Originally Posted By: Shannow
When jacked up, are you lifting the axle or the chassis ?
jack right under the pumpkin.
When jacked up, are you lifting the axle or the chassis ?
jack right under the pumpkin.
Rear brakes not working
- Thread starter Chris142
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If you replaced the wheel cylinders and the axle-to-frame hose...and the lines look to be in good condition, then the next logical point to check would be the proportioning valve and the master cylinder.
Did you happen to step on the pedal while the rubber line was disconnected from the steel line...to see if there was a blockage upstream??
A failed master cylinder *should* cause the brake light to illuminate when you step on the brake pedal (even if only on "side" fails).
Did you happen to step on the pedal while the rubber line was disconnected from the steel line...to see if there was a blockage upstream??
A failed master cylinder *should* cause the brake light to illuminate when you step on the brake pedal (even if only on "side" fails).
Originally Posted By: Gary Allan
He gets flow out of the bleeders. Not great, but flow. That should make any restriction merely a time difference. Just like one kinked hose on the front. It pulls one way on application due to slow filling. Then it pulls the other way due to slow releasing.
..but, hey, replace the hose..
While it seems it would work that way, in my experience that hose caused the brakes to not work at all...even though you got fluid, it was insufficient to actuate both wheel cylinders. Remember, fluid flow at the bleeder of one cylinder is actually halved because your filling two wheel cylinders when the bleeder is closed.
I fought with this on my 79 Ramcharger for months before I just by chance started replacing things...while heating up a fitting to disassemble the lines, it blew the hose off the axle "T"...the hose had less than a needle sized hole visible through its interior. If you cracked a bleeder at the wheel cylinder, you would still get fluid...but put the drum on (and even adjusted tight) and you could spin it by hand with the brake pedal applied.
I have since found it on two other vehicles of my own and it has solved several friend's braking issues as well. I now replace all the rubber lines on my Dodge trucks when they get to the 10 year mark.
And again, it was an item that most people (myself included) overlook.
He gets flow out of the bleeders. Not great, but flow. That should make any restriction merely a time difference. Just like one kinked hose on the front. It pulls one way on application due to slow filling. Then it pulls the other way due to slow releasing.
..but, hey, replace the hose..
While it seems it would work that way, in my experience that hose caused the brakes to not work at all...even though you got fluid, it was insufficient to actuate both wheel cylinders. Remember, fluid flow at the bleeder of one cylinder is actually halved because your filling two wheel cylinders when the bleeder is closed.
I fought with this on my 79 Ramcharger for months before I just by chance started replacing things...while heating up a fitting to disassemble the lines, it blew the hose off the axle "T"...the hose had less than a needle sized hole visible through its interior. If you cracked a bleeder at the wheel cylinder, you would still get fluid...but put the drum on (and even adjusted tight) and you could spin it by hand with the brake pedal applied.
I have since found it on two other vehicles of my own and it has solved several friend's braking issues as well. I now replace all the rubber lines on my Dodge trucks when they get to the 10 year mark.
And again, it was an item that most people (myself included) overlook.
Originally Posted By: deeter16317
A failed master cylinder *should* cause the brake light to illuminate when you step on the brake pedal (even if only on "side" fails).
How's that? My BRAKE light is just a simple float in the fluid reservoir that comes on when low.
I think chris should wedge a stick between seat cushion and brake pedal and start cracking banjo bolts and other connections on the lines from the axle forwards. When it sprays like it should the blockage has been found.
A failed master cylinder *should* cause the brake light to illuminate when you step on the brake pedal (even if only on "side" fails).
How's that? My BRAKE light is just a simple float in the fluid reservoir that comes on when low.
I think chris should wedge a stick between seat cushion and brake pedal and start cracking banjo bolts and other connections on the lines from the axle forwards. When it sprays like it should the blockage has been found.
Originally Posted By: eljefino
How's that? My BRAKE light is just a simple float in the fluid reservoir that comes on when low.
The dodge truck master cylinders have/had a piston-type switch in them that would "sense" if one of the "sides" lost pressure.
How's that? My BRAKE light is just a simple float in the fluid reservoir that comes on when low.
The dodge truck master cylinders have/had a piston-type switch in them that would "sense" if one of the "sides" lost pressure.
Today I put on a brand new made in Canada master cylinder. No change! Still no rear brakes.
I am getting fluid out of the rear bleeders.
Heres what I have replaced.
Shoes
Wheel cylinders
Hose
Proportuning valve
Master cyl
I am getting fluid out of the rear bleeders.
Heres what I have replaced.
Shoes
Wheel cylinders
Hose
Proportuning valve
Master cyl
I suspect you still have air in the line, especially after swapping a MC.
Originally Posted By: JackFish
I suspect you still have air in the line, especially after swapping a MC.
Well I bench bled it then ran a qt of fluid through the system with my pressure bleeder while opening each bleeder, RR,LR,RF,LF.
Pedal feels fine, not low or sinking. Just no rear brakes.
I suspect you still have air in the line, especially after swapping a MC.
Well I bench bled it then ran a qt of fluid through the system with my pressure bleeder while opening each bleeder, RR,LR,RF,LF.
Pedal feels fine, not low or sinking. Just no rear brakes.
Checked for TSBs, none found.
I'd say, give Raybestos Tech line a call. They are usually super helpful for situations like this.
I'd say, give Raybestos Tech line a call. They are usually super helpful for situations like this.
There has to be a restriction in one of the lines between the front and rear. A hunk of rust caught in a kink will let fluid pass, but won't give you stopping power.
You can verify this by doing an old fashioned brake bleed. When you open either of the front bleeders, the pedal will drop quickly. When you open the rears, it will drop much less quickly.
(I fixed a problem like this by opening the whole system past the restriction and stomping on the pedal a couple of times. It eventually broke free and blasted out the hole.)
You can verify this by doing an old fashioned brake bleed. When you open either of the front bleeders, the pedal will drop quickly. When you open the rears, it will drop much less quickly.
(I fixed a problem like this by opening the whole system past the restriction and stomping on the pedal a couple of times. It eventually broke free and blasted out the hole.)
Have you tried to recenter the proportioning valve?
Originally Posted By: Steve S
Have you tried to recenter the proportioning valve?
How do I do that?
Today I took it to a shop that we do business with often. They pulled everything apart and the only thing they found was that my drums were slightly past the max diameter.
One was .005 over and the other was .015.
Now......... I have driven a lot of junk that had drums way more oversize than that and they still stopped fine. But I went ahead and put 2 new drums(Chinese of course) on the rear anyway.
I sanded the shoes and put the new drums on.
It may take a few miles for things to wear in since the shoes are slightly used vs new drums. I will report back if it's fixed or not.
Have you tried to recenter the proportioning valve?
How do I do that?
Today I took it to a shop that we do business with often. They pulled everything apart and the only thing they found was that my drums were slightly past the max diameter.
One was .005 over and the other was .015.
Now......... I have driven a lot of junk that had drums way more oversize than that and they still stopped fine. But I went ahead and put 2 new drums(Chinese of course) on the rear anyway.
I sanded the shoes and put the new drums on.
It may take a few miles for things to wear in since the shoes are slightly used vs new drums. I will report back if it's fixed or not.
The rear circuit is sucking air. Just finished a rear wheel brake job on my Grandwag. An earlier version of what you have. I had replace a leaky wheel cylinder to get the system to bleed. Once the system is tight, the prop valve will reset.
Tonight I made a pretty hard stop, got out and felt the drums and they were very hot! The jeep is stopping much better too.
I think I got it licked.
I think I got it licked.
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There has to be a restriction in one of the lines between the front and rear
..but that's just it. A restriction would only result in a phase difference of application, not a lack of total fluid throughput. You have a restriction if one front hose is kinked or swelled internally. It results in a pull in both directions as the application is delayed to one caliper. The unrestricted hose applies its side caliper (limits of motion) and continues to apply the other caliper with the kinked hose. When you let off the pedal, the reverse scenario occurs. The free hose releases the piston, the kinked hose has a slower release.
It would have to be that he wasn't applying it long enough if it was just a restriction.
Normally this would require either the mc to be leaking or the proportioning valve to have some issue. The mc is pretty one dimensional so it points to the proportioning valve not reaching the threshold for applying fluid to the rear circuit. Since it's new, we assume that it's functioning normally.
That said, in both my 99 and 02 ..the rear brakes are the OEM assembly line shoes. 150k and 88k. Adjusting them produced more action with less pedal.
There has to be a restriction in one of the lines between the front and rear
..but that's just it. A restriction would only result in a phase difference of application, not a lack of total fluid throughput. You have a restriction if one front hose is kinked or swelled internally. It results in a pull in both directions as the application is delayed to one caliper. The unrestricted hose applies its side caliper (limits of motion) and continues to apply the other caliper with the kinked hose. When you let off the pedal, the reverse scenario occurs. The free hose releases the piston, the kinked hose has a slower release.
It would have to be that he wasn't applying it long enough if it was just a restriction.
Normally this would require either the mc to be leaking or the proportioning valve to have some issue. The mc is pretty one dimensional so it points to the proportioning valve not reaching the threshold for applying fluid to the rear circuit. Since it's new, we assume that it's functioning normally.
That said, in both my 99 and 02 ..the rear brakes are the OEM assembly line shoes. 150k and 88k. Adjusting them produced more action with less pedal.
Originally Posted By: Chris142
Tonight I made a pretty hard stop, got out and felt the drums and they were very hot! The jeep is stopping much better too.
I think I got it licked.
Still does not explain your original problem; nothing stops a wheel cylinder from traveling all the way. Even if your shoes and drums are completely worn, the wheel cylinder will eventually force the shoes to hit the drum or the wheel cylinders will pop out leaking all the fluid!
Did you have severely glazed shoes? You mentioned sanding the shoes in your last attempt. Was that tried before?
- Vikas
Tonight I made a pretty hard stop, got out and felt the drums and they were very hot! The jeep is stopping much better too.
I think I got it licked.
Still does not explain your original problem; nothing stops a wheel cylinder from traveling all the way. Even if your shoes and drums are completely worn, the wheel cylinder will eventually force the shoes to hit the drum or the wheel cylinders will pop out leaking all the fluid!
Did you have severely glazed shoes? You mentioned sanding the shoes in your last attempt. Was that tried before?
- Vikas
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If you get fluid out both rear bleeders, As unlikely as it is, the only other thing, its crazy to think all for pistons are seized...Its silly to think. Did you do a side by side comparison with the shoes new & old to see if there are any differences? do you have the shoes ajusted for a very slight drag when not applied?
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