Brake calliper piston will not retract

Pops_20

In a bit of a bind here, hoping someone can suggest a fix.

I disassembled the front driver side brake calliper on my 1999 Toyota Glanza today as the brakes have been sticking on for the last week or so and I wanted to give the sliders a clean and grease to see if that would fix it.

All was going well until I decided to pump the brake pedal while the calliper was off, just to get the piston to come out a bit so I could check the rubber boot and just give it a clean if necessary.

When I tried to push the piston back in, it would just not retract. I've tried a C-clamp, a brake calliper spreader tool and just brute force and it will not retract.

Brake fluid reservoir cap was off at the time and I even loosened the bleed nipple in case that was causing an issue.

I have a feeling pumping the brake pedal was a bad idea and maybe the piston has come too far out. I've never had this problem with brakes before. Can someone advise on this? Cheers

Cee-Jay-Cee

It's misaligned. You need to pump it out a bit further and try again. Get someone to pump the pedal slowly and you watch the piston. You only need it to come out another 5mm and hopefully it'll straighten up then press it back in with the C clamp. the piston cones out quite a bit before you reach the end and it pops out. The rubber boot will have cone off it at that stage so if the boot is still attached then it's not out too far.

dooroy

If the piston has come out to the point of almost being out of the caliper it may have gone a little to one side or other. The piston has to be exactly right to get it to go back in. Twisting the piston can sometimes help to get it started back in.
Try 'joggling ' the piston from side to side in various directions while at the same time applying some pressure. If you use too much force and its off centre the seal may be damaged.
If all else fails you may have to take the piston out and start from scratch as it were. Check that seal hasn't been pinched/damaged etc

Pops_20

Thanks for the help guys. The boot is still attached to the base of the piston so I assume that it hasn't come out too far?

I pumped the brake pedal a few more times to see if it would come out any further but it doesn't seem to be coming out any more. Maybe it needs a few more presses?

I'm worried now that the seal has been damaged as I was using alot of force with the C clamp to push it back.
What's the best way to joggle the piston from side to side?

dooroy

It should come out when you pump the pedal - I presume bleed nipple is closed and there is fluid in the system.
At this stage it may be better to take out the piston to check that seal is OK and seated properly in it s groove in the caliper ; when trying to get piston back in the seal could have been pinched or twisted .
Rocking the piston slightly from side to side in various directions while applying a little inward pressure can sometimes get the piston aligned again ; does the piston look 'square on' to the caliper when viewed from the side ?

Pops_20

Yup bleed nipple is closed and there's fluid in the system.
I presume if the piston comes out then all the fluid will spill out and the flex line will need to be clamped and that corner of the car bled afterwards?

Now that you mention it, I've had a closer look from the side and the face of the piston looks to be very slightly at an angle to the body of the caliper. I think you may be right that its misaligned.

At this stage I'm wondering would it be better to pick up a second hand caliper at the breakers, seeing as mine was sticking on in the first place, it might have needed a rebuild. I think the Glanza shares the same front caliper as a Corolla so it might be easy enough to pick one up.

pauldavis123

Reconditioned one are cheap in the motor factors, just bring in your old one as part exchange. Probably €30-€40 for something as common as that.

Pops_20

pauldavis123 wrote: »

Reconditioned one are cheap in the motor factors, just bring in your old one as part exchange. Probably €30-€40 for something as common as that.

Would it be common enough to find reconditioned one in any motor factors? If that's the case I'll drop in tomorrow and see if its possible to get one.

dooroy

Problem with second hand one is it may not be any better than your own - and you have no way of knowing; could start sticking on within a week.
Problems often arise when pistons need to be pushed back ; the part of the piston that has been out for some time may have started to rust etc (due for example to a faulty boot) and when you try to push it back its very stiff ; if the surface of the piston is rough /pitted etc it may damage the seal ; if the piston is very stiff to move then it will likely begin to stick on when used .
You may find units from motor factors quite expensive ; there are some places that will recondition your own caliper(s) or you can buy rebuild kits for the caliper and do it yourself.

pauldavis123

Pops_20 wrote: »

Would it be common enough to find reconditioned one in any motor factors? If that's the case I'll drop in tomorrow and see if its possible to get one.

Yeah, esp if its also on a Corrolla.

Pops_20

Thanks for all the help and suggestions everyone. Haven't really got a chance to tackle this with work and the weather since Saturday, but managed to take the caliper off today for a closer look.

To me it looks like the boot is slightly more compressed on one side and therefore the piston isn't exactly lined up, so looks like you guys were right.



At this stage I think I have two options:

1) Try my best to get that piston lined up and pressed back in, and continue with the sticky caliper.

2) The breakers have a Glanza caliper for €40, just need to go back and confirm the part number is right. I had a look at one today and it looks in worse condition and more corroded than the one I currently have, but I'd be willing to take a chance for 40 quid, seeing as mine is sticking anyway, and I might not be able to put it right.

New caliper is €150 plus VAT so I'd rather avoid that.

EDIT: Whats the best way to line this up? Press the pedal until it comes out more and risk it popping out, or use a pliers to try and pull it back in to line?

Cee-Jay-Cee

Can you post a photo of how far out the piston has come? It'll give an indication of how much more it can come out before popping out completely.

Pops_20

Don't have a photo of this at the moment I'm afraid, but I checked while it was off, and the base of the inside hollow part of the piston is still a few millimetres below the face of the body of the caliper, so I'd say it has a small bit left in it before popping out.
I will try to get a photo from the side-on tomorrow.

dooroy

That piston is well off judging by the pic .
You need to get the left hand side (as in pic) out a little to see if will line up,
However the piston may be really jammed at this stage - could be why pedal wasn't moving it out.
No point trying to force it in at this stage - but it will need pressure to get it out also, Do you have access to an airline - but remember if it moves that the piston will fly out.

CJhaughey

Get two ring spanners and put them back to back. Put the ring ends into the end of the piston and squeeze the open ends together the ring ends are offset and will grip the inside of the piston allowing you to move the piston with leverage and not damage the piston itself once you have it free by wiggling line it up straight and push it in slowly with the c clamp and a flat piece of wood. opening the bleed valve will make it easier and get rid of the old fluid.

pauldavis123

Parts are here anyway. Prices are MAD!

http://jp-carparts.com/toyota/cartypelist.php?maker=toyota&type=121150

Pops_20

CJhaughey wrote: »

Get two ring spanners and put them back to back. Put the ring ends into the end of the piston and squeeze the open ends together the ring ends are offset and will grip the inside of the piston allowing you to move the piston with leverage and not damage the piston itself once you have it free by wiggling line it up straight and push it in slowly with the c clamp and a flat piece of wood. opening the bleed valve will make it easier and get rid of the old fluid.

So you're saying to use this to lever the piston back in to line?
When you say back to back, do you mean one spanner laid flat on top of the other? I don't think I'm understanding this correctly.

CJhaughey

Lay two ring spanners back to back the ring ends will sit facing outwards if the handles are parallel. \ / like this insert the ring ends into the piston and squeeze the flats of the spanner together and the rings will push out into the piston and allow you to lever it.

If the piston was out all the way the o ring might be wrecked and not letting the piston go in,
I'm fixing one up atm and had this problem (a caliper not a starlet).

dodzy

That piston looks like there's more travel on the outward stroke available. I'd snap a vice-grips tightly on the left edge side of the piston (watch the boot-pinch) and try persuade it back on line. Defo looks misaligned (to the left as you look at the pic)

Cee-Jay-Cee

Get a pair of calipers and measure the height of the piston all round and see where it's sitting slightly higher and try and tap it in very gradually at that point to get the piston level and then use the C-clamp to try and press it in squarely again.

Pops_20

I ended up going to the breakers and got a caliper for 40 quid, which I fitted this evening with no issues after giving it a bit of a clean up. Need the car back on the road so didn't have time to try all your suggestions!

I'm going to have a go off getting that piston back in now that its off the car and I might have a use for it someday.
Thanks for all the help.

I got the piston back into the one I was fixing this morning.
Got a new ring and boot off ebay,

Bit of silicone grease on the ring and got the caliper in the vise and wound it back in with a long nose pliers .

It wound back really easy in the end.

Pops_20

BrownFinger wrote: »

I got the piston back into the one I was fixing this morning.
Got a new ring and boot off ebay,

Bit of silicone grease on the ring and got the caliper in the vise and wound it back in with a long nose pliers .

It wound back really easy in the end.

Was the O-ring noticeably damaged when you took the piston out?

Cee-Jay-Cee

BrownFinger wrote: »

I got the piston back into the one I was fixing this morning.
Got a new ring and boot off ebay,

Bit of silicone grease on the ring and got the caliper in the vise and wound it back in with a long nose pliers .

It wound back really easy in the end.

There's no pressure so it'll always wind in easily on a bench.

Pops_20

Pops_20 wrote: »

Was the O-ring noticeably damaged when you took the piston out?

Yea,
the boot had been pulled out at some stage and the edge was rounded off the ring and it was just a bit rough over all.

Took it out and gave the channel a good cleaning with a pic and compressed air.

I believe its that square "0" ring that makes the caliper retract just enough to let the disc move.(also to keep the juice in !)