Poll on total brake failure in 100 series (5 Viewers)

Has your 100 series LC experienced total -or near total- brake failure?

  • No.

    Votes: 1,271 73.1%
  • Yes. My truck had between 0 and 50k miles at the time.

    Votes: 1 0.1%
  • Yes. My truck had between 50k and 100K at the time.

    Votes: 14 0.8%
  • Yes. My truck had between 100K and 150k at the time.

    Votes: 72 4.1%
  • Yes. My truck had between 150k and 200k at the time.

    Votes: 145 8.3%
  • Yes. My truck had between 200k and 250K at the time.

    Votes: 138 7.9%
  • Yes. My truck had between 250k and 300k at the time.

    Votes: 76 4.4%
  • Yes, My truck had over 300k at the time.

    Votes: 41 2.4%

  • Total voters
    1,738

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Well, we got in "The Zombie" to go to the restaurant this morning, started it up and... alarm, lights, NO BRAKES. Phun.

I stumbled across this one on ali express:
for 7 and a half bills. It is very tempting, but I think I'll get one from LoT (Tulsa) for six bills more. It should get here faster, LoT has been good to us, I know it will be the right part. These people are probably just fine, but occasionally the vendors on AliExpress will be somewhat creative on you.
 
Well, we got in "The Zombie" to go to the restaurant this morning, started it up and... alarm, lights, NO BRAKES. Phun.

I stumbled across this one on ali express:
for 7 and a half bills. It is very tempting, but I think I'll get one from LoT (Tulsa) for six bills more. It should get here faster, LoT has been good to us, I know it will be the right part. These people are probably just fine, but occasionally the vendors on AliExpress will be somewhat creative on you.
This is a part that I personally would only get from Toyota direct and be done for life with it. Mine should be here in the next few days and hopefully never have to think about it again.
 
Thank you.
But understand, you do want to evacuate a few times. IG key off, pump pedal 40 times. IG key on, booster motor runs filling accumulator, than stop in less than 40 seconds. repeat repeat
 
So I replaced my rotors and calipers after the driver rear seized and had damage. I got it put together and did a little around the block run and something is dragging. I thought it might be my parking brake (which has been seized as well...meh) so I fiddled with it then just removed it to eliminate the possibility and something is still dragging. It sounds pulsed when I'm going slow. That would point to my rotor being out of round wouldn't it? I bought a bunch of parts from "LexusPartsNow" and they showed up in a pretty banged up box. I thought I was going to be missing things since I had bought stuff to rebuild the calipers (before I saw that the caliper had a casting crack in it...) but everything was there.

I'm taking the cruiser to a muffler shop to have them fix that for me and plan to ask them to diagnose the brake problem I can't figure out but after thinking things through I feel like I've eliminated everything else and a warped rotor is the only thing left. Am I missing something?
 
@abuck99 just brought to my attention. We sometimes have issue with new rear OEM rotors. They rub on dust shield mount. Dealership have been shaving rotor back side on a lathe to solve. We also have the oil defector shield gasket breaking up and falling partially out rubbing on rotor. But you would have seen gasket, when you pulled the rotor back off.
 
So I replaced my rotors and calipers after the driver rear seized and had damage. I got it put together and did a little around the block run and something is dragging. I thought it might be my parking brake (which has been seized as well...meh) so I fiddled with it then just removed it to eliminate the possibility and something is still dragging. It sounds pulsed when I'm going slow. That would point to my rotor being out of round wouldn't it? I bought a bunch of parts from "LexusPartsNow" and they showed up in a pretty banged up box. I thought I was going to be missing things since I had bought stuff to rebuild the calipers (before I saw that the caliper had a casting crack in it...) but everything was there.

I'm taking the cruiser to a muffler shop to have them fix that for me and plan to ask them to diagnose the brake problem I can't figure out but after thinking things through I feel like I've eliminated everything else and a warped rotor is the only thing left. Am I missing something?
Now you got me questioning doing mine. I have them on the shelf and my ebrake bell crank seized on both sides this winter and I was going to do it while I was doing my Master cylinder swap this week.
 
@abuck99 just brought to my attention. We sometimes have issue with new rear OEM rotors. They rub on dust shield mount. Dealership have been shaving rotor back side on a lathe to solve. We also have the oil defector shield gasket breaking up and falling partially out rubbing on rotor. But you would have seen gasket, when you pulled the rotor back off.
You don't know how much needs to be shaved off do you?

The muffler place I dropped it at at 8 this morning didn't have time to do anything on it which is ridiculous. It's supposed to be a first come deal and they opened at 8. Anyway, so still loud exhaust and they didn't look at the brakes so I'm going to maybe try this again. The guy basically just read me.back what I told them when I dropped it...
 
@abuck99 just brought to my attention. We sometimes have issue with new rear OEM rotors. They rub on dust shield mount. Dealership have been shaving rotor back side on a lathe to solve. We also have the oil defector shield gasket breaking up and falling partially out rubbing on rotor. But you would have seen gasket, when you pulled the rotor back off.
The Parking Brake Plate Sub Assembly AKA "Backing Plate" is apart from the dust shield.

The "backing plate" fits inside the rear rotor hat intended to keep larger debris out of the shoes. It is the outer edge of the backing plate that rubs (or actually scrubs) on the unmachined portion of the inside edge of the rotor. You mainly notice this on new rotors when turning- you hear a repetitive scraping noise. Not sure if excess axle runout from worn bearings is the main cause but its a likely contributor. Differences in rotor machining can be another contributor. My last set of new OEM rotors did it, and the new set of DBA rotors I installed last week are doing it. It will eventually wear down and stop contacting, but if its annoying find a shop to cut down the edge. This was a common issue on 07-12 Tundras and a TSB was issued for it.

On my OEM rotors I measured scrubbed off wear to a range of 0.22mm to 0.45mm deep-if you have them cut maybe 2mm would be a safe target. Too little you have to pull and do again, too much and you might allow more debris into the inside rotor hat.

The pen is pointing to the scrubbed area
1657155401757.jpeg


1657155450186.jpeg
 
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Just thinking out loud here but without a metal lathe I feel like it'd be easier to hit the backing plate with a flap disk to knock that down rather than modifying the rotor. I didn't have time last night to pop the tire and rotor off but will try and look at it tonight. It should be pretty apparent where its rubbing on the backing plate right?

Anyway, thanks for the tip on that, I'm getting fed up with some of this ticky-tacky stuff and with the heat we're having I just want to be done with the maintenance.
 
I think these other brake issues are best left to their own thread. Let's keep on track with the premise of this thread, please. Thanks.
 
Scary stuff! Mine is a '99 with 225k and it came into my family's possession at 164k in 2013 and no brake failure yet. I don't know if previous owner(s?) ever had the issue.
 
Scary stuff! Mine is a '99 with 225k and it came into my family's possession at 164k in 2013 and no brake failure yet. I don't know if previous owner(s?) ever had the issue.
Ours failed at 234K. I'm kinda thinking this should be a "scheduled maintenance item."
 
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Miles and years, is only small part of equation. It's more about proper maintenance.

Here's the PM:
1) Never over fill reservoir.
2) Flush often. (I only use Toyota brake fluid these days. Not even Dealership do that and they're replacing a lot of master these days on all Toyota & Lexus.)
3) Make sure vent at bottom of pump, does not become clogged. This is rare to happen, in a stock DD.
4) Check for leaks, end to end. Master assy, flare nuts, hard lines, flex lines, caliper. Leak need repair without delay.
 
Scary stuff! Mine is a '99 with 225k and it came into my family's possession at 164k in 2013 and no brake failure yet. I don't know if previous owner(s?) ever had the issue.
Just get a complete master from a dealer and be done. I just did mine and it's a easy job. Comes out in like 15 min. Bleeding is straight forward. 1200 for the master and another 40 for 5 pints of fluid from toyota and your done for the life of the rig. I have been stressing it for years and then noticed a leak. Feels good to not worry about it anymore or stress on a rebuilt unit. FYI mine failed at 200k with regular fluid service.
 
Just get a complete master from a dealer and be done. I just did mine and it's a easy job. Comes out in like 15 min. Bleeding is straight forward. 1200 for the master and another 40 for 5 pints of fluid from toyota and your done for the life of the rig. I have been stressing it for years and then noticed a leak. Feels good to not worry about it anymore or stress on a rebuilt unit. FYI mine failed at 200k with regular fluid service.
Great price on that new unit, I have done a couple of these and never got one out in 15 minutes, and I bow in your general direction for your skill and dexterity. This really is the elephant-in-the-room item with this mature ABS booster setup. The best I could find for prices earlier this year was about 1600 out the door. Dallas Tx
 
Someone posted a link on here for the 4th of July sale and that was with free ship and no tax. My local dealer wouldn't match, 1575 was the best they would do. I thought it was going to be a bigger project than it was that's for sure. :banana:
 
So glade everyone is okay. Fortunately that always seems the case!

I'd be very interested in what you find is cause.

Also when you say total brake failure what happen, in detail please? What first alerted you? Then what happened?

Typically sudden brake failure, where pedal goes to the floor. Is booster motor failure. Alarm and dash lights go on and we get 1, 2 or 3 strokes (each weakening) before pedal goes to the floor after motor failure. This is due to loss of booster pressure, because booster motor failed to run. Motor failure!

There is also certain very rare condition where no power (12V) gets to the motor. So motor is good, just no current to run it.

The accumulator can fail but usually a slow death.

If a brake fluid leak developed and fluid is lost, the same thing happens, in we've no pressure. We can have a line leak and still have brake in other three wheels. I've seen where reservoir has totally emptied. No brake fluid no brakes. But here alarm should sound very early on, Just as level drops below low line. Failure happens when empty.

A small leak will result in pressure loss. This will activate booster motor excessively. Someone that rides there brake or a tail gate-er or heavy stop and go traffic using brakes often. This all uses motor more than HWY miles of a proper service brake system. So mileage is not a good indicator of life of motor.

I'm most interested in the wire from bottom of your ABS (black unit on side of brake master) that runs to the booster motor. I find ~30% of these wires corroded. In all failure I've repair, the wire was corroded. I've a theory, that the wire being corroded is increasing resistance. This a non reusable wire according to factory. This 8 " two wire harness list for $170, I kid you not. It's because it's a resistance wire. My theory is, this is leading to early failure of the motor from increase in resistance. In some cases, wire may be responsible, for failure of ABS unit, which current flows through.

My interest in this is in trying to inspect for failure before it happens. In that, the corroded wires may mean we need to replace wire and rebuild motor when we find this. The more cases I find with failure and a corroded wire associated to it, the stronger my theory becomes.

So please report back with detail and pictures.

Here some pictures of the wire corroded. In ~30 % of 100 I inspect, I found the brake fluid reservoir was over filled. Shop top brake reservoir without reading instruction embossed on reservoir on how. I suspect brake fluid gets into the wires boot, attracting moisture.

1999 w/150Kmiles from CO
View attachment 1945585
2007 w/100K from GA/TX. Inspection with mirror.
View attachment 1945593
07 after wire & screw clean up. You can see reservoir if you look close to orient yourselves as to wires location.
View attachment 1945594

2005 w/85k miles from SoCA
View attachment 1945595
I also just inspected a 2000 LX very clean with 200K miles. It also had corrosion on wires.

I've a 2000LX w/350K miles and some undercarriage rust and bolt rust in engine compartment, as came from CN and Boston. Wires are not corroded. So it does not seem to matter the climate the rig was in or the age or the mileage. It also does not matter if engine washed. As my 01 w/160K miles was washed so much over 13 years you could eat off the engine. So why are some corroding! Brake fluid is my theory from over filling. Book stated do not over fill.
Can you provide your advice on how you removed these really corroded screws and kept the integrity of the surrounding parts? I have a new wire harness on order but am willing to use a proven removal technique on these screws so the new harness can go on and have the best chance of a successful full life. At this point, I think my initial thoughts on removal are too aggressive. One screw came out on the motor side, the mate of the other side is reluctant but not seriously corroded, and the other end of the wire is barely recognizable as a JIS screw. Have sprayed penetrant, but had a cup of coffee and decided to have a conversation with you.
 

Just get a complete master from a dealer and be done. I just did mine and it's a easy job. Comes out in like 15 min. Bleeding is straight forward. 1200 for the master and another 40 for 5 pints of fluid from toyota and your done for the life of the rig. I have been stressing it for years and then noticed a leak. Feels good to not worry about it anymore or stress on a rebuilt unit. FYI mine failed at 200k with regular fluid service.
Just a new master brake cylinder or the whole system? I thought we also needed to worry about corroded lines and the booster motor.
 

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