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| Rotate rear caliper piston or not? (Page 1/2) |
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gregr75
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SEP 07, 02:41 PM
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i bought brand new 87 rear calipers, with ebrake lever and springs installed. I havent installed the calipers on the car yet because with new pads and new rotors theres not enough room, i have to push the piston out of the way (further in the caliper body) a liitle bit to make room.
I'm confused over what I think is conflicting information regarding pushing the caliper piston. some say use the rotator tool which grabs the piston notches, others say just push with c-clamp/channel locks. the 87 service manual says use channel locks but thats if the caliper is already mounted to the car.
which methid should i use to push the piston? and should i temporarily take off the ebrake spring to make it easier?
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PFF AI Bot
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SEP 07, 02:41 PM
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DISCLAIMER: This is an AI generated response. It may produce inaccurate information about people, places, or facts.
The Pontiac Fiero uses a type of caliper on the rear brakes where the piston needs to be rotated as it's pushed back into the caliper to provide clearance for new brake pads and rotors. It is better to use a brake caliper piston tool that engages the notches in the piston and allows both rotation and pressure to be applied simultaneously, making the job easier and less likely to damage the piston or seals. However, it is possible to use a C-clamp or channel locks to press the piston back into the caliper. This will require you to rotate the piston by hand or with pliers before using the C-clamp or channel locks to exert direct pressure. This method may be more challenging and increases the risk of damage, so use caution if this is the approach you choose to take. As for the e-brake spring, you can temporarily remove it if you feel it would make your task easier. Just be sure to properly re-install it afterward as it's a critical part of your car's emergency braking system. Click to see AI response
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gregr75
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SEP 07, 02:45 PM
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damn thats actually a pretty good answer from the bot! it sounds right, but em, ill wait to see if a real human agrees🤔
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Vintage-Nut
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SEP 07, 03:16 PM
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theogre
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SEP 07, 05:39 PM
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The bot is wrong.
Do Not Rotate the piston.
Fiero FSM shows the pliers but also require removing the P-brake arm. That "version" is so can remove the caliper on old rotor w/o damaging the pads.
See cave covering the C-clamp & how to use it etc.
If has pads on it, outer pad is remove/install easier by "pinching" the spring ears in the middle w/ pliers.
If you need force to retract then something is wrong. Good C-clamp can compress that w/ you turning by finger effort.
Example: Many Rebuilt Calipers have "rebuilt" or used Pistons & have problems & many seem to retract but needs more effort. If True, watch them very carefully or can drag the pads or way worse depending on exact problem.
New/Rebuilt rears often have wood or other soft blocking to fight piston moving during shipping etc. but often can move enough so can't install them. More so w/ used rotors w/ rust on edge of them.
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theogre
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SEP 07, 05:45 PM
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P-brake spring is easy if have "door spring compressor" sold @ auto part stores, amazon, & more.
Can do that w/ big pliers & grab 1 end then push to bracket holding the cable but is hard for many & spring & other parts can hurt you when goes wrong.
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gregr75
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SEP 08, 01:04 PM
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ok if i understand correctly, its
1 use spring compressor to aid in ebrake lever removal
2 compress piston with c-clamp and socket to protect acuator screw
3 reassemble ebrake lever with spring compressor to help
would not detaching the ebrake lever but just mashing the ebrake spring closed with giant channel locks work too? and then compressing the piston. i dont currently have a spring compressor
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Vintage-Nut
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SEP 08, 02:24 PM
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| quote | theogre:
P-brake spring is easy if have "door spring compressor" sold @ auto part stores, amazon, & more.
Can do that w/ big pliers & grab 1 end then push to bracket holding the cable but is hard for many & spring & other parts can hurt you when goes wrong.
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The act of selecting or making a decision when faced with two possibilities:
The Hard Way: giant channel locks might work when taking the spring 'off' BUT putting it 'On' ....?
The Easy Way: 'Door Hinge Spring Compressor' on eBay at $11
Choose wisely....[This message has been edited by Vintage-Nut (edited 09-08-2023).]
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gregr75
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SEP 08, 03:11 PM
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right, im choosing the cheap/fast way if at all possible. i bought a full face shield months ago for situations like this😀
but i meant, can i squeeze the spring and ebrake lever assembly together with channel locks without removing the
ebrake lever. and then compress the piston while im doing this.
or does the ebrake lever definitely have to come off.
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Vintage-Nut
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SEP 08, 03:39 PM
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I guess you didn't read Orge's page from the link above:
| quote | From Ogre's Fiero Cave - Parking and Brake Service
To compress the piston into the caliper...
If this method will not work then either the actuator screw is binding or the piston is damaged. You need to repair or replace the affected caliper as soon as possible.
Notice that the C clamp do not rotate/turn/whatever the Piston! It makes the actuator spin when the piston is push. The socket, # 3 below, is only a spacer. If C clamp is very hard to turn or the piston rotates, more that a couple degrees, then something is wrong. Bad parts need replace.
Work the hand brake lever on the caliper to make sure the actuator screw rotates freely.
Remove the hand brake lever from the caliper. Don't loose the plastic washer between the lever and seal.
Cover the actuator screw with a large socket to protect it. The socket MUST NOT touch the screw or seal!
Use a C clamp to compress the piston / cover the actuator screw (with a socket as shown) / piston compresses the screw will rotate under the socket. Do Not allow the clamp to damage the plug in the piston face!
Clean away any corrosion build up around the actuator screw and on the lever. Especially on the side of the lever facing the caliper.
Reassemble the lever. Don't forget to put the plastic washer back between the lever and seal. The washer protects the seal from wearing against the lever. Coat the area where of the lever facing the caliper with silicone brake grease. DO NOT use petroleum products!
Here are pictures of how to position the clamp. If your clamp is in rough shape, use a block of wood or old brake pad to protect the face of the piston. I know some of you have clamps that are in fairly bad shape... Trashy clamps can damage the piston or the plastic plug in the old style piston.
Retract the piston how far?
Just bottom them out... Not sure when there bottom out or have suspect piston? See clamp images at bottom. |
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Ogre's Photos:
https://web.archive.org/web.../brakes6.htm#retract
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