Topic: Toyodaaddict's 1980 "The Blue Truck"

[Ritchie]

My truck no longer nose dives when applying the brakes.
I did remove all of the ABS garbage when I did the Diamonds front & rear.
With the Tundra 231mm front disc upgrade, it stops on a dime.

Here is the block...

[RUGER]

looks super clean ritchie

RUGER

[toyodaaddict [OP]]

After installing the washers and adjusting the brakes, I just took it for a test drive. When I got back the passenger side drum was cold and the driver side was warm enough that it was uncomfortable to hold my finger on it too long. I jacked it up and the tires spin free 

[LittleSteve]

After installing the washers and adjusting the brakes, I just took it for a test drive. When I got back the passenger side drum was cold and the driver side was warm enough that it was uncomfortable to hold my finger on it too long. I jacked it up and the tires spin free 

Asking the obvious, have you checked the wheel cylinders?

[toyodaaddict [OP]]

Asking the obvious, have you checked the wheel cylinders?

I haven't paid them much attention. I changed them when I did the shoes not that many miles ago. I had someone press The brake pedal and I did see that the pistons on the rear of the cylinders are working. The front pistons didn't do much. I assume they work when the drums are on. They do appear to be retracting as they should.

I have now loosened the driver side adjuster a couple turns. Waiting on weather to test drive.

[osv]

After installing the washers and adjusting the brakes, I just took it for a test drive. When I got back the passenger side drum was cold and the driver side was warm enough that it was uncomfortable to hold my finger on it too long. I jacked it up and the tires spin free 

not relevant to your situation, but i've seen that overheated disc/drum problem when the brake hose was rotten on the inside; it'll look fine on the outside but it's swollen up on the inside, and with that small passageway it's too tight to easily release pressure, so the brake is still on after you let off of the pedal.

if there is a problem with the slave cylinder in that it takes awhile to release pressure, the drum could get hot but is still spinning free by the time you jack the truck up, but it sounds like you've already checked that.

[LittleSteve]

not relevant to your situation, but i've seen that overheated disc/drum problem when the brake hose was rotten on the inside; it'll look fine on the outside but it's swollen up on the inside, and with that small passageway it's too tight to easily release pressure, so the brake is still on after you let off of the pedal.

if there is a problem with the slave cylinder in that it takes awhile to release pressure, the drum could get hot but is still spinning free by the time you jack the truck up, but it sounds like you've already checked that.

I've seen master cylinder seals turned inside out do the same thing. Caliper free and easy with pipe disconnected but won't retract with pipe connected

[toyodaaddict [OP]]

I messed around with the brakes again today. I backed the adjuster off a couple more turns. Removed the tire and the brake was loose enough I removed the drum without any trouble.  I tapped on the shoes a bit with a mallet, to see If I could get any movement out of the wheel cylinder. Put the drum/tire back on and went for a drive.

Driver side still gets hot.  Passenger side is cold.  I don't know how it's getting hot with the brake loose enough that the drum slides on an off easily. The wheels spin ok, before and after the drive. I didn't even touch the Ebrake. 

[LittleSteve]

I messed around with the brakes again today. I backed the adjuster off a couple more turns. Removed the tire and the brake was loose enough I removed the drum without any trouble.  I tapped on the shoes a bit with a mallet, to see If I could get any movement out of the wheel cylinder. Put the drum/tire back on and went for a drive.

Driver side still gets hot.  Passenger side is cold.  I don't know how it's getting hot with the brake loose enough that the drum slides on an off easily. The wheels spin ok, before and after the drive. I didn't even touch the Ebrake. 

Jack it up and put it on stands, chock the front wheels. Have someone drive it like they were driving round town. Not above 50.  You will be able to see how quick the brake releases in a way you can't with it static. Do you have an fj80 master cylinder?

[toyodaaddict [OP]]

Jack it up and put it on stands, chock the front wheels. Have someone drive it like they were driving round town. Not above 50.  You will be able to see how quick the brake releases in a way you can't with it static. Do you have an fj80 master cylinder?

Sounds like a good idea.

Brakes are all stock, other than using an 87 rear axle. MC and wheel cylinders where replaced a few years ago. I'm thinking I need to give the wheel cylinder another look.

I keep thinking I've got something wrong in the adjustment but with the drum able to slide on and off, I dont know how they could be adjusted too tight.

The spool makes it a bit harder to gett a feel for what's going on.

[LittleSteve]

Sounds like a good idea.

Brakes are all stock, other than using an 87 rear axle. MC and wheel cylinders where replaced a few years ago. I'm thinking I need to give the wheel cylinder another look.

I keep thinking I've got something wrong in the adjustment but with the drum able to slide on and off, I dont know how they could be adjusted too tight.

The spool makes it a bit harder to gett a feel for what's going on.

The spool might help actually, act more like its on the road maybe.
They should be adjusted till you can just hear or feel the very slightest drag so assuming there's no lip in the drum then they should slide on and off with a wiggle.
The bell cranks that go through the back plate are free?

[toyodaaddict [OP]]

The spool might help actually, act more like its on the road maybe.
They should be adjusted till you can just hear or feel the very slightest drag so assuming there's no lip in the drum then they should slide on and off with a wiggle.
The bell cranks that go through the back plate are free?

Yes, bell cranks move freely.

To adjusted the brakes, I used the adjuster wheel to tighten up the brake until the tire was almost locked up. Then I backed it off until the tire spun nice and free and only a slight brake drag was heard. I have since used the adjuster to loosen the brakes on the driver side a few more turns, each time I have taken it for a test drive.  One thing I'll add is that I can still hear some drag, even though I continue to loosen the brake. Am I right to assume that because I can remove the drum easily, that there is no way the brake is over adjusted?

[LittleSteve]

Yes, bell cranks move freely.

To adjusted the brakes, I used the adjuster wheel to tighten up the brake until the tire was almost locked up. Then I backed it off until the tire spun nice and free and only a slight brake drag was heard. I have since used the adjuster to loosen the brakes on the driver side a few more turns, each time I have taken it for a test drive.  One thing I'll add is that I can still hear some drag, even though I continue to loosen the brake. Am I right to assume that because I can remove the drum easily, that there is no way the brake is over adjusted?

An over adjusted brake would mean resistance past a slight drag. Ergo you would not be able to turn the wheel freely let alone remove the drum.
Another test you could do is with park brake, again vehicle on stands apply the brake whilst the wheels are spinning slowly release the brake observe temporary drag. This should then demonstrate whether its mechanical or hydraulic.
Other things to consider. Wheel bearing or bent axle shaft  one causing the other. To heat up.
If you do the driving test mentioned previously consider removing the wheels when testing, that will allow the drums to react easier, the wheels can act as a dampener and disguise other faults

[Gnarly4X]

Perhaps I missed it, but have you bled the system really good?

If there is enough air in a line it can heat up and put pressure on that wheel cylinder.

Gnarls.

[LittleSteve]

Perhaps I missed it, but have you bled the system really good?

If there is enough air in a line it can heat up and put pressure on that wheel cylinder.

Gnarls.

If there is that much air in the system the brakes wouldn't stop the truck, the fluid would have to be at near boiling point for it to have any effect on the system.

So I don't think it's that.

[toyodaaddict [OP]]

 Update on the brake situation: It was a wheel cylinder.
 

Asking the obvious, have you checked the wheel cylinders?

On both wheel cylinders the pistons toward the front of the truck where seized. I guess I didn't realize this because both sides where acting the same but only one side was getting hot. That and I suck at troubleshooting  .
I guess the one brake shoe was stuck dragging just enough to cause the heat but not enough to cause any real drag on the wheel.

I did leave the washers on that Liveoak suggested. I'll keep an eye on things to make sure the brakes continue to self adjust correctly.


Aisin/Advics wheel cylinders
7/8" 4cyl  WCT-007
15/16" V6  WCT-027
1" FJ60  WCT-011

I went with the 7/8" cylinders for now. I need to upgrade my booster and then the rest of the system.