I can't drive 55

[island45]

What PB4ugo said in #416....I've had the delaminated brake hose twice. The bubble works like a check valve. Did you re-use the rubber hose when you replaced the caliper, and is it just one side getting hot or both? Yer definately onto something.

 

[pb4ugo]

If its both calipers it could be the soft line going from the frame to the axle or the adjustment rod between the master and booster. The latter would likely show itself if the master has recently been replaced. I think the lack of rod adjustment with a new master would effect the rear brakes too.

 

[hobbes]

Residual valve removed from the master brake front circuit if its a drum brake master cylinder?

 

[Pighead]

Residual valve removed from the master brake front circuit if its a drum brake master cylinder?

good question

 

[MatthewMcD]

Actually, jack up the wheels b4 the test drive 1st and see how easily they spin, then check them after the test drive also. You might have a sticking caliper or 2. If they're both drsgging then it could be the rod between the master and booster, as 45Dougal mentioned. It could be the soft lines too. As the rubber deteriorates over time, there can be delamination internally in the rubber line and a bubble can form inside it and restrict fluid from returning back to the master cylinder keeping the brakes on.

The exterior of the rubber lines is "not great" like most of the rubber on every other part of the truck. Is there a way to diagnose the issue without wholesale swapping the lines for new ones? (It's on my list...)

 

[MatthewMcD]

What PB4ugo said in #416....I've had the delaminated brake hose twice. The bubble works like a check valve. Did you re-use the rubber hose when you replaced the caliper, and is it just one side getting hot or both? Yer definately onto something.

I did not replace the rubber lines when I did the brake job. I'll check the hubs after another drive.

 

[MatthewMcD]

good question

Yes, as far as I know there is no other valve in the system. It's a 2-reservoir master.

 

[Pighead]

Yes, as far as I know there is no other valve in the system. It's a 2-reservoir master.

Those residual valves are little plastic bits that are inside the brake master where the brake lines threads in, you can't see them from the outside...

 

[hobbes]

If the master is prior to 1976, it is setup for drum front brakes. When switching to disks, the master needs to be swapped or the residual valve needs to be removed from the front circuit or the brakes drag.

Removing the valve is simple.

 

[MatthewMcD]

If the master is prior to 1976, it is setup for drum front brakes. When switching to disks, the master needs to be swapped or the residual valve needs to be removed from the front circuit or the brakes drag.

Removing the valve is simple.

I replaced the master back when I did the rear brakes. How can I tell if the valve is present?

 

[pb4ugo]

Do you recall what master you purchased?
Was it for your 75 40 or was it for disc brakes in the frt? How long ago did you replace it?

If the master was replaced recently, I'd 1st adjust the rod between the master and booster. You can probably buy a tool a parts store or make one.

 

[pb4ugo]

If the rod is putting pressure on the masters piston it will slowly build pressure each time you use the brakes and wont totally release all the pressure and make them drag.

 

[hobbes]

I replaced the master back when I did the rear brakes. How can I tell if the valve is present?

Easiest way is just to check the P/N. If you used 47201-60050 it is probably fine. If you don’t know, you’d have to remove the fitting on the front circuit.

Brake Master Cylinder for '76 to '80 Land Cruiser FJ40 BJ40 FJ55

Brake master cylinder for 9/'75 to 7/'80 Toyota Land Cruiser FJ40 FJ55 BJ40 with front disc and rear drum brakes. Equivalent to OEM number 47201-60050. Note: Brake pressure warning switches are not included. Either reuse existing ones or buy new separately. If your Land Cruiser has been...

www.cityracerllc.com

 

[MatthewMcD]

Easiest way is just to check the P/N. If you used 47201-60050 it is probably fine. If you don’t know, you’d have to remove the fitting on the front circuit.

Brake Master Cylinder for '76 to '80 Land Cruiser FJ40 BJ40 FJ55

Brake master cylinder for 9/'75 to 7/'80 Toyota Land Cruiser FJ40 FJ55 BJ40 with front disc and rear drum brakes. Equivalent to OEM number 47201-60050. Note: Brake pressure warning switches are not included. Either reuse existing ones or buy new separately. If your Land Cruiser has been...

www.cityracerllc.com

I was in a hurry. This is what I installed:

https://a.co/d/6l8CTZL

 

[hobbes]

That resolves to a 1975 master. I think those were disks.

I’d just go for a “fast drive” using your brakes minimally. Pull over and hit all 4 wheels with an IR gun. See how symmetrical the temps are. They should be cool if you didn’t use the brakes much.

 

[peesalot]

I bet dimes to donuts the pistons are sticky in the calipers and they are draging. If you power washed it and hit the calipers or drove in snow that can cuase them to rust up

 

[pb4ugo]

75 is 4 wheel drum.

 

[MatthewMcD]

I bet dimes to donuts the pistons are sticky in the calipers and they are draging. If you power washed it and hit the calipers or drove in snow that can cuase them to rust up

They are pristine clean, brand new calipers with less than 50 miles on them

 

[MatthewMcD]

75 is 4 wheel drum.

Right, but as I said earlier, this truck has a mini-truck conversion in front. Discs in front, drums in back.

 

[knuckle47]

@MatthewMcD did you find it necessary to use a rear brake proportioning valve or is there none?