SL/R107: How to remove a stuck brake piston
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Newbie
Joined: Dec 2021
Posts: 13
Likes: 4
From: Bristol
107,113,230
How to remove a stuck brake piston
I recently posted a YouTube video about how to remove a really stuck brake piston which might be of use to some members:
This is the sort of situation you might encounter if a car has been sitting for years...especially in a damp environment. In this scenario, no amount of pushing on the brake pedal, using compressed air or even baking in an oven and using freeze spray works. I have tried them all and even built an 'off car master cylinder arrangement'...which only partially worked on one piston. So here's what you will need:
1. Metal vice to secure cailper....a wooden work mate just isn't enough
2. Some small sockets...preferably ones you are not too precious about as you may end up deforming them
3. A breaker bar
4. 10.5m drill and the corresponding tap (a cheap helicoil kit off ebay/amazon will do the trick)
5. A caliper rebuild kit including new pistons
If possible, remove the outer dust seal and get some Plusgas or similar) in the gap the seal usually sits in. Next, pack the caliper with the correct size small sockets (see video) and use breaker bar to get some movement. Separate the two sides of the caliper and then drill a hole in the center of the piston and use the tap to wind it out. Good luck.
This is the sort of situation you might encounter if a car has been sitting for years...especially in a damp environment. In this scenario, no amount of pushing on the brake pedal, using compressed air or even baking in an oven and using freeze spray works. I have tried them all and even built an 'off car master cylinder arrangement'...which only partially worked on one piston. So here's what you will need:
1. Metal vice to secure cailper....a wooden work mate just isn't enough
2. Some small sockets...preferably ones you are not too precious about as you may end up deforming them
3. A breaker bar
4. 10.5m drill and the corresponding tap (a cheap helicoil kit off ebay/amazon will do the trick)
5. A caliper rebuild kit including new pistons
If possible, remove the outer dust seal and get some Plusgas or similar) in the gap the seal usually sits in. Next, pack the caliper with the correct size small sockets (see video) and use breaker bar to get some movement. Separate the two sides of the caliper and then drill a hole in the center of the piston and use the tap to wind it out. Good luck.
MBWorld Fanatic!
Joined: Sep 2018
Posts: 3,244
Likes: 933
From: New Orleans Area
2015 E400 Sedan
O-rings are simple to find if you know the size:
The O-Ring Store LLC, We make getting O-Rings easy! (theoringstore.com)
So measure OD, Cross Section and go searching..
If destroyed measure groove they go in OD/ID and depth Add a little bit to Depth until you get a proper cross section in charts then find one that fits groove.
We do this all the time in hydraulic repairs.
The O-Ring Store LLC, We make getting O-Rings easy! (theoringstore.com)
So measure OD, Cross Section and go searching..
If destroyed measure groove they go in OD/ID and depth Add a little bit to Depth until you get a proper cross section in charts then find one that fits groove.
We do this all the time in hydraulic repairs.
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