Seized 4-pot calipers?
Discussion
Im getting alot of vibration related noise from the 4-pot front brakes on my Classic. Im suspecting sticky pistons are to blame; the rubber piston seals weren't too healthy last time I checked. So to remedy the situation, Ive a full set of disks/pads, and a seal kit to fit.
Does anyone here have experience with freeing out & cleaning up these 4-pot calipers? Im hoping its not an awkward job!
Does anyone here have experience with freeing out & cleaning up these 4-pot calipers? Im hoping its not an awkward job!
I've refurbished a set in the last month, using stainless pistons.
I found it quite easy to do, but I used a bearing puller on the groove around the pistons. I had tried prying them out but gave up very quickly!
The rebuild was more of a pain. You have to get the bores spotless and in your case the pistons as well, lube everything liberally with brake fluid and carefully put back together.
Be very careful when pushing in the pistons, as you don't want them going in all the way. One of mine did, and it was a right bugger to get out again!
If you need to know any more, let me know
I found it quite easy to do, but I used a bearing puller on the groove around the pistons. I had tried prying them out but gave up very quickly!
The rebuild was more of a pain. You have to get the bores spotless and in your case the pistons as well, lube everything liberally with brake fluid and carefully put back together.
Be very careful when pushing in the pistons, as you don't want them going in all the way. One of mine did, and it was a right bugger to get out again!
If you need to know any more, let me know
No, I was pre-emptive in my rebuild. I bought a second hand set off of fleabay and replaced everything bar the banjo bolts and bleed nipples with new. Gave everything several coats of paint and then replaced them for my old ones.
It's just as well I did, for the pad retaining pins were seized solid and had to be cut out of my old ones! I would never have been able to change the pads.
Have you checked for uneven pad wear? If one side of a pad is wearing down faster than another, it'd be a sure sign that a piston is seized.Also check your discs, it's possible there could be some run out on one or both sides. If they're near the end of their lives anyway, I'd replace to be sure.
Just read that you've bought new discs. I'd put the new pads and discs in and see, it could just be the discs.
It's just as well I did, for the pad retaining pins were seized solid and had to be cut out of my old ones! I would never have been able to change the pads.
Have you checked for uneven pad wear? If one side of a pad is wearing down faster than another, it'd be a sure sign that a piston is seized.
Just read that you've bought new discs. I'd put the new pads and discs in and see, it could just be the discs.
A bit of feedback!
I changed the discs and pads before the Christmas break. On closer inspection, I found three of the eight rubber dustboots were split on the front calipers. There was evidence of rust on those pistons and they were tighter to actuate than those with intact boots; almost seized in fact.
I advanced them out, one at a time and cleaned the chrome surfaces with 2000 grit paper, then lubed the piston with clean brake fluid. The old dustboots were then replaced with new. All sliding surfaces were copper greased. I also bled the system and flushed out the old brake fluid with new.
Inspection of the discs showed extensive radial cracking, but very little actual disc wear. Its likely this was due (in-part) to glazed rear pads and old discs. It would seem the fronts were doing all the hard work and getting very hot as a result.
Anyway, the pedal feel is now very well weighted and not as 'wooden' as it felt before. The vibration is also gone.
An easy job all round
I changed the discs and pads before the Christmas break. On closer inspection, I found three of the eight rubber dustboots were split on the front calipers. There was evidence of rust on those pistons and they were tighter to actuate than those with intact boots; almost seized in fact.
I advanced them out, one at a time and cleaned the chrome surfaces with 2000 grit paper, then lubed the piston with clean brake fluid. The old dustboots were then replaced with new. All sliding surfaces were copper greased. I also bled the system and flushed out the old brake fluid with new.
Inspection of the discs showed extensive radial cracking, but very little actual disc wear. Its likely this was due (in-part) to glazed rear pads and old discs. It would seem the fronts were doing all the hard work and getting very hot as a result.
Anyway, the pedal feel is now very well weighted and not as 'wooden' as it felt before. The vibration is also gone.
An easy job all round
Edited by MLoc on Friday 27th December 09:12
Edited by MLoc on Friday 27th December 09:13
Gassing Station | Subaru | Top of Page | What's New | My Stuff