I'm in the middle of my L67 swap and I was putting on new pads for the back. I just can't seem to get the piston to go back in. I got it to fully extend (grr) but now it won't go back in. I've looked at ogres cave and did everything I could. The piston starts to move a very little and just stops. I can turn the screw on the piston and it starts to go back out. I remove the parking lever and If I keep turning the screw to the left it keeps spinning but nothing happens. When I go to the right it starts extending the piston.
I can't see this being a bad caliper as they were working fine a few weeks ago when I was driving the car. Any ideas?
might Ran screw out of piston If your lucky, pushing piston and turn screw until threads catch. push in piston rest of way. If not, very short: Get rebuild seal kit in case you tear rubber Pull piston and screw. thread screw into piston. Carefully reinstall.
Or piston is dead. get a another caliper.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
You may be able to remove the lever and screw the piston back using a GM disk brake piston tool. It's a small cube that snaps onto a ratchet. I got one at NAPA but other parts stores sell them as does The Fiero Store.
Ok. Is the thread on the inside of the piston to the screw a reverse thread?
Also. should I be able to pull the piston screw (hand brake piece) out? it's pretty rusted but wasn't sure how far it should come out.I'm not sure what inside of the piston chamber looks like.
Well that sucks. I finally got the piston to go in. Put everything back together and then the rotor wouldn't fit between the pads. I noticed that when i turn parking lever the piston goes out but doesn't go back in when going the other way.
Messing with it the piston came out. Now I can't get it to go back in. Everything looks ok. The screw in the piston moves freeley but I'm kinda stuck now.
When you put the inboard pad on, the clips should hold it to the piston. The D tabs on the back of the pad must rest in the D slots on the piston. This keeps the piston from rotating and keeps the pad in full contact with the piston,. It also helps to keep the pad from moving around and allows the Ebrake to adjust as you use it.
piston should be <5mm when compress fully. if doesn't then very likely piston is bad. Then pads will clear the rotors most times. (Heavy Rust on edge of rotor can be a problem.) See my Cave, Clamp Method notes
You need to get the GM piston retract tool to get the piston to retract. The e brake lever will only push the piston out. The design is the piston retracts only by bring rotated you can not push the piston back like the front pistons.
Joe Sokol
------------------ 85 SE Daily driver with a 3.4 DOHC OBD II 88 Formula/GT 4.9 Allante Intake (My Baby) www.fieroking.com
Originally posted by Fieroking: You need to get the GM piston retract tool to get the piston to retract. The e brake lever will only push the piston out. The design is the piston retracts only by bring rotated you can not push the piston back like the front pistons.
Wrong. see same cave page or read 84-87 FSM. 87 is best because GM finally fix rear brake section of FSM.
GM made a tool for 88 to retract w/o removing the Pbrake level to save dealer service time but can retract w/ clamp method etc but iron for outside pad blocks the C clamp. If piston and screw are ok and remove the lever, can return by carefully using a pry bar. Don't pry on friction material or can break the pads.
This is possible because the "threads" on the screw is not made the same as normal bolts/nut combo. In fact, it take so little effort to move that when out of caliper and clean the screw can literally drop into or out of the "nut" just from gravity when piston face is pointing up or down.
Turning the screw in the direction the ebrake lever would move when handle is pulled causes the piston to go out, turning the other way allows the piston to be pushed back.
Before I learned this I used a harmonic damper puller to push the piston. You could do that to push the piston back in.
[QUOTE]Originally posted by Fieroking: You need to get the GM piston retract tool to get the piston to retract. The e brake lever will only push the piston out. The design is the piston retracts only by bring rotated you can not push the piston back like the front pistons.
Wrong. see same cave page or read 84-87 FSM. 87 is best because GM finally fix rear brake section of FSM.
GM made a tool for 88 to retract w/o removing the Pbrake level to save dealer service time but can retract w/ clamp method etc but iron for outside pad blocks the C clamp. If piston and screw are ok and remove the lever, can return by carefully using a pry bar. Don't pry on friction material or can break the pads.
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Not sure how he is wrong. Mine simply could not be compressed without rotating the piston. I borrowed the tool from a tire shop.
[This message has been edited by weaselbeak (edited 09-17-2016).]
Is there a way to get the piston back in the rubber sleeve? I'm holding the piston and the spring in my hand but I just can't seem to get it back in past the rubber sleeve.
Or do I have to buy a repair kit? I'd rather not have to buy a new caliper if I don't have to.
You mean outer seal/dustboot? Boot is like axle and crank seals that have metal edges to meet trans or timing cover. Try Carefully pry out the metal part out of the caliper. Work around the boot, not pry in one spot.
If you wreck it or anything else like the seal on the PB screw or o-ring for piston, need a seal kit.
Install piston (Lube o-rings w/ brake fluid.) then put boot on the piston and "drive" it into the caliper again.
1.5" plastic plumbing and old inner pad or scrap metal to make a driver. (you can/will wreck the pad) stack pipe and pad on boot then tap w/ hammer to drive the boot.
Don't need much force but is a bit hard w/o a driver.
