Coupeman's 33 hot rod

[Coupeman]

I just bought a completed 33 Hot Rod with 11700 miles on the odometer. I have driven it about 300 miles without incident. It all worked great. As I returned from my last trip as I pulled into the garage I noticed a soft brake pedal. Didn't think much about it until I tested it a couple days later. The brake pedal went straight to the floor!!! ( no brakes) No evidence of leaks on the floor, reservoirs are full! There is a minimal amount of resistance at the pedal but is is small. What the heck could the problem be? Anybody got any ideas? Thanks!!

[JimLev]

Any brake fluid on the carpet below the pedals?
Sounds like it possibly could be leaking past the rubber seal inside one or both master cylinders if you don't have any external leaks. Have you looked at all of the calipers and connections where the lines are connected together?

[FF33rod]

Coupeman
Welcome to the family.
The upside is that there's nothing like troubleshooting a problem to get to know the beast a bit better.
An indirect suggestion, if you haven't already, you should get hold of a construction manual. That will give you a better idea of what's under the hood so to speak.

Steve

[JimLev]

Coupeman, put your Location and some car info in your profile like FF33rod and I have. It sometimes help so we won't have to ask many questions.
You may find there is another Factory Five guy close to you that is willing to help you out.

[Coupeman]

Jim; No fluid anywhere, carpet or floor or on the garage floor either. The reservoirs are brim full. Must be an internal valve somewhere?

Thanks!

[NAZ]

No leaks anywhere and the reservoirs have plenty of fluid? Sometimes a leak can be trapped in the push-rod bellows so check that. Then ensure that the M/C pistons are returning all the way home when your foot is off the pedal. If you have to pull the pedal up to the stop, determine what is keeping it from returning on its own. The pistons must be at the top of the stroke to draw fluid from the reservoir.

See Fig-1: https://www.wilwood.com/TechTip/TechPedalTip

[Coupeman]

No leaks anywhere, reservoirs are tip top. Great info from Wilwood. I will check the pedal return !! Sounds like that may be the problem! Thanks!

[Coupeman]

Thanks Steve; I have the manual the guy used to build the car. It has been a great help already. Not so with the brakes though so far.

[FF33rod]

Excellent, good to hear. I don't know that much about the inner workings of master cylinders so I'll let the more experienced in that area guide you. Hope you find it quick and continue enjoying!

[JimLev]

There is a drawing on the cylinder in the link NAZ supplied. It's not that clear.
Here is more info, it's for a clutch, but very similar. Look at about the 4 min mark for the guts of the cylinder showing the piston and seals.
https://m.youtube.com/watch?v=ImRXe1g4iE8