Sticking caliper piston???
Thread Starter
Pro
Joined: Jun 2008
Posts: 680
Likes: 3
From: charlotte N.C
Sticking caliper piston???
Here is my dilemma. When I lift the front wheels off the ground on my 76 vette and try to rotate the wheels they both wouldn't move as smoothly as it’s suppose to. It is a two hand operation that takes a small amount of muscle to turn the wheels. So first off I thought it was the caliper so replaced them; but the problem was still there. Next I replaced the rubber break hoses thinking they could have internally damaged, but that also did nothing. There is a new master cylinder on it as well. The rotor turn fine when the calipers are off it but once the calipers go on I can't turn it at all until I put the wheels on. Now that explains why I get 9 mpg. Has anyone else had this problem and what do I have to do to fix this? 
Instructor
Joined: Jun 2009
Posts: 157
Likes: 1
From: Sebring florida
I have the same problum. Maybe if I can get them to release I'll get 1/4 mile times down to 6 seconds.
I beleave these caliper pistons are spring loaded and that keeps the pads against the rotor. I don't know what would happen if we were to remove these springs and let the pads float.
I beleave these caliper pistons are spring loaded and that keeps the pads against the rotor. I don't know what would happen if we were to remove these springs and let the pads float.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
I have the same problum. Maybe if I can get them to release I'll get 1/4 mile times down to 6 seconds.
I beleave these caliper pistons are spring loaded and that keeps the pads against the rotor. I don't know what would happen if we were to remove these springs and let the pads float.
I beleave these caliper pistons are spring loaded and that keeps the pads against the rotor. I don't know what would happen if we were to remove these springs and let the pads float.
Instructor
Joined: Jun 2009
Posts: 157
Likes: 1
From: Sebring florida
I just checked Ecklers and according to their caliper rebuild parts there is piston springs which keep the pads in contact with the rotor at all times. I wonder if you can remove these springs?
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
no do not remove those springs.....you want the tension they create or else you waste pedal effort on pushing them out and run out of brake pedal.....the pads will walk away from the rotors and create a small gap then when you push on the brakes your effort goes into pushng them back to the rotors and only after that does the braking start.....some racers remove the springs, but i certainly would not on a street car
Thread Starter
Pro
Joined: Jun 2008
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From: charlotte N.C
Team Owner
Joined: Jun 2000
Posts: 38,923
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From: Southbound
Cruise-In II Veteran
The pads on Corvette discs are in contact with the rotor at all times by design. That's why the springs are there.
Do you have the brake drag problem on the rears? You could have a bad pressure switch. Have you reset it?
Where did you get your rebuilt front calipers? It's possible they might have incorrect springs in them.
Thread Starter
Pro
Joined: Jun 2008
Posts: 680
Likes: 3
From: charlotte N.C
The pads on Corvette discs are in contact with the rotor at all times by design. That's why the springs are there.
Do you have the brake drag problem on the rears? You could have a bad pressure switch. Have you reset it?
Where did you get your rebuilt front calipers? It's possible they might have incorrect springs in them.
As for the rear, I just checked it and it feels just like the front as well. Stupid question but how do you reset the pressure switch?
I got the caliper for autozone:
http://www.autozone.com/autozone/cat...&parentId=44-0
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Advanced
Joined: Dec 2006
Posts: 50
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From: Houma La
check out duntovmotors.com. There is and excellent article on this subject. Go to articles and tips and then click on caliper school. There is also an artical on caliper seals and why GM designed them the way they are.
Sorry but I haven't learned how to post a link. Maybe someone could do that in a future post.
Good luck.
Sorry but I haven't learned how to post a link. Maybe someone could do that in a future post.
Good luck.
Burning Brakes
Joined: Dec 2005
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From: Baldwinsville, NY
Team Owner
Joined: Jun 2000
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From: Southbound
Cruise-In II Veteran
Thread Starter
Pro
Joined: Jun 2008
Posts: 680
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From: charlotte N.C
I understand the springs and floating pistons but is it supose to be this tight? Is every C3 vette like this where is almost inposible to rotate the rotor if the wheel is off and when the wheel is on it's extremely tight.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
The springs should just keep a little pressure on it, nothing that would make the wheel that hard to turn. Now you say the wheel turns with the calipers off, so we know it has something to do with the calipers. The only things that would put pressure on the rotors is the pads. Either the pads are not centered and they tighten up when you bolt up the wheel or they are too thick. I still thing you should place the pads in the calipers and snug up the lug nuts with the wheel off. Then look closely at their alignment in the slots. Pry out on the pads to loosen their grip on the rotor. See if there is enough clearance to free the pads.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
i wonder with your new master cylinder if it is some how getting applied when the car is turned on and the power comes on.....i am thinking the length of the push rod on brake pedal that activates the master cylinder is some how too long for the master cylinder you got and it is applying the brakes.....get up there and get some one to pull the brake pedal all the way back and see if wheels turn better.....then take the master cylinder cap off and see when the bubbles appear when you push on the brake pedal.....you should move the pedal just slightly to get those bubbles.....i wonder if you will not see the bubbles because its already being engaged???? maybe you have the wrong master cylinder they are different for pwr brakes vs manual brakes
