Electronic brake booster in the 100? (1 Viewer)

[Jim_Chow]

Check this out

Wasn't there someone on this forum who recently found out his 100 series master was going bad? How can it take 4 hrs labor to install the master? One can install a FJ80 master pretty quickly. Maybe for those $1800, there's a hamster inside turning an impeller that moves the brake fluid.

As far as greasing driveshafts, why don't you do it the same time you rotate tires and put the rig on stands. Then, all you do is put it in neutral and turn the shafts by hand to get the zerks in the correct position. Can you even put the ECT tranny in neutral w/o having to run the engine? If not, this is where the manual tranny could help!

 

[calamaridog]

Interesting article on the AP today. It seems that GM is recalling 155,000 04-05 trucks (including the H2) equipped with their Bosch hydro-boost brake system, which is similar in function to the 100 series set-up.

 

[marques]

I'm the unfortunate soul who had to recently replace this master cylinder assembly on his '99 Land Cruiser to the tune of $1,400 (not including labor). And that's a discounted price. The booster is electric, and is built into the master cylinder/ABS pump, all in one unit. In my case the ABS/booster pump's electric motor failed, and since it was the most expensive part of the whole assembly (close to $900 for the pump alone), I decided to replace everything in case the master cylinder failed later down the road (not available separately).

That master cylinder assembly includes everything from the push rod that hooks up to your pedal, to the acumulator, to the brake fluid reservoir, and even the electronics box that sits on the side where all the cables come in. All you have to do to replace it is remove the 4 nuts on the firewall (under the dash), undo three or 4 brake lines, disconnect the wires, and off it comes. Then just put the new one in and flush/bleed the system with 2-3 quarts of brake fluid. The cool thing is that the rear brakes will bleed themselves with the pump if you just push the pedal a little bit. The fronts you will have to push the pedal in and out the old fashioned way.

The system is great while it's working. The problem is that if it fails, it "failsafes" to hardly any brakes. Oh yea, it probably helps if you have the ignition on when doing the rolling down the hill experiment

-Luis Marques

 

[Jim_Chow]

I'm kind of surprised that your 99 master (or pump) has failed so soon. But the master part of it was still working from what you say. It's made by Aisin in Japan, right? I replaced the master on my 86 runner back in 2002. The brakes were never bled in those 16 yrs (family member was PO), so there was a bunch of rust and sludge at the bottom of the old master, fluid was darker than brown gravy, rear drum cylinders rusted internally and started to leak...But ithe master still worked! I was amazed. The fact that the electric pump in your master failed and not the master part suggests that all those little electric motors in today's modern cars (power steering column, power seats/windows, etc.) can't be relied on 15 yrs down the road, and to have such a critical part (brakes) rely on a pump....

I'm sure the design was mainly to save space from having to use an oversized master in an already tight engine compartment. I saw a pic of a new 4runner V8 and it seems to have a similar (same?) master as on the 100 (no booster visible), whereas on the JDM models, they retain what looks like an 80 series master/booster combo (but they only offer smaller engines in the JDM prado's/surf's...3.4L V6 is the biggest you can get).

 

[ShottsUZJ100]

Anything can fail guys. The fact remains that the 100 again shines as the best Land Cruiser ever. This is a great safety feature we all should be glad exists. Hope it trickles down into every vehicle.

Well, the Aussies are familiar with this and have these responses:
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From HUW:
It is a feature of 100 series since '98. The electric brake booster is
certainly fitted to my diesel '98 model.

It will last for however long you have the main switch on at least to the
'accessory' position and until you run the batteries flat.

From Peter N:
Hi Guys - I believe this is the difference between a vacuum assisted
braking system as on to 80's and an electronic accumulator assisted
braking system as on an ABS equiped 100's.

Don't know if all ABS systems work the same but they must have a way
of pulsing the hydraulic fluid pressure to each wheel so an
accumulator with a "reserve" of hydraulic fluid pressure would be
required.

I too have noticed the purring noise at ignition switch to the on
position and even with the engine off - so I presume that the
accumulator keeps a reserve of pressure provided the key is in the on
position (must check to see if it works in the accessories position
too).

I am sure GG could explain some more details of how the 100s braking
system (with ABS & accumulator) works.

From Greg Goulden:
Peter your response is spot on, the ABS equipped 100 series have electric
over hydraulic assistance, instead of the vacuum over hydraulic assistane
we're used to on non ABS equipped 100's, all 80 series and most other road
going vehicles. The electric system is independant of the engine, as opposed
to vacumm and hydraulic systems (like GM Hydraboost).

I think what John was referring to was the fact that the assistance was
available with the engine off. Of course as long as the key is ON, and power
in the battery, the pump should maintain suitable pressure in the
accumulator to offer brake assistance. I bet the ABS would still work too
If you're listening out for it, the pump runs for a few seconds every
time the ignition is switched on, and will also run again after a while if
the key is left on.

Although John doesn't specify I would think he had the ignition switch on
(although he says he "killed the motor"). However it wouldn't suprise me if
the system would still work if certain conditions were met, eg. detected
wheel speed greater than X, request for braking (as sensed by brake light
circuit energised) etc. Manufacturers try to build these cars idiot proof
nowdays...

And again from HUW:
Although John doesn't specify I would think he had the ignition switch on
(although he says he "killed the motor"). However it wouldn't suprise me if
the system would still work if certain conditions were met, eg. detected
wheel speed greater than X, request for braking (as sensed by brake light
circuit energised) etc. Manufacturers try to build these cars idiot proof
nowdays...

With the ignition switch in the off position then it works very much like
that of a vacuum system in that it will provide assistance for a number of
brake actuations before the system becomes depleted and a large increase in
leg effort and decrease in efficiency is noted. It is certainly not idiot
proof in that if the ignition were off while coasting in this way then the
steering column lock would prevent steering which is obviously not
particularly idiot proof :-(

 

[Jim_Chow]

So how much are those extended warranties? It might not be a bad idea, considering the master assembly alone could cost as much as the warranty.

 

[ShottsUZJ100]

So how much are those extended warranties? It might not be a bad idea, considering the master assembly alone could cost as much as the warranty.

How many have died? 1, 2, 3 out of 25,000? H2 maybe?

 

[powderpig]

The Bosch Hydro boost system is nothing like the toyota one. It runs off the power steering system, uses the pressure of that system to provide boost. Where the toyota one has its own independent electric pump creating the fluid pressure. GM has been using this type of system for many years on it bigger trucks. If something went wrong with the serpentine belt or hose you would loose both the boosted parts of the braking and steering at the same time. Want a hand full at the worst time, lose your brakes and steering at the same time. later robbie