I don't think the ani-seize would be a possiblity. I use it for everything (and so does ny dad) and neither of us have had any problems.

Maybe this will be interesting:
According to my Chilton's 3rd Gen Manual, the caliper bolts should be torqued to:
1982-1988 30-45 ft-lbs
1989-1992 Upper 26 ft-lbs Lower 16 ft-lbs

Is it possible you missed any of thee values?

I don't htink you'll ever know 100% why this happened.

As far as parts are concerned, there is supposedly a junkyard out towards Pittsburgh Airport that specializes in 3rd gens. I don't know the name and have never been there. Twice I had planned to drive out to ahve a look on a Saturday and both times something came up.

I would post a "Wanted to Buy" in the classifieds on this site if you don't find them alerady listed.

My 3rd Gen is down too. I blew up my tranny at an autocross on Sunday. Oh well.

 

That would be it, I tighted them as good as I could get them with a 1/2" Ratchet, thats a blunder I just assumed that since they were froze when I took them off, that they were a hand tight thing. I hate learning things thata way. How'd the autocross go? I've been busy with work/school but would like to go out and see it sometime perhaps if theres something local.

Thanks Again
Martin

 

Autocrossing has been good to me. I bought the IROC to be an autocross car and a winter beater. It has performed extremely well up until Sunday (that's nearly 40 events!). In addition, the IROC has been flogged on Watkins Glen and Nelsons Ledges (twice).

Since my wife had a baby yesterday (boy!), I'm going to have to miss the event on Sunday at IUP. In addition, my tranny is still hosed and I won't even have a chance to think about it until next week probably.

I run autocrosses with 3 "local" Pittsburgh groups. Here are their websites if you are interested:
http://www.fyi.net/~nhscc/
http://www.wizco.net/NOVR/
http://www.steelcities-scca.org/

Bear in mind that "Solo II" is another way of saying autocross. Should you check the results, my car is 30 FS. FS is the class for f-bodies. At some sites, they stopped putting our names in the results because insurnace companies have started sdropping people who autocross.

Stock, our cars are in with Mustangs, etc. Pretty good match-up. If you decide to come to an event, look for a red IROC (me) and a Yellow C4 Vette (my dad). You'll find the competitors are very open and helpful. I or my dad will lend you a helmut.

See you at the races!

 

Congratulations!!! I'll have to check that stuff out. Maybe I will see you around. I also discussed what happend with a friend of mine. We thought it through, theres no way that the force, even if I over torqued them coulda screwed up the bolts. It had to be the caliper jamming up. Somehow the caliper piston put a force in such a way as to rip the bolt out. Hydraulic force more then likely destroyed that bolt. I should have detected the caliper was bad, but atleast I dont feel like a complete idiot. Thanks for all your help, and again congrats!!!

Martin