Builds Goat. A 1967 survivor FJ-45 LWB (6 Viewers)

[Michael B]

Nolen it sounds like you have a very small leak in your rear system.

 

[wngrog]

Nolen it sounds like you have a very small leak in your rear system.

I did before all the replacement parts.

No change at all in the fluid level after driving it and it sitting the last 2 weeks.

If I still have issues after the bleed and proportion valve I will start looking for bad cylinders.

I’m WAY deep into these drum brakes now. I keep telling myself that they had to sell these vehicles with drum brakes. If I keep tossing parts at it eventually I’ll have a new system.

At this point the only thing not new is the drums themselves but I put a mic on them and they have plenty of thickness.

 

[middlecalf]

Nice! I’ll be hitting up Mr. Rainman for some breaklines, I have at least one section that’s broke. Possibly more. You’re almost there.

Maybe this has something to do with that front bumper?

Yes. 45’s do. That was one reason I went to 1” all around. I knew this truck will never see those loads so we took some “power” out.

By using the same size cylinders fore and aft you’ve actually increased the power to the rear relative to the front. Physics - same input pressure from MC (single circuit) means less fluid to move for smaller cylinders hence quicker pressure buildup to what’s needed (and that’s apparently 10psi for cruiser drums). So your rear actually needs bigger cylinders to “slow” them down in pressuring up since there is no stock (OEM) proportioning valve - proportioning is by different sized cylinders from the factory for single circuits. But now you’ve added in a proportioning valve so you can get the necessary proportioning in the rear compared to the front even with same size cylinders. And you can still put a $utt-load of weight in the bed to help compensate (but that’s not for slick road surfaces - a quick way to see where you’ve come from).

You can bench bleed the MC in place too, but you need a wench.

 

[wngrog]

Well hell. That’s the opposite of what my tiny brain was thinking on the wheel cylinder size.

That’s what me and @cruiseroutfit get for trying to outthink Mr Toyota.

I just want the damn thing to stop.

 

[waiting for time]

Pressure is equal through the whole system and a bigger surface will give a bigger force on the brake segments.
As long as the brake segments are the same as in the front the force/surface is bigger with the bigger cilinders.
The idea is that with a smaller MC diameter and bigger WC’s you need less force on the brake pedal at the cost of a longer stroke.

The proportion valve is a good solution to prevent locking rear brakes.

The other issue, having to pump the brakes, is most likely caused by a failling bottom valve (don’t know if this is the correct terminology in English). In a drumbrake system the MC has a valve that holds the brake system slightly under pressure after releasing the brakes. This is not enough to engage the (drum)brakes but it makes sure your system engages at the first touch of the pedal.

Keep in mind that when you pull the handbrake the residual pressure in the system is gone and in most cases the bottom valve releases its pressure. You need to pump the brake to regain that pressure.

 

[wngrog]

This residual pressure you speak of and @FJ40Jim spoke of in another thread.

I was expecting some pressure in the system when I unbolted the main line from the master and there was not even a leak.

If the system kept pressure wouldn’t it flow out when disconnected here?

 

[middlecalf]

Handbrake has nothing to do with drum brakes on early cruisers.

 

[waiting for time]

Handbrake has nothing to do with drum brakes on early cruisers.

Then the residual pressure should stay in.
It looks like a broken MC.

 

[waiting for time]

This residual pressure you speak of and @FJ40Jim spoke of in another thread.

I was expecting some pressure in the system when I unbolted the main line from the master and there was not even a leak.

View attachment 1699501


If the system kept pressure wouldn’t it flow out when disconnected here?

This is not a lot of pressure, just enough to keep the system alert.

 

[wngrog]

This is not a lot of pressure, just enough to keep the system alert.

Well I leaked no fluid replacing the entire line and then pulling the master.

Looks like the master was bad too.

This is why my strategy of tossing new parts at problems tends to work eventually

 

[waiting for time]

A new master should fix it.

 

[FJ60Cam]

Drum brake residual valves are typically ~10 psi, so it stands to reason (in my head at least), that you should have 10 psi worth of brake fluid coming back out of the line when you opened it.

I hope that’s the problem...

...so I can gloat

What’s the history on the master cylinder? @FJ60Cam suggested maybe my residual valve is bad.

 

[middlecalf]

Sorry Nolan - it’s raining this am, so no pasture seeding right now. And shoulder is sore so no shop time right now either. And church in a couple of hours. So you’re stuck with me, lol. For future reference this brake thing needs clarity.

We need to separate your two issues - soft pedal and rear’s locking up first. For the soft pedal, you’re running the table on potential problems as needed - adjustments, leaks, bleeding, etc. That is the path for fixing this problem. Ok choir, you can stop singing now.

For locking up, it’s a proportion issue. Toyota (and others) have done this in the past with different sized brake cylinders for single circuit systems, which is what you have (had actually). So there’s one source of pressure, and that’s the MC driven by the brake pedal, and that pressure is the same to all cylinders assuming no leaks. (There is a fractional delay in that pressure due to hydraulic line length but that works in our advantage because the rear brakes are further than front). We’re not trying to lift more with a bigger hydraulic system, we’re trying to reach a point of minimum pressure at each wheel to achieve sufficient braking power (Toyota says 10psi IIRC) and doing this so the front brakes get there a bit sooner than the rears for stability reasons. So it’s a timing thing. And smaller cylinders will reach that point sooner than bigger cylinders because of the smaller volume of fluid (which is constant unless there is a leak). Sure, the bigger ones can get to more brake pressure on the pads but that’s not needed in a properly designed system which we’ll assume the Toyota engineers achieved 50 yrs ago. What’s needed is proper minimum break pressure at each wheel, and that is fronts (equally) first, than rears. Hence why you had bigger rear cylinders.

Your system is different now with the proportioning valve. That is now your means to achieve front lockup first then rear lockup. Keep plucking on the soft pedal chase first, you’ll get there. Then you and the misses can make a road trip to IderHo and you can help me with my brakes . And I’ll get my large format photo gear out and we can chase pictures of sagebrush at sunrise instead of brake (and other) issues, lol.

I can delete this post if you want. Paul

 

[wngrog]

Man no. This is great. I appreciate all the lessons. One reason I document so much (besides the fact that I like virtual friends more than most people) is so others can learn from my mistakes and wins.

I’ve had a LOT of Land Cruisers and generally the first thing I do is upgrade the brakes to dual master and front discs but the Goat is just too special to do that.

If is not rubber or a fluid I would love to know this truck can turn 100 years old like it rolled off the floor in 1967.

 

[FJ40Jim]

The master cylinder is fine, because it works. A failing MC will leak externally, or it will leak internally, i.e. bleed down when holding the pedal.

I don't have time to read back through the whole thread, but a few things to check:
Are all the ramps on the cylinders oriented correctly? (implicit in this sentence: understand the cylinders have a ramp on one piston, know the correct orientation)
Is the pedal height and pedal free play correct?
Are the shoes oriented correctly?
Have all 3 rubber hoses been replaced?

HTH, I'll check in later.

 

[wngrog]

The master cylinder is fine, because it works. A failing MC will leak externally, or it will leak internally, i.e. bleed down when holding the pedal.

I don't have time to read back through the whole thread, but a few things to check:
Are all the ramps on the cylinders oriented correctly? (implicit in this sentence: understand the cylinders have a ramp on one piston, know the correct orientation)
Is the pedal height and pedal free play correct?
Are the shoes oriented correctly?
Have all 3 rubber hoses been replaced?

HTH, I'll check in later.

Master is fine. The new one changed nothing.

Cylinders are all correct. Rears can only go one way because there are only adjustment slots on one side each.

I found that out the hard way.

Shoes have a thick end that only go on the adjustment wheel of the cylinder.

They are right.

I did reuse springs. They were crazy tight still.

I replaced all the hoses.

Height and freeplay area correct.

The brakes are bled out and the proportion valve is working

The brakes lock up nicely now but I still have one full pump then whammo. Big brakes.

 

[FJ40Jim]

Ramps in the pistons? Some aftermarket pistons don't have the ramps. Are they there? Oriented correctly?

Ramped piston slots have a very noticeable effect on brakes. And it's impossible to get a good adjustment when the ramps are backwards.

 

[wngrog]

Quick recap for @FJ40Jim I adjusted the brakes to full drag and backed off to where they would spin by hand but maybe 1 spin max.

The only thing I have not done is have the drums turned.

I may just learn to live with it now that the rears don’t lock up when the brakes catch and nothing is leaking.


One thing I can’t wrap my head around is the proportion valve.

My brain tells me if I turn it to the right and close the valve I would cut off the pressure to the rear brakes.

Turns out if I loosen the valve completely it dials out the pressure to the rear brakes.

How does that work?

 

[TOMSRYD]

I would think when they burnished in they will be good. If you have to pump the first time they need adustment.

 

[FJ40Jim]

Post some closeup pics of the pistons/slots and the shoes in the slots.