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 »

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 »

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.

jon1
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Re: Panhead rear Brakes

#3

Post by jon1 »

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 »

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

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Re: Panhead rear Brakes

#5

Post by Raytag »

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 »

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 »

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 »

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 »

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 »

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 »

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 »

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 »

No lo siento.

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Re: Panhead rear Brakes

#14

Post by jon1 »

Replaced the rubber brake line with the V-Twin replacement, its a little smaller in diameter than the OEM. Bled the brakes, same issue, but maybe a little worse. Going to evaluate the alignment of master cylinder and brake pedal plunger. If that doesn't repair, then probably going to start with the master cylinder and rework back to the rear wheel again.

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Re: Panhead rear Brakes

#15

Post by panheadrider1961 »

Get motorcycle level rear wheel off ground no more than 2 inches , brake system already configured thru design air goes to highest point the wheel cylinder,Take floorboard off and put the size bolt needed back in mount hole with a nut snugged down no play from master cylinder, take off m/cyl cap fill to bottom of threads with fluid place cap back so no trash can get in cyl, loosen lock not on plunger rod making sure it can turn freely,slide rubber boot back turn rod by finger only ,no wrench until you feel it stop when aligned in m/cyl piston hole no more turns in, it should not have any free play at all now back up rod no more than 3/16 or feel free play up and down in piston port, tighten lock nut, turn rear wheel and listen for light scrub sound if to free then follow book directions on turning cams to get slight drag on shoes , get clean glass jar and clear clean hose that will fit bleeder screw fill jar half full of fluid put hose on bleeder screw and put other end in jar , back to m/cyl take off cap ,and look at cap good it does vent making sure the hole is not gummed up , with hand on brake pedal " TICKLE" the m/cyl, you should see either bubbles or light stream of fluid arching into threads if bubbles keep tickling until fluid arches onto threads tighten cap, loosen bleeder screw very good and bleed into jar, no air, tighten bleeder snug and pump brake lever couple of times and let it set for 15 or so minutes then loosen bleeder , bleed again check m/cyl fluid level when you are satisfied no more air in system button it all back up and , i feel the symptom you are describing is saving you and scooter from a accident mine you have to pump slightly also and everything is to spec,drum brakes if not set right and being careful will lock up quickly and throw you out of control hope this helps you

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