leaking calipers, or bad "o" ring

[mike weyman]

i,m replacing the brakes on the car today, mostly cause they all leak brake fluid.
once i got the tires and rims off you could see the fluid coming out the seam, "not the piston.should i replace the o ring and try or am i wasting my time.is this where it usually leaks?

 

[GTR1999]

They usually leak around the boots. I think you're referring to the small O ring in between the caliper halves? Are they SS liined calipers? If so I would get a caliper rebuild kit and reseal them. Clean them with clean brake fluid. The torque for the fronts is 130 ft/lbs and the rear are 60 ft/lbs soemof the GM manuals failed to distinguish betqween the two which can cause you to shear the rear bolts going up to 100+ ft/lbs. Check your hoses and check for runout. Replace the hoses if they're more then 4-5 years old and the runout should be less then .005,I stay under .003"

 

[mike weyman]

well,i thought the rotors were bad, but they are at 1.30, the minimum re-cuttable thickness is 1.23 so i'm safe. the calipers in question seem to be fine, rubbers are all good , pistons move freely etc, they just leak at the seam. i think a new o ring will solve the problem, but maybe someone has done this and it leaked in a month, i'm trying to determine if it's worth it.
I have gotten so deep into this car,i'll have to sell it when it's done,but i still want this car to be "excellent" in all aspects as i will need to get top dollar to break even.maybe i should replace all the calipers so that the next owner will have no problems for a while .mike

 

[GTR1999]

Mike,If you're going throug all the trouble of rebuilding the car why sell it? Are there many vettes on the Island?

The minimum thickness after rebuilding is 1.215" new rotors are 1.250 so there's only.035" to play with when turning and you have to consider both sides. I don't turn them unless they're grooved or warped and even then only slightly. Most times I'll "dress" them with a 100 grit D/A and they're fine.

If you just have one leak check to be sure you don't have a porious or cracked housing. The seal kit is cheap,at least in the USA they are.

 

[mike weyman]

i got a good deal on calipers from a dealer in the area,360.$ for 4 stainless lifetime calipers.the rotors are only surface rusted.i'll try the paper but i think it may just need a dressing on the brake lathe.mike

 

[GTR1999]

Mike you can true or "face" the front rotors but the rears will not be concentric with the spindles and may not be correct. In fact you may make them worse. If you have a shop that can face them while on the spindle rotating then that would be great,but to face tem off the spindle on a conventional braek lathe is chancing more runout then you started with.

 

[Vettehead Mikey]

Mike you can true or "face" the front rotors but the rears will not be concentric with the spindles and may not be correct. In fact you may make them worse. If you have a shop that can face them while on the spindle rotating then that would be great,but to face tem off the spindle on a conventional braek lathe is chancing more runout then you started with.

Same advice about machining as a set also holds true for the front hub and rotor.

 

[GTR1999]

Agreed,I should have said that the fronts,if still riveted to the hubs, can be faced.If the rotors are being replaced or have been replaced they should be checked on the hubs first for runout. Thanks Mike for catching that for me. It's a lot easier to tell someone on the phone or in person about a procedure then it is writing it out.

 

[mike weyman]

the brake machine i refer to holds the rotor straight (locked on cone)and cuts the front and back at the same time,i've used this service before and have never had a hump or wobble,is there anything diffrent about the vette rotors??

 

[GTR1999]

Sounds like the std Ammco lathe that holds the rotor by the bearings races. This will work on the fronts with the hubs riveted or bolted together. The rear rotors are different. If you have the spindles out then a toolrom lathe could be used to true the rotors. Hold ing hte spindle on the journals with the rotor again secured to it will turn them concentric. If you "chuck" up the rotor alone it will not be on center with the spindle and the finish my be ok but you might have runout.


I would check the runout on all the rotors to see what you have and if they are under .003" and there are no scores on them, I'd clean them up with a 100 grit D/A.

 

[mike weyman]

I used the sander and they only had surface rust, the runout is o.k.i thought there was bad corrosion, but when i ran the d/a sander on them , they look like new, they definately look o.k.
got the rest of my brake parts today, i'll have brakes tonight....now, if i only had it running...mike

 

[GTR1999]

Good job and it save you a lot of work knowing the rotor run out is within spec and they look good