Master Cylinder Rebuild - DIY (4 Viewers)

[Skidoo]

Did the ABS unit of the GS look like it would match the 100 series perfectly?

Even if the outside of the ABS unit looks the same, valve sizes or routing inside may be different. The ABS unit also does VSC and A-TRAC, while a lot of functionality is in controllers it may require different ABS valve units. When VSC has problems it can be very scary in panic situations. While some GSs are all wheel drive none have A_TRAC. The Cruiser brakes need more fluid flow. Not just length of brake lines, LC front calipers are 4 piston, GS are 2 piston.
Not to deter you but would hope you do all manor of emergency stops and VSC activation testing, so it does what it is suppose to do when you swerve to avoid that deer on a narrow mountain road with your family riding with you.

 

[2001LC]

Would be nice to find replacement ABS units that are exact matches inside and out, to broaden pool of availability. Toyota does makes some parts that fit across platforms. I don't think cross matching parts # possible with ABS unit, as they're not sold separately.

If it looks the same, may be worth tearing down one of each to compare.

I've got a failed ABS on the shelf, but it's out of a 98, that's limited to 98 & 99 use.

 

[Bripars40]

Did the ABS unit of the GS look like it would match the 100 series perfectly?

It was a 100% perfect match. Plug and play.

All of my dash lights went away and so did the continuos buzzer. I’ll drive it this week and give a review at the end of the week.

 

[2001LC]

What I'm most interested in is the ABS unit itself. This is because it is a failure point that IMHO we're going to see more failure with over time. We're seeing too many of the two wire leads at the bottom of the ABS corroded. Toyota doesn't show any parts for the ABS unit that I'm aware of. So to find alternative to Land Cruiser/LX ABS unit would a great benefit.

@Skidoo made some very good points. Any difference internally and it could be dangerous.

 

[abuck99]

I would be concerened that using anything but the LC/LX ABS actuator on ATRAC equipped models (MY 2000+). Can it manage to handle the continuous cycling and system pressure ATRAC demands long term? The smaller reservoir capacity might impact fluid life and system functionality.

If the rig is strictly a driver and doesnt see offroad, its maybe less of an issue, but I think its commonly understood that when ATRAC is cycling offroad it gets pretty hot and shuts down if its cycled for more than a few minutes at a time. Cant imagine how a smaller lesser system would hold up.

 

[Bripars40]

All,

I've rebuilt my Brake master cylinder twice in the last 6 months to still have a spongy pedal. I thought I botched the first job, so attempted it again. After having a spongy pedal again on the 2nd time I'm thinking my master cylinder was fine and I instead should have done the following. This is an adjustment that I found in the FSM and wanted to share with everyone. This is a 10 minute job that requires a 14 mm open ended wrench, needle nose pliers and no dis-assembly of anything. This is a step you should take before attempting a rebuild and it is also a step that needs to be performed if you do rebuild your master cylinder.

Below is a diagram that IDs the brake push rod location. This is where the brake master cylinder connects to the brake pedal. I only performed steps (e) - (g) in the service manual shown in the pic. You can reach the push rod by laying on your back on the drivers side and reaching up past the gas pedal and over the steering shaft.

Brake Push Rod ID

• Eliot
• Feb 8, 2016

This image shows the measurement of the adjustment you would be making. To adjust this measurement, first, loosen the 14 mm push rod lock nut. Then use the needle nose pliers to turn the pedal push rod (I would describe this as a screw). At the base of the push rod, there is a geared surface that is perfect for grabbing with the needle nose pliers. You may need to push back the rubber boot to see this geared surface.

Adjusting in the red arrow direction will give you a firmer brake pedal. Be careful not to adjust this too much or you will have too much pressure which will cause your brakes to always be applied (ask me how I know). Adjusting the push rod in the blue direction will give you a softer (spongy) pedal.

Brake Push rod adjustment

• Eliot
• Feb 8, 2016

*Note: The only place that I could see the master cylinder leaking would be in the foot well on the drivers side. If you don't have brake fluid leaking onto the floor in the foot well or if you remove the rubber boot and don't see any brake fluid, then it is most likely not your master cylinder. You likely just need to make this adjustment.

Thought I had adjusted properly because I measured the old masters pushrod length. Well I had to double pump with the new one and this solved the double pump. I’m slightly shorter than spec but I confirmed the shortest length within spec was still applying the brakes ever so slightly.

 

[Roosevelt T]

Hey guys, I am searching for the Part Number for a non-ATRAC equipped 100 series. I am confused because some parts finders list the part number in the first post as compatible with my vehicle, but others do not.

I have a 1998 LX470 that has a soft pedal, and slowly losses fluid. Recently I had a one time issue of the ABS light and alarm blaring at me, but it hasnt occured again (although I have not really driven the vehicle since). I think this DIY is the first step to hopefully solving the issue... but as I said, I cant seem to confirm if the part numbers are identical.

Can anyone lend a hand?

 

[sorich]

I’ve had spongy brakes on my LX470 for the last year (ever since I bought it), and finally got around to trying the brake pedal adjustment before doing what I expected was a necessary master cylinder rebuild.... why didn’t I try this sooner!?! The brakes feel like NEW now. Holy cow, I’m amazed at the difference.

Only question is.... how do I know if I’ve gone too far and brakes are always being aplies? I looked for contact between the pad and rotor, and as far as I can tell, they are always in contact, even if I adjust the push rod to sponge-City.

 

[Roosevelt T]

Ok, I could use some advice.

I did the job. Btw is pretty damn easy. Prior to this I got the ABS light and alarm once, and lost brakes in the process (pretty scary). This was about 3 months ago. Btw, the truck has always lost fluid (somewhere) since ive owned it... Which is about 18 months.

I have another car and just got around to doing the job last weekend.

During the bleeding process the abs light and alarm would go on. We bled all 4 sides until no air came out. (Possibly of note: The rear driver side did not bleed as well as the others. Very little fluid came out.) Then drove it, the light and alarm came on again. Next day we added fluid, everything was fine in all the test drives. We tried bleeding the fronts again, just in case. When I bled the fronts the abs light and alarm came on (no air came out), but as soon as i dropped it down, and turned it on, the pump came on and no alarm. I tested it a bunch through the day and no issues. I hear the pump coming on intermittently, which i assume is correct and it doesn't grind, it sounds like a pump.

However, I have driven the truck about 80 miles over the past 2 days and the abs light and alarm has come on twice now, for about 1 min each and then goes off. I do not lose brakes when this happens. I'm confused. I hear the pump working. I have brakes. I have a new MC. The truck seems to hold the fluid (not losing any anymore).

Any ideas? Im stumped.

 

[toymi]

Hi,
I followed your advice and I changed this soft master cylinder! Thank you very much !!!!
On the other hand after reassembly, my UZJ100 does not want to start ?????
Help please, I do not understand. arrives at the filter, the starter turns, the battery is good ????
Fuel arrives at the filter, the starter turns and the battery is good ????
Thanks you

 

[Skidoo]

Hi,
On the other hand after reassembly, my UZJ100 does not want to start ?????
Thanks you

Only thought is you didn't reconnect something you disconnected or damaged wiring somewhere. Double check all wiring around areas you worked on.

 

[toymi]

yes I think, but there are 3 hours that I inspect my work .....
The vehicle can not be safe because I disconnected my battery and the master cylinder wiring ?

 

[DubYoda]

Ok, I could use some advice.

I did the job. Btw is pretty damn easy. Prior to this I got the ABS light and alarm once, and lost brakes in the process (pretty scary). This was about 3 months ago. Btw, the truck has always lost fluid (somewhere) since ive owned it... Which is about 18 months.

I have another car and just got around to doing the job last weekend.

During the bleeding process the abs light and alarm would go on. We bled all 4 sides until no air came out. (Possibly of note: The rear driver side did not bleed as well as the others. Very little fluid came out.) Then drove it, the light and alarm came on again. Next day we added fluid, everything was fine in all the test drives. We tried bleeding the fronts again, just in case. When I bled the fronts the abs light and alarm came on (no air came out), but as soon as i dropped it down, and turned it on, the pump came on and no alarm. I tested it a bunch through the day and no issues. I hear the pump coming on intermittently, which i assume is correct and it doesn't grind, it sounds like a pump.

However, I have driven the truck about 80 miles over the past 2 days and the abs light and alarm has come on twice now, for about 1 min each and then goes off. I do not lose brakes when this happens. I'm confused. I hear the pump working. I have brakes. I have a new MC. The truck seems to hold the fluid (not losing any anymore).

Any ideas? Im stumped.

You might want to pull your bleed valve all the way out since you said minimal fluid came out at bleeding. Mine were nearly rusted closed and a cheap $1.74 per nipple solved my bleeding issues and I got quite a bit of fluid and air out that way. This was just on the rears, which lead me to think that water in my lines settled there and added the right chemical balance to rust the bleeders. It was surprising because my LC is a southern CA truck and very rust free.

My alarm has stopped since the MC rebuild, bleeder replacement and a mega 1 gallon flush fluid exchange using a vacuum pump bleeder. My alarm only came on in under 25 degree days (moved to Colorado 4 years ago from San Diego).

 

[Ozsuba]

Just removed my brake master cylinder and found this when I was removing the pump motor.
Any ideas where the fluid is coming from, to me it looks like its leaking from between the the master cylinder and the ABS module.

 

[2001LC]

Hard to see wet (fluid) spot in picture.
Is it around where wires attach (electroids) only?
Is it all the way across aluminum block between black plastic and master?
Any above these point coming down side, indicating possible grommets of reservoir or sensor o-ring?

Often times some spillage occurs while removing master. If certain that spliage didn't occur there are seals. My understanding Toyota doesn't sell seals for ABS, just master kit, grommets and some o-rings.

I've broken plastic of ABS into pieces, to trace electroids. It would be near impossible for fluid leak to follow their path out.

Here is the main one between master and aluminum block held together with the 6 bolts.

 

[Ozsuba]

Hard to see wet (fluid) spot in picture.
Is it around where wires attach (electroids) only?
Is it all the way across aluminum block between black plastic and master?
Any above these point coming down side, indicating possible grommets of reservoir or sensor o-ring?

Often times some spillage occurs while removing master. If certain that spliage didn't occur there are seals. My understanding Toyota doesn't sell seals for ABS, just master kit, grommets and some o-rings.

I've broken plastic of ABS into pieces, to trace electroids. It would be near impossible for fluid leak to follow their path out.

Here is the main one between master and aluminum block held together with the 6 bolts.
View attachment 1731090
View attachment 1731096

No spillage, the reason for removal was fluid leakage. Looks like the brake fluid was coming from where the wires for the ABS pump motor attaches to the plastic of the ABS module cylinder itself, first picture. Are there any o-rings/seals near that area?
Any further pictures would be most helpful, thanks.

 

[2001LC]

It's very limited on what we can buy from Toyota. This has some good diagrams if you'll input your VIN PartSouq Auto Parts Around the World that may help answer your question.

Were you losing so much you had to add fluid?
Did you pump brake pedal 40 time with key off, before topping?

If leak was from above you "may see" fluid come down the face of master. Possible from a flare nut of hard pipe, a seal (like one pictured above), grommet, etc or spillage. But it may be very hard to see except when active. Then boot covering wires may hold this fluid and attract moisture leading to corrosion. Also possible, fluid is from spillage when topping. I find very often, reservoir is overfilled, leading to leakage from cap or grommets. Overfilling happens because instruction printed on top of reservoir are not followed. So we've many possible sources of leak.

Here is why I busted one open and asking all mud members to send me old master/ABS units so I can keep looking at solving this mystery:

After replacing the ABS with one from a $100 salvage yard donor, for a local mud member saving him a ~$5K Dealer wanted to R&R. I noticed corrosion on wires. I started wondering if brake fluid was leaking out electriods (wire attachment points) attracting moisture. In fact I started inspecting all 100 series for corrosion on wire nuts and screw because of this. I found 30% so far with corrosion. Interesting; Toyota will sell us nuts, screws and wires but not much else, possible because of corrosion issue they may be aware of.

Because of corrosion on wires, I too thought a we may have ABS units leaking where wire attaches (I call electroids). My theory was brake fluid was leaking (weeping) a very small micro amount internal and following path of electroids out to wires. Fluid getting into boot was attracting moisture as brake fluid is hygroscopic. So I begin inspect all 100 series for this condition. I also found if we have corrosion at ABS wire, we often find at other end of wire (pump connection). So if corrosion at both ends (ABS unit & Pump) of wire then the likelihood from micro leak follow electroid out the ABS was reduced!

Anyway I busted the black plastic apart and followed the electroids looking for possible leak. It wasn't that the unit had a noticeable leak, but did have corrosion. What I found was that the electroids snake up through plastic. It was very clear the plastic was molded around electroids, basicly fused to the electroids for quite some distance. I could not see a way for fluid to leak through following electroid out to wire nuts in boot. Although it is possible this is leak point, seem manufacture went to great lengths to make sure it would not. Additionally it look like ABS black plastic unit, only had a few passage that fluid flowed into. That between ABS plastic and the aluminum block connected to master we do have some seals which are a more likely leak point. These seals are not available or replaceable as far as I know..

Form what I could tell no fluid is in the face behind plastic cover held by 4 screws. This one from a 1998 LC.

There is six bolts going through master holding on ABS unit. If these bolts loosen, a leak may devople at seal plate (picture posted in post #175)

Leaks can be very difficult to find source. I've found photographing, then cleaning spotless and then watching for start of source best practice. That seeing a leak for the first time in any area, we jump to conclusion that are often wrong.

If you find leak is actually from electroids, I'm all ears.

Check to see if all six bolts holding ABS unit on are tight. If not tightening and you may get lucky.

Bottom line if you are sure leak is from electriods, then you must replace the ABS unit.

 

[Ozsuba]

It's very limited on what we can buy from Toyota. This has some good diagrams if you'll input your VIN PartSouq Auto Parts Around the World that may help answer your question.

Were you losing so much you had to add fluid?
Did you pump brake pedal 40 time with key off, before topping?

If leak was from above you "may see" fluid come down the face of master. Possible from a flare nut of hard pipe, a seal (like one pictured above), grommet, etc or spillage. But it may be very hard to see except when active. Then boot covering wires may hold this fluid and attract moisture leading to corrosion. Also possible, fluid is from spillage when topping. I find very often, reservoir is overfilled, leading to leakage from cap or grommets. Overfilling happens because instruction printed on top of reservoir are not followed. So we've many possible sources of leak.

Here is why I busted one open and asking all mud members to send me old master/ABS units so I can keep looking at solving this mystery:

After replacing the ABS with one from a $100 salvage yard donor, for a local mud member saving him a ~$5K Dealer wanted to R&R. I noticed corrosion on wires. I started wondering if brake fluid was leaking out electriods (wire attachment points) attracting moisture. In fact I started inspecting all 100 series for corrosion on wire nuts and screw because of this. I found 30% so far with corrosion. Interesting; Toyota will sell us nuts, screws and wires but not much else, possible because of corrosion issue they may be aware of.

Because of corrosion on wires, I too thought a we may have ABS units leaking where wire attaches (I call electroids). My theory was brake fluid was leaking (weeping) a very small micro amount internal and following path of electroids out to wires. Fluid getting into boot was attracting moisture as brake fluid is hygroscopic. So I begin inspect all 100 series for this condition. I also found if we have corrosion at ABS wire, we often find at other end of wire (pump connection). So if corrosion at both ends (ABS unit & Pump) of wire then the likelihood from micro leak follow electroid out the ABS was reduced!

Anyway I busted the black plastic apart and followed the electroids looking for possible leak. It wasn't that the unit had a noticeable leak, but did have corrosion. What I found was that the electroids snake up through plastic. It was very clear the plastic was molded around electroids, basicly fused to the electroids for quite some distance. I could not see a way for fluid to leak through following electroid out to wire nuts in boot. Although it is possible this is leak point, seem manufacture went to great lengths to make sure it would not. Additionally it look like ABS black plastic unit, only had a few passage that fluid flowed into. That between ABS plastic and the aluminum block connected to master we do have some seals which are a more likely leak point. These seals are not available or replaceable as far as I know..
View attachment 1731757

Form what I could tell no fluid is in the face behind plastic cover held by 4 screws. This one from a 1998 LC.
View attachment 1731756

There is six bolts going through master holding on ABS unit. If these bolts loosen, a leak may devople at seal plate (picture posted in post #175)

Leaks can be very difficult to find source. I've found photographing, then cleaning spotless and then watching for start of source best practice. That seeing a leak for the first time in any area, we jump to conclusion that are often wrong.

If you find leak is actually from electroids, I'm all ears.

Check to see if all six bolts holding ABS unit on are tight. If not tightening and you may get lucky.

Bottom line if you are sure leak is from electriods, then you must replace the ABS unit.

Do you know if you able to separate the ABS plastic block from the aluminium valve body?, In my case it would appear that like the fluid is coming from between the two blocks!

 

[2001LC]

I did separate, but sorry I don't recall if I busted it to do so.

 

[Roosevelt T]

Ok, I could use some advice.

I did the job. Btw is pretty damn easy. Prior to this I got the ABS light and alarm once, and lost brakes in the process (pretty scary). This was about 3 months ago. Btw, the truck has always lost fluid (somewhere) since ive owned it... Which is about 18 months.

I have another car and just got around to doing the job last weekend.

During the bleeding process the abs light and alarm would go on. We bled all 4 sides until no air came out. (Possibly of note: The rear driver side did not bleed as well as the others. Very little fluid came out.) Then drove it, the light and alarm came on again. Next day we added fluid, everything was fine in all the test drives. We tried bleeding the fronts again, just in case. When I bled the fronts the abs light and alarm came on (no air came out), but as soon as i dropped it down, and turned it on, the pump came on and no alarm. I tested it a bunch through the day and no issues. I hear the pump coming on intermittently, which i assume is correct and it doesn't grind, it sounds like a pump.

However, I have driven the truck about 80 miles over the past 2 days and the abs light and alarm has come on twice now, for about 1 min each and then goes off. I do not lose brakes when this happens. I'm confused. I hear the pump working. I have brakes. I have a new MC. The truck seems to hold the fluid (not losing any anymore).

Any ideas? Im stumped.

Just an FYI for anyone reading through this thread... when I searched for recommendations on my issue, everything I found pointed to rebuilding your master cylinder. However the problem for me was the motor in the actuator.

Certainly put a new master cylinder in there when you do this job (its really easy), but if your pump is not coming on randomly and/or if you have to tap it to come on, IMO save yourself some time and buy a rebuilt actuator and do both at once. Its not that either job takes a ton of time, but bleeding the brakes twice, trying to track down potential issues, etc is annoying. I recommend buying both and getting it all done at once.