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Discussion Starter #1
Hi all - 1968 GTO with front disc conversion from Right Stuff. Basically regular single piston A-Body calipers 69' and beyond. I installed new semi-metallic pads. greased in the appropriate areas only, reseated calipers and bled front brakes. Now, just as I apply brakes, I can hear the pads "clack" once. No noise when driving or on bumps, appropriate pedal feel and stopping power. But I HATE weird noises. Almost always a sign of something not correct. The conversion, and thus calipers are 12 yrs old but only about 5000 miles on them. They look fine, fluid fine. etc. What gives? did I seat them incorrectly?

thanks Joe
 

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Discussion Starter #9
Calipers aren't new, but seriously have maybe 5000 miles on them. Nothing like that
 

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Calipers aren't new, but seriously have maybe 5000 miles on them. Nothing like that
You mentioned that they were 12 years old....and have <5k miles on them. The old pad ears may have etched the surface of the caliper causing them to hang for an instant before sliding. I would take a wire wheel/emery cloth and polish where the ears of the pads ride on the caliper.
 

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Jack it up again....take the wheel off and put light pressure on the brakes and try turning the rotor with a tire iron or breaker bar and see what gives.
 

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Throwing things out at you...we do several thousand brake jobs a year. Almost everybody's pads now have the backers powder coated or coated with some other thick layer. So very often we have to grind that off or the pads won't fit (newer cars with shims) or they won't slide easily (like your application). If you can duplicate the issue while on a lift/jack, then that is always best. You should be able to see what's going on. Often you can't, as you need the forces applied by 2 tons of moving car.
I asked if you threw these in w/o new rotors and went for a quick ride. If you've only gone a short distance and you have new pads/old rotors the whole situation may solve itself when those pads seat. They won't do that as well over old rotors.....A very common equation..new pads+old rotors=noises
 

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Discussion Starter #14
Yes, old rotors. Surface of rotor and thickeness no issue. Replaced pads because they were clacking and one of the reminder tabs loose. IDK. They did not need replacement.

Il try cleaning ears and also Jack up, light apply brakes, turn with breaker bar to see what gives.

Thx guys
 

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Discussion Starter #15
Throwing things out at you...we do several thousand brake jobs a year. Almost everybody's pads now have the backers powder coated or coated with some other thick layer. So very often we have to grind that off or the pads won't fit (newer cars with shims) or they won't slide easily (like your application). If you can duplicate the issue while on a lift/jack, then that is always best. You should be able to see what's going on. Often you can't, as you need the forces applied by 2 tons of moving car.
I asked if you threw these in w/o new rotors and went for a quick ride. If you've only gone a short distance and you have new pads/old rotors the whole situation may solve itself when those pads seat. They won't do that as well over old rotors.....A very common equation..new pads+old rotors=noises
Ive only got 50 miles on new pads. I'll play with it tomorrow (clean ears e.t.c) try to duplicate noise with Jack in air and breaker bar. Then report back
 

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Ive only got 50 miles on new pads. I'll play with it tomorrow (clean ears e.t.c) try to duplicate noise with Jack in air and breaker bar. Then report back
I was going to ask you if there is a shim on the back of the outboard pad? Is it lubed where the caliper contacts it?
Unless both sets of pads were installed without/misplaced shims or lubed, it's probably not the pads now that you say the pad change was an attempt to stop this same noise.
So what is the same? Rotor, caliper, bracket. Right stuff disc swap kit? Did the car ever not make this noise with those brakes? The kit that has the steel caliper brackets that you bolt on? Not unusual for those to hold things not quite square. I used a similar kit. When it happened to me, I was expecting it so I recognized what was going on. Everything all fits together but the pads don't float freely due to the brackets not being perfectly parallel to each other. You should be able to see this on a lift.
If all is well there, there really aren't too many other options. The noise is the pads moving/not moving, they might not be sliding well due to imperfections in the sliding surface caliper/bracket or in the pad itself. They may be moving too much due to the same reasons. Or, either of those may be occurring not to defects in those parts, but to associated parts. Rotor have a ridge at the edge?, not parallel, not true? all can cause an otherwise properly functioning pad/caliper make noise. Loose bearings or a real loose ball joint can cause the rotor to be out of parallel with the pads.
There's a lot of small reasons for something small to be going on and that's likely what you have. The pads are either moving/not moving correctly or being made to move so by something else.
 

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Discussion Starter #17
Everything is same from swap kit. I installed at same time as complete suspension overhaul. New everything, stock Moog components thru Ames. Agree that pads are not causing this as problem remains. I can't imagine a ball joint being bad. I noticed clack noise on driver side originally, but believe i have on both sides now. Rotors have no ridges or imperfections. Brakes feel good and track straight when applied with free steering wheel.

It's an odd one. Calipers/ piston sticking maybe?
 

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Discussion Starter #18
Think I will exercise a "free brake inspection" via Les Schwab , thus being able to utilize lift vs. Jack stands. :cool:
 

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Discussion Starter #19
I was going to ask you if there is a shim on the back of the outboard pad? Is it lubed where the caliper contacts it?
Unless both sets of pads were installed without/misplaced shims or lubed, it's probably not the pads now that you say the pad change was an attempt to stop this same noise.
So what is the same? Rotor, caliper, bracket. Right stuff disc swap kit? Did the car ever not make this noise with those brakes? The kit that has the steel caliper brackets that you bolt on? Not unusual for those to hold things not quite square. I used a similar kit. When it happened to me, I was expecting it so I recognized what was going on. Everything all fits together but the pads don't float freely due to the brackets not being perfectly parallel to each other. You should be able to see this on a lift.
If all is well there, there really aren't too many other options. The noise is the pads moving/not moving, they might not be sliding well due to imperfections in the sliding surface caliper/bracket or in the pad itself. They may be moving too much due to the same reasons. Or, either of those may be occurring not to defects in those parts, but to associated parts. Rotor have a ridge at the edge?, not parallel, not true? all can cause an otherwise properly functioning pad/caliper make noise. Loose bearings or a real loose ball joint can cause the rotor to be out of parallel with the pads.
There's a lot of small reasons for something small to be going on and that's likely what you have. The pads are either moving/not moving correctly or being made to move so by something else.
No shims used
 

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Everything is same from swap kit. I installed at same time as complete suspension overhaul. New everything, stock Moog components thru Ames. Agree that pads are not causing this as problem remains. I can't imagine a ball joint being bad. I noticed clack noise on driver side originally, but believe i have on both sides now. Rotors have no ridges or imperfections. Brakes feel good and track straight when applied with free steering wheel.

It's an odd one. Calipers/ piston sticking maybe?
Did the car ever not make this noise after the brakes were converted to disc? I would very much doubt you had a piston sticking. Generally won't cause the noise you're having and you would likely have other symptoms.
 
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