Help, hot brakes
Discussion
Having just replaced the front pads, I noticed that the right hand pads were a lot more worn than the left. I have now noticed that the right wheel gets hot!! 
so I suspect a sticking brake. I have greased the two allen bolts that hold the pads in and sprayed WD40 onto the piston under the piston seal after I put new pads in. Please help, it is something I have never come across before, cheers
stevej
so I suspect a sticking brake. I have greased the two allen bolts that hold the pads in and sprayed WD40 onto the piston under the piston seal after I put new pads in. Please help, it is something I have never come across before, cheers stevej
4 reasons for front brakes sticking on:
1. Sticky sliders - the allen key bolts you describe. Make sure they are properly greased with brake grease or copaslip, not ordinary grease.
2. Pad catching on frame - you'll see that the pad has slots that sit over guides on the caliper and frame. Make sure these are copaslip greased as well.
3. Piston sticking - ie it moves out when you press the brake, but then sticks and isn't pushed back when the pedal is released, holding the pads in contact with the disk. This can only be repaired by removing the piston, checking for piston or bore damage, possibly removing rust on the piston, resealing, reassembling and bleeding. ALternatively, a new caliper might be cheaper and easier. You shouldn't spray WD40 anywhere near brake seals by the way.
4. Internal collapse of the rubber hose, reducing the internal hose diameter (sometimes to nothing) - again it allows brake pressure through, but doesn't allow it to release.
1. Sticky sliders - the allen key bolts you describe. Make sure they are properly greased with brake grease or copaslip, not ordinary grease.
2. Pad catching on frame - you'll see that the pad has slots that sit over guides on the caliper and frame. Make sure these are copaslip greased as well.
3. Piston sticking - ie it moves out when you press the brake, but then sticks and isn't pushed back when the pedal is released, holding the pads in contact with the disk. This can only be repaired by removing the piston, checking for piston or bore damage, possibly removing rust on the piston, resealing, reassembling and bleeding. ALternatively, a new caliper might be cheaper and easier. You shouldn't spray WD40 anywhere near brake seals by the way.
4. Internal collapse of the rubber hose, reducing the internal hose diameter (sometimes to nothing) - again it allows brake pressure through, but doesn't allow it to release.
Steve,
It is fairly easy to see what the problem is by a process of elimination. It just requires removal of the full caliper whoile still connected to teh system.
A large G clamp will help as you will need to push the piston back into its bore.
If you try this first while still connected to the system and then again with the bleed valve open, this should let you know if the problem is hydraulic or mechanical. Hydraulic means you need to look at hoses/pipes or master cylinder. Mechanical means either piston or sliders. With the caliper removed the sliders will be obvious if they are a problem.
I had a similar problem which was cured by removing the pistons and tidying them up. The problem was that they had started to corrode so were too tight in the calipers. Fine Wet n Dry around pistons and bores sorted the problem.
This worked for a while but before long the problem was back.
A pair of new calipers cured the problem for about £35.00 each IIRC.
It also helped the MPG and accelration as a sticking brake is a significant drag..
It is fairly easy to see what the problem is by a process of elimination. It just requires removal of the full caliper whoile still connected to teh system.
A large G clamp will help as you will need to push the piston back into its bore.
If you try this first while still connected to the system and then again with the bleed valve open, this should let you know if the problem is hydraulic or mechanical. Hydraulic means you need to look at hoses/pipes or master cylinder. Mechanical means either piston or sliders. With the caliper removed the sliders will be obvious if they are a problem.
I had a similar problem which was cured by removing the pistons and tidying them up. The problem was that they had started to corrode so were too tight in the calipers. Fine Wet n Dry around pistons and bores sorted the problem.
This worked for a while but before long the problem was back.
A pair of new calipers cured the problem for about £35.00 each IIRC.
It also helped the MPG and accelration as a sticking brake is a significant drag..
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