Drum Brakes! (1 Viewer)

[Cruiser_Nerd]

Jim, what direction do the lower adjusters rotate for minimum (notches facing each other) to maximum?

The lower adjusters are at minimum with the notches facing each other. The max adjustement is at 180* so when they are exactly opposite that's all the adjustment you have.

I have a couple brand new Toyota OEM shoes if anyone needs to borrow them for someone to look at when relining.

 

[LandCruiserSteve]

The lower adjusters are at minimum with the notches facing each other. The max adjustement is at 180* so when they are exactly opposite that's all the adjustment you have.

Got it!! Thanks.

 

[LandCruiserSteve]

Frustrating problem:

I just rebuilt the M/C and wheel cylinders. (PO had recently put on new shoes, so they've got decades left on them. Drums are near perfect.)

Two of us bled the system to death. (Not a trace of air anywhere in the M/C, lines or wheel cylinders.)

Adjusted the shoes to the above precision (including backing them off a tad to make the wheels hand-spinable).

End result was fantastic brakes, good pedal and geat stopping power.


However, 1-2 days after each drive, the wheels start locking up on their own and begin dragging like crazy . . . eventually to the point where the vehicle can't even be rolled.

Keep repeating the above process, but it keeps returning to the same lock-up condition.

Any ideas?

 

[foxfab]

Mine was doing this at CMCC. You need to allow more play in the pedal adjustment of the M/C. It seems to have cured mine for now. Its almost as if the M/C wouldn't release the pressure when you let off the brake pedal, right?

 

[LandCruiserSteve]

Its almost as if the M/C wouldn't release the pressure when you let off the brake pedal, right?

Yep, that kinda sounds like it. But, the pedal isn't really stiff or anything. Matter of fact, the brakes don't really start engaging until about a third of the way down.

It's almost like a runaway self-adjusting system that's gotten out of control (on a truck that doesn't even have self-adjusters).

 

[Cruiser_Nerd]

First, like Mike says be sure that your brake pedal is adjusted correctly. When you say it doesn't start engaging until a third of the way down, is that pedal travel.......or is that actually the piston travel?


Second, you didn't read my warning in the M/C thread?? ;p

This happened to Eric and me after rebuilding the master cylinder. My problem seemed to be heat, as soon as it warmed up under the hood, the brakes pressurized. Exactly as if the pedal were too tight......except it was loose.

I also wasted countless hours bleeding, rebleeding, taking the check valve out, putting it in, insulating the brake lines......

It turned out that the master cylinder piston was not returning far enough to allow the fluid to return to the reservoir. You can check this by siphoning out the reservoir and using a small nylon or plastic rod to probe down through the hole into the cylinder. If it feels rubbery the cup is in the way. Do not use anything pointy or sharp as you'll ruin the cup. What I had to do is remove the washer behind the retaining clip and grind half of the thickness away. This allowed the cup to clear the passage to the reservoir. My brakes have been perfect since.

I don't know if this is a problem with the dimension of the new piston that comes in the rebuild kit, but it's looking that way. You could just as easily turn down the end of the piston also.

 

[LandCruiserSteve]

When you say it doesn't start engaging until a third of the way down, is that pedal travel.......or is that actually the piston travel?

That would be about a third of the way down from the dash to the firewall on the pedal travel.

I guess I'll start off by checking the pedal adjustment, and then go probing into the M/C. Both of those remedies sound logical for what's happening.

Matter of fact, after one time of adjusting the shoes, I didn't even start the truck, let alone drive it. And it still ended up 'swelling out' to a lock up after a couple of days of just sitting there. (Plus, the brake light has decided to start coming on by itself just sitting there in the garage. It must be calling out for help. )

 

[LandCruiserSteve]

BTW, how do I determine proper pedal adjustment?

 

[foxfab]

Ditto on the brake lights. It freaked out my wife one night when she pulled into the driveway.

 

[Cruiser_Nerd]

(Plus, the brake light has decided to start coming on by itself just sitting there in the garage. It must be calling out for help. )

You don't know how many times I saw that.......good part is you know the battery is still charged. I even got to watch Mike's for a while at CMCC, but lucky his was just the pedal too tight.

To adjust the brake pedal:
Pull off the M/C boot and check that the piston is coming all the way back (if it's not that's probably the problem).
Remove the return spring and you should see the slop in the pedal.
Loosen up the jam nut on the rod and if it's not too rusty you should be able to turn it out until you have about a 1/4" of pedal play at the top of the pedal.

 

[Cruiser_Nerd]

Ditto on the brake lights. It freaked out my wife one night when she pulled into the driveway.

I had flashbacks when I saw yours on! Damn, this was a pain in the butt for over a year.

 

[LandCruiserSteve]

......good part is you know the battery is still charged.

Not if it's been sitting there all day and all night turned on.


Anyway, it's a relief to know I'm not the only one that's experienced this.
I'll check the above possible fixes and let ya know. (Only a quarter inch of pedal play at the top??)

Thanks.

 

[LandCruiserSteve]

You need to allow more play in the pedal adjustment of the M/C. It seems to have cured mine for now.

Mike, was it just the pedal adjustment on yours, or did you also have a problem with the M/C piston not returning all the way because of the piston length??

 

[Cruiser_Nerd]

Mike's was just the pedal.....typical just like a FJ40 sometimes. I think Eric had the same problem as me, he just decided to ditch the system.

 

[LandCruiserSteve]

There was literally no play at the top of the pedal, and it took a zillion turns on the rod aduster nut to bring it out to @ 1/4 inch of free play.

And, sure enough . . . after I did that, I was able to roll the truck in the garage with one hand with no apparent dragging at all!! I took it for a quick spin and great brakes!!

So, if it stays this way for more than a day or two, then that must've been the problem. I'll let you know.

Thanks again, guys. Couldn't have done it without you!!


BTW, does the 1/4 inch pedal play apply to the clutch pedal as well?

 

[Cruiser_Nerd]

BTW, does the 1/4 inch pedal play apply to the clutch pedal as well?

Hope it continues to work Steve. 1/4" is what I remember and try to do for both.....the FSM probably has a different idea, haven't checked.

 

[LandCruiserSteve]

I guess it was too good to be true. After a little five mile trip today, the brakes were locked up again (with the brake lights stuck on) by the time I got home. All that quarter inch play in the pedal disappeared.

After the truck sat for a couple of hours, some of the free-play came back and the shoes loosed up a bit.

I suppose it's time to jump into the master cylinder and find out what the heck is going on in there.

 

[foxfab]

damn, sounds like we all have the same problem.

 

[LandCruiserSteve]

damn, sounds like we all have the same problem.

Yep, it sure does.

Do any of the newer FJ style M/Cs fit the 25 without going to a booster unit (even if it meant new mounting holes)?

Stock is good, but stopping is even better.

 

[Cruiser_Nerd]

Don't give up yet Steve! Don't go to the dark side! (And if you're thinking about it, the biggest advantage would be a dual circuit cylinder for safety).

Stop fooling around and replace that retaining washer with something thin, once you get it you'll be like me....... At least you didn't wrap your brake lines in foil covered insulation .... You'll be pleased with the way it stops, I don't think you need any extra power with little tires.