Rear brake discs /help needed

[coolmint]

Hi all have a 2013 1.4 si.problem with rear brakes ..Driver's side rear caliper seized at 81 k.
 New discs and pads fitted and new caliper ..still a problem ..

. Brakes only seem to cover half of disc , mechanic thinks that slider pins may be bent . Anyone experience any similar symptoms ? Any help guidance greatly appreciated.

Hi all have put a pic up

Many thanks

[GBH]

Very strange.  Do not have any specific experience of Jazz brakes but can you give more detail?

Is it both rear brakes now giving problem?  If so, could be wrong brakes supplied.

Never heard of sliders being bent - I would have thought it would need a catastrophic accident to bend the pins so that the pads only cover half the disks.

can you post any photographs?

[coolmint]

Thanks having a problem sending a photo as an attachment , it says error file too big? Any other way if sending one to you ? 

[bill888]

Try retaking the photograph using a lower camera resolution?

[fashionphotography]

could be the brake hose collapsed.. they can work like a one way valve and not releasing the fluid back when brake is released ?

[coolmint]

Thanks attached photo

[GBH]

Do the brakes now work (ie stop the car and then release so that the wheel can be turned by hand?).

All the photograph is showing is that the pads have not yet had a chance to bed in.

It is difficult to diagnose without being there and getting hands on, but I don't think you have a problem if the wheels lock when the brakes are applied - check both hand and parking brakes - and then release and turn freely without binding.  They just need bedding in so that the pads wear and settle in.

[embee]

I wouldn't be happy with that.

My guess is either the pad isn't seated properly in the caliper body, maybe some dirt or a burr or something, or the pad itself (or even the disc) is not parallel. These sort of issues often come back to the quality of the parts fitted. The only way to check is measure accurately using micrometers etc.

Are the pads/discs a reputable make? I try to use only makes which I trust to be good quality, either OE or Brembo or Bosch for most brake parts, and sourced from reputable outlets, not anonymous auction site sellers far too many fake parts out there.

[Lord Voltermore]

I'm not a trained engineer and have never worked on these brakes. But from looking at photos of the calipers I'd say they look particularly vulnerable to engineering tolerance problems

 The holes through which the pins pass look fairly 'spindly' and appear to be located  quite a long distance from where the main  force is applied to the pads.  If the pins are relatively long this could multiply the amount of bending force  applied to them (and the holes through which they pass if reusing callipers) .  Longer pins would also multiply the effect of any free play between the pin and the holes in the calipers.   

Its possible that some calipers  might have  holes slightly oversize  to overcome problems if re using pins   that  might be otherwise be a tight fit due to corrosion or gumming up.   Or simply sloppy machining tolerances.

They might bed in eventually, but I suspect it may be good workshop practice to replace both pins and callipers at the same time, preferably both the same brand.

[embee]

Sliding calipers on cars normally* are arranged such that the braking force on the pads is reacted by the main body of the caliper which is bolted solidly to the hub. The sliding part of the caliper with the piston installed does not directly take the braking force, it just provides the "squeeze", so no side/bending forces should be put through the guide pins.

* I say normally because I know of at least one example (Suzuki car rear) where the whole caliper body slides on pins, but these are large diameter, something close to 20mm diameter, and the main caliper bolts go through the middle of them and are thus very substantial. This is not at all common on cars. Motorcycles do often transfer braking forces through sliding pins but obviously the forces are much smaller than on cars.