Brake caliper pistons not retracting - Lateral-g Forums

J-440 · #1 09-27-2014, 03:54 PM

Evening all. Have a brand new manual brake setup from Wilwood. 12 1/2" with 6 piston calipers for the front and 4 piston rear. My problem is the driver side caliper pistons are not retracting when the pedal is released. Now, the outside pistons are but the inside ones are not. Wheel is hard to turn obviously. So I took off the caliper, disassembled it, inspected and cleaned the pistons and O-rings, put it back together with the caliper shimmed correctly, re-bled the entire system, stepped on the brakes and now I'm back to where I started. The other 3 wheels are fine. Any ideas?

**Spiffav8** · #2 09-27-2014, 05:23 PM

Quote:

Originally Posted by J-440

Evening all. Have a brand new manual brake setup from Wilwood. 12 1/2" with 6 piston calipers for the front and 4 piston rear. My problem is the driver side caliper pistons are not retracting when the pedal is released. Now, the outside pistons are but the inside ones are not. Wheel is hard to turn obviously. So I took off the caliper, disassembled it, inspected and cleaned the pistons and O-rings, put it back together with the caliper shimmed correctly, re-bled the entire system, stepped on the brakes and now I'm back to where I started. The other 3 wheels are fine. Any ideas?

That's strange. Wish I had an answer for you man.

Vegas69 · #3 09-27-2014, 09:58 PM

Is the brake hose new? They can collapse internally trapping a bit of pressure. Otherwise, send it back to Wilwood and they will replace it if defective.

**GregWeld** · #4 09-27-2014, 10:32 PM

Did you use teflon tape on any of the line fittings? Could you have a piece of that tape interfering with the fluid - lots of pressure pushing but ZERO retracting and a little bit of that tape could retain enough pressure to hold the caliper out??

Is the caliper piston(s) "free" when you take it off the rotor and push the pad back? Is it still free if installed on the rotor and you attempt to push it back?

If it's not - I agree with Vegas - could be a defective piece.

**GregWeld** · #5 09-27-2014, 10:34 PM

Also -- make sure it's the pad/caliper that's the issue --- can you see the mounting bolts?? Make sure you've installed the right bolts -- I've seen them where they go thru the bracket and are interfering with the rotor. Could explain why it seems fine until you reinstall the assembly.

J-440 · #6 09-28-2014, 09:21 AM

Am using braided steel line with no tape whatsoever. The outside pad slides out no problem, but the inside pad I have to pry out. The pistons are only about 1/8" sticking out on the defective side, the other side the pistons are flush with the caliper.
What causes the pistons to retract anyway? When you release the pedal, is a suction created to draw the pistons away from the pads?