Brake Seizing Problems

[BIGAIR64]

My '92 LS400 has had front brake problems for several years. The problem is intermittent. We'll occasionally notice vibration during driving that seems to be one brake or the other dragging. It goes away and then comes back randomly. Eventually, it gets more frequent and severe so we take it in and get the brake caliper and warped rotor replaced. It seems to help but within 2-4 months, the problem is back. We've now replaced the right caliper/rotor 3 times and the left twice. Tonight, we went for a test drive and the first mile or so was smooth and normal. Then, we noticed the pulsing/vibration. We stopped for 5 minutes and the problem was gone when we started back up. However, within a mile it was doing it again. Once home, I jacked up the front and the left wheel is locked. I'm wondering if we don't have an ABS/Traction Control issue that is the root of these problems. Anyone experienced this type of failure that can point me in the right direction? I thought to troubleshoot by disabling the ABS by pulling the 60A fuse but couldn't pull the thing. Any tricks to pull these monsters? Thanks.

[CReynolds]

Have you replaced the rubber brake line going to the caliper? I'd suspect that this may be collapsing on the inside keeping the fluid trapped in the caliper.

[oldskewel]

Have you replaced the rubber brake line going to the caliper? I'd suspect that this may be collapsing on the inside keeping the fluid trapped in the caliper.

I've had similar but not nearly as bad problems on my '91. Still working through things carefully. Rebuilt calipers, turned rotors, and balanced wheels fixed the pulsing, but it still pulls right even after an alignment (3 actually).

Regarding the brake hose theory ... here's a way to test for it without just R+R'ing the hose: If the wheel is locked after driving it as you say, open the bleed valve on that caliper. If pressure in the caliper was still high due to a brake hose problem, the bleed valve would release the pressure, freeing up the wheel. You'll be lucky if that's it - relatively easy to replace compared to other things it could be.

Related to that, if both front wheels are locked and opening one bleed screw frees them both, it indicates a problem with the brake master cylinder (that is holding pressure high when it should be released).

I'd be interested to hear what you find out regarding the ABS.

If you've thought of everything else and nothing looks right, here's an idea: maybe there's some play in a suspension component that creates an instability at some speed, allowing the whole wheel to wobble, which then leads to some other bad response.

[curiousB]

I think oldskewels releasing the bleed valve is a great test to perform next time it happens. Also if you detect it happening check the temp of the wheel and rotor (don't touch it just move hand close) and feel for heat. If the brake is really dragging that one wheel will be much hotter than the rest.

If its something else like a seized wheel bearing then you will have seizing without the brakes being overly warm. My guess is if its a bearing then there would be some serious noise going on though.

I'm a little skeptical of the brake hose as it would have to fail like a valve to pull off the pattern you see. That is it lets fluid through in one direction but not in reverse. That is possible I guess but seems a freakish failure pattern. Maybe a small pebble or bead of steel inside the line is acting as a ball valve? Possible but not obvious.

I'd be sniffing around the master cylinder if it was me.

[91LS400pilot]

I think oldskewels releasing the bleed valve is a great test to perform next time it happens. Also if you detect it happening check the temp of the wheel and rotor (don't touch it just move hand close) and feel for heat. If the brake is really dragging that one wheel will be much hotter than the rest.

Then what? What's next?

I do not have any brake problems so far but I noticed one day after a short trip when I cleaned the wheels the left front was really hot but not the right.

[curiousB]

Then you have to find why it’s dragging. The point for BIGAIR64 was to see if it was a dragging brake or some type of problem in bearing. Brake will be hot bearing won't be.

If you have noticeably warm brake on one side then the rotor will likely warp if you don't fix it (not to mention lousy gas mileage you must be getting). It could be stuck piston in caliper (won't release properly) or it could be a master cylinder issue like it sounds could be the case with OP. My bet is sticky caliper as most likely cause. Simple fix is to buy a new caliper and bleed brakes. If you're more adventurous get a caliper repair kit and remove pistons clean it all up and reinstall pistons with new seals and boots. Replace pistons if they are scared or nicked (binding).

[91LS400pilot]

Then you have to find why it’s dragging. The point for BIGAIR64 was to see if it was a dragging brake or some type of problem in bearing. Brake will be hot bearing won't be.

If you have noticeably warm brake on one side then the rotor will likely warp if you don't fix it (not to mention lousy gas mileage you must be getting). It could be stuck piston in caliper (won't release properly) or it could be a master cylinder issue like it sounds could be the case with OP. My bet is sticky caliper as most likely cause. Simple fix is to buy a new caliper and bleed brakes. If you're more adventurous get a caliper repair kit and remove pistons clean it all up and reinstall pistons with new seals and boots. Replace pistons if they are scared or nicked (binding).

Thank you, now I got a project.

Best

Chris

[IS400]

Do you want to fix your problem for $7? Here is how you do it, pull out the slider pins and replace the two rubber boots that keep grease between the pins and the caliper pin bores.

Go to local parts store, ask to look at exploded diagram of front brakes for LS400, point to twin pins on the caliper and ask for the boot kit that has four boots in a pack for $6.95.

Grunt and groan as you pry the jammed pin that is not sliding and binds up the brake as it gets hot. A slide hammer works wonders if you can't pry the pin out with a big screwdriver and liquid wrench dousing.

What do I know about cars....., I'm just a girl! LOL!

Good Luck!

[VBdenny]

The Lexus calipers are really easy to work on. One you take it apart, what you need to do will be fairly obvious. In addition to the slider pin, many people also experience problems so after replacing the pads. The boot gets extended out pretty far when the pads are worn. Dirt and grime accumulates. When the boot is pushed back in when the new pads are inserted, it binds. I always wipe them off with WD40 before I compress them. A girl knowing all that is excellent in my humble opinion.

[IS400]

Awwwwwwe! You made me blush!

Those slider pin boots can tear or break down over time and then they leak out all the grease. Water and debris like you said, gets in and they rust up and jam.

So many people concentrate on the rotors and brake fluid when the floating piston has to be working properly first for the brake to work any where near good enough to diagnose other issues with the system.

If you can't move the pin in and out of the boot with two fingers and a thumb, they need to be re-greased and re-booted.

I change the re-grease the pins and boots of any one that drags even a little, with every pad change. What is $7 for four replacement boots, compared to knowing the pads are actually floating as designed each time you depress the pedal.

Priceless! LOL!

[lenore]

My friend had the exact same problem on a GMC truck. The brake kept hanging up. replaced the rotors, calipers, etc. still happened. The right answer was the rubber brake line as mentioned above. What happens is when you apply the brakes the fluid pressure is enough to actuate the caliper, but the hose is expanded on the inside, kind of like coronary artery plaque, and when you release the pressure the fluid doesnt back up the hose. Kind of like a one way valve. Replace those lines on the left and right side and you should be fixed....Hard problem to diagnose, but a cheap fix....

[curiousB]

My friend had the exact same problem on a GMC truck. The brake kept hanging up. replaced the rotors, calipers, etc. still happened. The right answer was the rubber brake line as mentioned above. What happens is when you apply the brakes the fluid pressure is enough to actuate the caliper, but the hose is expanded on the inside, kind of like coronary artery plaque, and when you release the pressure the fluid doesnt back up the hose. Kind of like a one way valve. Replace those lines on the left and right side and you should be fixed....Hard problem to diagnose, but a cheap fix....

Maybe but if your were to rank order what order to attack these I would go

1. Slider pins and boots
   
2. caliper overhaul (o rings seals, and cleanup)
   
3. brake hoses
   

While it may be possible for the hose to fail as you state I think it is far less likely than the other failure modes discussed. I'd try them first. If you're going to do #2 then maybe you do 2 and 3 together as the cost of the hose is fairly small and who wants to bleed the system twice.

[lenore]

On a 17 year old car I would replace the hoses, I am sure they are getting aged and brittle...

He already replaced the calipers, the next step are the hoses....

[VBdenny]

It does make sense to change the hoses if they look in any way compromised however, my 20 year old hoses still as in excellent shape. I suppose it depends a great deal on the climate in which the car is operated

[BIGAIR64]

Thanks to all that have responded. I took a look at the seized left caliper. The inside piston was locked. Opened bleed valve and checked lines. All seems fine. Caliper was still locked. Could get piston to move for anything. Finally replaced caliper and now all is well. No noticable play in suspension. Will do better job of cleaning and servicing caliper on regular basis and see how it goes. If I get more heating or other symptoms of dragging, I'll just replace lines a suggested by lenore. Thanks again to everyone. You've been very helpful.

[IS400]

Cool! Glad we could help!

[VBdenny]

I had a back caliper lock. Man, I couldn't get that free. The dealership quoted me "at least $750" to change it out. They also wanted $280 for caliper. I bought it at Bap Geon in Virginia Beach. An EXACT Asian Caliper. $90 with pads (not Lexus, not used) and a lifetime warranty. Took me less than 45 minutes.

Now I see that name IS400. Is there such a car? If there was, it would be sick fast.