[dmaddox]

Ok, short story:

1. Bought rig (1963 Model Cruiser) Had single circuit system, it would drive for about 25 miles, and then start locking up (pedal would get higher and tighter.....higher and tighter until knee is in my chest).

2. Replaced the master cylinder. Still did it.

3. Gutted the entire rig's brake system put in all new 8 cylinders, new lines, and a power booster/master setup. Damn thing locked up again after about 50 miles. PLEASE NOTE: EVEN FLAT TOWING this with the drive shafts disconnected - brakes locked up - all four!!!

4. Replaced THAT master, adjusted push rod, on and on and on......still the thing locked up.

5. Gutted it all AGAIN, cleaned, inspected, adjusted, etc....this time putting ONLY a Toyota mini-truck master cylinder and new brake lines in. Onto the third system. Well, low and behold the damn thing locked up again.

The pedal starts off down at the floor, drive a little bit, it's 50% up and hard as a rock (brakes work great however) then the pedal can't be pushed, it's solid....2 miles later - bam all four bind up and I come to a stop.

I am at my wit's end here.....It is one system after the next on this thing.

I tried to shorten the push rod....and no dice.

After this is solved, I am going to install a carb fan for vapor locking issue.

Thanks for any advice,

Dallas

[dmaddox]

Ok, I cracked the Haynes open again. I just set the pedel play to 4mm (3mm-6mm is what the book says). This is the clearance between the pushrod and master plunger that gives this pedal play.

Pedal goes right to the floor. Bam. I re-bled them all. Still, pedal goes to the floor. I have to pump and pump and pump to build pressure up in the pedal for braking power.

Dallas

[orangefj45]

somebody else on here was having the same issue not too long ago, but i forget who it was. i think the flat towing issue was traced back to the pedal bouncing back and forth building up pressue.
i think either butch baker or markl whatley had the fix for this issue.

best of luck

[Pin_Head]

Brakes locking up like that is usually due to a misadjusted push rod (too long) that won't let the piston fully return. Drum brakes that require pumping to get a pedal need to be adjusted (thghter). I know that it sounds like you have done that, but maybe you haven't done it properly yet.

A carb cooling fan is not about vapor locking; it prevents the fuel from boiling out after you shut it off. True vapor lock is very unlikely in cruisers which have the fuel pump inlet below the lowest level of the tank, so gravity flow feeds the pump.

[dmaddox]

Cool - going to check out the brake issues as the week unfolds.

On the vapor lock issue, it was very hot today - and I was stalling at intersections. Never has done that before. (never have drivin it on that hot of a day before either tho).

[numby]

Check all your fuel line connections and your fuel pump assembly screws around the perimeter of the pump. If even the tiniest bit of air is getting in you'll get vapor lock on the first hot day as your under hood temps will spike compared to what they are with snow on the ground. Tough to get fuel to boil when it's -20. Not the case when it's 90+ outside.

On a side note... Did you ever get me a final price/shipping total for the 78 carb fan control you were selling?

[orangefj45]

Originally Posted by Pin_Head

Brakes locking up like that is usually due to a misadjusted push rod (too long) that won't let the piston fully return. Drum brakes that require pumping to get a pedal need to be adjusted (thghter). I know that it sounds like you have done that, but maybe you haven't done it properly yet.

A carb cooling fan is not about vapor locking; it prevents the fuel from boiling out after you shut it off. True vapor lock is very unlikely in cruisers which have the fuel pump inlet below the lowest level of the tank, so gravity flow feeds the pump.

that should be the issue with the brakes. to properly adjust the brakes i usually tighten them till i can't turn the drum and then back the wheel cylinder adjusters down so i can turn the drum again. you can cheat and remove the drum to do so. that way you can see which one of the adjusters needs to be tweaked and how much. just slide the drum on and then off again to adjust visually but you should be able to do it with the drum and wheel/tire on the truck. not a big deal.

the carb cooling fan was also designed to prevent the manifolds from cracking. the phenolic carb spacer is there to insulate the carb from the engine heat and help prevent the fuel in the carb from boiling.

[mooker82]

Possibly a dumb suggestion but.....are the brake shoe return springs installed?

[igotta40]

"Ok, I cracked the Haynes open again. I just set the pedel play to 4mm (3mm-6mm is what the book says). This is the clearance between the pushrod and master plunger that gives this pedal play."

Either I'm misreading this or you're descibing two separate adjustments and calling them the same thing.

There's pedal play, and there's push rod adjustment. If your push rod between the master and booster is 4mm your pedal should go to the floor or very close to it. That adjustment is 0.10 mm per the Toyota service manual. What is the 'master plunger' you refer to? Got pictures of what you're doing? I had similar issues a while back. I made an adjustment tool for the push rod that worked great. I can share it with you if you need me to.

[Pin_Head]

It depends on whether you have power brakes or not. His 1963 does not have power brakes, so setting the pedal free play is the same as adjusting the master push rod.
On power brakes there are two settings: Pedal free play and the gap between the end of the PB booster pushrod and the master piston.

[desertpat]

Dallas,
I had the issues you are dealing with on both my restorations.
Brake lock up ..... I reckon this is due to expansion of brake fluid - coming from engine bay heat. (I have no explanation for that flat towing lock up you mention) When it hapenned to me, I cracked a brake line connection and bled off "pressure" (when hot and locked). The wheels were then able to rotate and I could drive away. I did not re-bleed or re-adjust the brake system after this - the brakes work fine when cold and no longer locked up when hot.
When brake fluid heats up and expands, it puts a force against the wheel cylinders (no other place to go) and applies the brakes - in effect.

Vapor lock ..... I had hard starting after shutting the hot engine down - It would always start great when cold.
To slove this problem, I insulated the gas line between the fuel pump and carb with a rubber hose over the steel gas line and the wrapped with a foil reflecting tape. It starts much better now.
good luck.

[bsmith123]

read pinheads post again x2

heat expansion should not cause brake pressure
the fluid should flow to the master,

a residual valve is needed to hold any press in the line and once it built above that it should crack and relieve it back to the master

unlikely a bad residual but you could check but a piece of garbage in the line could block the backflow into the master

most likely you are not understanding the adjustment process for the rod though go back through the FSM procedure for that

let us know how it goes

[kiwidog]

Do you think the booster has ever been apart?
You may not have taken it apart but PO may have.
You may want to check
If it is assembled wrong it can cause the brakes to lock-up as the fluid is not draining back into the reservoir when you release the pedal. The diaphragm has to go in a certain way where the four bolts for the firewall bolts go through the booster cover. The diaphragm has what looks like a grommet on the middle of it, the groove has to go onto the booster housing the correct way. If you install with the grommet like part not fitted correctly it has some effect on the push rod length of the booster to master cylinder setting.
I can't remember exactly how it goes however if you follow the picture in the Toyota shop manual that should show you the correct way.
How do I know this?
Well years ago I assembled one the wrong way and it worked but the brakes tended to remain on after they got little hot from use and the dragging created more heat which locked them up tighter.

Worth a try, seems like you have tried everything else.

Hope this helps.

"experience is what you get when you don't know what you are doing"

Thanks jb

[dmaddox]

UPDATE:::::::

Ok, went and bought another Master cylinder just to be safe.

Procedure this morning:

1. Removed each drum, inspected and adjusted each wheel cylinder and adjusted the brake pads until just dragging, then back it off a touch.

2. I went and bought a "bench-bleeding" kit at the parts store.

3. I removed the lines, bench bled the master extensively.

4. I bled each of the 8 wheel cylinders starting with the farthest away, etc... Again extensively bled them (power bled them with my brother building up lots of pressure then slamming to the floor as I opened the bleeder, one by one.

5. Adjusted the pedal play (again, this is a NON power setup) pedal moves 4mm, gap between push rod and master cylinder plunger is about 2-3mm. So, the piston is allowed full movement and not held in by a mis-adjusted rod.

6. Nothing. Pedal flops to the floor, and the only way to get pressure is to pump the pedal.

That would now be 4 master cylinders - same results.

Next is to rip out my original 63 drum axles and replace with late model disk front/drum rear fine splined axles.

I didn't want to have to do this becuase I have 3 sets of spare "ball and claw" axles and I wanted to stay original, but then again - I'd like to have a working brake system as well.

Thanks for the comments everyone,

Dallas

[fj404life]

Originally Posted by dmaddox

UPDATE:::::::

1. Removed each drum, inspected and adjusted each wheel cylinder and adjusted the brake pads until just dragging, then back it off a touch.

Dallas

That be your problem I think. You want to adjust until you can barely turn the wheel...then back off a couple clicks. They will and should DRAG!
Hmmm actually you should still be able to pump up the brake pedal I would think if this is the case....

Where are you getting your masters?

[dmaddox]

Well, if I pump 3-5 times quickly - brakes build up... and hold for that matter. If I let off, then push them again, they go to the floor.

So the pressure easily builds up.

I have purchased two from a salvage yard, one came on it, and a new one from Checker auto parts.

I have a lead on late model axles. I am at my wit's end with this dang brake system!

Thanks again! - Dallas

[fj404life]

Your drums need to be adjusted tighter then. You want to almost come to the point of not being able to turn the wheel by hand...then back off 2-3 clicks max on all 8 wheel cylinders.

No clue on the lockup syndrome...but like I said above...I gave up after 2 aftermarket masters would not work well and started leaking after a week or 2. Went toyota oem from cruiser dan...been good since!

[numby]

The axle change will not solve your problem as the brake hydraulics are unrelated to things like which size birfield or full floating/semi floating axles, knuckles, etc. The problem MUST be somewhere between the brake foot pedal and the furthest wheel cylinder (right rear) in the system and be contained therein.

If the pedal goes to the floor repeatedly and CAN NOT be pumped up you have a leak. This could be internal i.e. - brake fluid is squeezing past a seal in the master cylinder and thus the master is not pressurizing OR your leak is external i.e. - fluid is escaping the system such as squirting out a loose bleeder or damaged line (hard or soft) or past a wheel cylinder where you will eventually see it on the ground. You would see a noticeable drop in the reservoir (front or rear) after half a dozen pedal depressions (unrelated to "Non-Functioning Cruiser Depression").

If the pedal goes to the floor on the first pump but repeated pumping increases pedal pressure that DOES NOT diminish as you hold the pedal down on the last pump you have air in the system. Period. Fluid is used in hydraulic systems because, unlike gas (air), fluid is difficult to compress. An air bubble in a closed hydraulic system will eventually compress and allow a modicum of service UNTIL you release pressure and the air expands again at which time you will need to re-apply pressure (pump your pedal) until the air is compressed enough to force fluid thru the lines.

If the pedal goes to the floor until you pump it up it and then, after re-establishing pressure, the pedal slowly goes to the floor while continuing to hold it down - you have a slow leak either internal or external.

Two further points:

1} Any contamination to the system from conventional petrochemical compounds will cause hydraulic seal failure. And dang fast, too. Is it possible you inadvertently used the wrong type of assembly lube when installing your new components? Grease on your hands? Did you blow out the hard lines with brake cleaner?

2) A hole or leak in a hard or soft line can exhibit a one way effect at times. Fluid may not leave the system with the application of pedal pressure but air may enter the system as pressure is relieved (foot off the pedal). The air is sucked in thru the hole as pressure drops. This is uncommon but I've known it to happen. A poorly fitting connection at any point in the system can contribute to this affect. Whether you would see a rising fluid level in your reservoir or not is dependent on how much air is entering the system and contributing to system volume. Air may be drawn into your system as the pedal moves up and be expelled as pressure is applied as well. Fluid can also be forced past a leaking wheel cylinder seal, collect under the dust cap, and then be re-drawn into the system. You'd eventually see a visible leak due to the fact that the wheel cylinder dust cap is not designed to hold any pressure. Look at the inside of your bleeder valves. Are there any nicks/gouges or are they shaped irregularly. They must make a perfect metal-to-metal seal or you will have problems.

I am a little unhappy with your description of bleeding the system with your brothers help. The brake bleed valve at each wheel cylinder should be closed firmly until pressure is applied to the system (your brother's foot on the pedal). This need not be excessive. Then open the valve. Fluid/air will be forced out of the bleed valve and pressure will begin to diminish (leak). YOU MUST CLOSE THE BLEED VALVE BEFORE ALL PRESSURE IS LOST OR AIR WILL RE-ENTER THE SYSTEM. Sorry for the emphasis. The volume of fluid moving thru the system displaces air better than high pressure. If your assistant's foot bottoms out it can prove too late and air can re-enter the system before you close it off. Close the valve as the fluid is still squirting from the bleed screw hole and begins to tail off. You only need to turn the bleed screw about a half turn (or less) either way. If his foot comes off the pedal or he raises his foot so much as a millimeter or two you will doomed to a never ending cycle of air contamination.

Here's what I would do. Re-check all connections for tightness. Confirm that your hard and soft lines are in perfect working condition. Be honest about your sterility level when assembling your system and then diagnose either a LEAK or AIR IN THE SYSTEM. I'd hate to see you spend a lot of money and effort and end up with the same problems all over again. Once you get your brake skills in order it will matter little whether you're working on a disc or drum system or whether or not it's boosted. HTH

[Pin_Head]

The problem you describe is a classic sign of brakes that need adjustment and you haven't properly adjusted the brakes yet. You tighten each adjuster until the wheel locks and you can't turn it; then you back off 3 clicks. Drum brakes drag. It is normal.

I don't think it is a problem with bleeding. Air bubbles make the pedal feel spongy.

[65swb45]

Since you have now eliminated the misadjusted pushrod problem that started this thread, just go ahead and adjust all your wheel cylinders until the tires won't move any more.

I am serious.

At that point, you should have pedal pressure without having to pump. That will prove your hydraulic system is working.

Then loosen your wheel cylinders one by one, note pedal drop, and make adjustments accordingly. You should have full pressure with 1" of travel when you are done.

Best

Mark A.

[My wife said no FJ!]

OK, I have a question...if indeed it is getting too hot, can Dallas step up to DOT 4 or 5 ?

[numby]

Originally Posted by 65swb45

Since you have now eliminated the misadjusted pushrod problem that started this thread, just go ahead and adjust all your wheel cylinders until the tires won't move any more.

I am serious.

At that point, you should have pedal pressure without having to pump. That will prove your hydraulic system is working.

Then loosen your wheel cylinders one by one, note pedal drop, and make adjustments accordingly. You should have full pressure with 1" of travel when you are done.

Best

Mark A.

So the multiple pumps are to fully seat shoes that are much too far from the drum surfaces (or at least one side or the other)? I assumed the shoes were adjusted. I feel stupid now...

[numby]

I also remember an old TLCA discussion concerning a cruiser that had brake lock-up while towing. I think the problem turned out to be a missing return spring on the brake pedal. Just the subtle bouncing of the pedal/push rod against the MC plunger was causing the lock-up. A weak return spring might allow this to happen as well.

Assuming that everything is adjusted correctly... are you certain you're getting all the air out of the lines. You must bleed repeatedly to remove air that may be trapped a good distance from the bleed screw. Sorry if this is painfully obvious. Just trying to help you cover all the bases.

[Mr. Toad]

x2 on Mark A.'s advice. Especially the part about locking them all up to see if the system is working.

One last thing, though, is something I've had problems with in the past. It is this: Not all cruiser master cylinders pump the same volume of fluid per stroke. I had symptoms similar to yours on my '75 until I finally sourced a MC with the correct internal piston chamber diameter. (the bore size should be cast into the MC housing)

[Living in the Past]

When rebuilding wheel cylinders I use a very little white grease on the adjusting bolt of the wheel cylinders to keep it free. Then when adjusting the brakes I adjust one side then the other than go back to the other side and adjust again. I keep doing along with spinning the wheel and having someone push on the brake pedal to make sure the brake shoes stay perfecly centered. Once I started doing it this way I had no problem with my drum brakes. That is as long as they stay dry. That to me is the big advantage of disk brakes.

[fj404life]

Originally Posted by numby

So the multiple pumps are to fully seat shoes that are much too far from the drum surfaces (or at least one side or the other)? I assumed the shoes were adjusted. I feel stupid now...

Yes as long as you have a good hard pedal and it stays that way once you pump em up and hold it. I got soooo sick of adjusting and bleeding....it gets easier once ya get the hang and the drums stop as fast as I would (hopefully) ever want to stop a 40.

[rockcod]

Dallas,

This is why I am in the process of installing 4 wheel power disc brakes in the 45. Are you keeping the truck now?

[dmaddox]

Truck is still for sale for the most part, but because no one was interested, I am pretending it's not and am continuing to work on it and improve it's reliability :-)

...as if I have nothing else on my plate to do. ha ha ha.....

Take care,

Dallas

ps. I don't like working on brake systems. . . and they don't like me.

[e rock]

You can't properly adjust the shoes without the master cylinder installed. It's been mentioned, but just for clarity, you need to use the hydraulic brake system to seat the shoes against the drums periodically during adjustment.

You could adjust clickers until the tire won't turn, and still have it be too loose once the shoes center themselves under a braking load. Since you can pump it up and it holds pressure at this point, it sounds like everything works fine - you just need to adjust more.

[Pin_Head]

Originally Posted by rockcod

This is why I am in the process of installing 4 wheel power disc brakes in the 45. ?

That is a lot of work and expense compared to adjusting your brakes, isn't it?