brakes binding when humid

Hi guys. I have a 95 XJ Sport. For a couple of months now, on humid, warmer days the first time I come to a stop after the Jeep has been sitting for awhile, I'll apply the brakes, begin stopping, and then a second or two later there will be a large, startling "THUNK!" and the Jeep starts to decellerate more rapidly. I thought it was suspension at first. It almost feels like you slide forward for a second on your suspension before you begin slowing. But today it did a REAL strong one while I was turning and stopping, and I even felt the brake pedal sink a tiny bit when it happened. It usually only does this the first stop or two.

This means that the brakes- I think it is the rear but not sure- are binding for a second when I apply them, and then snapping free all of a sudden and ending up where they should be. And the warmer and more humid it is, the worse it happens. Today is mid 70's and rainy, so it is doing it pretty bad today. I'm going on a 3000 mile trip in 2.5 weeks so I really need to get this taken car of ASAP.

So...any ideas on how humidity affects brakes?

Thanks
-Adam

What you noted has been commented on many times and seems to be fairly typical. There was a thread on this topic just a few weeks ago. It is the rear brakes, and they do grab when damp. I don't believe the previous threads ever fully identified the cause. My theory is that some lining materials swell when damp, causing the brakes to grab until heat from friction dries out the moisture. I don't recall what I'm running for rear shoes these days, but I haven't experienced it for a long time, so it may be that a different brand of shoe or a different type on lining (like a semi-metallic or a ceramic) would alleviate the problem.

Sorry I can't be more specific than that.

no- that was very helpful. I used to lurk here all the time a year or two ago and never saw this problem come up.

Also, these brakes are over 3 years old and didn't start doing it until a couple of months ago. I thought that was pretty strange.

If the pads were swelling, it seems like they would just rub all the time rather than having a delayed reaction like that though.

This might be it.

Hi guys. I think I found the problem.

Here is a picture of the star adjuster of the driver side rear brake. You can see that there is no contact. I really don't know much about how this part works. How do you recomend I fix it, and how might this have happened?



This is the rear shoe on the same brake. Clearly, most of it isn't making contact with the drum. The front shoe looked OK. The passenger side showed more wear on both shoes.

So...what should I do?

I had exactly the same problem. Perhaps overkill but I replaced the shoes and drums. After looking at my drums - 12 years old, caked in salt induced rust I tossed 'em and bought replacements from Advanced. I did the front pads and rotors at the same time. All up just under $200 for parts. Two easy hours work and what a difference - no more binding, braking is excellent. Nice and "sharp".

Did you also have the adjuster problem shown in the photo above?

I haven't changed drum brakes since I was 16, and that was enough to make me not want to do it again! Too many little fuggin parts and springs! I nearly poked my eye out trying to get a spring back on with a screwdriver. I don't know...maybe it would be easier now that I'm older (by 10 years) and wiser.

The XJ brakes aren't so bad. New springs and adjusters are pretty inexpensive. Make sure you get the correct adjuster cables for your drum size, and make sure you put the adjusters on right way around (they don't look all that wrong when they're in backwards).

When I did mine recently, the shoe hold-down springs were in pieces. New springs a must.

I've found the best tool for pulling brake springs is the large size needle-nose vise-grips. You can grip the spring a little back from the hook and pull the hook right up to the hole or post.

Even after my recent brake job I was plagued by binding and pulliing, but repeated adjustment seems to have cured it at least for the moment.

Eagle said:

What you noted has been commented on many times and seems to be fairly typical. There was a thread on this topic just a few weeks ago.

Click to expand...

does anyone have a link to this? I'm selling my XJ and want to print this for the buyer so they don't think I'm a scumbag. I searched the archives but couldn't find it. It's prob from the old naxja site..?

thanks, I saw that too, but thought there was another one where the topic was more on moisture?

also what ARE the general rules on selling? ie about 5 years back, some guy broke my oil pressure sensor when doing an oil change. it was replaced but never read right after that. do I need (karma-wise) to tell the buyer? he's already left a deposit, but I have an enormous amount of guilt already set in about not telling him that. it runs perfect, and I ignore it because it's a calibration issue. it's a grrl thing I guess to not have someone curse us... guys would take the money and run???