1960 Bel Air. Converted from 4wheel drum to disc up front. Dual manual master cylinder. Do I need to add residual valves? Thanks in advance,
I am going to say no. Most newer masters have them built in, but since the master is higher than the calipers, you should be good to go. How does it stop? I used a Ford style disc/drum master when I did the conversion on my '59 Ford and it stops fine.
If you used one of those aftermarket "Corvette" style master cylinders and you may find you need to install a 10 psi residual for the rear brakes.
Residuals, either internally in the master cylinder or 10# external, are needed on older drum brakes, and will also benefit later ones.
Ok so it won’t hurt to add them?have red and blue residual valves. I haven’t driven the car yet; was waiting for some feedback.
The 10# valves are for drum brakes; the 2# valve is for disc brakes only when the master is located below the floor.
I doubt you'll find a residual pressure valve in a disc/drum dual master cylinder. If you can, please show me a picture of one? Residual pressure valves seem to have gone away, in new cars, about 40 some years ago.
All the late '60s/early '70s Ford disc/drum masters I have or have purchased recently have the drum residual in the rear brake port. Residuals did go away by the mid-'70s, mainly because of wheel cylinder cup expanders, but if you buy a vintage disc/drum master, the residual should be included.
You all handled the residual valve issue nicely, but what about the need for a proportioning valve on his disc/drum set up he just changed to? dtbbcs, did you add a proportioning valve to that new M/C?
I don't know of any master cylinders that did not have internal residuals for drum brakes, up to the mid '70s. Has nothing to do with bleed back on drums. Now, with discs and a master located below the calipers, the aftermarket 2# residual is sometimes needed.
I recommend installing an adjustable proportioning valve in any disc/drum or disc/disc conversion or custom system.
Not yet was going to see how the brakes act. I can put one on the front if you think it’s necessary;as I will have to add the residual valves also Sent from my iPhone using The H.A.M.B. mobile app
I think you are going to need it, better to add it now than open the lines back up later and do it over. CPP makes a nice little PV that is adjustable and a bracket that makes it easy and attractive to add. JMHO
Never mind I would have no idea what I am talking about, listen to the experts and I'll just bow out of this thread.
Dumb question time. If I’m using the 10 on the rear end and 2 on the front why would I need the adjustable PR on the rear and not the front Sent from my iPhone using The H.A.M.B. mobile app
Don’t you want to slow down the front from grabbing too soon Sent from my iPhone using The H.A.M.B. mobile appto even the brakes
That's a metering, or hold-off valve. It prevents pressure from going to the fronts until there is enough pressure to activate the drums. Disks start to work at about 5psi, but drums need as much as 100 psi. Activating the rear brakes first makes braking more stable. (random example) https://www.speedwaymotors.com/Brake-Metering-Hold-Off-Valve,8904.html The proportioning valve limits the maximum pressure to the rear. As the brakes slow the car, weight transfers off the rear wheels to the front. Limiting the rear pressure keeps the rears from locking up as weight comes off. Factory disk/drum cars have a combination valve. This includes the metering and proportioning valve in one unit. For a conversion, you'll probably have separate, adjustable units to dial the braking in.
It would depend on your master cylinder. If it's a disc/drum MC then you don't need additional valves. If it's a disc/disc MC then you need one on the drum end. Proportioning valve controls how fast the rear's hit compared to the fronts. SPark
Yea I'm still trying to determine which windmill is worth my time. But some of them seem like such worthy opponents. LOL
I am putting residual valves on both the front and rear lines . Do I need to put an adjustable proportioning valve on one or the other??
Yup. Me too. I'm just a senior engineer at General Motors these days. What the hell do I know. Sent from my SM-G900T using The H.A.M.B. mobile app
Please get some expert advice and follow their instruction. If you mess up a paint job no one dies, that is not true of brakes.
Okay.....if you have a firewall mounted master, disc disc system, DO NOT ADD RESIDUAL VALVES. Got that? If you have a below the floor master, on a disc disc system, add a two pound residual valve in both the front and rear brake lines, it keeps very slight pressure on the calipers and stops fluid from travelling back to the master. In a drum brake system, a 10 lb residual valve keeps the cups inside the wheel cylinder pressurized so they don't leak. There should be one already in the rear brake port of the disc drum master, if not, add one. Firewall mounted masters are mounted high enough so that the fluid is slightly pressurized by gravity keeping the calipers from retracting far enough to stop excessive brake pedal travel. So....if you want your front brakes to drag and spend a long time pulling your hair out trying to figure out why, go ahead and install them, it'll be good for a laugh.
Don't add anything yet, IF your master has the res valve installed in the rear (smaller cup or pot) then you need NOTHING. To check, take off the line for the rear brakes, insert a un bent paper clip into the center hole and push in GENTLY.....you should feel a slight spring back if the res valve is inside. The reason I say to check is I've had a few rebuilt masters from parts stores that they were missing. After this you might still have a brake bias issue, with that you would use a prop valve.
I went back to see what mc I have. It is a universal power/manual master cylinder 1" bore corvette style .Ported on both left &right sides.3/8"-24 openings on all 4 ports. Part # 9103447 at Speedway motors. Getting different responses here. Do I need the residual valves added and possibly an adjustable proportioning valve also?
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