what are symptoms of worn caliper piston seal?

[fenixus]

just a quick question. some time ago I noticed that both front calipers on my V6 have visibly worn out piston seals.
what may happen (any symptoms?) to caliper operation if those seals are worn out too much?

I am trying to postpone as far as I can a total replacement of calipers with rebuilt/remanuf units and decided to give it a shot in spare time if its worth it.

I could get caliper piston seal kit cheap, they are like a few $ each side. Just to make it clear, I do not want to disconnect calipers and replace all the set of seal, boot and set ring on each piston. I am only thinking if it could impove anything if I replaced the outer seal on pistons (with caliper hose connected).

I will also replace the slide pin dust boots finally, but that's a different story. want to get out as most effective miles as I can from hardware I currently have without investing more and more money into another replacement projects...

[fenixus]

thanks!

yeah, that's my plan for now, not replacing anymore of stuff until I am 100% something is wrong lol

so the piston seal itself, not worth it alone, I also noticed I cannot even buy it alone, only in a kit and I guess rebuilding calipers in parking lot (no electrical power, no running water and no compressor here) is pointless LOL

for now, I have only dust boots to replace, something I wanted to do long time ago, but never did. I already have dust boots for both front and rear caliper slide pins, it should be fairly easy to do.

thanks for a tip on front Nastra calipers, never heard of them, will check it out. I was thinking about getting Cardone for both front and rear (both with brackets, only minus pads) in future if all fails. and of course painting them (to avoid rust problem on sand blasted units)

need a few more weeks and a weekend road trip to confirm new MPG. keep your fingers crossed, I'm hoping for better than it was

[JohnGD]

If it's visible then it must be the dust boot (leftmost in the link below). It helps keep water and dirt away from the piston underneath. The actual piston seal is a square cut o-ring in the bore (center in the picture).

If the piston seal hardened, then the piston may be hard to move (that's why I asked about the resistance when you tried to push the piston back into the bore). The other can be the piston seal won't be able to "grab" the piston back as much (and therefore let the pad ease off the rotor) when you release the brakes. Given all the rust in the MC, my main concern is the caliper bore and maybe some part of the piston are rusted too.

However, if the booster push rod on the MC side is sticking, it will be like applying brakes for the duration too.

From the looks of it, you should be able to remove the dust boot from the caliper without disassembling the caliper but I'm not sure. Clean the exterior of the caliper first then carefully remove the retaining ring (rightmost in the picture) with a small screwdriver, then run the screwdriver around the circumference of the seal (on piston and in bore). This should tell you if you want to proceed in pulling it. That said, keeping it clean can be the hardest part. You don't want dirt getting in there and mess with the piston seal.

http://www.rockauto.com/catalog/moreinfo.php?pk=878340

[fenixus]

yeah, it's the one on the outside. so it's the piston boot then? ok, my bad wording.

I heard some people replaced them without removing pistons from calipers (neither detaching the hose and such) and it's doable.

however I have no idea if that is what may cause calipers to stay a tad too close to rotors. I will try doing the slide pin dust boots first, finally found the replacements I had hidden in a box some time ago I also picked up the ones for rear caliper slide pins.
they all should be fairly easy to remove from bore with a large screw driver and a hammer. I also plan on cleaning the bracket bores a tad with brake parts cleaner after dust boots removal. then cleaning as much as I can from the bore. this is the project for now.

as per "how easy the piston is to push into the caliper" I will say only this - if it was easy (ever) we wouldn't need to use C-clamp to do this ... so I think what you are referring to is related to a caliper detached from the brake hose. otherwise I know only one answer to this question on all calipers I've seen so far, they are a bitch to push back into caliper, but I think that's how things work if all is filled with fluid and I am fighting fluid pressure all the way back to MC when doing so.

I am not going to detach brake hoses yet. I may however open each caliper bleeder valve just to see if caliper pads move away from the rotor if I do that.
If they do then that would mean brake hoses are shit and calipers are still good.
If they don't then I may start thinking about getting remanuf calipers faster than I expected I wil pass on rebuilding them myself.

[bronzemaxell]

Originally Posted by fenixus

just a quick question. some time ago I noticed that both front calipers on my V6 have visibly worn out piston seals.
what may happen (any symptoms?) to caliper operation if those seals are worn out too much?

I am trying to postpone as far as I can a total replacement of calipers with rebuilt/remanuf units and decided to give it a shot in spare time if its worth it.

I could get caliper piston seal kit cheap, they are like a few $ each side. Just to make it clear, I do not want to disconnect calipers and replace all the set of seal, boot and set ring on each piston. I am only thinking if it could impove anything if I replaced the outer seal on pistons (with caliper hose connected).

I will also replace the slide pin dust boots finally, but that's a different story. want to get out as most effective miles as I can from hardware I currently have without investing more and more money into another replacement projects...

I bought the front caliper get well kit from stealership $30+, and they only sell in pair kit, left and right, but include everything, caliper seal, piston dust boot, c clip for dust boot, bleeder valve cover, sliding pin boots, and grease.
I can only see the caliper dust boot from outside, the the caliper seal is inside the caliper, the piston have to come complete out, i just removed brake pads, and stepped on brake pedal until the piston pop off.

as far as tool goes, power tools are not neccessary, just drain pan to catch brake fluid,
tools to take off wheel, 14mm (12mm for rear) for sliding pin, 8mm for bleeder valve.

caliper seal easy to go in, but dust boot c clip, took me a while, but once i got the hang of it, very easy. and with the bleeder valve open, the my brake piston slide back in evenly and easily, i didn't disconnect the brake hose at the caliper. bleed brakes afterward to flush air bubble

[JohnGD]

Originally Posted by fenixus

I also plan on cleaning the bracket bores a tad with brake parts cleaner after dust boots removal. then cleaning as much as I can from the bore. this is the project for now.

Brake cleaner likes to stay at the bottom corner of the bore. So make sure it's dry before you assemble.

Originally Posted by fenixus

as per "how easy the piston is to push into the caliper" I will say only this - if it was easy (ever) we wouldn't need to use C-clamp to do this ... so I think what you are referring to is related to a caliper detached from the brake hose. otherwise I know only one answer to this question on all calipers I've seen so far, they are a bitch to push back into caliper, but I think that's how things work if all is filled with fluid and I am fighting fluid pressure all the way back to MC when doing so.

If you can turn the c-clamp with two fingers then it's easy. If MC cups aren't covering vent ports and you have to turn the c-clamp with the full hand grunting, then I'd say it's rebuild time.

During rebuild you can push the piston back with two fingers (on opposite edges of the piston cup) and pull it out with two. But once installed a c-clamp is needed.

Originally Posted by fenixus

I am not going to detach brake hoses yet. I may however open each caliper bleeder valve just to see if caliper pads move away from the rotor if I do that.
If they do then that would mean brake hoses are shit and calipers are still good.

Yeah, no need to disconnect the hose at this time. The dust boot looks doable, I just haven't done it this way.

In normal operation the amount of movement by the piston seal is very small and not visible. This is different from the locked caliper because of a hydraulic problem (blocked MC ports, restricted hose, etc). In the typical test by opening the bleeder, if the ease of rotation of the rotor change, then it's a hydraulic lock problem.

Originally Posted by fenixus

If they don't then I may start thinking about getting remanuf calipers faster than I expected I wil pass on rebuilding them myself.

I don't think the dust boot will do anything as far as brakes dragging however. It does help protect the piston from the elements.

[bronzemaxell]

oh, the sliding pin dust boot, a bitch to remove, , with the caliper bracket removed, i have to hammer a the mid size flat head screw driver to pry open and separate it from the caliper bracket, to put it back is even trickier, I laid the sliding pin dust boot with rubber end on a 2x4 wood stud, then hammer the caliper bracket,

[bronzemaxell]

i don't trust the aftermarket chinese/rebuilt caliper, if the oem caliper serve me well in the past, i rather keep them, the only thing destroy the caliper is the rust from brake fluid not being change frequently enough, and collects water.

[fenixus]

ok, guys thanks for opinions.

I think I have a better grasp now.

fact is that v6 front calipers were much harder to compress with a C-clamp than on 5s-fe some time ago ... so I'd guess it means only one thing ... time for change is coming hehe.

I'll take my chances with dust boots soon. I will leave front brackets bolted to shield though and work around it with a hammer and screw drivers.

as per rear caliper, it's just rubber, isn't it? I guess those should be easy to replace ... and the boots sit in caliper over there, not in bracket? unless I remember it wrong.

also need to check what is causing the binding for sure, calipers vs rubber lines.

I doubt the booster clunking/popping membrane (or whatever it is) can actually cause the brake drag.

[JohnGD]

Originally Posted by fenixus

I'll take my chances with dust boots soon. I will leave front brackets bolted to shield though and work around it with a hammer and screw drivers.

Or you can remove the bracket and use a socket to help install the dust boots. Stuff the rubber into the socket so you hammer mostly on the metal flange.

Originally Posted by fenixus

as per rear caliper, it's just rubber, isn't it? I guess those should be easy to replace ... and the boots sit in caliper over there, not in bracket? unless I remember it wrong.

According to this yes:
http://www.rockauto.com/catalog/moreinfo.php?pk=572093
and for the front:
http://www.rockauto.com/catalog/moreinfo.php?pk=1152178

The groove where the dust boot sits can collect break cleaner that's harder to evaporate. So make sure it's dry or the petro solvent will make the rubber swell.

Originally Posted by fenixus

I doubt the booster clunking/popping membrane (or whatever it is) can actually cause the brake drag.

The booster, if it's actually sticking, will cause a *temporary* drag. Similar to when you step on the pedal. That's all.

But I think the piston seals and maybe the dust boots/pin bushings are more likely the causes. Less likely are the hoses, but if you do the calipers in the future swap them out too.

I recently saw that brake hose life is estimated to be 6 years. It's shorter than I expected, but if car manufacturers say 6 years for tires that may be reasonable. I guess they keyword is "reliable life":
http://www.brakequip.com/support.html

[bronzemaxell]

Originally Posted by fenixus

ok, guys thanks for opinions.

I think I have a better grasp now.

fact is that v6 front calipers were much harder to compress with a C-clamp than on 5s-fe some time ago ... so I'd guess it means only one thing ... time for change is coming hehe.

I'll take my chances with dust boots soon. I will leave front brackets bolted to shield though and work around it with a hammer and screw drivers.

as per rear caliper, it's just rubber, isn't it? I guess those should be easy to replace ... and the boots sit in caliper over there, not in bracket? unless I remember it wrong.

also need to check what is causing the binding for sure, calipers vs rubber lines.

I doubt the booster clunking/popping membrane (or whatever it is) can actually cause the brake drag.

Last month, i changed the brake pad on my 99 solara v6 se, around 170k miles, the front caliper was much harder to push in than the rear, i took an extra large channel lock/plier, and squeezed extra hard to push the piston back in, that was when i also discovered the dust boot was torn, i thought the piston would be rusted and stuck, thought of buying another one from ebay, but i chose to take a look at the current condition first, when i took everything apart, the piston cup is still very shiny, easy to slide in and out (of course only if I position the piston cup evenly), if the bleeder valve is open, don't need the c-clamp to push it back in, one finger will do.

even though front caliper piston very hard to push back when the bleeder valve shut, but the brake power is one of the best among my vehicles, and front brake pads seem to worn evenly. i think the V6 brake system are different than the i4

[fenixus]

JohnGD, the booster on its own cannot apply as much force as me pushing on the pedal... sticking membrane pressure vs my foot on brake pedal is an incomparable amount of force. besides whatever causes the clunk, happens almost immediately (or a few secs later) after releasing the pedal.

brakes are not dragging, at least not like I feel it. I reaaaly doubt booster has anything to do with the fact the pads are siting a tad too close to rotors. besides they still do sit close to rotors with car shut off for a long time (booster inactive), so I'd think it's rather the caliper hardware causing them to stay there. maybe I'm wrong, but that's how I feel it

so bronzemaxell, was it worth it to rebuild the old OEM calipers on V6?
last time I compared 5s-fe and V6 have same calipers and everything in brake system (solara models).

[BMR]

fenixus, you might want to read this article about caliper seals. If they're "square cut" (most are, AFAIK) like in this article, they provide more than a sealing function. They also serve to retract the piston a little bit, taking residual pressure off the brake pads. I don't believe they can go bad so quickly that they need to be replaced with *every* pad change, but at more than 100k miles, yeah, they could.

Edit: after reading this thread more closely, I see JohnGD's already mentioned this, but I'm not sure you caught his meaning.

[bronzemaxell]

Originally Posted by fenixus

JohnGD, the booster on its own cannot apply as much force as me pushing on the pedal... sticking membrane pressure vs my foot on brake pedal is an incomparable amount of force. besides whatever causes the clunk, happens almost immediately (or a few secs later) after releasing the pedal.

brakes are not dragging, at least not like I feel it. I reaaaly doubt booster has anything to do with the fact the pads are siting a tad too close to rotors. besides they still do sit close to rotors with car shut off for a long time (booster inactive), so I'd think it's rather the caliper hardware causing them to stay there. maybe I'm wrong, but that's how I feel it

so bronzemaxell, was it worth it to rebuild the old OEM calipers on V6?
last time I compared 5s-fe and V6 have same calipers and everything in brake system (solara models).

my 99 solara v6 se caliper piston very hard to push back in, but with bleeder valve open, i can push it in with one finger, almost like effordless, i think my old caliper seem to be working fine.

it is a 30min to 1 hour job, can be done at a parking lot too.
cheap, both front calipers kit cost only 1/2 tank of gasoline nowadays.
sometime i am afraid the new non-oem part quality is worst than the old oem parts.

i always thought the 4cyl has smaller rotor, or different caliper, because one time i was trying to put a v6 front rotor into a 4cyl, and it doesn't fit, maybe bigger rotor require more heavy duty caliper or brake component, even the v6 brake pads are bigger than the 4cyl.

[fenixus]

OK, thanks man. I will do the mentioned checks and if it comes to that I will think about rebuilding OEM calipers.

I am too not very fond of any aftermarket parts, they fail me way too often ...

not sure about 4cyl camry, but my '00 4cyl solara has exactly same front brakes as '02 v6 solara. they are totally interchangeable.
all part numbers are same as per www.toyodiy.com/parts

same rotors, same calipers, same pads, etc.

perhaps 4cyl camry has smaller front rotors, calipers and pads?

Originally Posted by bronzemaxell

my 99 solara v6 se caliper piston very hard to push back in, but with bleeder valve open, i can push it in with one finger, almost like effordless, i think my old caliper seem to be working fine.

it is a 30min to 1 hour job, can be done at a parking lot too.
cheap, both front calipers kit cost only 1/2 tank of gasoline nowadays.
sometime i am afraid the new non-oem part quality is worst than the old oem parts.

i always thought the 4cyl has smaller rotor, or different caliper, because one time i was trying to put a v6 front rotor into a 4cyl, and it doesn't fit, maybe bigger rotor require more heavy duty caliper or brake component, even the v6 brake pads are bigger than the 4cyl.