brakes when cold or wet.

[90xj06]

pk when my brakes get wet or cold the work great. if you hit the peddle they will lock up nicely. but then after a couple stops that lock up ability vanishes. i have a new master cylinder and pads and shoes.

i was just wondering. its strange tho it doesn't do it in the rain. but if you spray them with the hose.

[Dvipercop]

Mine do the same thing. Sorry I can't offer any advice on any of it, but just figured I'd relate to the issue. :D

[POSXJGuy]

oops, i read it way wrong. my bad.

[oz_hole]

Got the same thing that happens to my rears usually in the mornings... It's always funny when coming to a stop sign with a jogger crossing the road and you lock up doing 10mph...

[5-90]

Oddly enough, I think I've seen this before. It was caused by someone "getting on" the brakes within about 500 miles of a change, before the pads were bedded...

Fix? Try taking the pads out, breaking the surface with sandpaper or emery cloth (80-120 grit should work) or a fine cut flat bastard file (double-cut if you have it, and only if you're sure of yourself! A file is rather more aggressive...) and reinstall. Hit the rotors with Scotch-Brite wheels if they seem glazed as well - it's a possibility.

Glazing on the pads or rotors will cause them to retain heat, meaning you'll get "brake fade" that much quicker. Wetting them down will help them cool, until the water evapourates - and you can direct a hose (rain doesn't usually get on things undercar, unless you drive through a puddle.)

TAKE IT EASY the first 500 miles or so - and the first time you drive it after doing a brake job, you'll want to do some long, slow, gruadual stops while "feathering" the brake pedal to heat up the pads - but not overheat them. I usually pick a carpark downstreet, and just orbit the thing a couple of times, not applying the brakes for more than about two seconds (and getting off of them 3-5 seconds.)

Do that for about ten minutes, and then slowly increase to a full stop from street speeds (but not a "panic" stop - smooth and even. If people honk at you, wave back.)

Granted, this isn't like "pre-bedding" on a brake dyno, but it helped with friction logevity with an old girlfriend I had - she drove an automatic with both feet, and I did brakes (four wheels' worth!) every eight or nine months...

If they're glazed, you can save them. If they're cracked, replace them - even if you break the glaze, they'll usually "chunk off" when you try to re-bed them, or at the first time you have to panic stop...

5-90

[90xj06]

i think my rotors are glazed really bad. as for the pads i would have never thought. but it is the rears that lock and you can feel the difference. but why the rears. and is the way above usable for drums???

[jeepinairman]

i am anixously waiting on the answer to this also as mine do the same thing

usually just in the morning or when its raining ...im the morning..lol.......dont know why....after a couple of very light pedals though it stops.......

i dont know why..its done that since i got it 3 years ago........just something i deal with...lol...like alot of things on the jeep

[90xj06]

yes same here would love to get those results at any time. going up to school and screach side ways i a spot and park it nicely. i cant even get the e-brake to lock up the wheels. maybe there out of spec? but how could it be.

[5-90]

If the handbrake doesn't work, it's an adjustment problem (first,) lining/drum wear (second,) or cable stretch (third.) Since handbrake cable stretch is fairly rare, I'd check the other two first.

However, bear in mind that most of your braking, under normal circumstances, takes place up front - so if I have trouble with brake function in general, I'll start by looking at the front axle.

5-90

[90xj06]

yes im aware of the ajustments. they do work but they don't lock up. so im wondering if the drum linings are gone.

[5-90]

Ideally, the drum brakes should not lock up under normal operation - but they should prevent the wheels from moving (unpowered) when engaged.

5-90

[90xj06]

but why do they lock up in the morning. and they do it so easily. there must be a way. whose cheaper for drums if i have to get them napa. autozone.

[Matthew Currie]

For the hair trigger locking up when wet or starting out, try manually adjusting the rear drums. In my experience this happens when one or both of the self-adjusters stops working. Adjusting the brakes good and tight by hand seems to be the most reliable cure. All my XJ's have had this problem. I really don't like the design of those self adjusters. Polite forum posting rules forbid me to express in concise terms my opinion of those self adjusters. :gonnablow

[5-90]

For the hair trigger locking up when wet or starting out, try manually adjusting the rear drums. In my experience this happens when one or both of the self-adjusters stops working. Adjusting the brakes good and tight by hand seems to be the most reliable cure. All my XJ's have had this problem. I really don't like the design of those self adjusters. Polite forum posting rules forbid me to express in concise terms my opinion of those self adjusters. :gonnablow

True enough - they tend to get caked up with dust and whatever is used to lubricate them. I have had better luck using dry graphite, and I've seen some Teflon/MoS2 coatings I plan to experiement with later as well - keep brakes DRY.

Before buying drums, have yours checked. If they can be turned, you're only looking at $10-15, vice the cost of a new drum...

5-90

[philip_g]

tagging along on this one. When the temp is cold they're super grabby. When the temp is warm, they're mushy as heck. Will check the suggestions, thanks!

[fitbmxseries1]

did a search and came across this thread. im gunna pull them apart tommorrow and "adjust" the adjusters and give them a good cleaning hopfully that will help. is this a super common thing for the xjs? btw mine is a 99......... is it only happening on certian years?

[5-90]

I don't have any trouble (all RENIX,) but I do keep my brakes bled, change the fluid whole every two years, and try to keep things adjusted.

Could be just me...

5-90

[fitbmxseries1]

i drove my freinds jeep and it did the same thing a few months back, he replaced all the brakes and it didnt do it agian, he also has a 99. maybe mine just needs a good cleaning

[csr_011]

You can also adjust the rears while in park by pulling the hand brake up and releasing it about 30-40 times. Dont yank on it like you would a breaker bar, but just go through the motions about that many times and it should do the trick. I usually do this about every 3 or 4 months and my jeep doesnt nose dive or lock up at start in the mornings...

It has however done this after a rain or snow after drying and having a bit of rust build up overnight, causing the first or second quick grab when braking...but not very often.

Cory

[87manche]

I don't have any trouble (all RENIX,) but I do keep my brakes bled, change the fluid whole every two years, and try to keep things adjusted.

Could be just me...

5-90

regular adjustment is key.
Self adjusters don't work, period.
I did an axle swap labor day weekend, all new brake hardware including adjusters, with the exception of the drums.
3 months later, the passenger side adjuster had already failed and was stuck.
I adjust the rear brakes when I change the oil, and I can feel in the pedal when they need adjusted.
Poorly adjusted rear brakes should not cause the pedal to be mushy, it will cause the pedal travel to be farther.
So you'll end up using half the stroke of the master to expand the rear drums, then the brakes will get very firm as the fronts engage.

[rocklandxjer]

90xj06---
do you want the brakes to lock up?

they aren't supposed to

[fitbmxseries1]

90xj06---
do you want the brakes to lock up?

they aren't supposed to

yeah i was thinking thats not the safest thing on the street.

[8Mud]

Just a few possiblities, but some things I've seen before. Drums or discs will get a light coat of rust on them. First couple of stops can be pretty grabby and sometimes squeeky. Rear drums full of dust, sand, mud, salt whatever can get grabby.
If there is any kind of brake fluid leak (at the rear cylinders), the pads or shoes can swell, don't really know if it's the brake fluid itself or the moisture the brake fluid absorbs or the junk that sticks to the brake fluid and acts like sand paper. But they will grab, especially the rears.
I've had rear shoes, grab in the beginning then fade away to almost nothing. It turned out to be a leaky rear axle seal, the junk that stuck to the oil would stop me just fine a couple of times (sometimes to good), but when the junk wore off or got heated up, the shoes would slip from the oil.

[fitbmxseries1]

i just tore my rears apart today and discoverd the passenger side is worn WAY more then the driver side, and needs to be replaced but i dont have the parts now and no place is open any more so i just cleand and greased up a few parts, seems to be working now but the real test is when it rains. if this doesnt fix it i may try to replace the cylenders when i get new drums and pads.

[Flash]

if your replacing the brakes get the hard ware kit for both sides and the adj too

the grabbing problem when first applied is aether brake fluid or axle lube getting on the brakes! it sound completely wrong, but the fluid caused the brake shoe to be come softer and cause it to be vary grabby! if they get socked they will be grabby all the time.

Replace the shoes clean every thing up good, wash you hand before you install you brakes shoes with all new hard ware and they will work better the ever!
moisture amplifies the oil on the brakes problem

when the rear brakes are remove, lift the dust seal on the wheel cylinder and if they are not completely dry underneath, replace them!!!

[YosemiteXJ]

pk when my brakes get wet or cold the work great. if you hit the peddle they will lock up nicely. but then after a couple stops that lock up ability vanishes. i have a new master cylinder and pads and shoes.

i was just wondering. its strange tho it doesn't do it in the rain. but if you spray them with the hose.

You said that you have a new master cylinder. One of the causes of your symptoms is brake lines that need bleeding. Could you have air in the lines? I would bleed first the master cylinder, then all of the brakes... it is easy and quick, and could solve your problem.

[fitbmxseries1]

if your replacing the brakes get the hard ware kit for both sides and the adj too

the grabbing problem when first applied is aether brake fluid or axle lube getting on the brakes! it sound completely wrong, but the fluid caused the brake shoe to be come softer and cause it to be vary grabby! if they get socked they will be grabby all the time.

Replace the shoes clean every thing up good, wash you hand before you install you brakes shoes with all new hard ware and they will work better the ever!
moisture amplifies the oil on the brakes problem

when the rear brakes are remove, lift the dust seal on the wheel cylinder and if they are not completely dry underneath, replace them!!!

it was very dry inside of there no oils or brake fluid just dusty but i cleaned that out with some brake cleaner, and after driving it agian they started squeaking......... could be the front but every thing was replaced just recetnly up there so im thinking its the rear.

[Jeepski]

I have had this locking problem ever since I moved from Colorado to San antonio. I also had front axel work done right before the trip. I drive a 99 also. Only the front brakes lock, and they only do it for the first few stops when the jeep is cold and especially when it is wet outside. This sometimes happens when the jeep is less cold and the conditions are wet. One of the calipers was sticking so I had those replaced and the rotors turned a couple weeks ago. The problem persists. I've had a few close ones as a result of this. It's pretty sketchy to slide through a skid for forty feet to stop at thirty miles an hour. I've met ice that's easier to stop on than dry asphalt with cold brakes on my jeep. I think the next step is to try and re-bleed.

[Garden Spyder]

HyJack.. I have brake problems also, and thought I would add to an existing thread.
Before going to Colorado mountains a few months ago, I replaced the discs on front and put on new pads, after being out in Co. for a few days, my front end started to grab like there was a gear binding up, or bearing locking up, and it only did this going forward, not backward (verified by jacking up the front end and manually turning it.)
Then I replaced hub assemblies to eliminate that as being a possibility, changed diff oil and inspected the gears, which were like new, replaced calipers, replaced hoses, and still it does the same thing. I had a stroke of luck to see what was happening when I jacked up the front end and turned the wheels again and could see the caliper jumping when the wheel locked up. to release it, I had to turn it backwards, and it turned perfect backwards, but turned it back forward again, and it kept ratcheting.
someone mentioned master cylinder, but I am wondering if it doesn't have something to do with glaze,(not sure what that is) or some of this other stuff you guys are talking about.

[Matthew Currie]

HyJack.. I have brake problems also, and thought I would add to an existing thread.
Before going to Colorado mountains a few months ago, I replaced the discs on front and put on new pads, after being out in Co. for a few days, my front end started to grab like there was a gear binding up, or bearing locking up, and it only did this going forward, not backward (verified by jacking up the front end and manually turning it.)
Then I replaced hub assemblies to eliminate that as being a possibility, changed diff oil and inspected the gears, which were like new, replaced calipers, replaced hoses, and still it does the same thing. I had a stroke of luck to see what was happening when I jacked up the front end and turned the wheels again and could see the caliper jumping when the wheel locked up. to release it, I had to turn it backwards, and it turned perfect backwards, but turned it back forward again, and it kept ratcheting.
someone mentioned master cylinder, but I am wondering if it doesn't have something to do with glaze,(not sure what that is) or some of this other stuff you guys are talking about.

Make sure the pads are engaged correctly on the rails, and the rails haven't lost a big enough chunk to cause them to hang up.