Panhead rear Brakes

Fast Pedal , no brakes, slow pedal great brakes.

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jon1
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Panhead rear Brakes

#1

Post by jon1 » Mon Oct 28, 2019 9:49 pm

Here is my dilemma, I have wonderful front and rear brakes 95/97 % of the time. I want 100%.
My rear brakes work great when normal braking, like slowing down to make a turn, up coming stoplights and decreasing speed.
The issue presents when I need to stop quickly, if someone short stops, or too far from changing light. I have full pedal, but it feels like no pedal or fluid moves when I quick depress the pedal.
Today I took a ride and tested the theory and 100% of the time, if I quick hard pressed the foot brake, it was like the pedal didn't move or respond, however slow pedal, great brakes every time.
I do not see anything binding or loose at the pedal or master cylinder, and I changed and flushed the brake fluid.
So, I need better brains to lead me in the right direction....Thanks in Advance....Jon



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Re: Panhead rear Brakes

#2

Post by Sarre » Mon Oct 28, 2019 10:05 pm

Don't know if I can supply the specific brainpower, but I'll give it a try;
jon1 wrote:
Mon Oct 28, 2019 9:49 pm
Today I took a ride and tested the theory and 100% of the time, if I quick hard pressed the foot brake, it was like the pedal didn't move or respond, however slow pedal, great brakes every time.
If you hard press the pedal, do you immediately release it or do you keep it pressed down? If the latter, is there a delayed response?

Hydraulics: So the pressure has 3 options:
- It is not transferred to the liquid (i.e. leak)
- It is absorbed by air in the liquid, a "sumpy" brake gives the idea like you do not apply pressure on the brake while you are operating the brake.
- It is not transferred to the piston (i.e. leak)

After that its mechanical again, area of contact between pads/lining and drum OK? No grease inside the drum on the brake surface? Rough up the brake pads/linings.

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Re: Panhead rear Brakes

#3

Post by jon1 » Tue Oct 29, 2019 12:52 am

Nothing wet around brake system that I see.
As to the question, if I continue to press hard, yes it will transfer fluid to the shoes. but not like a slow steady applied pressure. more rapid release, but not instant, and sometimes a tire slide. again, nothing spongy, very hard like the pedal is bound.
I think I might have a bad rubber final hose, or maybe a flap of rubber in that final hose that flips down on quick pressure???
Has perfect brakes on a slow steady pressure, pedal feels perfect in slow scenario.

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Re: Panhead rear Brakes

#4

Post by Buddhahoodvatoloco » Tue Oct 29, 2019 1:36 am

The hose is culprit, it's balloing I bet. :lol:

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Re: Panhead rear Brakes

#5

Post by Raytag » Tue Oct 29, 2019 6:03 pm

Is the brake lever rocking bad from the right to the left cause of a worn out bushing ?

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Re: Panhead rear Brakes

#6

Post by jon1 » Tue Oct 29, 2019 6:36 pm

no left or right movement, Everything feels good and tight as the brake should. the only issue is on quick hard braking. going to replace the rubber portion of the hose. ill give update if this fixes.
Thanks for the suggestions.

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Re: Panhead rear Brakes

#7

Post by RooDog » Tue Oct 29, 2019 7:02 pm

If your master cylinder and wheel cylinders' rubber parts are in good shape, then the hose is the only other degradable item in the hydraulic system. It's worth looking into.

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Re: Panhead rear Brakes

#8

Post by Andygears » Tue Oct 29, 2019 9:56 pm

RooDog wrote:
Tue Oct 29, 2019 7:02 pm
If your master cylinder and wheel cylinders' rubber parts are in good shape, then the hose is the only other degradable item in the hydraulic system. It's worth looking into.
I’m thinking one piston sticking in the wheel cylinder, gives you half the breaking swept area, or the hose.

Andygears

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Re: Panhead rear Brakes

#9

Post by white1j0 » Wed Oct 30, 2019 12:58 pm

I had the same problem on a '78 Shovel I bought off a co-worker of mine about 40 years ago, I had it in the shop numerous times no one could fix it, it turned out that the previous owner had dumped it quite a few times and the backing plate for the master cylinder was bent and the push rod was going in crooked,I straitened it out problem was fixed, what was happening was when you jammed on the brake the push rod was tweeking the plunger.

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Re: Panhead rear Brakes

#10

Post by Raytag » Wed Oct 30, 2019 2:01 pm

white1j0 wrote:
Wed Oct 30, 2019 12:58 pm
... and the push rod was going in crooked,I straitened it out problem was fixed, what was happening was when you jammed on the brake the push rod was tweeking the plunger.
Experienced the same except for the bushing of the lever was worn out and the lever wasn`t true with the plunger/piston anymore. The ball-type seat in the piston was buggered up by the plunger with burrs and the piston moved rocky when pushed in. Subsequently I`ve had to hone the masterbrakecylinder, install new piston, polish the plunger, install a new bush. The hole for the spring in the bracket was elonged by the spring too :?

Just a bit of negligence on myside for maybe 20.000mls and I got punished that hard, not nfair :lol:

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Re: Panhead rear Brakes

#11

Post by RooDog » Wed Oct 30, 2019 6:25 pm

Raytag wrote:
Wed Oct 30, 2019 2:01 pm
white1j0 wrote:
Wed Oct 30, 2019 12:58 pm
... and the push rod was going in crooked,I straitened it out problem was fixed, what was happening was when you jammed on the brake the push rod was tweeking the plunger.
Experienced the same except for the bushing of the lever was worn out and the lever wasn`t true with the plunger/piston anymore. The ball-type seat in the piston was buggered up by the plunger with burrs and the piston moved rocky when pushed in. Subsequently I`ve had to hone the masterbrakecylinder, install new piston, polish the plunger, install a new bush. The hole for the spring in the bracket was elonged by the spring too :?

Just a bit of negligence on myside for maybe 20.000mls and I got punished that hard, not nfair :lol:
Alignment between the pedal, pushrod and the center line of the master cylinder is important. Seemingly a little known fact is that there are two spacer washers, about 3/16" thick, that go between the MC and the mounting plate/bracket, PN 50668-35, used with all iron MCs from Wagoner. Perhaps this will help....
....RooDog....

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Re: Panhead rear Brakes

#12

Post by Buddhahoodvatoloco » Wed Oct 30, 2019 9:40 pm

Showing off now, shame on you. :lol: :lol: :lol: :lol:
RooDog wrote:
Wed Oct 30, 2019 6:25 pm
Raytag wrote:
Wed Oct 30, 2019 2:01 pm
white1j0 wrote:
Wed Oct 30, 2019 12:58 pm
... and the push rod was going in crooked,I straitened it out problem was fixed, what was happening was when you jammed on the brake the push rod was tweeking the plunger.
Experienced the same except for the bushing of the lever was worn out and the lever wasn`t true with the plunger/piston anymore. The ball-type seat in the piston was buggered up by the plunger with burrs and the piston moved rocky when pushed in. Subsequently I`ve had to hone the masterbrakecylinder, install new piston, polish the plunger, install a new bush. The hole for the spring in the bracket was elonged by the spring too :?

Just a bit of negligence on myside for maybe 20.000mls and I got punished that hard, not nfair :lol:
Alignment between the pedal, pushrod and the center line of the master cylinder is important. Seemingly a little known fact is that there are two spacer washers, about 3/16" thick, that go between the MC and the mounting plate/bracket, PN 50668-35, used with all iron MCs from Wagoner. Perhaps this will help....
....RooDog....

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Re: Panhead rear Brakes

#13

Post by RooDog » Wed Oct 30, 2019 11:50 pm

No lo siento.

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