sticky caliper - again

smarjoram · Post by **smarjoram** » Mon Aug 14, 2006 12:53 pm

About this time every year my front right caliper sticks. I had the calipers overhauled at great expense with new seals and hoses replaced two years ago. It did it a bit last year and the mechanic freed it up somehow and it's been ok up to now.

Drove 14 miles this morning - three wheels were cool, one was almost to hot to hold for long.

I wanted to drive to north wales this afternoon - would it be a bad idea? is there a danger of it warping the disks, boiling the fluid or other such horrors. I suppose I'll have to take the Toyota. Ho hum - I was looking forward to the drive.

Any ideas as to why it occurs so frequently? Not enough use? (it's a weekend car). Any ideas for what I could do to eliminate it?

Thanks for any help.

Alan @ CanfordClassics · Mon Aug 14, 2006 1:09 pm

I wouldn't drive it with binding brakes. As it gets hotter the problem will get worse as the fluid expands.

This is normally due to either sticking pistons in the calliper or swollen flexes not allowing the pressure to release when you take your foot off the brake pedal. If you have had them rebuilt but do not use the car much it could just be a sticking piston. Your mechanic probably just moves the piston in and out several times to free it up. If you have a piston separator it’s easy enough to do. Take the pads out and pump the brake so the pistons move out (make sure the tool is already on the disc) and then turn the tool so it pushes the pistons back in.

HTH

Alan

Ian Donkin · Post by **Ian Donkin** » Mon Aug 14, 2006 1:11 pm

If the calipers were fully rebuilt and new hoses fitted, you are unlucky to be experiencing this.

Who did the work and do they have any views on why it should be happening?

Nige · Post by **Nige** » Mon Aug 14, 2006 1:12 pm

yup warping the disks most definate, if excessive can build up that much heat that the grease in the bearings melts away and run dry.

Mine wear sticking earlier this year due to lack of us, I replaced the pads so the travel of the piston is now different therefore no sticking, will probably show itself again shortly, but I am now using the car daily, which helps.

johndglynn · Post by **johndglynn** » Mon Aug 14, 2006 8:48 pm

Stefan, you will boil the fluid pretty quickly if it is well and truly sticking on, but there is a lot of research out there now to say that warped discs are actually not warped at all, just baked with pad deposits - a mere 4 thou (which is more or less invisible) will make the pedal feel like it's going to jump out of the floor apparently.

One of my front calipers was really sticking on when I last tested my SC, the day before we left for Classic Le Mans. Brought it home, blew out the pistons and cleaned the offending article up inside and out, took less than half an hour to do, including bleeding the brakes again afterwards.

One thing you could do on yours is make sure the piston marks are aligned at 20 degrees or whatever the spec is, or they can jam. I know Porsche say this is to kill pad squeal but Tuthills do all their tests at my MOT guy's place and he reckons they will stick very quickly if the marks are not properly aligned on reassembly - problem he has on 911s quite regularly.

I did some pics etc of my caliper rebuild - the thread is on impactbumpers.com in the 'Brakes' section if it's of any use.

smarjoram · Post by **smarjoram** » Sat Aug 19, 2006 10:48 am

Thanks for all the advice - I didn't take the car in the end - some lovely roads up there though.

The car is in for its mot next week so I'll get them looked at then - I'll then brave a look myself one day - other than changing pads, brakes scare me a bit - I'm sure there's no reason to be though.

Got back to find I got £60 knocked off my insurance by going with RH - and breakdown cover included too. It's now £160