R&R 100 Master Cylinder / Booster

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Nardulli

GOLD Star
Joined
Jul 12, 2025
Threads
10
Messages
117
Location
St Louis, MO
My booster pump / accumulator / master cylinder has started making the dreaded 'I'm about to fail' noise. I have a brand new OEM unit in stock. Anyone done this job? Any tips / hints? Thanks in advance.
 
 
@OTRAMM has a good video on this:

Not much to it, just swap the part. Need to remove the charcoal canister to get access.

You'll want the gasket that goes between the master cylinder and the firewall (mine was 44785-60010). Also plenty of new fluid (00475-1BF03). I ordered (7) 12oz bottles to refill and flush the lines.

Note that one of the part numbers for the complete assemblies is apparently no longer available but all that changed was the 3-wire pigtail, so it necessities a pigtail swap.

This may all be covered in the big thread posted above.
 
I had to swap mine out almost 3 months ago. My LX is a 2000. I had to do the re-pin of the pressure sensor. Besides that, it was easy. Removal was easy, Clevis pin on the brake pedal was a little finicky and the be careful with the brake lines when putting the new unit in. I recommend a second set of hands to assist with holding back the brake lines. Other than that, rather straight forward. Bleeding was straight forward too.

while I didn’t use Techstream, I did use the snap-on diagnostic tool to bleed the ABS as I had access to that.
 
Tip:

There's a piece of carboard in top of new brake master box. It can be placed between master and/on brake hard lines, to keep hard lines out of the way. I find it a bit tight when trying use carboard during removing. But used during install, the carboard works very well to keep line out of the way. Make job easier and less chance of damage to brake line.

I use rubber caps on hard lines and push up over flare nuts. Keeps them clean and reduce chance of damage to flare end of pipe and threads of flare nuts. You can get rubber caps from hardware store.

Keep spray bottle of water handy. To wash down any brake fluid spillage ASAP. Brake fluid eats paint.

98-02 have charcoal canister in the way. Remove wires, and one bolt from side. Lift up out of holder bracket and set to kind BK1 of side engine, out of way. Just let it rest there.


Over view:

If booster motors working, pump old brake fluid out a rear bleeder. Simply turn IG key on, hold brake pedal down and open a rear bleeder. Make sure to attached hose to bleeder, run hose to catch can. We get about 1 qt. from reservoir, out the read bleeder. We do not have to remove fluid.

  • Disconnect negative battery cable. Make this a habit, whenever touching anything with wires attached.
  • Remove flare nuts, from each hard line attached to master. Cap each flare pipe end, pushing rubber cap over flare nut threads. So you cover end of pipe and threads of flare nut. You can get rubber caps from hardware store.
  • Place temp shipping plastic plug in old master. In place where flare nut removed from master. You'll find them, in new master. Reduces leakage of brake fluid from old master.
  • Remove wire housing blocks, from master.
  • Remove the one 10mm bolt, holding hard line bracket to firewall. This frees up hardline(s), and easier & faster than pulling hard line from bracket.
  • Remove hard lines from bracket on master.
  • Now move to inside cabin. Remove two 10mm nut holding ABS computer bracket. Found just to RH of brake pedal on studs. Push bracket w/ABS CPU to side. This reveals 12mm nuts hold brake master to fire wall on RH side. I use 12mm long socket.
  • Reach up and pullout key, locking the clevis pin in. Then remove clevis pin. This disconnects brake pedal arm form brake master plunger.
  • Remove the four 12 mm nut from stud passing though firewall, that hold brake master to firewall.
  • Remove brake master. Be care to not bend hard line pipes. Work pipes out of the way, as you remove master. Out more from bottom free the four stud on master from firewall, as you tilt front up and out.
  • New master and old on the bench. FSM, wants us to pre flush. With shipping temp plugs removed from master, press in plunger a few times. Then put temp plugs back in new master.
  • You'll find a seal on master, fit over the four studs. It set between master and firewall. Remove from old and put on new master, in same orientation.
  • Install master, sliding down the carboard, that holds back hardline pipes.
  • Install four nut securing master to firewall. (in footwell) Toque to 11ft-lbf.
  • Attach pedal to master, with clevis pin and lock in with key.
  • Attach CPU bracket with two 10 mm nuts. Torque 67INCH-lbf
  • Attach hard line. But first make sure end of flare, pipe inside of flare and threads clean. You can pull/slide back flare nut of flare pipe. Place a drop of oil on pipe. To insure flare nut spins on pipe easily. Install flare nut by hand. Thread all the way in by hand. Pull out lightly of pipe as you thread on flare nut. Torque to ~10ft-lbf to 11ft-lbf. I use a digital 1/4 torque wrench with flare nut crows foot socket.
  • Attack hard lines in bracket, on master. The bracket with hard line to fire wall w/10mm bolt.
  • Attach wire housing blocks.
  • Fill reservoir.

Next comes flush and bleed. I do old school first. Then come back with tech stream to air bleed. I'll use about 7 bottles of Toyota brake fluid (only Toyota brake, for life) Flush every 2 to 3 years. Also, Flush before brake pads R&R.

Warning:
Don't not spill brake fluid on master, or any painted surface. Clean with water from fender well, frame and sure ASAP.
Do not over fill. Read what is written on reservoir.
 
Last edited:
Thanks for the concern. I've been a wrench turner for over 45 years. Have a side business building engines - I don't mess with the high tech Euro stuff- mostly small and big block GM units. This is my first Land Cruiser and my experience (so far) is that these are a different breed. I recently replaced the head gaskets, did a complete valve job after sending the heads to the machine shop, and this redoubled my opinion that the engineering found in these rigs is of a different breed. Many thanks for all the info you all are willing to share.
 
Tip:

There's a piece of carboard in top of new brake master box. It can be placed between master and/on brake hard lines, to keep hard lines out of the way. I find it a bit tight when trying use carboard during removing. But used during install, the carboard works very well to keep line out of the way. Make job easier and less chance of damage to brake line.

I use rubber caps on hard lines and push up over flare nuts. Keeps them clean and reduce chance of damage to flare end of pipe and threads of flare nuts. You can get rubber caps from hardware store.

Keep spray bottle of water handy. To wash down any brake fluid spillage ASAP. Brake fluid eats paint.

98-02 have charcoal canister in the way. Remove wires, and one bolt from side. Lift up out of holder bracket and set to kind BK1 of side engine, out of way. Just let it rest there.


Over view:

If booster motors working, pump old brake fluid out a rear bleeder. Simply turn IG key on, hold brake pedal down and open a rear bleeder. Make sure to attached hose to bleeder, run hose to catch can. We get about 1 qt. from reservoir, out the read bleeder. We do not have to remove fluid.

  • Disconnect negative battery cable. Make this a habit, whenever touching anything with wires attached.
  • Remove flare nuts, from each hard line attached to master. Cap each flare pipe end, pushing rubber cap over flare nut threads. So you cover end of pipe and threads of flare nut. You can get rubber caps from hardware store.
  • Place temp shipping plastic plug in old master. In place where flare nut removed from master. You'll find them, in new master. Reduces leakage of brake fluid from old master.
  • Remove wire housing blocks, from master.
  • Remove the one 10mm bolt, holding hard line bracket to firewall. This frees up hardline(s), and easier & faster than pulling hard line from bracket.
  • Remove hard lines from bracket on master.
  • Now move to inside cabin. Remove two 10mm nut holding ABS computer bracket. Found just to RH of brake pedal on studs. Push bracket w/ABS CPU to side. This reveals 12mm nuts hold brake master to fire wall on RH side. I use 12mm long socket.
  • Reach up and pullout key, locking the clevis pin in. Then remove clevis pin. This disconnects brake pedal arm form brake master plunger.
  • Remove the four 12 mm nut from stud passing though firewall, that hold brake master to firewall.
  • Remove brake master. Be care to not bend hard line pipes. Work pipes out of the way, as you remove master. Out more from bottom free the four stud on master from firewall, as you tilt front up and out.
  • New master and old on the bench. FSM, wants us to pre flush. With shipping temp plugs removed from master, press in plunger a few times. Then put temp plugs back in new master.
  • You'll find a seal on master, fit over the four studs. It set between master and firewall. Remove from old and put on new master, in same orientation.
  • Install master, sliding down the carboard, that holds back hardline pipes.
  • Install four nut securing master to firewall. (in footwell) Toque to 11ft-lbf.
  • Attach pedal to master, with clevis pin and lock in with key.
  • Attach CPU bracket with two 10 mm nuts. Torque 67INCH-lbf
  • Attach hard line. But first make sure end of flare, pipe inside of flare and threads clean. You can pull/slide back flare nut of flare pipe. Place a drop of oil on pipe. To insure flare nut spins on pipe easily. Install flare nut by hand. Thread all the way in by hand. Pull out lightly of pipe as you thread on flare nut. Torque to ~10ft-lbf to 11ft-lbf. I use a digital 1/4 torque wrench with flare nut crows foot socket.
  • Attack hard lines in bracket, on master. The bracket with hard line to fire wall w/10mm bolt.
  • Attach wire housing blocks.
  • Fill reservoir.

Next comes flush and bleed. I do old school first. Then come back with tech stream to air bleed. I'll use about 7 bottles of Toyota brake fluid (only Toyota brake, for life) Flush every 2 to 3 years. Also, Flush before brake pads R&R.

Warning:
Don't not spill brake fluid on master, or any painted surface. Clean with water from fender well, frame and sure ASAP.
Do not over fill. Read what is written on reservoir.
Thank you for the effort you put into this response. Most helpful.
 
Yeah. Hard parts or rather time consuming, is the flush and bleed.
Master is easy, with right tools and procedures. R&R <1 hr.

Number one. Be very careful with flare pipe ends & nuts. Don't damage or cross thread!
 
Yeah. Hard parts or rather time consuming, is the flush and bleed.
Master is easy, with right tools and procedures. R&R <1 hr.

Number one. Be very careful with flare pipe ends & nuts. Don't damage or cross thread!
Cross thread = nature’s locktite… lol
 
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