FJ62 Brakes getting stuck (1 Viewer)

[echodeuce]

Brakes are fine for the first 5 minutes or so when I first leave the house. Brake pedal has its usual give and brakes function as they should. After I drive for a bit and it warms up, the brake pedal becomes stiff with no give. Engine is noticeably pushing through what seems to be stuck brakes. I’ll let it sit for a while and back to normal. Once I drive it again, the cycle starts all over again. Thoughts?

 

[g-man]

I'd start by checking the for a vacuum leak at the brake booster, and also the vacuum line going to the booster. My reasoning is that these are things that could cycle from normal to faulty depending on vacuum/vacuum leak.

So no wheel is overheating or smoking? I'm guessing if a brake shoe or pad were stuck ...that it would stay stuck.

 

[poptart]

Check your soft lines. If they're old they can look fine but they'll sometimes swell internally. This basically creates a check valve, lets you push fluid to the wheel cylinders or calipers but it won't flow back.

 

[Dallas Cruiser]

Drive it around until the brakes are sticking then jack up the front end and verify the wheels are hard to turn. With it still jacked up loosen the bolts between the booster and master cylinder, if they release it's in the booster. If they don't release loosen the brake line at the master cylinder to see if the brakes release. If they do the problem is in the master cylinder.

 

[Prairie Swamp]

Check your soft lines. If they're old they can look fine but they'll sometimes swell internally. This basically creates a check valve, lets you push fluid to the wheel cylinders or calipers but it won't flow back.

This. I had a 76 Chevy truck I bought from a family friend type construction company. It started doing this. I said something to Paul who had an immediate answer. His brother Art - self taught fricking genius of all things mechanical - said to look at the flex brake line brackets. He said they rust and therefore thru rust jacking pinches the flex line shut. The master cylinder has pressure to push fluid thru the restriction but the fluid can't find it's way back quickly enough resulting in stuck brakes. Sure enough pried open the rusted bracket problem solved.

 

[Michael Hanson]

Hi, How many miles are on that booster? How old are the calipers? Mike

 

[echodeuce]

Hi, How many miles are on that booster? How old are the calipers? Mike

No idea. I’m the 3rd owner for the past 5 years. Wagon only has 167K miles on it.

 

[EscapeWagon62]

The symptoms are oddly identical to either a poorly adjusted brake booster rod (between booster and master) and/or brake pedal rod/brake switch adjustment issue.
Since you did not mention working on either of those I think the comments regarding backflow sound solid.

 

[echodeuce]

The symptoms are oddly identical to either a poorly adjusted brake booster rod (between booster and master) and/or brake pedal rod/brake switch adjustment issue.
Since you did not mention working on either of those I think the comments regarding backflow sound solid.

Funny you mentioned that. I had the little rubber nipple that presses the rear brake light switch tear. I stuck a nickel in there so the rear brake lights would shut off. I have the rubber piece, I just haven’t installed it yet.

Could that possibly be doing something??

 

[EscapeWagon62]

It absolutely would. My bet is that your pedal rod/freeplay was set based on an old concave brake pedal cushion.
Simple adjustment, loosen the 12mm (or 14 I cant remember) hex nut on the rod and turn the rod counter -clockwise (from the perspective of the drivers seat looking at the firewall.
There needs t be a bit of freeplay in the brake pedal. Without freelay, the brake master engages slightly due to heat expansion of the fluid.
Your first couple brake applications of the day will feel slightly mushy, after that they will be firm.
Simple fix.

 

[rhah]

Funny you mentioned that. I had the little rubber nipple that presses the rear brake light switch tear. I stuck a nickel in there so the rear brake lights would shut off. I have the rubber piece, I just haven’t installed it yet.

Could that possibly be doing something??

Not at all,

mess with the soft lines, had that same penny in there for over 60k miles on my s*** box

 

[archtimb]

If memory serves, and it often doesn't, if it was the push rod the pressure would not subside after sitting for a while. You would need to open a fitting to relieve the pressure and release the shoes.
Maybe, perhaps, waiting could work if the master was going bad.

 

[EscapeWagon62]

If memory serves, and it often doesn't, if it was the push rod the pressure would not subside after sitting for a while. You would need to open a fitting to relieve the pressure and release the shoes.
Maybe, perhaps, waiting could work if the master was going bad.

I've had the situation where the rod was set and brakes were fine until they warmed up then dragged after warmup.
Don't know if that is due to expansion of brake pressure after warm up or expansion of brake components after warm up but either way the adjustment of the pedal rod solved it.
My brake pedal cushion was worn like a bowl and I had the pedal set pretty tight to it. When the cushion failed (and brake lights stayed on since the switch plunger pushed right through the pedal arm) I put in a nicklel, Brakes started dragging day one.
Realistically it was all because I didn't have the correct pedal freeplay set to begin with, the small delta was enough to slightly engage the brake booster.