Sticking Brake Caliper Query

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Todd

RMS Regular
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4,000
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Ballymena
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M3 | A6 | A3
I have a sticky rear caliper on my E92 335D.

I took the calipers off this evening to see what was going on.

So far I have completed the following:

- Replaced worn pads with new pads.
- Cleaned up discs
- Cleaned and greased sliding pins.
- General clean around the brake area.

With the caliper removed, the disc moved freely so it isn't the handbrake mechanism in the drum holding the wheel back. The sliding pins are all moving freely and the piston slide back in with ease.

When all reassembled the wheel is a little more free but it is still very tight. I noticed if you gave the caliper a slight knock it free'd up and allowed the wheel to spin freely again until the brake was applied.

Any idea's what could be causing this?

Thanks in advance.
 

mcmurray

RMS Regular
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3,924
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M3
Hole in the dust seal causing rust on the piston? Could be tiny and you haven't noticed. Had the same problem recently with a front caliper.

Caliper off, piston would wind back fine, greased everything and put it back together. Worked great for a couple of days till it started sticking again.

This was the piston once I stripped it.

piston.jpg
 

dddrrift

RMS Regular
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3,569
as above, you need to remove the piston from the caliper and clean or replace if needed
 

Nicky

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HiluxSurf
Another thing to consider is the flexi to the caliper breaking down inside.

Pump the brake up and if it remains tight, try and push the caliper back from the disc by hand. If this can't be done, slacken the bleed nipple and try again. If the caliper moves back freely and pushes brake fluid out, you'll know the reason for it sticking is the fluid not being allowed to return up the line.
 

davey-dimples

RMS Regular
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12,071
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E90 330D
Another thing to consider is the flexi to the caliper breaking down inside.

Pump the brake up and if it remains tight, try and push the caliper back from the disc by hand. If this can't be done, slacken the bleed nipple and try again. If the caliper moves back freely and pushes brake fluid out, you'll know the reason for it sticking is the fluid not being allowed to return up the line.

This happened to me in the V70 and the 330d (E46)

Got the Volvo home one night and the calliper was actually glowing in the darkness :scream: it was scrapped a short time later (due to a list of reasons not just this) after multiple attempts at what you have done above.

The 330d got a new calliper which sorted it out (y)
 
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