Alright, rear caliper was fully seized, I mean I had a cast iron 20" jaw C-clamp (the really heavy bastards) on the piston and I bent the C-clamp so badly she don't line up right no more. Add to this that I now realize I have a frozen caliper and it's the middle of the night, well, I'm a tad peeved. So after the ramble here is the meat of the questions: 1. Why the heck didn't I have any pull or smoke or any other indication of the caliper seizing? The pads were so worn down that they seemed almost fused to the rotor (did I mention my rotor is fragged too?). Did I miss any obvious symptoms? 2. The caliper is only 5 yrs old (new caliper) (pads were only a year old!!), what are the typical causes for this? All the hardware is in exceptional shape, yet I presume I have a seized caliper. 3. I have as yet to pull the right side, so I am dreading the site I find, however, if all is well would it behoove me to swap all the rear hardware now? 4. Could there be an outside possibility that the proportioning valve also seized up, thus causing this? It seems like an outside chance, however, if this is the case, shouldn't I be able to break loose the piston? Thanks guys! ------------------ "Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason, than that of blind-folded fear." -Thomas Jefferson

Are you saying the piston is stuck in the bore?

Jason

[This message has been edited by 89BlwnRs (edited January 31, 2001).]

Rut roh....

What year car ya got Red? I havent messed with an 89 up, but if its the earlier style caliper that looks just like the front one, you just hosed your caliper. To put the piston back into the caliper on the rears up to 88, you have to turn the piston as you press it back in. It has a self adjusting mechanism (at least GM claims its self adjusting... I'd like proof) that doesnt allow the piston to be forced back into the caliper unless you turn it too.

madmax is most certainly right! but they does seize up alot,because they don't get used enough. a good habit would be to use your emergency brake whenever you park the car. that way the rear calipers are always being used.

How did you get a C-clamp on that rear caliper? I just rebuilt my calipers 2 weeks ago and if you still have the E-brake actuator arm on there where did you put the C-clamp? When I reassembled mine, I got the "campaign" kit from GM that came with the new pistons, seals, pad retainers and springs, and I left the actuator arm off until the piston was in. I bought one of those piston insertion tools, (like $6.99 at Autozone) and had to use that, but didn't have to turn the piston because as the piston was pushed in it turned the screw which could spin freely since there was no actuator arm. Madmax is right, that piston and the actuator screw are well, for the lack of a better word, screwed. I have the part # for that kit at home which I can give to you later if you want it, I think GM had MAJOR problems with the J65 rear disk brakes all the way up until 89. The rebuild kit for those calipers cost me about $50.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

The part # for that rear caliper campaign kit is 1#18019028 (that's exactly what is on the box, with that pound sign inbetween the 1's.

Red Devil, I like that quote by the way.

Yeah you never said what car you have, but I can tell you about my 86 Irocz.
The rear brakes never worked since I bought the car. The dealer explaination is that the parking brake wasn't used enough. My solution was to remove the rear brakes, and parking brake cable/handle.. problem fixed. I had driven the car for months before I discovered that the rears never worked, so I never missed them once they were removed. I also tossed the prop-valve and plugged the hole on the master cyl... then later tossed the vacuum booster & master cyl and replaced with a 1-pound Howe master cylinder that works much better than the factory stuff... just manual brakes now & had to get used to the pedal feel.
So I have no idea how to actually fix the factory rears but I know it was going to be very expensive and not worth the trouble. There are great lightweight and hi-performance disc brake setups that you can get to replace your rear equipment for about the same fortune that you'll spend to replace with more factory parts.
I think you know that the rear brakes you have right now are probably goners, so you do have a choice as to what to do.
Now what I do know is that the rubber connecting lines that go to the calipers are nothing but trouble waiting to happen. They collapse inside and commonly cause brake seizures(?) you know what I mean. Up until that point they cause excess residual fluid pressure on the calipers which not only cause your parts to wear faster but cost you performance from the excess drag. I have also seen master cylinders, vacuum boosters, and proportioning valves add excessive drag even when they are functioning within spec. That's one of the reasons why I switched to a very simple manual system and it did decrease drag dramatically. Oh and yes the car stops just fine.
So just giving you my 2 cents and more to think about.
Good luck,


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White 1986 Irocz, 305/383 with Edlebrock Performer-RPM intake and Performer #1407 carburetor, +110hp shot of crack, 700R-4 tranny, 3.25:1 rear, Mcreary Road-Stars, single 3" Borla exhaust, Linginfelter-TPI camshaft pulls 17" vacuum solid. N/A runs 10.9 @124, Crack-runs 10.3 @135... haven't run at track since Oct-99

Hmm... another thing to add to the list, write my bloody info down!! How did I miss that one?
It is an '89. I really think they seized from the heat. I looked at them again today and tore one down. Needless to say it is ugly. So I will now assume it was fine until it melted the bloody pads, but this leaves me in a sort of chicken and egg quandary. Either ir seized and melted the pads, or they abnormally wore out and seized the caliper. I still can not understand how this much wear happened in a matter of months and no squeeking or pulling, that is bloody unheard of!! Oh well, I'm open to shoot some thoughts, however, the calipers are both entirely scrap.


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"Arguments are like fire-arms which a man may keep at home but should not carry about with him."

-Samuel Butler

Seized brake parts are usually the sign of water/moisture in the brake fluid. I'd start with flushing out the brake fluid, and go from there. I really doubt temperature caused it.

you took off your back brakes OBD????? doesn't it seem kinda silly? GM put them on there for a reason. how in the world do you pass inspection????????

what type of pads did you use? I bought rotors last march from tuffy for about $150 (brand new, front only, and yes I overpaid!) and used the Raybestos Brut Stops (ie everything but the calipers/hoses was brand new). In a scant 13000 miles, the pads were gone and had damaged the rotors. I've since had the rotors turned professionally and had a mechanic (NO!!!) install normal raybestos pads from napa or somewhere. I've sinced traced my difficult braking problems back to the damn hose slipping off the booster, so that has a clamp now. When I changed my struts the other day, my right rotor had a burn mark on it, and I must conclude I have either bad rotors or that raybestos totally sucks. Hope all that helps.

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"We lost Dale. This isn't fun anymore"

R.I.P. #3

"The inevitability of death serves as the most clear evidence that to truly live, one must constantly court death, flaunt death, smack death around, and basically grab death by the throat and dare it to come too soon."

- Me

Look at the pistons, if they are solid and have a couple of indentations in them, they usually screw in to push them back.

If they are hollow, they just push back.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

R.I.P. #3
My favorite quote about D.E. "He can see air"

[This message has been edited by Engineboy (edited February 24, 2001).]

I really hate GM's design for rear brakes and ditched the e-brake. I know about 5 places that will inspect me no prob. A question i'd like to ask is if it is possible to put a front caliper on the back. Changing brakes could then be accomplished in record times!

Mr. F,

GM also programmed a speed limiter on may cars to "protect us from ourselves". Where's the logic in that?

Some cars pass track inspection with only a two-wheel hand brake and a drag chute... Did you bother to ask if he drives it to the road safety and emissions inspections?

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Later,
Vader
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"No matter how hard you try you can't stop us now..."
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