how the hell do you do it, these ones aren't on the car or anything i can't get the pistons out, they aren't fully seized but i am having problrms getitng them apart!!! how do you do it? compressed air?!?!





thanks Kevin

I'm assuing you have full rebuild kit so you can split the halves, there should be some piston rings under the dust boot.

To late for the edit, in addition, so I don't get my ass chewed out, you don't have to split the halves, but it isn't the end of the world if you do.



Compressed air can be used but you have to pad it well and contain the pistons, otherwise one or two might fly out, bounce around the shop, and become worthless.

you basically just have to fight with them until they come out. just keep in mind that they are a close fit so pull them out as even as possible. the seal kits that i got from mazdatrix didn't have the o-rings that go in between the two halves so i naturally left them together. make sure to clean out all the garbage before you put them back together and not to scuff the sides of the piston.

We used a bicycle foot pump hooked up to the brake line - I've heard of air compressors used but I wouldn't because of the danger and also calipers are not designed for the pressure. Some of the pistons will come out before the others - when they get unstuck just clamp them once they come out a bit so all the air doesn't escape.



Mark

i took them apart, i'm not too worried about the orings, they still sit above the flat so it will squish down again, it's just getting the damn pistons out really sucks, i've been prying on them evenly they pop every once and a while, but it's hard to make any progress.

if i can't get them fixed i'm going to colins house and kicking his ass.

not without brakes you're not.



If I remember correctly I used compressed air and many many cuss words. But remember to take it easy and go slow and even.

You need to do the old screw driver trick. Use a flathead screw driver on each side of the piston, with something under it, a exhaust clamp works great. You just need something to hold the screwdrivers at a higher height than the pistons. Then wedge the flat heads in the groove near the top of the pistons, and with equal pressure it will come out with some work.

put a half inch piece of wood in between the pistons when you pump them out that way they don't go flying everywhere. I kept mine connected to the car so all i had to do was push the brake pedal. But then i just got rebuilt ones because mine were too far gone.

I fought mine all Sunday and made 0 progress...I'm open to more suggestions besides compressed air. https://www.nopistons.com/forums/pub..._DIR#>/sad.png

if your calipers are out just put them in a vice and use some vice grips to slowly turn the piston until it comes out. Or just fork out $300+ dollars for new ones.

[quote name='donhayes' date='May 25 2005, 10:12 PM']if your calipers are out just put them in a vice and use some vice grips to slowly turn the piston until it comes out. Or just fork out $300+ dollars for new ones.


[/quote]



Vice grips? it will ruin the pistons, even if you get them out, you'll have to buy new one's anyway.



Air pressure should get them out without too much trouble, maybe you guys haven't blocked all the openings sufficiently.

or $52 each from autozone

[quote name='Dysfnctnl85' date='May 26 2005, 06:09 AM']I fought mine all Sunday and made 0 progress...I'm open to more suggestions besides compressed air. https://www.nopistons.com/forums/pub..._DIR#>/sad.png


[/quote]

You can put a grease nipple instead of the bleed screw and pump them full of grease,but it's messy. If they're well stuck you're probably not going to find an easier way than a footpump.



Mark

[quote name='inanimate_object' date='May 26 2005, 07:21 AM']You can put a grease nipple instead of the bleed screw and pump them full of grease,but it's messy. If they're well stuck you're probably not going to find an easier way than a footpump.



Mark


[/quote]



Time to pickup a footpump! That should build up sufficient pressure as long as I block the openings, and probably keep the pistons from shooting out.

[quote name='inanimate_object' date='May 24 2005, 07:35 AM']We used a bicycle foot pump hooked up to the brake line - I've heard of air compressors used but I wouldn't because of the danger and also calipers are not designed for the pressure. Some of the pistons will come out before the others - when they get unstuck just clamp them once they come out a bit so all the air doesn't escape.



Mark


[/quote]



Not designed for the pressure?



1. Single stage air compressors develop around 120 psi peak, dual-stage typically around 175 psi (although larger industrial units do commonly develop higher pressures... 250-300 psi is not unheard of). Now, you can lower the pressure far below that with an air line regulator... you can drop the air pressure to below 5 psi, so excessive pressure is not a worry. Air line regulators are cheap to buy, as well... $20-$50 is common pricing.



2. The hydraulic system is a high-pressure system. With the pdeal fully depressed, system pressures far exceed over 1500 psi.



So they can definitely handle a mere 120 psi. https://www.nopistons.com/forums/pub...DIR#>/wink.png



I typically use 60 psi to force out my pistons.

[quote name='Dysfnctnl85' date='May 26 2005, 10:12 AM']Time to pickup a footpump! That should build up sufficient pressure as long as I block the openings, and probably keep the pistons from shooting out.


[/quote]



Even easier...

Mount the calipers back in place, with the brake pads removed, but rotor still in plcae.

Pump the brakes.

Take caliper off, grip fully extended piston with rag, and twist out.



Takes a couple minutes.



I only use air when I have the calipers already off the car.

[quote name='scathcart' date='May 27 2005, 03:23 AM']Not designed for the pressure?



1. Single stage air compressors develop around 120 psi peak, dual-stage typically around 175 psi (although larger industrial units do commonly develop higher pressures... 250-300 psi is not unheard of). Now, you can lower the pressure far below that with an air line regulator... you can drop the air pressure to below 5 psi, so excessive pressure is not a worry. Air line regulators are cheap to buy, as well... $20-$50 is common pricing.



2. The hydraulic system is a high-pressure system. With the pdeal fully depressed, system pressures far exceed over 1500 psi.



So they can definitely handle a mere 120 psi. https://www.nopistons.com/forums/pub...DIR#>/wink.png



I typically use 60 psi to force out my pistons.


[/quote]

Ok if you say so! I was going on the basis that if a foot can provide enough pressure for un-servoed brakes then a foot pump would be better suited. Better safe than sorry and all that.



Mark

my fav is a hammer and a block of wood https://www.nopistons.com/forums/pub...>/bigthumb.gif

[quote name='inanimate_object' date='May 27 2005, 03:52 AM']Ok if you say so! I was going on the basis that if a foot can provide enough pressure for un-servoed brakes then a foot pump would be better suited. Better safe than sorry and all that.



Mark


[/quote]



I'm not sayign a foot pump wouldn't work, in fact, I think it would work great. I was simply saying that using an air compressor will not produce enough pressure to do any damage.



I've installed a few roll control systems on cars (to help with staging/burnout), with a brake pressure gauge installed for consistency. It sure is interesting to watch the pressure climb over 1500 psi, and to watch the pressure during different braking situations.

[quote name='scathcart' date='May 27 2005, 11:11 PM']I'm not sayign a foot pump wouldn't work, in fact, I think it would work great. I was simply saying that using an air compressor will not produce enough pressure to do any damage.



I've installed a few roll control systems on cars (to help with staging/burnout), with a brake pressure gauge installed for consistency. It sure is interesting to watch the pressure climb over 1500 psi, and to watch the pressure during different braking situations.


[/quote]

I think you're misunderstanding me - I agree with you 100%. If I were asked again, I guess my real reservation with air compressors is they're probably a bit overkill for the job, thre's a needless danger element - unless of course you use a regulator which is exactly what you suggested https://www.nopistons.com/forums/pub...#>/biggrin.png



Mark

Since the brakes came off a car in a junkyard, putting them back on was not an option!



I ended up getting the out with compressed air and careful attention to where air was leaking. I ended up getting them out, I'm just concerned now what I should do about the pistons, they look kinda shady.



[attachment=31184:attachment]



[attachment=31185:attachment]



Sorry for the blurry pic but you can still see the oxidation where the piston will contact the new seals...

Anyone?

They don't look too bad to me. If there's no rust on the outside I'd use em.



Mark

I've never been able to get stuck pistons out with compressed air. I've always left them hooked up the the car and pumped the pedal with a block of wood in place of the disk.

Dysfnctnl - clean the pistons and their bores up as best you can with *very* fine sandpaper. If either are pitted in the area that will contact the seal, then they're trash, unless you know of a way to fill the pits with something that will survive in brake fluid (then sanding back down smooth of course)... I've often wondered if jbweld would work, but I'm too scared to try. https://www.nopistons.com/forums/pub...IR#>/smile.png

Thanks for the advice guys, I'll get some very fine grit sand paper this weekend and give it a go.