stickng caliper

[Ed]

hey guys, one of my calipers has started dragging.. the piston not returning fully that is.

my first inclination is to strip the caliper, used compressed air to push the piston out and put in new seals and dust seals.

what causes calipers to drag? dirt and moisture in the fluid?

it's an alloy Girlock HQ caliper.

Cheers

Ed

[Glenn 'Stinky' Stankevicius]

The LH units that I am cleaning up were difficult to push in, a smear of grease on the rubber soon fixed that. Although the ordinary grease was promptly removed and replaced with rubber grease  :-[

[Jockster]

G'day Ed
Just check that the caliper is not sticking on the slide rails as these have a tendancy to rust  and stick more so than the caliper piston
Cheers
Jock

[FB_MAD]

Yep, damaged piston boots will let in dirt moisture etc and will soon cause the piston to drag or seize.Worn piston seal won't help either. Brake fluid being hydroscopic will absorb moisture even in a completely sealed system.Alloy and moisture are as much an enemy as cast iron and moisture.
 

Terry.

[Ed]

thanks for the advice.

the problem with the sticking calipers turned out to be this....

the guide/slide pins were lubricated with the incorrect grease.

the grease cooked with the heat, and caused the caliper to bind on the guide pins.

the fix?

cleaned the guide pins and re-lubed using "Synthetic Grease - brake caliper grease"

so.. use the right grease!.. you all knew that right?

Cheers

Ed