dragging brakes, please advise.

[hughjazz]

Hello again.

Had this thing less than a month and having lot's of p.o induced issues

Ok, Firstly I did search the faq and tech section. No dice.

It's a 1969 fj40

I have a REAR brake conversion on my truck, front's are drums still.
The p.o also put on a 4runner master cylinder.

According to him he ran the disc side of the m/c to the rear, and the drum side to the fronts. I don't know. I haven't owned a toyota 4x4 for 12 years.

I am rusty on the tech,

Anyway, The brakes worked absolutely flawlessely for about 500-600 miles. Even on the most slight incline it would roll freely.
Stopped straight, good pedal feel.

Tonight as I was cruisin' part way through the drive my pedal felt noticeably firmer, felt like the brakes were engaging even with the slightest travel of the pedal. where it used to have 2-3" of free play at the top. And like I said , to stop the truck it took much more effort than before. At the lights it was obvious that one or more of the brakes were dragging. It wouldn't roll on hills without letting out the clutch. felt slower etc.

So I get home and check the front brakes, (drums) and they roll pretty good, hubs were lukewarm.

The rear brakes were tight, and the rims were HOT the caliper was discoloured slightly:whoops:.

I found the line on the m/c that went to the back, and loosened it and the wheels rolled free again. tightened it up and duplicated the results. So it seems to be a M/C problem to me.

I have included a couple of pics of the M/c and what I believe to be a booster.

The rear lines run straight from the M/c to the calipers.
The front lines run from the M/c to the Booster? then to the drums?

WTH is that about? The booster is off to the side not connected to the M/c It's connected to a big vacuum line on the manifold.

Please help.

Residual valve?
If so How can I remove it?
suggestions?

 

[65swb45]

Thot. Considering it is now the middle of summer, maybe it's a heat-related problem. Line or lines too close to the exhaust warm and expand the fluid.

Second thot. That conversion is scary, and perhaps a 'higher force' is trying to get you to park the truck until you can afford to put a better system on the truck.

Best

Mark A.

 

[hughjazz]

Thot. Considering it is now the middle of summer, maybe it's a heat-related problem. Line or lines too close to the exhaust warm and expand the fluid.

Second thot. That conversion is scary, and perhaps a 'higher force' is trying to get you to park the truck until you can afford to put a better system on the truck.

Best

Mark A.

Yeah, is that booster stock? Never seen anything like it.

Like I said, until tonight it was stopping flawless. (pavement)

Also I'm game to convert all 4 to disc, like I said I'm new to toyota tech, more of a fullsize diesel guy, I can do the tactile work. I can use the tools, I Just have no Idea about the proven swaps and upgrades. LOL this truck was 7 yrs old when I was born
-So Is there a common consensus as to which is the best kit for the front
-Redo the rears with known pieces?
finally M/c and booster,,, which ones to use? Will a booster from another truck work?

I want to do this right, but only 1 time too.

 

[idcruiserboy]

master cylinder

it may be the m/c rod that connects to the brake pedal. it may need to be backed off a bit.

I had the same problem.

adam

 

[FJforty]

It looks like there is a line from the MC to the booster valve to me (picture) but anyway the rear brakes are the issue. Brake rod freeplay, you might want to do a search, we have covered that pretty well. Do you plan to keep that booster thing? What does it hook to?

 

[hughjazz]

No that booster is going in the trash.


It is bolted in place,
It has a 1/2" vacuum line
1 line in
1 line out

That's it.

Maybe ok for the old single circuit days


I'm going to get a mc/booster from a minitruck, or a bj60
And redo everything.


I ordered a new rear rubber brake line too as well as new 10 mm
hardlines for the rear axle.

 

[Fast Eddy]

I'm new to toyota tech, more of a fullsize diesel guy... this truck was 7 yrs old when I was born

No that booster is going in the trash.

I'm going to get a mc/booster from a minitruck, or a bj60
And redo everything.

I ordered a new rear rubber brake line too as well as new 10 mm
hardlines for the rear axle.

Maybe a newb, but wise. Welcome.

 

[hughjazz]

Ever wanted to choke your previous owner?

Well I think I have it figured out.


As I removed the wheels to check the rear calipers, I realized the braided lines were run straight from the hard lines to the braided flex lines with no tie down. Plus the drivers side was 8" too long.

So I
1.replaced the hard lines, to 10mm from the M/c to the calipers.
(the rubber line is on order)
2. Made up some mounts for the axle hard lines to the caliper flex lines
3. Backed off the rod from the pedal to the M/c and found the problem.

The rod was itself was too short. So instead of finding a longer rod, The P.O put in a 1/2" piece of ready rod or bolt to allow the pedal to work.

Know what I mean?

There was a little piece of metal in the "cup" of the M/C where the rod goes. It was there to enable him to use the original rod. (no proper booster)

WHAT AN IDIOT!!

It hard enough to keep a 41/yr old truck reliable without some dipsh^^ trying to sabotage it as well.



I am going to have to be real vigilant with the things he touched.

And put a rush on the front disc/axle rebuild.


Rant over.