Master Cylinder Rebuild - DIY (1 Viewer)

Joined
Apr 10, 2012
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Mombasa, Kenya
@2001LC thanks for replying to my post.
I noticed the delay when I put the car on a Cardiff with someone behind the wheel, put it in drive and the step on the brakes while I watch.
I've had the calipers all rebuild with new seal kits, and changed out the rear caliper pins and boots as well no so long ago. My flex lines aren't cracked or show no signs of swelling at all. But they are still stock and original, maybe I ought to change them out to new ones.
My pads are like the ones on the left on your pic (with coppery specs)
Pump run time is within spec, ill time it and post again.
 
Joined
Apr 10, 2012
Messages
23
Location
Mombasa, Kenya
@2001LC thanks for replying to my post.
I noticed the delay when I put the car on a Cardiff with someone behind the wheel, put it in drive and the step on the brakes while I watch.
I've had the calipers all rebuild with new seal kits, and changed out the rear caliper pins and boots as well no so long ago. My flex lines aren't cracked or show no signs of swelling at all. But they are still stock and original, maybe I ought to change them out to new ones.
My pads are like the ones on the left on your pic (with coppery specs)
Pump run time is within spec, ill time it and post again.
I timed the pump this morning to 29 seconds
 
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RV on the road in the USA
The flex brake lines can fail on the inside. Swelling to reduce flow. The ones on my Suburban did that and brake behavior was very weird.
I replaced the Land Cruiser's with stainless steel flex lines not long after I bought it, so haven't seen the issue on mine.
 
Joined
Sep 13, 2009
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15
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Gallatin, TN
Followed this write up and replaced the booster motor and accumulator. Started before I found this write up and almost lost my mind trying to get the assembly out. Thanks so much for the detail and arrows! Now the problem I'm having is the bleeders are frozen. Using a flare wrench and its still trying to round off the bleeder...always something. Thanks again OP!
 
Joined
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Logan Utah
So I found a gent on the Facebook that rebuilds these and am wondering if anyone has first hand experience with him . Andy Le, he is out of CA. he charges $550 to rebuild the whole assembly. found him on the UZJ100 page...
 
Joined
Nov 19, 2018
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Santa Clarita
So I found a gent on the Facebook that rebuilds these and am wondering if anyone has first hand experience with him . Andy Le, he is out of CA. he charges $550 to rebuild the whole assembly. found him on the UZJ100 page...

I'm not sure anyone is able to rebuild the master cylinder right now.... but rebuilding the motor should be possible.

I bought a new master cylinder assembly for $1,260.74 with shipping from McGeorge Toyota. It included everything but the motor and hydraulic cylinder


Unfortunately, my experience was buy many times, cry many times.... I should gone with buy once cry once. I rolled the dice on trying to get a used part to work, and my number didn't come up.
 
Joined
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Santa Clarita
Followed this write up and replaced the booster motor and accumulator. Started before I found this write up and almost lost my mind trying to get the assembly out. Thanks so much for the detail and arrows! Now the problem I'm having is the bleeders are frozen. Using a flare wrench and its still trying to round off the bleeder...always something. Thanks again OP!

You might be able to get some purchase on the nut with a pair of vice grips.
 
Joined
Sep 13, 2009
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Gallatin, TN
Good news! I used a deep 10mm socket to get those bleeders loose...both back bleeders were clogged and had to be cleaned out. I pushed out all the dark fluid from the rear passenger, but I never did get any fluid to come out of the rear driver. I used TIS to bleed the fronts and on the test drive everything seemed normal. I guess I'll send it for now and see how it goes. Very excited to have this repair complete!
 
Joined
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I'm not sure anyone is able to rebuild the master cylinder right now.... but rebuilding the motor should be possible.

I bought a new master cylinder assembly for $1,260.74 with shipping from McGeorge Toyota. It included everything but the motor and hydraulic cylinder


Unfortunately, my experience was buy many times, cry many times.... I should gone with buy once cry once. I rolled the dice on trying to get a used part to work, and my number didn't come up.


Why wouldn't anyone be able to rebuild cylinders right now? apparently he is sourcing the MC parts from Japan and the electrical parts from UAE?
 
Joined
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Santa Clarita
Why wouldn't anyone be able to rebuild cylinders right now? apparently he is sourcing the MC parts from Japan and the electrical parts from UAE?

There are no serviceable parts listed by Toyota, and no diagrams on disassembly/assembly.

With that said, they did have to build them, and put everything together, so it has to come apart somehow. On the front side there is a threaded cover which looks like it might be able to undone, but the housing has been deformed to prevent the cover from being removed. If that unthreads, it's unclear what could be replaced on the inside.
 
Joined
Feb 11, 2017
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12
Location
Philippines
Hi everyone! I replaced my MC 3 months ago and bought a rebuilt one. Last week I went out on a 300km trip and found my reservoir was low. Popped the hood and saw leaked fluid under the reservoir. Went to my mechanic who installed the MC and decided to bleed and replace the reservoir fluid in the hopes that it was just air in the system. Tested the abs on gravel road and bled again. But still the leak persists. Is there a possibility that the rebuilt MC was faulty? Why leak after 3 months? Hope you guys can help me im close to going nuts finding the cause of the leak.

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Joined
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Santa Clarita
the reservoir does have three seals on the bottom where it connects to the MC, one of those could be leaking. It could also be where one of the brake lines connects into the MC, or either end of the high pressure line that goes from the booster pump area into the master cylinder.

I suppose it could also be the plate that goes between the abs module and the master cylinder..... or it could be something else.

you might want to try and clean up all the fluid you can, and then try to see where new fluid is appearing from, that should help narrow down the search.
 
Joined
Feb 11, 2017
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Philippines
The 3 grommets I already replaced and checked brake lines of MC. All ok. After further investigation I saw the leaks coming from where the ABS black box meets the MC. Only the bottom 2 corners of the ABS black box have leaking fluid. Can this be and ABS seal leak?

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Joined
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Santa Clarita
There is a plate with several holes in it, those holes have seals that are molded to the aluminum plate. If one of those seals is shot, it makes sense that you would get a leak right where you're talking about.

You might be able to undo the 4 bolts that hold the ABS block onto the side of the MC without removing the MC... but will be a tight fit to get the bolts out and the ABS block off. But you should then be able to inspect the plate, MC, and ABS block for signs of damage.
 
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Santa Clarita
look at this post for a picture of the plate

 
Joined
Feb 11, 2017
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Location
Philippines
HI! Did another road test before pulling out the whole MC for inspection and troubleshooting (MC cleaned before road test). No leaks appeared whatsoever in the areas suspected. But this happened..... 😫

Despite the ABS VSC lights on brakes are functioning. No alarms or beeps. Weird thing is it goes away then comes back. The time I brake tested on gravel to know if ABS works it disappears then comes back on when at full stop and brake pressed (ex. waiting on a stop light). Any clues? I'm losing more hair figuring this out....😩

InkedIMG_0954_LI.jpg
 
Joined
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Santa Clarita
I think those lights will come on if the booster motor runs for too long and/or enough pressure can't be built up. If you have access to the computer scanner software thing (can't think of the name right now), you can read all of sensors and values and get codes to help narrow down what the issue might be.
 

Beto Cruiser

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The FSM, at this point, removes pump, accumulator and pressure switch from Master Cylinder Assembly. I did, but not sure if you need to.
Do this work over something to catch fluid.
To remove snap ring. Push in piston enough to clear snap ring, a deep socket and a few taps with hammer if it is sticking.
2nd photo shows hole used to push end of snap ring up so it can be pulled out. When reassembling position snap ring so end is just past hole.


Okay I'm stuck. The cylinder won't come out. I've move it part way out, but it is stuck in there. I'm hesitant to use too much force. I saw some commenters saying that they had to give it a hard pull to get it out, but it sounded like they may have also removed the pump, accumulator, and pressure switch like the OP. So, I'm wondering if you need to remove those three things to successfully remove the cylinder. Maybe they are causing some suction that is holding the cylinder in? Has anyone done it without removing those extras? Do I just need to pull harder? Don't want to mess it up and have to fork over the $$$ for an entirely new assembly...
 

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