Severe brakes loss problem!!!!!!!!!
03-13-2013, 02:08 PM
#21
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I had the same problem on the HRPT last year. Take a look here.
https://www.corvetteforum.com/c1-and...holy-crap.html
https://www.corvetteforum.com/c1-and...holy-crap.html
03-13-2013, 02:21 PM
#22
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Leaking calipers do not introduce air in the calipers, unless the fluid gives out. You can pretty much forget that. You obviously have a run out problem. The rotors and hubs were final machined as a unit. Chevy didn't even recommend servicing them them. They figured we didn't have enough sense to do it right, so they recommended changing them as a unit. If the person doing the job is not knowledgeable about this, he removes the rotors and turns them on a brake lathe, and re installs them. Now that sounds like a smart thing to do, but, because the surfaces were not necessarily true in relation to the assembly, error is introduced. And that's when all of these sucking air brake problems crop up. You need to check the run out on the rotors.
03-13-2013, 03:51 PM
#23
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Runout
I like to get the runout < .003. The GM repair book calls for < .005. You can move the rotor to different positions and see what the best position would be for the lowest runout. I think a few of the positions will not allow access to the star adjustor for the parking brake. I have used shim stock to get the rear rotors within spec. You could also go with an O-ring setup. They are more forgiving with respect to allowing air to be pumped in the system because of excessive runout. Jerry
03-13-2013, 04:50 PM
#24
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I like to get the runout < .003. The GM repair book calls for < .005. You can move the rotor to different positions and see what the best position would be for the lowest runout. I think a few of the positions will not allow access to the star adjustor for the parking brake. I have used shim stock to get the rear rotors within spec. You could also go with an O-ring setup. They are more forgiving with respect to allowing air to be pumped in the system because of excessive runout. Jerry
03-13-2013, 04:59 PM
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03-13-2013, 05:13 PM
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St. Jude Donor '05, '09, '15
Just so you know I had o-ring calipers on my car when I lost the front brakes. I don't think my issue was caused by the calipers but the stock design does not keep the pistons square to the bores. So, when my pads wore on an angle the pistons angled in the bores and the wear continued until the pistons were so off square even the o-rings would not seal. Hence my tapered pad wear and loss of brakes.
03-13-2013, 05:19 PM
#28
Just so you know I had o-ring calipers on my car when I lost the front brakes. I don't think my issue was caused by the calipers but the stock design does not keep the pistons square to the bores. So, when my pads wore on an angle the pistons angled in the bores and the wear continued until the pistons were so off square even the o-rings would not seal. Hence my tapered pad wear and loss of brakes.
03-13-2013, 05:29 PM
#29
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St. Jude Donor '05, '09, '15
Just saying what happened to me. As I said I don't believe it was the calipers that caused the problem. Something else caused the pads to wear like they did. But because the pistons are not held straight in the bores there was no corrective action by the caliper to square up the pistons and help reduce the tapered wear. The wildwood calipers use a square cut seal located in a grove in the caliper housing and full length pistons. Just my 2 cents. I fell better with the more modern design. Loosing the front brakes every 50 miles on a 3500 mile trip was not fun. Just my experience and opinion.
03-13-2013, 06:04 PM
#30
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Thanks Jerry, I was contimplating switching the the o-type. I want to nip this in the butt ASAP and be done with it. Turn the rotors, measure/adjust runout and throw on the o-ring type calipers. I'm in the military, so the car does see a fair amount of sitting in the garage back home.
I bought my 69 in the late 90's. Had brake problems, i.e. air pumping.
I rebuilt my calipers with "O" ring kits probably 12 years ago, and the brakes are still fine. My 69 sits a lot too.
Earlier in this thread, I belive you mentioned that your rotors had been removed previously, meaning that the factory rivets were drilled out.
You can fool around changing the position of each rotor, and measure the runout. Put the rotors back on in the position of LEAST runout.
No need to turn them unless they're deeply scored, etc.
THEN, do the "O" ring job. Easy. You can do it yourself.
Chuck
03-13-2013, 10:55 PM
#31
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Listen to Jerry.
I bought my 69 in the late 90's. Had brake problems, i.e. air pumping.
I rebuilt my calipers with "O" ring kits probably 12 years ago, and the brakes are still fine. My 69 sits a lot too.
Earlier in this thread, I belive you mentioned that your rotors had been removed previously, meaning that the factory rivets were drilled out.
You can fool around changing the position of each rotor, and measure the runout. Put the rotors back on in the position of LEAST runout.
No need to turn them unless they're deeply scored, etc.
THEN, do the "O" ring job. Easy. You can do it yourself.
Chuck
I bought my 69 in the late 90's. Had brake problems, i.e. air pumping.
I rebuilt my calipers with "O" ring kits probably 12 years ago, and the brakes are still fine. My 69 sits a lot too.
Earlier in this thread, I belive you mentioned that your rotors had been removed previously, meaning that the factory rivets were drilled out.
You can fool around changing the position of each rotor, and measure the runout. Put the rotors back on in the position of LEAST runout.
No need to turn them unless they're deeply scored, etc.
THEN, do the "O" ring job. Easy. You can do it yourself.
Chuck
I appreciate everyone's input
03-22-2013, 10:16 AM
#33
Safety Car
If you can't eliminate enough runout by re-clocking the hub/rotor combo, then install shims between them, and mark them for future disassembly if needed. Try aluminum foil. It's about .001" thick and works excellent.
03-22-2013, 10:26 AM
#34
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I know there are at least some out in the field now that are.
If the caliper brackets aren't bent and they hold the caliper bore square to the rotor surface, the simple action of pushing the caliper piston against the pad which then pushes against the rotor will keep the piston square with the caliper bore. I don't believe it's all that critical though. A severely bent bracket could be though.
Last edited by MikeM; 03-22-2013 at 11:48 AM.
