Try to explain this fast-1929 Model A Special. 1939 Ford truck brakes in front with new wheel cylinders. 10-bolt Chevy axle/brakes (drum) in rear. Correct lb. residual valves before and aft, proper distance from master. Master is after market oval Corvette style mounted backwards. Not losing fluid and all brakes adjusted and bled. I've always had to pump brakes to get it to stop-****s/dangerous!! Before I go and replace front drums/shoes, my question is......... Does it matter if the reservoir in the master closest to the piston being pushed in is plumbed to the front??? Both chambers in master are the same size-but I'm wondering if my brake lines need to be swapped. HELP!!!!!!!!!!!!!!!!!
not sure about the front to rear fittings,( but i think you have it correct) i fought and fought a brake system not to long ago and turned out i had the wrong plunger rod, was not depressing all the way and getting all the air out,,,
if its a true vette master its not gonna work as they were disc disc. get one for a 72 maverick drum drum and try that.
only way to remove air trapped in some systems is use a method that moves the fluid fast enought and long enought that the trapped air bubble is removed from the system............
Brake shoes out of adjustment or the master cylinder is simply not moving enough fluid. The second stroke is adding volume, which it apparently needs.
Man guys you're dead on with symptoms-that's what it feels like-not enough VOLUME of fluid being pushed. They are all adjusted with a little drag on the drums. And they seem to bleed out well. the first pump is like ***s on a boar-But by the second or even third pump, the pedal is good, holds and stops car. Maybe I got a cheap *** MC and it just can't get enough fluid out there!?
Im running juiced 42's on my '29 and they have mild pedal first, and strong on second pump. I dont have an issue with that. light drag. Drums back off mopre than discs you're used to driving,nothing to be scared about.
I hope I dont upset you but thats not good advice. If your brakes arent working properly on the first pump there is an issue and it needs to be fixed. You need a master cylinder that is designed to work with drums, not discs.
I had same probllem, tried everything, turned out it was pedal ratio,changed brake pedal to correct length...wala
there's still something wrong,,, would you find it acceptable to have to turn the steering wheel half a turn, then back to center and then turn again to change direction? Not trying to be an *** (first time for that) but you've got an issue that needs a remedy. You do have residual pressure valves? the part about the drum mc was pointed at the og poster, that vette mc isnt going to do the job, and everything else listed is good advice if you have all the correct components, but isnt worth that much if your using the wrong parts.
Calm down people. Next thing you know you'll be buying a late model like Ryan. He was also too puckered to drive it anymore.
really? not that excited about your problem, your far enough away that your not gonna run into me with your faulty brakes. Just trying to help is all.
Here's a question for you. Once you have had your 3 goes to get a hard pedal, can it be maintained, does the pressure stay there??
I had a similar problem. Called speedway and they realized that the master cylinder was too small...Bumped it up to 1 inch and we were good to go. Good luck
Vette master cylinder is designed for high pressure/low volume required for discs. Drums require more volume/less pressure. Peddle ratio is important to get the require volume. Also size of brake line effects volume too
The primary port, or port that is closest to the firewall, feeds the front brakes. The secondary port, or port furthest from the firewall, feeds the rear brakes. With front drum brakes the wheel cylinders are usually pretty big, with that said, looking up '39 Ford Master Cylinder shows a 1-1/16" Bore(.886²"). The Corvette manual MC is only a 1"bore(.785²") , but its power ***isted brother uses a 1-1/8" bore(.994²"). Do you know which Corvette MC you have? And if you can find out the size of your rear wheel cylinders, and know how much bigger or smaller there are compared to what the '39 Ford truck original rear wheel cylinders that would be helpful. '10 bolt' does not tell from what model or sub model it came from. A wagon will have larger wheel cylinders than a coupe. IMO, if everything is adjusted correctly with no air in the lines and the pedal allows for correct pedal travel, I'm going to go with the MC being too small for the system. BTW a Maverick MC is also only a 1" bore so that's not going to do any better than the manual Corvette 1" unit.
Yah, after two-three pumps its hard and does not fade. Still feels like I can't get enough fluid out there fast enough. Yah it's a vette stlye mc but the reservoirs are equal size. Still very much appreciate the ideas/info guys!
Thanks for clearing up the brake line question. I think I need to look for an mc that has a larger bore. The one I have now was simply part of an aftermarket pedal/mc set-up.
I'd go with a drum-drum master from a Chevelle or Nova. I always try to size the donor master somewhere close to the weight of the car it's going into. Bob
Not to pick on you 32Rules just using this as an example... The MCs do not know what kind of system they will be filling. The diameter of the bore is what will move the volume. By the 60s and the common use of dual reservoir MCs, there is no longer a 'disc' or 'drum' MC. Just Primary/Secondary port sizes and bore diameter. Bore diameter is key. Pedal ratio is important to have the correct leverage to properly actuate the MC. The correct size MC for the wheel cylinders will have the correct volume to operate the system, but if the pedal ratio is wrong you may not be physically able to operate the pedal or not allow for correct travel of the pushrod to actuate the brakes.
PEDAL TRAVEL, PEDAL TRAVEL, PEDAL TRAVEL!!! I fought the exact same problem through 3 new master cylinders. The last (the one I'm using now) being a NOS 67 'vette disc/disc MANUAL brake MC (1" bore). Installed it.. SAME problem!! MC bled, system bled, etc etc. Just for grins, I slid in, in front of the seat and pushed the non existant pressure pedal in by hand and watched the pedal travel ...nowhere NEAR the necessary pedal travel. I had drilled a hole in the pedal shaft to keep the push rod in line with the MC, which wasn't allowing enough travel. I moved the push rod way down to the original hole, and it hit the bottom of the MC half way through the travel...but I got pedal. I "Z'ed" the push rod, lengthened it till it was the correct length, an VOILA! PERFECT brakes! BTW, the other 2 MC's would have worked fine if I had done this earlier. No residual valve, proportioning valve, etc, etc, but my brakes are disc/disc...
Masters with small bores give high pressures needed for the newer disc brake setups, but they wont give the volume you need for a drum/drum setup. You need a master with a larger bore to transfer volume.
While "Z'ing" the push rod would give you clearance, It had better be awful beefy as you will be adding side load, Your pedal effort is being multiplied anywhere from 1-4 to 1-6 times, If the original push rod wasn't straight I would think that it bending in a panic stop would be awful likely wouldn't it?
Don't mean to pick on you but you are WRONG. There is most definitly a difference between a drum/drum, disk/drum, and disk/disk master cylinders.
I think also it is best here to get specs on the actual MC from its supplier. The basic oval Vette cylinder has become a sort of aftermarket standard, and it is available in lots of versions and with different check valve combos that are not necessarily similar to actual Corvette parts! This is not necessarily much related to a Vette part. I am pretty sure you can now buy disc/drum and drum/drum versions of this, and also different bore sizes.
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