Front brakes binding after sitting for months during winter

[maxbraketorque]

I had to move my XJ out of the garage an into a covered parking area last winter. It sat virtually all winter and into spring. As is typical for the Portland, OR area, it rained pretty much all winter and spring. The vehicle didn't get wet, but of course it was outside and exposed to the high humidity associated with rainy weather.

I've started driving it a bit again, and I'm finding that the front brakes are binding slightly. Its just enough to feel it while driving. The disk and calipers get pretty warm. If I stop and let the brakes cool off, it seems to kind of fix itself, although I haven't driven it enough to be sure its completely fixed itself. It happened first with the RF wheel and then the LF wheel (but not at the same time). Before I take off the wheels to have a look, I'm wondering if this is a known issue, and if yes, is it an issue with the caliper becoming stuck, or maybe something with the master brake cylinder.

 

[lawsoncl]

I would pull the pads out and examine the slides. They may be rusted up and not letting the pads back off. Verify the caliper pins are in good shaped and greased as well.

 

[maxbraketorque]

I would pull the pads out and examine the slides. They may be rusted up and not letting the pads back off. Verify the caliper pins are in good shaped and greased as well.

Thanks. Yeah, I'll pull a wheel off today to a have a look. Pins were greased perhaps 2 years ago, and the pin boots were in great shape at the time. Probably only been driven a few thousand miles in non-rainy weather since that time. Will be interesting to see how they look now.

 

[RCP Phx]

It's also a common issue with semi-metallic pads.

 

[maxbraketorque]

It's also a common issue with semi-metallic pads.

Interesting to hear. These are the pads that came with the XJ. Don't know if they are semi-metallic, however they don't produce much dust, so maybe semi-metallic.

 

[maxbraketorque]

Well, nothing wrong with the brakes mechanically. Pins easily slide. Caliper piston boots were perfect. I was able to readily increase separation between pads. Drove it to the store, and it was fine. Hopefully, this is the end of the issue.

 

[maxbraketorque]

Well, the left front brake heated up again. This is the brake that I disassembled. I had verified that caliper piston worked easily, I verified that the pins slide easily, and I put a dab of grease pad sliders when I put it back together.

I'm pretty perplexed. Could it be an issue with the master cylinder assembly?

 

[RCP Phx]

No to likely on the MC, but ridges on the glides are very common. Did you pull the piston and inspect it?

 

[maxbraketorque]

No to likely on the MC, but ridges on the glides are very common. Did you pull the piston and inspect it?

I didn't pull the piston from the caliper because everything looked and felt good. The pad sliders are not grooved. I did apply the brakes while backing-up to try to ensure that the pads were not somehow sticking on the slides. Didn't seem to help. I guess I'm going to have to take it apart again.

 

[75SV1]

How new are the brake lines? When did you last change the brake fluid? Sometimes the lining in the rubber brake lines delaminate. Then they act as a one way valve. I haven't experienced it directly. A neighbor had a locked up brake. Another neighbor fixed it. Said it was a delaminated brake line.

 

[RCP Phx]

Anything is possible, but for right now because it's free and doesn't even require tools would be to try and re-bed the pads. If it hangs up after that you've got a more serious problem.

 

[maxbraketorque]

Brake lines are what RC supplies with their lift kits. They are stainless braid, probably PTFE hose inside.

I'll post more info when I have it, probably in a few weeks when I'm back to the XJ.

 

[75SV1]

I had JKS ones on a '98 I had. Kind of makes me think, they are not the cause. Still, if a 3.5 to 4.5 list, Raybestos makes a regular brake hose type. I used them on a 2" lift.

 

[maxbraketorque]

I visited my XJ again this weekend. First thing I did was flush the brake fluid through the entire brake system. The fluid was fairly dark even though it was flushed back in 2020, so I guess it was good to have done it.

Frustratingly, that didn't help. Left front again slowly heated up due to brake pad friction against the rotors. The wheel mounting surface of the rotors was too hot to touch after perhaps 20 miles of highway driving, however, the caliper was not hot.

This time I pulled everything apart while the brakes were still hot. The pads were very clearly pressurized against the rotor. It took effort to spin the wheel with it off the ground. Removing the caliper mounting bolts had no effect. And there are definitely no ridges in the slides for the brake pads.

I could not appreciably pry open the pads while everything was toasty, but after everything cooled down, it was straightforward to pry open the pads away from the rotor by a few millimeters.

So bizarre. If the liner of the brake line is acting like a 1-way valve, then it shouldn't have been possible to pry open the pads away from the rotor after everything cooled down. I guess it still feels to me like its something to do with the master cylinder.

 

[RCP Phx]

More likely a bad caliper, the front brakes do not even divide into left/right until after the proportioning valve!

 

[maxbraketorque]

Looks like the front brake lines divide at the proportioning valve - LF comes out the rear of the prop valve, and RF comes out the bottom. If the prop valve is just Y at the point, then that would indicate its the caliper or brake hose. If the caliper piston has some rust around the piston exterior, then maybe when the caliper piston warms up, it seizes to the caliper body. That's about the best I can figure, well unless it is somehow the RC stainless braided brake hose.

 

[RCP Phx]

Any update?

 

[Unclewolverine]

Brake calipers can develop sort of an internal rust ring that causes this exact same thing. Happens a lot when you put new pads on a vehicle that sits a lot. Take the caliper loose, remove the pads and have an assistant pump the brakes until the piston is almost all the way out, then use a c clamp and push it all the way back in. Repeat several times and 95% of the time it clears up the issue.

 

[maxbraketorque]

Brake calipers can develop sort of an internal rust ring that causes this exact same thing. Happens a lot when you put new pads on a vehicle that sits a lot. Take the caliper loose, remove the pads and have an assistant pump the brakes until the piston is almost all the way out, then use a c clamp and push it all the way back in. Repeat several times and 95% of the time it clears up the issue.

I was wondering if something like that might fix the issue, but I was tired of messing around, so I bought a set of ACDelco reman calipers. I'll install next time I'm at my XJ, probably next weekend.

 

[maxbraketorque]

New (remanufactured) calipers resolved the issue. Pretty fascinating how the old can easily be spread when cold but get really stiff after warmup. Anyhow, I'm glad to be done with that issue. Now onto the next issue which is replacing the heater core.