Brake piston GQ

[Antznz]

Hi guys need a little help.

After the wife drove the truck I noticed a strange noise in the left rear wheel (there's the first problem I know). Now I had a look at the rotor through the wheel and it looked a bit more scratched than the other 3. So i've popped the wheel off and low and behold there is only an inner brake pad.. Thats right no brake pad or shim on the outer side at all. So I've got some TRW replacement pads ($95 Repco).

Now here's the problem.

The piston is 3/4 out and I can't seem to push it back by hand. I'm assuming its been like that for a while with there only being one brake pad.

Anyhow my question is do I simply bleed the break line at the nipple on the caliper to release the pressure. Push the piston and fit my shiney new pads?

I'm no mechanic more of a "give it a go and see what happens" person..

Last one how the hell does one loose an entire break pad????

[Silver]

I really only know the basics and a little knowledge and brakes is not a good combination. I'll just raise a few points that may save some time/trouble while we wait for a guru to come along.

No pad would ordinarily mean that the end of the piston has been working on the face of the rotor. How badly marked is the rotor? Is it still within specs?

When you push the piston back, the reservoir on the brake booster will probably over fill, if you have been topping it up. A clean syringe or some kind of dipper can be used to lower the level - there would be other options. Don't get busted taking something from the kitched drawers :-)

If the piston is square in the hole, and the rubbers are OK, then it should push back - at worst you may need to use a block of wood and a clamp. Have a good look to see why it does not want to go back now, before applying pressure via the clamp, which could make things worse.

dunno why the fall out, but yours isn't the first. Most people seem to blame the sheet metal clips etc - either absent or incorrectly installed.

[johno90]

Calipers can be at times a bitch to push back in, best thing is BIG set of multigrips and push it in, ALSO!! remeber to take the cap off the master cyl when pushing it back because if you dont it builds up to much pressure and will bust the seals in the master cyl.

[patch697]

Cracking the bleeder is one way to relieve pressure but as long as there is no damage to the piston it should go back with some help.

You can buy a tool to depress the piston (not very expensive) or another way is to find a socket that will go close to the inside of the piston but still be a fairly loose fit & use a "G" clamp to wind the piston back.

As to what caused your pad to escape????...... Who knows, its the first time I've come across that one.....

[Antznz]

Right o.

with a little help from you guys the problem is fixed.

Used a bit of tree branch to fit inside the piston (did not have a socket handy), a little bit of pressure with a G Clamp and undoing the bleeder valve got teh piston back in, albeit with a squirt of break fluid form the valve.

4 new brake TWR break pads (Are they any good $95?) a congratulations beer and I now have working, non squealing breaks.

As for the missing break pad in was on the outside so the piston was still on a break pad, but I think it was pushing the rotor against the outer side of the caliper. I can't see anyway it would have fallen out as there does not appear to be enough room.

Anyway thus far it has been a relatively easy fix thanks to the as always sound advise from across the tazie......

[Robo]

If the piston has been rubbing on the disc not good.
I'm no expert but, 1 would think there has been a significant amount of heat as a result of piston making contact with the disc correct !.
The seal and or piston may of been damaged as a result.
And the piston has had direct pressure against it in a side ways direction, the caliper bore should get a look at also.
"this is worst case stuff", but worth exploring.
Really removing wheel 1 at a time and clean externally then R&R cal with kit should be sat arvo's work, for some one with a 1/2 decent selection of tools and axle stands etc

A repair kit for caliper is very cheap under $50 each ,(no piston in kit).
brake cleaner $5.
cal kit x 2 $90.
fluid x 3 $30.
rubber grease (tube) $10.

Cheers

[patch697]

If the piston has been rubbing on the disc not good.
I'm no expert but, 1 would think there has been a significant amount of heat as a result of piston making contact with the disc correct !.
The seal and or piston may of been damaged as a result.
And the piston has had direct pressure against it in a side ways direction, the caliper bore should get a look at also.
"this is worst case stuff", but worth exploring.
Really removing wheel 1 at a time and clean externally then R&R cal with kit should be sat arvo's work, for some one with a 1/2 decent selection of tools and axle stands etc

A repair kit for caliper is very cheap under $50 each ,(no piston in kit).
brake cleaner $5.
cal kit x 2 $90.
fluid x 3 $30.
rubber grease (tube) $10.

Cheers

I think he said the piston side (inner side) was where he still had a pad & the out side was the one missing so there wouldn't have been direct contack between the piston & the rotor.

Bloody good sound advice though.

Cheers.

[Morton]

just something to think about, I have removed 1 pad when the piston was jambed, part brake was better than no brake, got me home without cooking everything, possibly the same here but they never got around to fixing it, I would monitor this caliper closely to be sure it is not stuck or sticking again, easiest way to check it jack the wheel, off the handbrake & spin the wheel, if it spins with no rubbing all is well, if not, have both rear calipers overhauled, safety first

[Antznz]

Hey thanks for the advise re checking the calipers, I'll keep and eye on them and re do them if there's any sign of rubbing or damage....Cheers

[Robo]

Hummm, my bad, work night and day it seems, need to unwind.
Got caught up in the need to have good brakes and didn't click to which pad missing.
Still, can't let the little women drive something suspect !! .
Cheers