Very hot rear wheel

[chicochapman]

After a shortish journey, a smell of hot metal led me to the O/S rear wheel.
I got to have a look at it a few hours later and the wheel rotated by hand ok - just a light rubbing noise.Took it out for a spin of a couple of miles and the wheel was hot again and quite stiff. I pressed the brake pedal and the wheel was almost locked. Two hours later, the wheel could be rotated again but a press on the brake pedal almost locked it again.
Could anyone suggest a cause for these symptoms please?
Thanks,
Malc

[suzublu]

Sticking caliper. You'll need to remove, clean, regrease sliders and maybe piston or, as I have done, fit new caliper

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[bl52krz]

As above. While you are doing that job, change your brake fluid. I bet it is years old causing sticking piston.

[Mike Noc]

The ones I've seen on our cars have all been due to corrosion of the lip outboard of the piston seal. Stripping it out and cleaning up the lip works, or, as mentioned, buy a new or recon one.

[DMGRS]

Another echo to the above - it's usually just a sticky caliper.
Clean up all of the guide pins when doing the job too, as they can also stick if they're badly corroded / gummed up.

[tony g]

this is a problem ive had to deal with on customers bikes for years, the problem is corrosion that gets behind the piston seal, the corrosion builds up under the seal and pushes the seal tight up against the piston. when you brake the piston mover forward but can't move back as its held tight in the seal. then everything gets hot due to excess friction. happens more on aluminium callipers (motorcycles) that the cast steel ones mostly used on cars. if the pistons are not rusty then a strip and clean will sort it, and maybe a new seal kit.

[Ducati750cc]

Originally Posted by tony g

this is a problem ive had to deal with on customers bikes for years, the problem is corrosion that gets behind the piston seal, the corrosion builds up under the seal and pushes the seal tight up against the piston. when you brake the piston mover forward but can't move back as its held tight in the seal. then everything gets hot due to excess friction. happens more on aluminium callipers (motorcycles) that the cast steel ones mostly used on cars. if the pistons are not rusty then a strip and clean will sort it, and maybe a new seal kit.

Not a well known fact is that only the 'square' piston seal alone retracts the piston.


It does it due to the fact that the outer of the seal is retained in the cylinder bore, the inner grips the piston tightly, when the piston moves outward to apply the brakes the seal is slightly distorted, when pressure is released, the seal returns to its rest position and in doing so pulls the piston back in.


One main culprit in preventing the piston moving backwards is the dust seal, due to the build up of rust, dust and road debris in and around the area providing a resistance that doesn't allow the piston seal to retract the piston.

[tony g]

Originally Posted by Ducati750cc

Not a well known fact is that only the 'square' piston seal alone retracts the piston.


It does it due to the fact that the outer of the seal is retained in the cylinder bore, the inner grips the piston tightly, when the piston moves outward to apply the brakes the seal is slightly distorted, when pressure is released, the seal returns to its rest position and in doing so pulls the piston back in.


One main culprit in preventing the piston moving backwards is the dust seal, due to the build up of rust, dust and road debris in and around the area providing a resistance that doesn't allow the piston seal to retract the piston.

yep I with I had a pound for every calliper ive had to strip and clean the problem with aluminium callipers is it corrodes faster than the cast steel ones, not helped if used in the winter salty roads.

[stevestrat]

Originally Posted by tony g

this is a problem ive had to deal with on customers bikes for years

Used to have the problem regular when I had bikes, so much so that I made up a footpump to caliper connecting pipe for blowing the pistons out.

[Retap]

Last year reaplced both rear calipers entirely as bleed nut snapped on me as well luckily it was same sort of price for two new rear calipers as it was for new seals n pistons, those calipers still good they where cheapos from the bay. Got a front caliper to refurbish soon, the fronts ones seem to be much more expensive so refurb kit for those at present. did the OSF caliper last year as it was binding bad with signs of copper grease on the piston applied by previous owner.