Rear, not front, Brake Caliper issues

[Dylan]

Has anyone else had issues with the rear brake calipers? More specifically, rust/dust/grime buildup that causes the channels that the pads slide in to become restrictive over time?

I got new rear rotors and pads when I did my complete front brakes a month ago. Yet, I've only heard of the countless issues with the notorious front calipers being stuck and so I didn't think I would need new rear calipers. When I installed the pads they were tight. They could still slide, but the driver's side one is especially snug and occasionally pops when I apply the brake pedal as the pad releases from whatever snags it.

There is a thread in the Maintenance/Detailing section as listed here, although I'm not sure why since it is specific to the 4th gens and would be better served in this section.

 

[HokieRunner]

The short answer is yes. Folks have had to replace frozen rear calipers. However, in your case it sounds like the pad channels are just dirty as opposed to it being the caliper piston seizing.

In which case, pull the pads and clean out the channels. Dirt and dust buildup is fairly normal which is why you should clean it up with brake cleaner and knock off any trouble spots with a steel brush or scrape out the channels with a screwdriver or similar implement.

 

[runnerito]

Hello,

Last week i replaced the pistons, seals and boot seasl of both of my rear calipers just for preventive maintenance, at least the bores (cylinders) were in very good shape but pistons being with some corrosion/pitting. In March, i did the same reconditioning job with my front calipers. So far no leaks or spongy feeling of the pedal.

Regards,

David

 

[Dylan]

Hello,

Last week i replaced the pistons, seals and boot seasl of both of my rear calipers just for preventive maintenance, at least the bores (cylinders) were in very good shape but pistons being with some corrosion/pitting. In March, i did the same reconditioning job with my front calipers. So far no leaks or spongy feeling of the pedal.

Regards,

David

Thanks for the info, but there's nothing that leads me to believe the hydraulics of my rear calipers need repairing. It's just the buildup in the channels where the pads slide that needs cleaning.

 

[TechWrench]

Thanks for the info, but there's nothing that leads me to believe the hydraulics of my rear calipers need repairing. It's just the buildup in the channels where the pads slide that needs cleaning.

When you pull the rear pads, specifically check under the small spring clips in the lower channel that the bottom notch of the pads fits into. It is common for rust to build up under this clip, which forces it up and causes the pads to stick. Just remove these clips and using a small file, clean all the built up rust from the channel. I use a small amount of never-seize under these clips when replacing them, to help keep rust from building up. Once cleaned, the pads should fit snuggly, but be able to move back and forth with little effort. This should solve your problem.

 

[Dylan]

So I thought it was rust build up and dirt, but now I'm thinking it's something with the hydraulic in the caliper itself because after cleaning, the symptom remains. Basically, when coming to a complete stop, after the pedal is about 3/4 pressed all the way, the rear-driver side brake has a sort of pop sound. I can slightly feel it in the pedal, which indicates some correlation to the fluid and the caliper. Here's what I did last night...

I removed the rear caliper and pads. I pulled the caliper apart to properly clean out the pad channels. I used brake cleaner, a wire brush attachment on my drill, and a Dremel sanding disc. I cleaned out and removed a layer of dirt and corrosion, although it wasnt a whole lot. I was down to clean metal though. I cleaned the shit out of the metal clips and replaced them. I also cleaned the little clip that attaches to the inside pad on the bottom, which slides within the channel. I put the pad in and it would slide better, but still have a slight bit of resistance in certain spots, so I cleaned it a little more. I used a little grease in the channels (not anywhere close to the pad surface) to ease the sliding. The pads were now sliding much more freely. I buttoned everything back up, and took it for a drive. It seemed like there was a slight increase in response from the brake pad moving more freely, but then...once I came to a complete stop after going about 35 mph the same symptom appeared....POP!

I think I'm just going to replace this factory caliper with a new one. This is annoying as shit trying to trouble shoot and I want to have normal rear brakes again. The question is do I do both rear calipers, or just the one with the symptoms? I already replaced both front calipers so I'm thinking I might as well.

 

[riceandpho]

Did you grease up them 17mm pins caliper pins? I would put a lot of grease on it, slide it in and out, top and bottom pins. Then remove the pins and add more brake grease to it, also when's the last time to flushed the brake fluid?

 

[Dylan]

Did you grease up them 17mm pins caliper pins? I would put a lot of grease on it, slide it in and out, top and bottom pins. Then remove the pins and add more brake grease to it, also when's the last time to flushed the brake fluid?

Flushed the brake fluid a month ago with DOT 4.
I did grease the pins...a lot, slid them around. Is moly-type or bearing grease the best kind? It's a PITA to keep pulling the wheel and removing the caliper trying to diagnose this. I feel like I'm going to keep pulling and putting back without actually discovering the issue which is why I may just buy new ones. Unless there is a tear-down diagram of the calipers that may show me how to rebuild them.


I feel like the piston may be messed up or something along those lines, since it's related to me pushing on the pedal and building pressure from the fluid on the hydraulic which eventually releases. I don't notice it on the right rear caliper.

 

[TechWrench]

Flushed the brake fluid a month ago with DOT 4.
I did grease the pins...a lot, slid them around. Is moly-type or bearing grease the best kind? It's a PITA to keep pulling the wheel and removing the caliper trying to diagnose this. I feel like I'm going to keep pulling and putting back without actually discovering the issue which is why I may just buy new ones. Unless there is a tear-down diagram of the calipers that may show me how to rebuild them.


I feel like the piston may be messed up or something along those lines, since it's related to me pushing on the pedal and building pressure from the fluid on the hydraulic which eventually releases. I don't notice it on the right rear caliper.

If you are sure there isn't an issue with rust build-up in the pad channels, then (except for the caliper itself), the only other thing I can think of is the rubber flex hose feeding the caliper. I don't recall exactly how this hose is routed, but it has my experience in the past that if this hose is supported by a clamp with a rubber inner bushing, it is possible that the inside of the metal clamp can rust over time. This can cause a build-up of rust between the metal clamp and the rubber bushing, which can squeeze the bushing around the hose. With time, this will pinch the hose enough to create a restriction. It acts like a one-way valve, in that the pressure created when pushing the pedal is sufficient to send fluid past the restriction, but when the pedal is released the fluid doesn't flow in the other direction so the pads don't retract properly. As I said, I don't recall at this moment if the brake hose has this support clamp or not. But, if yours does, it is worth a look see. It is easy to check out. Just loosen the clamp, so it doesn't hold the hose, and drive it. If the problem goes away, then just clean the rust out of the inside of the clamp and put it back together.

 

[Dylan]

This can cause a build-up of rust between the metal clamp and the rubber bushing, which can squeeze the bushing around the hose.

Thanks for the insight, I know exactly what you're referring to. I'll be sure to check this weekend when I go to tackle this. I sure hope this is what's causing the issue. Each time I've gone to mess with the calipers, I haven't loosened that clamp or even touched it really so I'll be interested to see it's condition once pulled open.

 

[Dylan]

I replaced the rear calipers with some lifetime warrantied NAPA Eclipses. The old calipers were shot. I checked to see if the hose was blocked, but there wasn't anything that could have kinked. The brake line connects to the rubber line directly without a metal clamp. The old piston was seizing in the rear caliper. Also I realized one pad in each caliper was missing the bottom little clip that slides in the channel, which probably didn't help things.

 

[Dylan]

It acts like a one-way valve, in that the pressure created when pushing the pedal is sufficient to send fluid past the restriction, but when the pedal is released the fluid doesn't flow in the other direction so the pads don't retract properly.

So I put the new calipers on. Braking is much better and more balanced. However....that rear, left pop still comes about. New Calipers, new rotors, new pads ( only 1000 miles on the rotors pads). I looked at the brake lines....there wasn't any restrictive clamp on the rubber line. The rubber line is maybe 10" long. It connects directly to the metal line that runs the majority of the distance up to the master cylinder. Is the rear rubber line going bad? It doesn't leak, but maybe it needs to be replaced with some new stainless ones. That, or I need to rebleed the rear brakes...but I cant think why this would present itself. I bleeded the brakes with DOT 4 a month ago, and rebled the two new rear calipers last night. Also, am I correct in that the rear caliper bleeders just need to be loosened and they will bleed automatically when pressing the pedal due to the brake booster pumping?? I'm trying to get this resolved once and for all. While I'm glad I've got new brake components, I want to get rid of this stupid clunk that happens every so often and stop throwing parts at it.

 

[MarkinWMich]

Sticky brake pads

Because of the rather high tolerances between the pads and calipers, it does not take much dirt, debris, dust, etc. to get them to stick. If the calipers, themselves, have a little bit of rust on them in those critical areas, the expansion from the rust, will make that interphase tighter, as well.

If you're interested, there is an "Eric the Car Guy" YouTube video showing how he goes about fixing the situation. Don't have the link right off hand. But, as others have said, lubrication on the retaining and wear clips, as well as, a light cleaning of the caliper-to-brake pad contact surfaces with a fine file or sandpaper will remove any corrosion. Basically, just get it down to the bare metal by lightly removing the rust, coat with grease, then reassemble with your clips and pads.

 

[MarkinWMich]

So I put the new calipers on. Braking is much better and more balanced. However....that rear, left pop still comes about. New Calipers, new rotors, new pads ( only 1000 miles on the rotors pads). I looked at the brake lines....there wasn't any restrictive clamp on the rubber line. The rubber line is maybe 10" long. It connects directly to the metal line that runs the majority of the distance up to the master cylinder. Is the rear rubber line going bad? It doesn't leak, but maybe it needs to be replaced with some new stainless ones. That, or I need to rebleed the rear brakes...but I cant think why this would present itself. I bleeded the brakes with DOT 4 a month ago, and rebled the two new rear calipers last night. Also, am I correct in that the rear caliper bleeders just need to be loosened and they will bleed automatically when pressing the pedal due to the brake booster pumping?? I'm trying to get this resolved once and for all. While I'm glad I've got new brake components, I want to get rid of this stupid clunk that happens every so often and stop throwing parts at it.

I know this may seem like a silly question, but are you using stock length rear sway bar links on a lifted suspension? My "mystery clunk" was found just this past week...that I was sure was a brake issue. My now-too-short links were binding at an abnormal angle, making the bolt in the sway bar to occasionally "pop". It just happened occasionally, especially with braking when the front would drop just enough to raise the rear a little bit. Slow speed maneuvers, little bumps, etc..."pop". Drove me nuts.

 

[Dylan]

I know this may seem like a silly question, but are you using stock length rear sway bar links on a lifted suspension? My "mystery clunk" was found just this past week...that I was sure was a brake issue. My now-too-short links were binding at an abnormal angle, making the bolt in the sway bar to occasionally "pop". It just happened occasionally, especially with braking when the front would drop just enough to raise the rear a little bit. Slow speed maneuvers, little bumps, etc..."pop". Drove me nuts.

My 2004 is stock suspension. Also, i put on brand new calipers yesterday...so there is absolutely no rust. the pads/rotors are a month old. Basically, they're all new components and shouldn't have any of those wear/rust issues.

 

[Dylan]

[MENTION=112471]MarkinWMich[/MENTION] [MENTION=937]TechWrench[/MENTION] [MENTION=5149]riceandpho[/MENTION] [MENTION=60181]runnerito[/MENTION] [MENTION=46025]HokieRunner[/MENTION]

So I'm embarrassed/relieved to say I determined the cause of the clunk/pop......my bottle jack was loose in the rear, left cargo compartment :doh: . I tightened it up so that it doesn't shake around anymore. Before when it was loose, momentum would cause it to move forward when braking and cause a clunk.

With this in mind, the rear calipers were shot...at least the left one was. The pads didn't have the slide clips, and long story short I'm glad I got them replaced. Back to normal braking for the 4Runner.

Now I can watch this thread slowly slip down the list and hopefully never see it again.

 

[TechWrench]

[MENTION=112471]MarkinWMich[/MENTION] [MENTION=937]TechWrench[/MENTION] [MENTION=5149]riceandpho[/MENTION] [MENTION=60181]runnerito[/MENTION] [MENTION=46025]HokieRunner[/MENTION]

So I'm embarrassed/relieved to say I determined the cause of the clunk/pop......my bottle jack was loose in the rear, left cargo compartment :doh: . I tightened it up so that it doesn't shake around anymore. Before when it was loose, momentum would cause it to move forward when braking and cause a clunk.

With this in mind, the rear calipers were shot...at least the left one was. The pads didn't have the slide clips, and long story short I'm glad I got them replaced. Back to normal braking for the 4Runner.

Now I can watch this thread slowly slip down the list and hopefully never see it again.

Most of us have been 'there' at one time or another. As least the 'problem' is now solved, and you got the rear brakes done right, which it needed.

 

[runnerito]

I am glad you solve the issue. At leats the jack does not need any service or maintenance!!!

 

[riceandpho]

Good thing you fix the problem, all you guys with brake problems, you guys must have snow and salt in the cold months? Here in the sunny part of northern California, I never read much about brake problems.