93 Ls400 Front Brakes Locking Up Bad !

[Milehigh3]

Started doing this about a week ago but would release if I let it sit for about a half hour.Did it last nite on the way home at a light but HAD to get right home so I drove it about 2 miles.I could get the car to move but it took alot of power and did get me home.When I got home the R/F brake was RED HOT and smoking like crazy ! Could see the outer pad glowing red.Tried the brakes this morning and pedal goes 3/4 of the way down before it even starts to get hard.I am assuming I have only rear brakes now and very little of that. ABS lite would come on last nite and then go back off on the way home.Anyone ever have this happen to them and any idea of how much damage I did ?? ANY help sure would be appreciated !!

[SRK]

First thing- don't drive the car anymore.

Second - you'll have to remove the caliper from the bracket supporting it, and more than likely the pistons will be seized. It's also possible that the overheat has loosened the pistons, but the caliper should be dismantled and rebuilt. I'd also have the rotor (disc) re-surfaced. In fact the other side caliper should be rebuilt, and the rotor resurfaced as well.

It might be a bear to get things apart. On the '92 the caliper slides on pins - not sure about the 93. The pins can corrode and lock the caliper in the applied position.

That much heat has done some damage - but caliper kits and resurfaced rotors are not expensive.

[landar]

Also, check or replace the flexible hoses supplying the calipers. When they get old they will sometimes collapse internally and fail to relieve the pressure.

[Edit] BTW, you can perform a rather simple test to see if your calipers are freezing up or remaining pressure is keeping them engaged. With the tires off the ground, press the brakes and leave off. Try spinning each wheel and note the effort. Of course the sticking side should be much harder and you may hear the brake pads rubbing. Then open (slightly) the bleeder valve on the side that is sticking. If fluid shoots out and the wheel free's up, you know the caliper is ok but the flexible hose is (most likely) keeping fluid pressure in the line. Else, it's the caliper itself.

[Milehigh3]

Thanks to both you guys !! Going to check everything out on Monday.Already got a price from junkyard I deal with for $40.00 for both the caliper and rotor.Seems like a good price to me.Thanks again...Butch PS-The ABS lite went on and off a few times when I was having the

problem and I don't have ABS .Think I'll just leave that one alone,lol.

[924S]

I had a similar issue with my rear brakes. We replaced all 4 lines and checked all 4 caleper and replaced one - and fully replaced all the brake fluid. Didn't help at all.

Took it to my trusted mechanic who started with releasing pressure at the MC freed the brakes, so we replaced the MC - twice. Ran good a week or so...and she started locking up all 4 wheels.

All 4!!

We've eliminated the booster, brake lines, the brake pedal adjustment, the brake & cruise switches - that leaves me with the ABS system.

I mention this to warn you of the road you may go down. . . . and to ask a simple question:

--> How do I disable the ABS so I can drive to work on my own?

Then... where can I find parts? I've searched Google for ABS parts to no avail except used parts on eBay.

[billydpowell]

I am happy to say, in all my 78 years, I have never had that happen to me... but follow their instructions, and have the rotors resurfaced, even one from the JYard.

NOTE: why WHY why did you wait a week, until you really damaged something before taking some action.. and in the future, when your "car" is not acting "right", look into it, find it and fix it...

sorry, that fatherly advise just comes out... sometimes..

[Howstern401]

I had a similar issue with my rear brakes. We replaced all 4 lines and checked all 4 caleper and replaced one - and fully replaced all the brake fluid. Didn't help at all.

Took it to my trusted mechanic who started with releasing pressure at the MC freed the brakes, so we replaced the MC - twice. Ran good a week or so...and she started locking up all 4 wheels.

All 4!!

We've eliminated the booster, brake lines, the brake pedal adjustment, the brake & cruise switches - that leaves me with the ABS system.

I mention this to warn you of the road you may go down. . . . and to ask a simple question:

--> How do I disable the ABS so I can drive to work on my own?

Then... where can I find parts? I've searched Google for ABS parts to no avail except used parts on eBay.

[Howstern401]

Replaced front rotors, calipers, Pads. After a few days driving all 4 wheels would brake about equally hard, judging by the heat generated all around and also confirmed up on a Hoist. After some time goes by they would sometimes release, sometimes not. Other times tap the Brakes a few times and they would release - for a while. No warning lights, no codes thrown, no codes in memory. ABS gone south?

[924S]

Supposedly the abs should thorw codes if any part is bad...but they could be masked by other symptoms.

[VBdenny]

The most likely cause of the brake issue you are having is sticking caliper pins. I had the exact same thing happen when a pin hung up and my front brakes went to xxxx. When I took it apart I found sure enough, one of the pins was really stuck and it forced one end of the brake pad against the rotor which wore the pad all the way down. I removed the pins, cleaned and greased then put n new pads and everything was back to good.

[Howstern401]

91 400LS. Am still experiencing same Brake issue. After replacing right front Caliper and both front rotors, new pads, things worked fine for about 1000 miles. After that period, the front wheel with the new caliper would start heating up, i.e. braking. This would happen every now and then until all 4 wheels would start braking fairly hard (all 4 wheels showing same amount of heat) without Pedal input. Opening Bleed valve depressurized system and confirmed on Hoist. Also, letting the car sit for 10 - 20 minutes will free them up. Disabled the ABS, bled the system, same still. Rubber brake lines replaced years ago with the braided steel type. Am certain no cross contamination of bona fide brake fluid ever took place. Talked with the Lexus Tech to no avail. Anybody else found the cause/fix for this? Thank's all.

[birdman4777]

I have a 1996 se300 that is doing the exact same thing. No lights no codes, nothing. The brakes lock while driving, even if I'm sitting still in the driveway without ever touching the brake peddle they still lock.

[cbttns]

I am having problems with my front brakes locking up. Pads and calipers wer worn and replaced. Brake lines also replaced. worked good for a week orso and started happening again. Could it be the MC? The locking releases when the nut off the MC for the front brakes is loosened and retightened. Is that a vallve before the nut?

[Exhaustgases]

In the old days when that happened is was the pistons in the wheel cylinders had corrosion build up and hold them in the brake on position. Not sure how ABS mechanically works I never had it on a car before. If I was having that problem I would use pressure gages in the lines to see what was holding the pressure. If its low from the master cyl, and high out of the abs then it must be the abs unit. Also some of these cars have the trac system and its supposed to apply the rear brakes to control differential slip that is how I understand it. I've read some stories about that goofing up and causing a rear end slide and spin out. Some owners recommend turning off the trac system in normal driving.

[Exhaustgases]

After a bit of study, the first simple thing to do is disable the ABS system. Then the brakes are supposed to act like cars without abs.

To disable just take out the abs fuse. If all abs are the same type of circuit, there is an accumulator in the control system that is supposed to take the bleed off pressure from the slave cylinders, to reduce brake pressure to that wheel. Not sure but if something is causing that accumulator to stay online that would hold constant pressure in the caliper / slave cylinder circuit. I'm learning about this abs stuff to not an expert, yet.

[VBdenny]

Over the years I've had all kinds of brake problems. I know Nissan brakes need the caliper slides lubricated every 50,000 miles or they stick on. I have never encountered Toyota vehicles have these locking problems that aren't from the caliper pins. I stand by most interested to hear the cause.