Adding Power Brake Capability

[pgtr]

I should add that, while clearly I'm more than satisfied w/ my manual brakes, this hydroboost adaptation is fascinating. I also like the idea of hydraulic actuated clutch on a C3. Thanks for sharing.

 

[norvalwilhelm]

I should add that, while clearly I'm more than satisfied w/ my manual brakes, this hydroboost adaptation is fascinating. I also like the idea of hydraulic actuated clutch on a C3. Thanks for sharing.

I drove my 75 for about 8 years with manual brakes and tried everything to get a better pedal feel and stop using 2 feet to get it to stop. I was totally dissatisfied with the stock brakes. MY son gave me the idea for the hydroboost and being a fabricator i tried a unit from the wreckers and it was so simple to adapt. The firewall accepted it in the stock holes already there.
For the hydraulic master it was another trial and error and a 85 1 ton master was my first attemp and again the existing cover plate in the firewall had the proper size and location of the holes to simply bolt the master cylinder in. All it needed was a remote resovior and I go that from Coleman racing, it was cheap and looks gread, it is under the fender and a piece of brake line to finish the connection to the slave cylinder on the bellhousing.
Try a set of brakes with a hydroboost and you will never go back to manual/vacuum brakes

 

[Vette/Berlina-coupe]

Maybe a case of mistaken identity...

:confused When a Manually-braked C3-Vette owner says it takes both feet to panic-stop, aside from possible excessive hardness of the Brake-pad material, i wonder if someone inadvertantly installed a Pwr.brake/Master-cylinder instead of the necessary Manual-brake/Master-cyl. (which has a smaller internal-bore to net longer-stroke/greater-pressure), --or that possibly the sometimes pesky Proportional-valve for the rear-calipers is not working right; --just something to seriously consider (the part-numbers are clearly cast on the Master-cyls., and would be a reliable reference unless deceptively resleeved to a different bore-diam.).... ~Bob vH

RESPONSE TO BELOW: :nono-well, maybe its ok to omit the Proportioning-valve(P-valve) (yes, -constructed in combination with a "system-failure indicator-switch, and indeed limits max.line-pressure to rear/Brake-calipers to prevent premature lock-up of rear-brakes), although i suspect MrGoodWrench would not install something of the costly sort unless really needed! However, maybe you did something clever like install relatively hard-pads on the rear/Brake-calipers, -which might indeed effectively balance things out more mechanically than hydraulically; --or, maybe you've simply substantially bigger-meat (or substantially lower tire-pressure) on the rear which likewise limits brake-lockup.
The pressure-differential/warning-switch portion of the P-valve is designed to constantly compare F-&-R -Line-pressures applied via the Master-cyl., and thereby instantly activate a Dash/warning-light in event of F-or-R system Hyd.-failure relative to the separate/dual-output portions of the Master-cyl.; -moreover, this special P-valve automatically resets-itself when the system-leak is repaired (when driver applies something like 450-psi line-pressure; --which i'me guessing might be on the order of maybe 75-lbs foot-pressure upon the Brake-pedal, and if someone had their hand on the P-valve one might feel/hear a reset-"click" at that instant). ~Bob vH

 

[norvalwilhelm]

:confused When a Manually-braked C3-Vette owner says it takes both feet to panic-stop, aside from possible excessive hardness of the Brake-pad material, i wonder if someone inadvertantly installed a Pwr.brake/Master-cylinder instead of the necessary Manual-brake/Master-cyl. (which has a smaller internal-bore to net longer-stroke/greater-pressure), --or that possibly the pesky Proportional-valve for the rear-calipers is not working right; --just something to seriously consider (the part-numbers are clearly cast on the Master-cyls., and would be a reliable reference unless deceptively resleeved to a different bore-diam.).... ~Bob vH

The master cylinders are not interchangable. The none power master while having the 1 inch bore also has a deeper hole or cavity in the center for the activation rod to sit in. If a non power master is used on a power assist the rod is too short.
I do not run a proportioning valve, they are also not proportioning valves but switches to turn the light on if one end fails.
Regardless I remove this annoying brass valve and plumb the lines directly.