Bad Clutch Master Cylinder?

1973Guppie · 10-27-06, 06:26 PM

So I was driving the FJ40 today and had some clutch problems. I am fairly sure that it must be a bad clutch master cylinder as logic dictates this and even more so the CMC is very old, can't remember even if I have ever replaced this. Symptoms are when sitting at a red light for awhile with the pedal depressed all the way and the truck in gear, the shift stick will get "stuck" in gear, meaning that normally, (out of habit) when the light turns green I will pop it out of gear and give the clutch another pump. To me it seems that the clutch master is losing pressure after being pressed and allowing the clutch to reengage a bit? Does this sound logical? Also, I noticed that when I push the clutch about half way down so there is some pressure, the pedal will move to the floor quickly with only a little pressure to it, is this normal? I don't remember it being like this. I searched and noticed that others reccomend replacing the slave cyclinder at the same time, why is this?? My slave is much newer than the CMC but if it is necessary I will replace it as well. Any and all comments appreciated. I don't want to have this thing puke on me out in the middle of nowhere.

Noah

Poser · 10-27-06, 06:28 PM

Quote:

Originally Posted by 1973Guppie

searched and noticed that others reccomend replacing the slave cyclinder at the same time, why is this??

Replace the master and slave cylinder together now or do the other piece later when it lets you down....

ducktapeguy · 10-27-06, 08:01 PM

Are you losing fluid in the reservoir? If the cylinder is loosing pressure, the fluid must be going somewhere. Is there fluid leaking down the firewall, or at the slave cylinder?

I just finished rebuilding both of mine, it's pretty easy to do. It's only been a week, so I don't know how long it'll last. But if you were gonna drain it anyway, might as well replace or rebuild both at the same time since it's pretty easy.

BTW, when you come to a stop, how come you leave the truck in gear then pop it out of gear before you take off? Why not just shift into neutral then you wouldn't have to hold the clutch down? Seems like it would save some wear on some parts.

1973Guppie · 10-27-06, 09:34 PM

that's what is weird, no fluid leaking anywhere. I don't always have the clutch in but usually put it in just before I know the light is going to turn green, that's what I meant to say. Either way, the point is that the clutch pressure seems to be going away slowly after the clutch is depressed. Any reasons for this? Is there anyway this could be caused by bad fluid? Is there anyway to surely test the clutch master cylinder to see if it is faulty? Could this be something else, ie: clutch or pilot bearing related??

Noah

honk · 10-28-06, 10:28 AM

Quote:

Originally Posted by 1973Guppie

that's what is weird, no fluid leaking anywhere. I don't always have the clutch in but usually put it in just before I know the light is going to turn green, that's what I meant to say. Either way, the point is that the clutch pressure seems to be going away slowly after the clutch is depressed. Any reasons for this? Is there anyway this could be caused by bad fluid? Is there anyway to surely test the clutch master cylinder to see if it is faulty? Could this be something else, ie: clutch or pilot bearing related??

Noah

that's probably the master cylinder. They can leak internally past the piston without fluid coming out for quite a while, or it can go into your booster.

They were sold as a complete system for quite a while and might be still - I'm not sure. But pinching pennies I'd go after the M/C. Do it right and change both. Nice new pieces on 34 year old vehicles gives a warm and fuzzy security, ya?

1973Guppie · 10-28-06, 11:21 AM

Honk! Much thanks, that's what I was looking for. I was wondering if they ALWAYS leak before going out or not. I think I am going to err on the safe side and just replace em and rebuild the other 2 for spares. I think your comment on the fluid moving past the piston is correct because the clutch pedal will hold pressure but only for a bit and then the clutch begins to engage on it's own if in gear or lose pressure if in neutral and then I have to depress it several times more to get it going. Where is the best place to get the rebuild kits for the clutch master cylinder? any auto parts store?

Noah

Walton · 10-28-06, 12:42 PM

My '67 was leaking fluid onto my floorboard...I replaced it with this from SOR....Shipped in a Aisan box...It is working great...You can still get OEM if you prefer

honk · 10-28-06, 05:54 PM

Quote:

Originally Posted by 1973Guppie

Honk! Much thanks, that's what I was looking for. I was wondering if they ALWAYS leak before going out or not. I think I am going to err on the safe side and just replace em and rebuild the other 2 for spares. I think your comment on the fluid moving past the piston is correct because the clutch pedal will hold pressure but only for a bit and then the clutch begins to engage on it's own if in gear or lose pressure if in neutral and then I have to depress it several times more to get it going. Where is the best place to get the rebuild kits for the clutch master cylinder? any auto parts store?

Noah

You might want to disassemble the cylinders before buying any rebuild kits. It's possible that the bore(s) are too worn or eroded to give a good result if rebuilt.

The bore should be exactly the specified diameter and not out of round through it's entire length. It shouldn't show any score mark or eroded area at all though the area between the seals isn't critical if the seal doesn't run in it. If you aren't equipped to measure it precisely and don't have the hones to put a new seal surface on them then why chance it?

I know, new costs more, some a lot more, but look how long the originals went before this.

1973Guppie · 10-28-06, 06:07 PM

well I purchased a rebuild kit from kragen for the clutch master and slave. I plan to pull them apart and rebuild em and use them solely as spares. I wil post up when I pull them apart to get comments on their status. the rebuild kits were only like $12 a piece so no biggie.

I figured better safe than sorry so I also went ahead and purchased a unit from www.joetlc.com as well as a slave cylinder. Here are the units:

http://www.joetlc.com/product_info.p...368a0bc6b45242

http://www.joetlc.com/product_info.p...368a0bc6b45242

Are these considered decent units? not sure if they are new oem but oem was much more expensive from spector, let me know if anyone thinks these are junk so I can cancel my order.

Noah

pbgbottle · 10-31-06, 05:29 PM

looked at the web link and under the title it has this
3141060041
don't no if it means anything but that is the toyota OEM part # for
75/01 to 80/07 clutch master

FJ40 CruiserEd · 12-18-09, 07:59 PM

Quote:

Originally Posted by 1973Guppie

well I purchased a rebuild kit from kragen for the clutch master and slave. I plan to pull them apart and rebuild em and use them solely as spares. I wil post up when I pull them apart to get comments on their status. the rebuild kits were only like $12 a piece so no biggie.

I figured better safe than sorry so I also went ahead and purchased a unit from www.joetlc.com as well as a slave cylinder. Here are the units:

Clutch Master Cylinder Toyota Land Cruiser 71-80 FJ40 55 - JoeTLC

Clutch Slave Cylinder Toyota Land Cruiser FJ40 FJ60 55 - JoeTLC

Are these considered decent units? not sure if they are new oem but oem was much more expensive from spector, let me know if anyone thinks these are junk so I can cancel my order.

Noah

Noah, How did these parts work out for you the past 3 years? I'm looking at the same problem myself.

Ed

1973Guppie · 12-19-09, 12:25 PM

still going strong, they are aisin and good quality.......