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Discussion Starter · #1 · (Edited)
Anyone has the experience in compressing the rear brake piston back in
by C-clamp or special tool? I accidentally hit the brake, which made the
rear piston stick out too much as shown on attached pictures. Can I use
c-clamp compress the piston back in? What special care should I take in
this process? I was trying to compress it back in by C-Clamp but I did
not success. Need help badly.:confused:


BTW, do we need to twist and compress the piston simultaneously or just
compressing by C-clamp shall be OK? I am concerned about damaging the interior oil seal.
 

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Discussion Starter · #2 · (Edited)
https://www.youtube.com/watch?v=rqim1KAzNhg

Take a look at this video regarding VW Jetta rear brake change. Do we have to
use that kind of special tool to twist and push the piston back in??????

I tried two types of tools as follows.
1. Stanley Disc Brake Spreader
2. C-Clamp

I had no problem with the front brake piston with these tools BUT neither
of them worked for the rear brake piston.
 

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I was able to use a C-clamp and a pair of channel locks with the teeth taped up. Tightened up the c-clamp and then turned the piston in with the channel locks. A little tedious since a you have to keep repeating the process until the piston is fully returned.
 

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Discussion Starter · #4 · (Edited)
I was able to use a C-clamp and a pair of channel locks with the teeth taped up. Tightened up the c-clamp and then turned the piston in with the channel locks. A little tedious since a you have to keep repeating the process until the piston is fully returned.
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Did you take the same approach for the front brake pistons? Or just for the rear ones?

How long did it take you to finish one rear piston compressing? By the way, was that a one-man job or need help from buddy???
 

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I've only done the rear so far. It was a one man job. It's not bad, maybe 5 minutes to turn the piston back in. Just takes a bit because once you start turning the piston back in, you need to keep retightening the clamp to keep the pressure up while you turn the piston.

Edit: I also had a metal hanger to support the caliper. Don't want to stress the brake lines.
 

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Discussion Starter · #6 · (Edited)
I've only done the rear so far. It was a one man job. It's not bad, maybe 5 minutes to turn the piston back in. Just takes a bit because once you start turning the piston back in, you need to keep retightening the clamp to keep the pressure up while you turn the piston.

Edit: I also had a metal hanger to support the caliper. Don't want to stress the brake lines.
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Thanks a lot. I will try your way. What size channel locks did you use?
Could you please show me the photo of the channel lock pliersyou used????

When you twist the piston clockwise, did you have the C-Clamp tightened simultaneously????
or you tighten C-Clamp first and then remove it before twisting the piston????

Is there only one rear caliper which needs twisting and compressing or BOTH????
 

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Discussion Starter · #7 ·
I've only done the rear so far. It was a one man job. It's not bad, maybe 5 minutes to turn the piston back in. Just takes a bit because once you start turning the piston back in, you need to keep retightening the clamp to keep the pressure up while you turn the piston.

Edit: I also had a metal hanger to support the caliper. Don't want to stress the brake lines.
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When twisting and compressing the rear piston, did you leave the cap
of master cylinder off or leave the caliper bleeder open in order to reduce the resistant pressure?

:rolleyes::confused::(
 

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Channel locks picture attached.

First you wanna put the c-clamp on and tighten it up. When I did mine I tightened it as far as I could. Then while the clamp is on there, take the channel locks and
Grab the pistons outer edge and turn it clockwise. The piston will begin to turn because as you're turning it it, the c-clamp is putting the pressure on it that you need to turn it back in.

As you turn the piston, you will see that clamp becomes loose, and thus will need to be retightened. Then you turn the piston again and just keep repeating this until it goes all the way back. You need to do this for both sides of the car.

I know the book said to remove some brake fluid from the reservoir, but mine was low. I just checked it as I turned the pistons back in. If your reservoir is pretty full you may have remove some fluid. I didn't remove the cap(since my fluid was low) or do anything extra with the caliper.
 

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correct tool

Easy job once you have the correct tool..LOL :p Remove the brake pads from the caliper, remove rotor, mount caliper back on the car just snug. Get you this small block tool from the local parts store for about $10-12 bucks and use a regular 3/8 ratchet with a small extension it fits perfectly to this block tool. Push in as you turn clockwise, once the piston starts to rotate it moves in faster.
 

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Discussion Starter · #10 ·
Channel locks picture attached.

First you wanna put the c-clamp on and tighten it up. When I did mine I tightened it as far as I could. Then while the clamp is on there, take the channel locks and
Grab the pistons outer edge and turn it clockwise. The piston will begin to turn because as you're turning it it, the c-clamp is putting the pressure on it that you need to turn it back in.

As you turn the piston, you will see that clamp becomes loose, and thus will need to be retightened. Then you turn the piston again and just keep repeating this until it goes all the way back. You need to do this for both sides of the car.

I know the book said to remove some brake fluid from the reservoir, but mine was low. I just checked it as I turned the pistons back in. If your reservoir is pretty full you may have remove some fluid. I didn't remove the cap(since my fluid was low) or do anything extra with the caliper.
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Here is a thread from other site talking about the approach of C-Clamp+Channel locks.
Retracting rear brake piston on Alfa 164 - Alfa Romeo Bulletin Board & Forums

I will try this way first.
 

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The block will work. You don't use the part you circled, you use the two posts that are farthest apart. The key is, you have to rotate WHILE you press in. Just rotating will not work.

That piston is really far out. I hope it goes back ok. Note that the dust seal must seat properly in that recess at the edge of the piston. If you tear the boot, just replace the piston. They do make rebuild kits, though...

This is rear only. Front calipers compress straight int.

If you want to to it easily, get this tool:

Disc Brake Pad and Caliper Service Tool Kit 18 Pc

 

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Discussion Starter · #14 ·
The block will work. You don't use the part you circled, you use the two posts that are farthest apart. The key is, you have to rotate WHILE you press in. Just rotating will not work.

That piston is really far out. I hope it goes back ok. Note that the dust seal must seat properly in that recess at the edge of the piston. If you tear the boot, just replace the piston. They do make rebuild kits, though...

This is rear only. Front calipers compress straight int.

************************************************************************

Note that the dust seal must seat properly in that recess at the edge of the piston.


Did you mean the dust seal should not be twisted along with the piston twisting??? Also, the dust seal should stretch out to the edge of the piston, always to cover the piston as shown on my photo dated 2/15/2015?
 

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Discussion Starter · #15 ·
How to make the piston straight---concentrically???

The other problem is the piston tilts upwards somehow and I have no idea of what approach to take to make it straight, by which the piston can be
compressed back in smoothly without damaging the oil seal or whatever inside. Anyone has any idea of how to make the piston straight???:confused: Can I just push it hard downward or twist counter
clockwise and compress it??? I tried it, but it was very hard to adjust
the piston to make it straight. Is there any better way to do it??:confused:

I just bought a piston block from a local part store. If the block does
not work, I will use C Clamp+Channel Locks. In my case, nothing is easy.

By the way, When I try to twist and compress the piston, the brake fluid
is bleeding out from a tiny hole on the dust seal's skin, is that OK???
 

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If it looks like the picture shows then it's probabally free of the inner screw and you might as well take it out of the caliper to look at the way it attaches. Take the boot off at that point bc you can and inspect it for tears. I don't have a caliper in front of me to look at but it helps to note how the rear ones work or rather differ from the front. Because of your emergency brake there needs to be a way to use leverage to clamp the rotor and hold it. This is where the threads come into play. Instead of a floating piston an arm on a threaded rod adjusts the pads outward as the surface wears down. if the brakes are applied when no rotor is present , the piston will unscrew itself from the rod ( that's what looks to have happened in this picture. Take it on out remove the boot to make sure it isn't stuck to the piston and lube it so it rotates around the piston's circumference. reposition the boot to the caliper and stretch its sphincter around the piston body, don't put the boot into the ring groove of the actual piston body. spin the piston back onto the threads and drive it home with a tool. (I have the Harbor freight kit and its a James Dandy investment - and does the fronts as well) As the piston goes home the boot will naturally return to the ring groove. I rebuilt Jetta Turbo front calipers to put on my non turbo 01. The kit was cheeeap at Advance Auto 12 bucks or less. You can rebuild rears just as easily, its just a boot and a seal (perhaps a bit more parts in the rear? ) I haven't done my back ones yet however they should be like most other manufacturers designs
 

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The small square block would not fit on my 2003 NBC rear calipers.

I just happened to have a pair of Long Reach Long Nose Pliers laying around. I put the tip in the piston grove, straight on through where outer pad mounts, pushed down on the pliers/piston while I turned the pliers clockwise. Had to push on the pliers pretty hard to "compress" the piston back into the caliper.

Example of what I used - TEKTON 3490 11-Inch Long Reach Long Nose Pliers - Needle Nose Pliers - Amazon.com
 

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