Brake Caliper Pistons HELP!!!
Thread Starter
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From: Southwest
Brake Caliper Pistons HELP!!!
Should all 4 pistons have the same amount of travel at the same time??? I pulled the wheels off and applied pumped the pedal 5-6 times and this is how they look!! This looks a little scary 
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From: Up Nort
I think the two same size pistons should move together, but without any resistance (brake pads) I'm not sure how accurate this test is. If you keep pumping, will they eventually catch up?
I have stuck pistons in my brembo's, causes some unsteady breaking at about 135mph on the track. Street use I cannot tell anything is wrong. This weekend I'm going to pump a few bottles of el-cheapo fluid through them, then flush again with Super Blue, hope they free up.
I have stuck pistons in my brembo's, causes some unsteady breaking at about 135mph on the track. Street use I cannot tell anything is wrong. This weekend I'm going to pump a few bottles of el-cheapo fluid through them, then flush again with Super Blue, hope they free up.
Three Wheelin'
Joined: Jan 2005
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From: Dubuque, Iowa.
This test means nothing. Piston force under load is really what you are concerned about. The best way measure piston force would be with a compression load cell between the inboard and outboard pistons.
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From: Southwest
Yea, yea, I know 
I only wanted them to move slightly and the top ones slid all the way over, don't worry, I'll get it back
I only wanted them to move slightly and the top ones slid all the way over, don't worry, I'll get it back
Originally Posted by FBIII
Why would you do that? Now you have a much greater problem of trying to push them back in without getting cocked.
Thread Starter
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From: Southwest
Thta's all I needed to hear for now 
I'll get deeper into the calipers when I have more time. I was trying to get the pistons out enough to clean them. I've got one or more sticking 
I'll get deeper into the calipers when I have more time. I was trying to get the pistons out enough to clean them. I've got one or more sticking
Originally Posted by 928drvr86.5
This test means nothing. Piston force under load is really what you are concerned about. The best way measure piston force would be with a compression load cell between the inboard and outboard pistons.
Three Wheelin'
Joined: Jan 2005
Posts: 1,664
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From: Dubuque, Iowa.
You could strain gage the rotor and measure lateral deflection as well, that would tell you which side is stronger. Piston pressures should equalize on all four though, so i doubt you would see any deflection.
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Racer
Joined: Jan 2004
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From: Houston, TX
I would not do that because you are exceedig the normal travel of the piston. If you applied more pressure to the pedal they would equalize.I would not expect the pistons to travel the exact same distance as the fluid will take the path of least resisitance and these pistons while very close in tolerances are not exactly the same.
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From: Up Nort
Originally Posted by Darien Nunn
Thta's all I needed to hear for now I'll get deeper into the calipers when I have more time. I was trying to get the pistons out enough to clean them. I've got one or more sticking
I'll get deeper into the calipers when I have more time. I was trying to get the pistons out enough to clean them. I've got one or more sticking 
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From: Austin, Texas
You'lll need multiple long/flat screw drivers (if nothing else) to pry those pistons back in at the same time...lots of fun!! Or, remove calper, put old pads in, then pry against the pads in an X configuration to return the pistons, then swap in new pads & replace caliper.
