# rear brake piston



## Thalweg (Oct 9, 2008)

I'm not familiar with the Passat, but I've never retracted pistons by turning them. I always use a big C-clamp and press them back into the caliper. If you do this, make sure to press straight back, not off to the side as you can "cock" the piston to a side and damage it.

However, like I said, I'm not familiar with the Passat, so make sure that there isn't some sort of "turning" mechanism like the book says, because pressing it might damage the caliper if there is.


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## rcm5835 (Dec 1, 2008)

*rear caliper piston*

yeah you were correct after some extensive probing on the web I found a site that mentioned using a C clamp went and bought a 6" clamp and put the pads on about 30 minutes just a little important tid bit thats not mentioned thanx for the help

Robin


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## polarzak (Dec 1, 2008)

rcm5835 said:


> yeah you were correct after some extensive probing on the web I found a site that mentioned using a C clamp went and bought a 6" clamp and put the pads on about 30 minutes just a little important tid bit thats not mentioned thanx for the help
> 
> Robin


You were lucky they were not the turn in type or a C Clamp would have completely destroyed them. Most GM rear wheel drive and probably some European use a different type of piston on the rear disks. You have to turn then in using a pair of needless nosed pliers or an appropriate tool. For future readers if the pisiton doesn't look like a normal "cup" piston, then you have the "turn in type. Do not use a C Clamp on thise.


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## slickshift (Aug 25, 2005)

polarzak said:


> You were lucky they were not the turn in type or a C Clamp would have completely destroyed them.
> 
> You have to turn then in using a pair of needless nosed pliers or an appropriate tool.
> 
> Do not use a C Clamp on thise.


Lucky indeed
As the OP's project turned out fine, I normally wouldn't add to this
But as many, if not most, rear disc brake pistons need to be turned to be pushed in, and many people merely peruse threads rather than post when seeking answers, I'd be remiss not to mention this fact again

Most rear disc brake pistons need to be rotated to be pushed in
Some you can use needle nose pliers, some you need a special tool


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## rcm5835 (Dec 1, 2008)

now I am a little nervous because that is what I did in the first place I used needle nose pliers and after turning the piston clockwise 25+ times the piston was in the same position as when I started so I loosened the screw for the brake fluid and used the C clamp the brakes are real spongey on the first press and really grab on the second press called a local shop and said that I didn't have pads positioned in the calibers correctly so now it sits in the driveway


slickshift said:


> Lucky indeed
> As the OP's project turned out fine, I normally wouldn't add to this
> But as many, if not most, rear disc brake pistons need to be turned to be pushed in, and many people merely peruse threads rather than post when seeking answers, I'd be remiss not to mention this fact again
> 
> ...


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## polarzak (Dec 1, 2008)

rcm5835 said:


> now I am a little nervous because that is what I did in the first place I used needle nose pliers and after turning the piston clockwise 25+ times the piston was in the same position as when I started so I loosened the screw for the brake fluid and used the C clamp the brakes are real spongey on the first press and really grab on the second press called a local shop and said that I didn't have pads positioned in the calibers correctly so now it sits in the driveway


They don't retract into the caliper, just go flush. Perhaps they were fine, because you were able to install the pads and caliper. If the piston was out even a little, you would not have been able to install the pads and the caliper. Once the piston is in, you can turn it a thousand times, it will go no further in. Spongy brakes usually indicate air in the lines.


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## Wethead (Oct 30, 2008)

rcm5835 said:


> yeah you were correct after some extensive probing on the web I found a site that mentioned using a C clamp went and bought a 6" clamp and put the pads on about 30 minutes just a little important tid bit thats not mentioned thanx for the help
> 
> Robin


If you don't have a c clamp , a trick is to carefully put a flathead screwdriver between the pad and rotor to free it up,

Then you could always use a pair of water pump pliers


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## slickshift (Aug 25, 2005)

rcm5835 said:


> now I am a little nervous...


I have run across rear pistons that did not need to be rotated
...once
I can't remember if it was a VW
It may have been, I've worked on very few VWs



rcm5835 said:


> the brakes are real spongey on the first press and really grab on the second press called a local shop and said that I didn't have pads positioned in the calibers correctly so now it sits in the driveway


The other issue with working on ABS rear discs is the extreme importance of proper bleeding sequence (each brake, front and rear, may now need to be bled, in a specific order) once the system is compromised (beyond simple pad replacement), and possible need of specialized equipment to do so (vac and 'puter)

Definitely refer to a model specific manual or online source such as AllData for the procedure for your car


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