Brake problems.. after new pads, shoes, wheel cylinders. (1 Viewer)

[onelesssblues]

I just put in new front pads, new rear wheel cylinders, and new brake shoes.

few things going on here:

Installed just the front pads two days ago. afterwards brakes were spongy, go all the way to the floor, braking was weak.

installed wheel cylinders and shoes yesterday and braking was about the same. I could get the rear to lock up but just barely. Fronts still didnt seem to be doing anything.

I adjusted the rears by everyones advice... opened the shoes until they were barely touching the drums, then backed off two clicks. Ebrake was working while on the jacks... was firm. but when I dropped and drove it ebrake wasnt doing anything, pulled up with ease.

I bled the brakes RR,RL,FR,FL and spent 30 minutes looking for the LPSV until I found out 60s dont have them. Didnt bleed the MC because I never ran it dry while doing the rears, but Im going to do that today. I dont know how to bleed the MC so any help would be great...

I know now I should bleed the brakes RL,RR,FL,FR. Do I do the MC before this or after?

with truck off pumping brake pedal pedal, the pedal gets stiff eventually but still goes to floor, with truck on pumping the brake pedal the brakes get stiff but if I hold the pedal down it slowly keeps sinking further.

looked at the hard lines going into the wheel cylinder now after going out there and pumping brake pedal... not leaking bad at all but there was brake fluid on the underside of the nut that holds on the hard line. Do I have it cross threaded?

Yesterday I didnt see the brake pads moving when friend was pumping the pedal, now this might sound stupid but how much movement should I see? the pads just barely slide in there when I pushed the pistons back. Ill put the front on jacks and have a friend push the brake pedal and see how well they're working. How can I know if the front brakes are working right? Should i just watch the pistons on the calipers and make sure the four on each side are moving when brake pedal is pushed?

Apologize for the length of the post, im trying to be thorough in describing whats going on. If i got the rear brakes to lock up does that mean the MC is doing its job?

Well if you're still reading after all that, thank you and thanks in advance for any help

 

[Rigger]

"but if I hold the pedal down it slowly keeps sinking further."

This symptom indicates a leak. It could also be a bad master cylinder seal, which is simply an internal leak.

"there was brake fluid on the underside of the nut that holds on the hard line."

In other words, a leak. You have fouled the threads, cross threaded it, or the fitting is just not tightened enough.



I'd say you have to start by making sure you don't have any leaks. Once that is done, you have to properly bleed the system.

 

[Tinker]

Spongy pedal = air in line(s) &/or weak M/C. Get a rebuild kit & a good (Snap-On) brake hone - it's an easy job.

If you compressed the front pistons all the way back into the cylinders some of them could be hung up. You won't free 'em until you get the sponginess out. Try rotating the front wheels with the truck on stands & a friend behind the wheel operating the brake - you shouldn't be able to turn the wheels. With the brake off the wheels should turn easily with the pads contacting the rotors no more than twice a revolution.

Back before automatic adjusters for drum brakes (when wheels were square & tires were rock) I was taught to run the star adjuster out all the way so the shoes were tight against the drums. Then you back off until there's just a slight shh-shh when you rotate the wheel.

You could have a cross-threaded coupling or a spongy soft line. You're on the right track & it'll be right when you find everything that's wrong. In the meantime be patient.

 

[japshoff07]

Brake calipers could be leaking. When changing my brakes I noticed mine were so I bought new ones and all is good.

 

[onelesssblues]

If you compressed the front pistons all the way back into the cylinders some of them could be hung up. You won't free 'em until you get the sponginess out. Try rotating the front wheels with the truck on stands & a friend behind the wheel operating the brake - you shouldn't be able to turn the wheels. With the brake off the wheels should turn easily with the pads contacting the rotors no more than twice a revolution.

.

can I pull the pads and have someone pump the brake pedal while I manually free up the front pistons? If not how else do I get the sponginess out... by rebleeding all 4 brakes along with the MC? Ill double check the rear hard lines where they were dripping maybe I didnt tighten em or something but i double checked as i was putting them in to make sure they werent cross threaded.... there wasnt extra resistance or anything, they went in nicely.

If possible could you describe bleeding the MC?

Thanks,
-Dave

 

[onelesssblues]

Brakes were fine before, aside from the fact that I ran the rears so low I blew the left rear wheel cylinder. Thats why I replaced the wheel cylinders, all other hardware in their was fine... guessing PO replaced them at some point because the springs were in good shape. I didnt replace the e clip or horse shoe clip hoping thats not a problem. Why did the e brake work while on the jacks and goof once i dropped it and drove it?
trying to be patient haha, first time doing anything with brakes, I worked on em for 7-8 hours yesterday

 

[RunTrout]

Same thing happened on my GF's 62. We did all the bleeding, but the brakes were still very spongy and required active pumping to stop quickly. Shop diagnosed bad master cylinder. After the MC was replaced the 62 stops very well. good luck!

 

[RunTrout]

Also, the e-brake cable is probably stretched when the truck is jacked up (ie tight and functioning), and probably loosens when the truck is sitting on its wheels. Maybe adjust for the current ride height?

 

[RunTrout]

Also, if the cylinder is stuck, I would not expect the pedal to be spongy (actually I would expect the opposite). If the main seal in the MC is shot, then you would be losing pressure as you try to build it up, which would give a spongy feeling. I'm no expert, It just sounds exactly like what my GF's truck was doing before the new master. It was pretty cheap to have replaced I believe.

 

[onelesssblues]

thanks for the help guys, I bled the MC and rebled all 4 brakes that helped... I was able to fix the rear too, Im guessing what was going on is the back left drum was really warn down and really ought to be machined, it has a big ridge from running the brakes down too far. I think the shoes had to settle into place because I would adjust the shoes until lightly touching, go drive it come home and they would need to be adjusted out further, i adjusted them drove, repeated once more and now they are finally in place and staying, e brake is at proper 7-9 clicks till tight. Thanks for the help!

 

[kling-on]

I had the same thing going on with mine... After looking and looking I gave up and just bought a new master ... And found out it was leaking into the booster ... That's why I couldn't find it, also took out my booster. I would unbolt the master and see if there is fluid back there

 

[onelesssblues]

I had the same thing going on with mine... After looking and looking I gave up and just bought a new master ... And found out it was leaking into the booster ... That's why I couldn't find it, also took out my booster. I would unbolt the master and see if there is fluid back there

Thanks ill have to check that... maybe in a week or so. my hands are too sliced and cut up from the last job to deal with that right now

 

[dbleon]

Didnt read whole thread, but sounds like a leak at cylinder or elsewere in the system.

 

[dwillmo]

If you mash on the pedal and it goes slowly to the floor, the MC is bad. If the pedal is just spongy then there's air in the lines somewhere.

 

[Freewheel]

Ditto on Master cylinder replacement.

It is possible to damage your (previously working) master cylinder when you bleed your brakes. If you let your pedal go further toward the floor (with the bleeders open) than it did when the system was closed, you can push the MC piston further than it's normal travel - With a new MC that's OK, with an old one you end up pushing the piston into the rust and pitting often found at the end of an older cylinder, thus wrecking it.

Hopefully that's not what happened, but your description of the pedal going right to the floor is worrying me a bit...

( And definitely check your brake booster for fluid if you have been losing fluid and can't figure out where- I found about 1/3 liter in mine)

 

[thadl]

same problem here...been working on them for a couple of weeks now...have replaced the mc, both front calipers & pads, rear shoes, wheel cylinders, turn the drums and have replaced the e-brake cable...my brakes still go to the floor after bleeding them time and time again...bench bled the mc...not sure what to do next except go inside and grab a cold beer and get on MUD...help, what am i not doing or doing wrong

 

[DrivingMissRosey]

Ditto on Master cylinder replacement.

It is possible to damage your (previously working) master cylinder when you bleed your brakes. If you let your pedal go further toward the floor (with the bleeders open) than it did when the system was closed, you can push the MC piston further than it's normal travel - With a new MC that's OK, with an old one you end up pushing the piston into the rust and pitting often found at the end of an older cylinder, thus wrecking it.

Thats what I did to mine. Now I have a brand new master and hopefully that fixes the issue.

Does anyone know how to bench bleed a new MC?

 

[thadl]

Thats what I did to mine. Now I have a brand new master and hopefully that fixes the issue.

Does anyone know how to bench bleed a new MC?

Make up some lines that run back into the reservoir, fill the reservoir and depress the piston until you have both lines flowing with no air bubbles. I had to pinch off one line that was flowing to force fluid thru the other line then released the pinched line and pumped til both were flowing. I used clear tubing I was using to bleed my brakes. Worked great.

 

[onelesssblues]

I ended up not having to replace the master cylinder. the rear shoes had to settle into the grooves that were formed by excessive wear in the drums. it took a few days but they stiffened up. I did bleed the MC RR,RL,FR,FL.

 

[Dynosoar]

Bleed order should be MC, RL, RR, FL, FR Always go from the farthest away to closest. If you look at how the lines run you will see which is the greatest distance.


Dynosaor