Another clutch master cylinder/booster question...

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87 HJ60

87 HJ60

10 Year 15 Year
Joined
Jan 23, 2008
Threads
229
Messages
794
Location
East York, Canada
Here's a question for all you guys that have a BJ/HJ60 that have a vacuum assisted clutch master cylinder.
I've had an on going problem where the diaphram seems to have a leak in the vacuum booster assembly that creates a loud and very, very, very annoying hiss. My question is can a remove that vacuum line supplying the vacuum to the clutch booster unit, plug it and continue to use the clutch without doing damage to anything?
I know without the vacuum assist that the clutch will require more pedal effort but it sure beats being deafened by the annoying hiss.
This would only be a temporary solution until I can find another clutch master cylinder/booster assembly. And speaking of which, does anyone have one for sale...??
 
I recently converted my FJ60 to an HJ61 and had to convert the Aussie right hand drive components to my left hand vehicle. I was having problems with the clutch vacuum booster leaking down and the clutch getting progressively harder/stiffer to push in. Looked at my firewall when a buddy pushed in the clutch and watched the firewall flex. Yours will most likely do the same and if done long enough I believe it will weaken your firewall through metal fatigue.
 
87 HJ60,

If you live in a metropolitan area, there are shops that specialize in brake booster rebuilding. While a clutch booster is something kinda rare, a rebuilder of brake boosters may still have enough generic materials to get your clutch booster repaired.

Does the leak occur only while operating the pedal or does it constantly leak?

Rick
 
Yes found one the two check valves on the vaccum tank was sticking and not holding vaccum. In addition there was a metal "Y" connection in the vaccum lines that had a restriction that didn't let it recover very fast after you worked the clutch several times. Replaced it with a brass "T" and now have 27" of vaccum and the system works properly now. Clutch is stiff upon first depressing it to start since there is no vaccum but once it fires up it quickly build vaccum and the clutch pedal pressure is light. Have you checked all your vaccum lines for holes or leaks? Are yousure it is in your master cylinder? I was sure it my MC but then found the real problem. Good luck.
 
The leak occurs all the time but there are certain areas where it leaks more than others. That is, depending on if the pedal is not depressed or how far the pedal is depressed the leak varies. For example if I don touch the pedal it leaks like crazy, along with a real annoying and loud hissing noise. But when I begin to depress the pedal the noise goes away, or is very quiet, but still seams to leak.
After I shut the engine off (foot off the clutch) I can hear the vacuum hissing out from the system. Within a couple of seconds the vacuum is all gone.
As for repairing the master cylinder, everyone I've mentioned this to (vacuum assisted master cylinder) has never heard of such a system.
I was planning on hopefully buying a working used unit and replacing mine with it. I haven't really considered taking mine apart and figuring out what's wrong with it and fixing it myself since I've never taken one apart. I wouldn't be afraid to try and fix it myself except I don't have a repair manual and I have no idea what's on the inside....
 
If the leak is determined to be with the clutch booster it can be rebuilt. The 12HT uses a specific brake booster unlike the other diesels and mine in the 1/2 cut was bad. Marve Spector had it rebuilt at a local shop and it works perfectly now. Inside there is a diaphram that may be your problem. They use a heavy spring inside so it takes some special equipment to disassemble and reassemble these parts but they can be rebuilt.
 
Disconect it, it donsen't afect anything else ( more than your left leg :) ) and block the vaccline from the vacc tank

But .. been pased this issue, I recomend adapt a non vacc clutch master .. as I do in my Tencha, I used a minu truck clutch master cilinder .. and it's by far more soft than the factory vacc one ..
 
What you are describing sounds like the leak may be only the operational shaft seal, where the rod from the clutch pedal goes into the booster. As the rod slides through the seal, areas of contact change the amount of sealing, thus making the noise vary.

That seal(s) will probably be available at a brake booster rebuilding shop, like the above poster mentioned Marv used. I anticipate the parts are the same as used for Japanese cars brake boosters. You will want the rod to be inspected and cleaned/polished as well.

Your truck won't be down for more than a day if you locate a rebuilder shop first and plan your approach to have it repaired. Your idea to replace it is sound, but more expensive and complicated, due to availability of another unit.

Will you please post photos of your system? I have not seen one of these units.

Rick
 
Will you please post photos of your system? I have not seen one of these units.

Rick[/quote]


Here's some pics of what's in my Land Cruiser.
The first picture shows the vacuum system and connection to the brake and clutch master cylinders.
The second picture shows the clutch master cylinder/booster unit.
The third picture shows the vacuum reservoir. The two hoses at the end of the canister supplies the brake and clutch master cylinders. The two hoses connecting at the top of the canister is the supply from the vacuum pump on the rear of the alternator.
 
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Tapage said:
Disconect it, it donsen't afect anything else ( more than your left leg :) ) and block the vaccline from the vacc tank

But .. been pased this issue, I recomend adapt a non vacc clutch master .. as I do in my Tencha, I used a minu truck clutch master cilinder .. and it's by far more soft than the factory vacc one ..
Click to expand...

Hey, Tapage! Do you have any info/pix of that booster? what is a minu truck?
Thinking of getting a oem clutch booster, but after reading a few problems with it, i am not so sure any more.

Running 2H with 12ht clutch soon, and i guess its gonna be a hard pedal.
 
Man, you're going to have a huge right leg!! Occasionally in the cold, I get low vacuum in my HDJ81 and the clutch and brakes are really hard to push. I wouldn't want to drive every day with no vacuum assist in my clutch!! Especially in traffic!!!
 
FJ60's run what I would assume is the same clutch as a 2H, no booster, no problem.
I disconnected my clutch booster in my BJ60 when it started to have a slight vac. leak, and I didn't want to kill my vac. pump.
The pedal is not heavy enough on a diaphragm style pressure plate to need a booster, IMO.
 
I know on the Patrols that there are two clutch master cylinders: one that is for use with a booster and the other with no booster. I have a leaky booster which gets worse in hot weather. (Strangely, in cold weather it is fine) Tired of the sick cow sound, I disconnected it last summer for a drive to the lake. By the time I got to the lake, I quickly hooked the hose back up. It was like having to do a one leg 50 lb leg press on every shift. I think this summer I will fix it by either getting my friend to rebuild the diaphragm or by ordering a new booster-less clutch master cylinder. The master will cost me about $150 delivered from Australia verses the OEM new booster of $1300 from the dealer.
 
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TLC Norway said:
Running 2H with 12ht clutch soon, and i guess its gonna be a hard pedal.
Click to expand...

not at all .. actually Tenchas clutch it's way softer than Marilu clutch pedal .. muddy pic

main.php
 
ah... soo... different opinions... it seems my two 2h's had different clutches. Not the same diameter on the release bearings. the smaller one is from my donor rig, and cant see if its a aisin or toyota unit, maybe its aftermarket. but still strange if the smaller one on the donor is aftermarket, since it only had 180 k km on it. the one on my 81 hj60 had the same diameter release bearing, and unless the springs on the pressure plate is way more heavy duty, it should almost feel the same as the old unit. (vs the new 12ht unit.)

But still, i had great response from Radd Cruisers, they could ship me a booster unit if i felt the need for it, he ment it could be retrofitted to my hj60.
Or can i get a clutch master with bigger ID, to get more pressure out of it... (?)

In a few days i'll know how it feels, when the rig is running again.
See my thread for pix of the parts. maybe someone can give feedback on the dimensions.
The 12ht had three different part numbers on the three throw out bearings.

btw, great pix, Tapage! ;)
 
sporty said:
Hello Pal and others

A bigger ID main cilinder is a heavyer clutch with a long stroke, a smaller ID main is a lighter clutch with a shorter stroke. Minitrucks like hilux have a smaller main cilinder.
Click to expand...

I know... Therefore i was thinking i could use a even bigger ID and stroke.
But i'm just thinking loud, probably just noise in my head.
I'll figure it out when i've run it as it is.
 
sporty said:
Hello Pal and others

A bigger ID main cilinder is a heavyer clutch with a long stroke, a smaller ID main is a lighter clutch with a shorter stroke. Minitrucks like hilux have a smaller main cilinder.
Click to expand...

I think you made a typo.

Don't you mean "bigger ID + short stroke" and "smaller ID + long stroke"?

(Noting that with the slave unchanged ... you need to move the same amount of fluid to achieve engagement/disengagement.)

:beer:
 
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