Hi all When building this sedan for my friend frank, We used ford 1939 front and rear brakes, all renewed, Wilwood proportioning valve Master cylinder is a 1'' bore, this one : http://www.speedwaymotors.com/Dual-Feed-Master-Cylinder,1985.html And after 3 times adjusting the shoes and 3 bleedings,, the pedal is still super soft...you have to pump 1 to 2 times before you can stop... Do I have to bleed again? master cylinder isn't the good one? Any ideas? Many thanks for your help
Three bleeds on a new system may not clear the air if there is some trapped in the fittings or high points of the lines. Open the valve all the way then adjust it later for correct brake bias. Did you bench bleed the master? If the master is under the floor did you install 10 lb residual valves? Is the master getting enought stroke? Is the pedal ratio correct? There are a bunch of threads about brake setups and bleeding you might want to do a quick search.
Did you check to make sure the pedal can fully stroke the master? Do you have the front axle plumbed to the primany (larger chamber) outlet? Are you sure the brakes are adjusted properly? A prop valve should not be necessary with the '39 brakes, but if you keep it in the system, turn it through it's enrire range while bleeding the rears, then leave it adjusted full "in" to start with, which should allow full master pressure up to the valve limit of around 1000 psi. What is needed are residual valves. Check the master for internal valve(s), and add if necessary 10 lb valves to each axle. Make sure all fittings and connections are tight. The technique when bleeding can sometimes be the problem. You want to slowly and fully stroke (not pump) the pedal while bleeding each cylinder. (the pedal MUST full stroke the master BEFORE the pedal hits the floor!) It's best to use a 3' or so length of clear Tygon tubing pushed over the bleeder, coiled up slightly higher than the cylinder, and then empting into a container. This allows several inches of good visual of the flow of fluid and air coming out of the bleeder. The bleeder should only be opened enough to have a slow steady flow, and then shut when the pedal bottoms out. The person stroking the pedal should hold it down until the bleeder has been closed. Good communication between the pedal pusher and bleeder is important. When some pressure can be developed, do a leak check by applying high (max) pedal force. If the pedal remains solid and does not move to the floor, and there are NO leaks or weeps, repeat the bleeding process two or three more times per wheel until only clear fluid comes out of each bleeder. And it doesn’t matter which wheel or system is bled first on a dual system. Just check the fluid reservoirs often. Use isopropyl alcohol to clean all the connections, fittings, as well as tools and spillage on the vehicle and your hands. Using a spray bottle makes it very convenient. You will find the alcohol makes finding leaks and weeps much easier, and does a great job cleaning up fluid messes.
Try bleeding every fitting working away from the master cyl. after a bench bleed. Make a mess. Personally I'd: - Ditch the Wilwood proportioning valve. - Bench bleed (You could do it mounted in the car) - Bleed each cyl. unitl bubbles stop coming out a submerged tube off the bleeder.
The 1 inch bore mastercylinder is not big enough for those brakes, try a 1 1/16" and you don't need a proportioning valve.
The prop valve isn't completely neccesary, but It shouldn't be making the pedal soft. To me it sounds like you need residual valves, and you might still have some air in the system. I personally like to pressure bleed systems with a pressure pot.
39 brakes,...Have an adjustment on the anchor pins...(bottom of the shoes) And this must be done correctly, before adjusting the cams ("upper" adjustment) The Ford shop manuals go thru this in detail. They refer to it as "Major Brake Adjustment". 4TTRUK
Nice car, Now throw away that proportioning valve, early Ford brakes require adjustment to index the shoes to the drums. If you have bled the brakes and they require a pump up to seat, its pretty sure that you dont have the brake shoes in correct adjustment and they are retracting too far. There are a couple posts in the search section that will detail the operation. V8 Bob is pretty sharp with his brakes so read his post also as I have seen people that think pumping the brakes real fast is the way to get the air out, not so all it does it trap more air.. If you still cant find the brake adjusting instructions post back and I'll go over it .
Thanks to you all! very helpfull, we will bleed and re adjust with the original instructions.. If not working, ditch the wilwood prop. and so on...
OK, end of the story, the brakes are working and working good! I first try to bleed the master cylinder alone, and even more bleed... no result 2- add the valve residual, no change... 3- Ditch the Wilwood prop. OURA, it worked! Thanks again for your help guys
im suprised that the 1" master pushes enough volume through the lines for those wheel cylinders. should give you better stopping power, but how much travel do you have?
less than 1 inch play at the pedal and very firm after 1 to 1.5 inch, it brakes like a normal regular car at the moment, will go to the inspection and check for balance left to right and front to rear, will tell you more after that ;-)
comme quoi en pensant bien faire avec une proportionning valve, c'est pas forcement mieux!!! je m'en rappellerai quand je ferais les ligne du roadster!!!
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