Difficulty braking

[John_parkeriv]

So, I finally got my project '66 up and running, and quickly realized the brakes do not work as intended. They work fine after pressing the brake to the floor a few times, almost like I have to prime my brakes.it's not too bad just driving it up and down my own road, but I think this is something I should get fixed before I take this out on the highway .

Anybody have any fixes for this?
Thanks!

 

[thegreatjustino]

Air in the lines. Need to bleed the system.

 

[B RON CO]

Hi, first, what you have done so far.
Did you pull each brake drum, inspect the wheel cylinders, no broken or missing springs, and the small primary shoe to the front?
While the front drums were off you can make sure the wheel bearings get packed.
If everything looks good you should be able to adjust the brakes and go.
Good luck

 

[Broncobowsher]

Adjusting the shoes would be my first stop. Not knowing the history of your Bronco, what has or has not been done. Sounds like this may be the first time you drove it, maybe since you got it and it had been sitting a long time? Maybe one of the reasons it was parked was the brakes needed work.

 

[John_parkeriv]

Hi, first, what you have done so far.
Did you pull each brake drum, inspect the wheel cylinders, no broken or missing springs, and the small primary shoe to the front?
While the front drums were off you can make sure the wheel bearings get packed.
If everything looks good you should be able to adjust the brakes and go.
Good luck

the entire system's been redone, new master cylinder, new shoes, new springs, new brake lines, the works. They've also already been bled and adjusted...

 

[73azbronco]

Adjusting the shoes would be my first stop. Not knowing the history of your Bronco, what has or has not been done. Sounds like this may be the first time you drove it, maybe since you got it and it had been sitting a long time? Maybe one of the reasons it was parked was the brakes needed work.

This, right after pulling each hub to verify no leaks at each wheel brake cylinder.

Then, you have air, need to bench bleed the master, then the brakes.

 

[73azbronco]

the entire system's been redone, new master cylinder, new shoes, new springs, new brake lines, the works. They've also already been bled and adjusted...

This, been over 10 years, all new cylinders and master. All of this less than $100, just buy the best ones, dont get cheapest.

 

[DirtDonk]

Sounds like it could also be a defective master cylinder. But plenty of things to check first.

the entire system's been redone

Just recently? By you, or a shop? If a shop, did they specialize in older vehicles, or are just a regular shop?

new master cylinder

Stock single reservoir master, or dual/tandem master?

new shoes

Do you know for sure if there are primary and secondary shoes, and if they were installed with the primary shoes in the front position at each brake?

They've also already been bled and adjusted...

This is the part that is concerning. If it bled well, and it still acts like it's either got air or a worn out piston seal, then it might be harder to track down.
Did you do the bleeding? Does it have a firm pedal with the first pump while sitting?
And how tight are the brakes adjusted? Do they scuff/rub the drum pretty good? To the point that you can feel a slight resistance when turning the tire with it up in the air?

At this point it would be good to know if there are primary shoes where they should be. This actually does help a lot with the pedal feel. Not having one does not necessarily mean you will have bad braking, and it normally would not give the symptoms you site. But it's still worth checking.

Good luck!

Paul

 

[John_parkeriv]

Sounds like it could also be a defective master cylinder. But plenty of things to check first.



Just recently? By you, or a shop? If a shop, did they specialize in older vehicles, or are just a regular shop?



Stock single reservoir master, or dual/tandem master?



Do you know for sure if there are primary and secondary shoes, and if they were installed with the primary shoes in the front position at each brake?



This is the part that is concerning. If it bled well, and it still acts like it's either got air or a worn out piston seal, then it might be harder to track down.
Did you do the bleeding? Does it have a firm pedal with the first pump while sitting?
And how tight are the brakes adjusted? Do they scuff/rub the drum pretty good? To the point that you can feel a slight resistance when turning the tire with it up in the air?

At this point it would be good to know if there are primary shoes where they should be. This actually does help a lot with the pedal feel. Not having one does not necessarily mean you will have bad braking, and it normally would not give the symptoms you site. But it's still worth checking.

Good luck!

Paul

It was finished just this week, did it myself because of the whole quarantine thing, stock single reservoir, yes I know there are different types of shoes and I put them in the same direction they can out in.

It may just need to be bled again, maybe while blessing the master cylinder ran to low and air got in...

 

[DirtDonk]

Very possible. Might even need to bench bleed it if it does not cooperate.

But I wonder, maybe the shoes just need to be adjusted up tighter than they are? Seems possible.
Not sure if this is a legit test of this or not, but how do the brakes act if you drive with the parking brake applied one or two clicks?
In fact, how many clicks does it take to set the parking brakes anyway?

After all the work you did, I hope it ends up being a simple fix.

Paul

 

[AC932]

Kinda out there, but are the backing plates on the correct sides? Dunno if that's even possible on these trucks, but on our T-bird, "the guy" we had restore it put the backing plates on the wrong side, so the automatic adjusters were constantly un-adjusting themselves.

 

[SS396]

Might want to check if your master has a residual pressure valve and if it is working correctly. I’ve had a few new master cylinders without proper residual pressure to keep shoes from retracting entirely. Easily solved with installation on an in-line residual pressure valve. Symptom of this issue is having soft pedal on first press but firming up on second.