Retracting Caliper Pistons, How to? Options

[Vince-Noir]

My new rear discs are on and the calipers are off waiting for me to retract the pistons before i replace the pads, but i have no idea how to retract the pistons on my 98 GT (3SGE). In fact they look fully extended!

Can anyone tell me how to do this please?

Many thanks

[playr158]

get a c-clamp and compress them back in...

or put the pads into the caliper, then take a large screw driver (flat head and the biggest head you can find) slide it between the pads and push them apart, thus compressing the pad.

[LewFX]

c-clamp with the old pad still on the piston so you dont damage the piston directly

[Vince-Noir]

Thanks guys, i had a crack using the old pad to help compress the piston back in. The result was that the rubber seal bulged some what and oozed brake fluid... can't see that as being a good thing! Thoughts?

[njccmd2002]

Thanks guys, i had a crack using the old pad to help compress the piston back in. The result was that the rubber seal bulged some what and oozed brake fluid... can't see that as being a good thing! Thoughts?

mm, when i retracted, the seal budged, i liftef it carefuly from one side and air came out and it sat properly. did not have any fluid come out. when you pushed the piston in, did you have the cover of the brake fluid reservoir open. that usually helps to relieve the pressure on the fluid...

[Vince-Noir]

Yeah, i've had the cap off since i got it jacked up and wheels off Hmmmm...

[D-Man]

Woah, that dont sound good at all...

It leaked out of a rubber seal? The ones on the back side of the caliper? Because you'll bolt those back down, and it *may* not be a problem... Unless it was on the lower seal on the rear of the car. then i would recommend immediately seeking medical attention...

Otherwise... You should look for cuts or rips in the seal, (remember it comes off as a whole) so if it leaked out of the edge where it attaches, than it *may* be okay. If it's cut or riped or something similar, than you *may* have to replace it.

(D-Man is not responsible or liable for any damages incurred by one's self of as a result of: *may*)

[hongkongnerdboy]

well i got nothing on the fluid leaking.. just have the seal release near the piston.. get a c-clamp with a fake brake pad from pepboys for like 10 dollars... works everytime

[alltracman78]

Two problems.

1-When you pushed the piston back in, if brake fluid leaked out past the piston, the piston seal is leaking.
It might or might not leak when the caliper is back on the car and you use the brakes.
If it does leak, you won't have much braking force at all.

2-You left the cap off the master cylinder, which pretty much means ALL your brake fluid is junk.
This is why:
Your brakes get really hot when you use them. The harder you brake the hotter they get. This heats up the brake fluid in the line a lot. Brake fluid is designed with a very high boiling point [tells you on the bottle of fluid] so it won't boil from the heat. If it boils, you lose braking force.
Water on the other hand boils at a relatively cool 212*F.
What does water have to do with brake fluid?
Brake fluid absorbs water. Really bad.
Imagine the brake fluid is Michael Jackson and the water is a cute 8 yr old boy. It can't stay away.

So, while the brake fluid might not boil when you brake hard, the water will. Which once again makes you lose brake force.

My suggestion is to
replace the caliper
flush your brake fluid COMPLETELY
This can be done with a mighty vac or having one person pump the pedal while the other loosens the bleed port. The second one will take a while.

[6strngs]

sounds like you blew the seal on the caliper piston. it'll probably need replacement.

what you're SUPPOSED to do when compressing the caliper is not to open the resevoir cap but just crack the bleeder screw open. this will relieve the pressure so you're not compressing the brake fluid (liquids don't compress, meaning something else will give out) and yes, use a c-clamp to compress them. you can get one at any auto parts store for about $10.

and as alltracman said, brake fluid absorbs moisture from the atmosphere, therefore you should never leave the resevoir cap open, or use brake fluid that's been sitting in an opened container. brake fluid should be completely flushed and refilled every two years anyway, so now you've got an opportunity for that.

[Vince-Noir]

Ok thanks for all your help guys, appreciate it! Well it looks as if the seals *may* have gone, however i did end up using a C Clamp and an old pad to compress the piston back in, using the bleed valve to relieve any pressure. Unfortunately the guide i was using was telling me to leave the cap off the reservoir, in fact it omits actually replacing it at all throughout the entire process Thats pretty infuriating. However, it has been about 20 months since brake fluid was replaced (its still not in the slightest bit discoloured thankfully), but as you said, altracman78, the res cap was off long enough to allow our very humid english air to diffuse with the fluid - not good.

The whole set up has been reassembled now and thankfully there has been no more leaking, even after the 5mile run i gave the car. But unfortunately; the braking is fairly spongey - and i don't think it's because they are new pads/discs - more likely is that there is air/water in the system compressing a far sight easier than if it were all brake fluid.

Just for my peace of mind i'm thinking of taking to a garage to check it all out, after all the last thing anyone wants is dodgy brakes.

Thanks for the knowledge guys, always a pleasure to listen and learn

[malecrod]

From my personal experience, I will advice you to replace the caliper that leaked. Same thing happened to me when I was changing pads. I put everything back and couldn't see any more leaks. But when you step on that brake hard enough you will notice stream of brake fluids all over your rotor and tire.
So for safety sake's replace the caliper or have a shop look at it for you.
G/L

[Vince-Noir]

Ok took the GT into my local trusted garage yesterday arvo and their initial reactions were that awful sharp, rapid, inhaling through the teeth sound! First of all the mechanic thought that it was going to be a job of replacing the seals in the calipers and having to purchase a seal kit from Toyota to do this... We also realised that i had somehow got the pistons basically all the way out (as they were free turning) he definitely thought i would not have got away without wrecking the seals when reinserting them. Did well so far didnt i?!

Anyway, as we discussed it further it would seem that i managed to get them back in gently enough so that i did not cause anymore leaking when fully re-assembled... so i may have got away with it - fingers crossed! What he did say tho, from the way i was putting the pistons back in is that i probably took some air back into the system, explaining the sponginess of the middle pedal! So all i theoretically need to do is perform a bleed from each of the rear calipers (showed me the coke bottle method so as not to further soil the driveway).

Also asked him about the condition of the brake fluid after having had the cap off for a couple of hours, both he and the mechanics from next door (toyota) said theres no problem... only if it had rained or something more drastic would it have ruined the fluid! Sounds interesting considering that previous posts about it made perfect sense...

Anyway, we shall see what happens

[alltracman78]

If the cap was only off for a few hours it shouldn't be a big deal, I was under the impression it had been of for several days +.

Side note, how often do you visit Boston?

[Vince-Noir]

Thanks altracman78, i should have made the facts more clear actually. Just bled the brakes and i'm pleased to say they seem razor sharp upon the test drive

Side note, how often do you visit Boston?

Just got back from Boston 4 days ago after being there since 3rd Jan Got family and the lovely lady in the Wrentham/Walpole area so i'm usually there every 3 months or so - give or take I try and get as many Pats games in as i can while im there too! Love it! (Trying to forget the superbowl tho )

[alltracman78]

No worries

Damn, I live right next to Wrentham

Shoot me a PM next time you come by if you'd like.

[Vince-Noir]

Franklin Street! Very random indeed, can't say i saw many Gen 6's while i've been over and the few i've seen looked sadly quite tired so i'm well up for seeing some in good 'nick. They're definitely a rare sight in NE! I will indeed PM you next time im over (anythings got to be better than looking disappointingly at my girlfriends Elantra 'GT'!!! )