Thread: Residual check valve

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Since I've pulled my engine on my 37 and wound up doing alot more than what I expected I found my self with no room to mount my master cylinder except under the floor board.Do I need a residual check valve now since gravity is not going to be working for me. Also how far should I mount it from the master cylinder? Since I have disc on the front and drums on the back do I need to mount two and if so what size(pound) should I buy?

2 # RPV , you should have because it would be the lowest point in the system, the fluid would fill back to the resivore, mount it as close to the master Cylinder as possible, that is what the directions say for the Willwood RPV's, I put a 10 # on my Falcon due to the disc drum master, and followed the directions, the valve ended up 8" from the master cylinder, and 12" from the Preassure differential valve.

if you have a double resivoir type master you will need one in each line . if drums 10 lbs if disks in the front a 2 lb in the front and ten in the rear.
what i have been told it is to keep backpressure in the lines as the brake cylinders can pull air back in after application and let off.
i put them in my bucket and they seenm to work

Originally posted by canadianal
if you have a double resivoir type master you will need one in each line . if drums 10 lbs if disks in the front a 2 lb in the front and ten in the rear.
what i have been told it is to keep backpressure in the lines as the brake cylinders can pull air back in after application and let off.
i put them in my bucket and they seenm to work

for rear drums, a 10# will keep the wheel cylinder pistions from compleatly retracting into the bore, which if they did, would cause a soft pedal due to the shoes being too far in, air has no factor in them, because if there was any air in the system, you could feel it at the pedal. an aftermarket master cyl would need at least the 10 # in the rear circut for the drums but an OEM would have the 10 # built in. the front 2 # keeps fluid from reterning to the master cylinder resivore if the master cylinder is the lowest point of the cylinder, a 10 # on a disc brake circut will cause brake drag.

I'm running a dual master cylinder so I'll take your advice and run #2 on the disc and #10 on the drums. Thanks for the help.

Originally posted by chevy 37
I'm running a dual master cylinder so I'll take your advice and run #2 on the disc and #10 on the drums. Thanks for the help.

Summit has the best price on them. $16.99 each, I bought my 10 # from speedway for $17.99 when Summit still had the 17.99 price, but I recently noted, the price had been reduced.

using a Fiero master cylinder, no added residual valve externally.
Car has difficulty backing up, unless jacked up with the brakes removed, where the wheels move very freely.
Excess back/residual pressure? Replace master cylinder with same or other?

sounds as tho, the rotational forces are pulling the shoes into the drum, they are supposto going forward when you apply brakes, but not at any time in reverse, do the shoes line up right on the anchor pin? if they don't there could be your problem

oh yeah, big shoe on the rear, small shoe on the front.

shoes are for drum brakes, I have 4 wheel discs

Attached photo: setup of Master cylinder, residual values and proportioning value on my 29. (under floor mount)

jc