25 Master Cylinders

[1962fj40]

Help on my FJ40 Brakes

Hey guys,

Thought that I would post here since I didn't get any good resopnses from the 40 section. I have a 1962 FJ40 with stock brakes (single circuit master cylinder) that always seem to leak on the inside of the cab after it's sitting awhile. Does anyone have any good ideas besides changing it all out that may fix this?

Takes a couple of months for it all to empty of the maste cylinder and of course the rubber boot does a good job at concealing the leak too.

Thanks

Robert

 

[foxfab]

return spring on the pedal?

 

[LandCruiserSteve]

return spring on the pedal?

Intact and working good.

 

[Cruiser_Nerd]

May sound silly, but when they warm up, if you crack a bleeder or line, do they release?

Also once it's hot and you released the pressure with a bleeder (yes I actually did this) drive it around without ever touching the brakes . That might tell you if its strictly a heat issue.

Might not tell you anything, but it feels like your doing something, and you might get lucky!

 

[foxfab]

ok, my selfishness is coming out. Tell us more on the 82 FJ40 wheel cylinders and what mods need to be done?

 

[Cruiser_Nerd]

Hey guys,

Thought that I would post here since I didn't get any good resopnses from the 40 section. I have a 1962 FJ40 with stock brakes (single circuit master cylinder) that always seem to leak on the inside of the cab after it's sitting awhile. Does anyone have any good ideas besides changing it all out that may fix this?

Takes a couple of months for it all to empty of the maste cylinder and of course the rubber boot does a good job at concealing the leak too.

Thanks

Robert

Robert, I don't have to tell you, it shouldn't be doing this. I think you said it was a new Toyota cylinder, if it was aftermarket get an OEM cylinder. Not much if anything you could have done on an install that would cause it. Hate to say it, you probably had a run of bad cylinders, and luck worse than Steve!

 

[Cruiser_Nerd]

ok, my selfishness is coming out. Tell us more on the 82 FJ40 wheel cylinders and what mods need to be done?

I think Steve described it before, change the pistons to the FJ25 kind and a little opening up of the two mounting bolt holes. Order up four already, lets try it on yours! ;p

 

[LandCruiserSteve]

I think Steve described it before, change the pistons to the FJ25 kind and a little opening up of the two mounting bolt holes. Order up four already, lets try it on yours! ;p

Yep, that was basically it. I meant to snap a pic yesterday when I had the drum off on one wheel, but in the midst of my anger and frustration, I didn't think about it. However, you'd be hard pressed to even tell the visual difference between the old and new.

Got them at Advanced Auto for $17 a pop. The bolt mounting holes are a tad closer together . . . about 5 seconds of Dremel towards the inside solves that. I also renewed the 1" cups once again when I swapped over the OEM pistons.

 

[LandCruiserSteve]

May sound silly, but when they warm up, if you crack a bleeder or line, do they release?

Yep. Tried that. It released a little, but not completely. Complete release required backing off the shoes on the adjustment and then readjusting again (and of course, re-bleeding again). Time to start buying brake fluid in bulk by the barrel.

 

[LandCruiserSteve]

I have a 1962 FJ40 with stock brakes (single circuit master cylinder) that always seem to leak on the inside of the cab after it's sitting awhile. Does anyone have any good ideas besides changing it all out that may fix this?

Robert - I have to completely agree with Cruiser_Nerd on this. Sounds like you've got yourself a bad MC that needs to be replaced. (I wouldn't waste time or money rebuilding it.) I got my brand new Toyota OEM single circuit MC through CruiserDan for about $80. Good luck.

 

[FJnotCJ]

Yep. Tried that. It released a little, but not completely. Complete release required backing off the shoes on the adjustment and then readjusting again (and of course, re-bleeding again). Time to start buying brake fluid in bulk by the barrel.

So after the shoes are adjusted perfectly and driven a mile they need to be adjusted again? No amount of time will let the fluid cool and unbind the shoes? Hmmm...Are you positive the brake hardware is 25 and not some "Chev-close-enough" ....shoes are the right size for the drum, pistons dont jam in bore of cylinder, adjusters dont move on their own? Mr Murphy has had a little over 40 years after all...

What type fluid are you dumping on your driveway? Old fashined DOT whatever or that silicone stuff? I tried the silicone on a drum braked rig with no luck, it seemed to swell or otherwise ruin all the cups...made the brakes drag, but I powered out of it

Please get this figured out so there are no mysteries by the time I get mine ready to stop, you have plenty of time!

 

[1962fj40]

Robert - I have to completely agree with Cruiser_Nerd on this. Sounds like you've got yourself a bad MC that needs to be replaced. (I wouldn't waste time or money rebuilding it.) I got my brand new Toyota OEM single circuit MC through CruiserDan for about $80. Good luck.

This is actually my 3rd MC in like 18 months or so. I even have one that I clend eally well sitting in a vise. I has leaked a few drops. Makes me wonder what is really going on.

I'm pretty sure that I bought an Aftermarket, so that may be the problem. Guess I will go get the OEM and see how it goes.

Thanks

Robert

 

[LandCruiserSteve]

So after the shoes are adjusted perfectly and driven a mile they need to be adjusted again? No amount of time will let the fluid cool and unbind the shoes? Hmmm...Are you positive the brake hardware is 25 and not some "Chev-close-enough" ....shoes are the right size for the drum, pistons dont jam in bore of cylinder, adjusters dont move on their own?

What type fluid are you dumping on your driveway? Old fashined DOT whatever or that silicone stuff?

Yep, perfectly adjusted before each test drive.

Sometimes they unbind by themselves over a two or three day period, most of the time they don't.

Yep, they're OEM shoes.

Pistons aren't hanging up at all.

I've been marking the postion of the adjusters to see if they're moving on their own. They're not.

Good old-fashioned DOT-3 brake fluid . . . not the silicone stuff.

And, the two T-connector splitters (engine compartment and rear axle) are clear and doing their job properly.

 

[LandCruiserSteve]

I'm pretty sure that I bought an Aftermarket, so that may be the problem. Guess I will go get the OEM and see how it goes.

Sounds like you may've nailed it. I've had a couple after-market brake MCs go bad over the years on previous FJ40s. (Although I've never had a problem with the CCOT aftermarket clutch master in my current '78 40. But then again, brake MCs endure substantially more use and abuse than the clutch.)

 

[Cruiser_Nerd]

Try to narrow it down Steve.
When it locks up:

1- If you bled off pressure at the M/C and the shoes didn't release it could be something further down the line hydraulically - between the M/C and wheel cylinders.

2- If you bled off pressure at the wheel cylinder and the shoes at that cylinder didn't release, that's it. Not hydraulic, something mechanical must be doing it, return spring, binding piston, shoes wedging in the drum (shoes too wide? wrong drum?)......but not hydraulic. Once you open that bleeder on the wheel cylinder there is nothing involving fluid bearing on the system.

So, if you did #2, it's got to be something inside the drum. Next time you have it apart, take a picture of the drum and what's inside. I've got a few apart and we can compare.

 

[LandCruiserSteve]

The problem is, there's no consistency whatsoever about this other than the fact the brakes perpetually bind up after a complete adjustment, bleeding and eventual driving.

Sometimes the brakes bind up immediately after driving . . . . sometimes an hour or a day later. Sometimes bleeding off at the wheel cylinder releases them . . . . sometimes it doesn't. Sometimes backing off the adjusters without popping the bleeder frees them . . . . sometimes it doesn't. Sometimes I feel like a nut . . . .

 

[Cruiser_Nerd]

Post up pictures next time you have the wheel off......I'm leaning towards something stickin in there. Suspicious of the shoes and drums either one too wide or the other to narrow.

Meanwhile, drive around without ever touching the brakes. Besides being great fun, it could tell if it's a heat issue or if it happens as soon as you expand the brakes in the drum.

 

[Living in the Past]

You could always do what one of the PO did to one of my 25s, convert over to early FJ40 brakes. First time I looked at the vehicle I didn't catch what was done, I thought they used spacers to make the FJ40 15" wheels fit a 25. I got all the pieces for the front axle if you want them. Now the question since the 40 brakes are thicker did Toyota make longer axles or shorter axle housings? The front is a full floater but the back is aC clip axle and the axles have to fit into the diff just right. If the track is the same on both it would shorter housing. Or maybe the backing plate was offset for the larger brakes. Does anyone have a parts manual for the early 40 to compare part numbers with the 25 part numbers? Might be a solution to the problem. The early brakes weren't the greatest but it sounds like they are better than the 25s. Plus you can find parts alot earier.


John

 

[1962fj40]

You could always do what one of the PO did to one of my 25s, convert over to early FJ40 brakes. First time I looked at the vehicle I didn't catch what was done, I thought they used spacers to make the FJ40 15" wheels fit a 25. I got all the pieces for the front axle if you want them. Now the question since the 40 brakes are thicker did Toyota make longer axles or shorter axle housings? The front is a full floater but the back is aC clip axle and the axles have to fit into the diff just right. If the track is the same on both it would shorter housing. Or maybe the backing plate was offset for the larger brakes. Does anyone have a parts manual for the early 40 to compare part numbers with the 25 part numbers? Might be a solution to the problem. The early brakes weren't the greatest but it sounds like they are better than the 25s. Plus you can find parts alot earier.


John

John,

Check out my Microfiche online, it should have what you are looking fir:

http://tlcfiche.dyndns.org:8081

Be sure to install the "AlternaTIFF ActiveX control"

Robert

 

[LandCruiserSteve]

Post up pictures next time you have the wheel off......I'm leaning towards something stickin in there. Suspicious of the shoes and drums either one too wide or the other to narrow.

The next time I pull a wheel off, I'll snap a couple pics. If something were to be sticking in one wheel, it's doing the same thing in all four. But, sometimes it's just the rear wheels locked up; sometimes just the front; sometimes the right rear combined with the left front; sometimes all of them. A couple of times, the wheels locked up after a few hours just sitting there in the garage after the adjustment/bleeding procedure without even driving the damn thing to get it warm. Like I say, there's absolutely no consistency to this mystery.

As far as the shoes being too narrow or wide, are there any other shoes out there that would coincidentally have the exact same shape and configuration as the FJ25's shoes that would attach, line up and work with the 25's lower adjuster system and the cam style uppers?

If the drum was too wide, wouldn't it scrape the backing plate when completely seated with the wheel lugged on? And, if it was too narrow, the worse that would happen would be the shoes wouldn't be grabbing the entire drum surface (which would seem to make it even less likely to lock up since there would be less contact surface). However, the rear of the drum disappears nicely under the protruding lip of the backing plate and the drum puller extraction holes match up perfectly with the ones on the hub.

Matter of fact, looking at the pics in your drum brake thread, Jim, my backing plate, hardware, shoes and drums are literally all identical to yours. Not to mention, there's enough partial wear on the shoes to indicate that these brakes must've been working properly at one time or another up to this point.

Other than the brake lines (which appear to be okay), the only thing I have yet to replace are the three rubber brake hoses (two front wheels and the rear axle attach point). Is it possible that the interior of these hoses may've broken down on the inside to create some sort of "one way valve," so to speak?