Hard brake pedal

[wehring]

Hey folks. Working on a deuce this weekend. First one in a few years so it has been fun getting back into one. This is a bobber that I made a few years ago for a friend. The brake pedal is hard but it still stops. Searched on here and talked to a few fellow SS. All info pointed to the booster so I changed it out. Also did a full flush of the fluid because it was a mix that had turned to jello.

Here are the current symptoms. Brakes worked fine for the first few times I hit the pedal. After the first few times I use the pedal it gets hard again. After it gets hard I opened the bleeder at the rear tire without pushing the pedal. Fluid shoots out to the leaf spring. After I bleed off pressure the brakes work fine again for the first few tries then it gets hard again.

it feels like releasing the pedal does not release applied pressure.

what say yea???

justin

 

[doghead]

Look into the master cylinder and see if you can see both tiny holes flowing fluid on the pedal return.

They may be plugged or the MC needs adjustment.


I would also remove the J tube on the new booster and be sure it is not leaking air into the booster cyl. Do this with you finger over the tube and see if you get any pressure build up with it running.

 

[wehring]

Good info. Thank you.

Justin

 

[Clay James]

That happened to both my trucks recently. Turned out to be like doghead mentioned. The differential ports were plugged and not letting fluid back in and the brakes started dragging.

 

[wehring]

FIXED - the answer was a little of each input. The small orfice in the master cylinder was obstructed but not by junk. The jello mix of DOT5 and DOT3 made the rubber cup in the master cylinder swell enough to cover the relief orfice so each time the pedal was pressed it added (and maintained) pressure to the lines. I trimmed the edges of the rubber cup to clear the relief orfice when the brake pedal is fully released. good to go.

Thanks all for the input and help.

Justin Wehring
979 997 3112

 

[Clay James]

I would flush the whole system and rebuild the master cylinder in your case. There is no room for error in a single circuit system on trucks this heavy.