Hydraulic brakes

Changed my 31 Tudor (Banger powered) from mechanical brakes to the '48 Lincoln Bendix setup as sold by MACS.
Originally used a 1" master, but according to the instruction sheet, based on the "no pressure" issue, it is too small, so drove down to Summit to buy a 1 1/8".
I am now using a 1 1/8" dual master cylinder, with 10# residual check valves mounted next to the master cylinder.
Lines are plumbed with 3/16" hard line, flex lines are #3 AN.
I've bled this system every which way, pressure bleed, foot, not a leak anywhere. The pedal still goes to the floor unless you pump it up, then there is a firm pedal, no drop in pedal height when held.
Not sure where to start, do I need larger brake lines, 1/4"?
Ken

 

Brake shoes may need adjusting, you could have too much travel.

 

Ditto

 

X 3, except if anchor end of Bendix brakes are adjustable, make sure you follow the correct procedure to adjust anchors first.
Dave

 

Anchors are fixed, non-adjustable.

Thanks

 

i had a similar problem a couple years ago,,is your M/C push rod length correct?

i fought a car for 2 days... only to find the master cylinder i thought correct had a deeper push rod depth and wasnt depressing fully..just a thought to check...

 

Set your shoe drag.

 

Verified 1.5" stroke length. Have 1/16" freeplay with pedal up.
Master cylinders were both new, Wilwood (1"), Strange (1 1/8")

Ken

 

how much drag do you have on your brakes when you adjusted them?

 

Adjust the brakes tight, so the wheel does not move, than back off till they turn with a drag.

The repop Lincoln brakes I have seen had adjustable top anchors, maybe the MAC's (MT?) ones don't.


1-1/8" master seems kinda big, large bore=large volume=high pedal effort.

 

Can still turn them by hand. There is sufficient adjustment to lock them with the star wheel.
Adjusting them tighter doesn't make any measurable difference.

Because they will build and hold pressure on the second pump, tells me that there is insufficient volume being supplied.
Tomorrow morning, I'm going to double check the actual piston stroke at the master cylinder. Even though the pedal ratio allows for 1 1/2" stroke, I want to verify that the pushrod is moving the piston that far.

Thanks for the responses.
Ken

 

When you initially installed the master, were you able to bottom the dry master before the pedal itself actually bottomed out?

 

Yeah, somethin' ain't right. I can't imagine a 1-1/8" master cylinder not having enough delivery volume. The pedal should be rock-hard. The line size is fine. I suspect pedal travel/ratio.

 

Line diameter is not the problem although i would have used 1/4 since I think it would be easier to find the fittings. No matter what the diameter of the lines they are full of brake fluid when you first press the pedal and still full when it is all the way down.

Charlie Stephens

 

The problem is most likely shoe adjustment, even the 1" M/cyl. should be plenty big.

 

Guys,

Due to brain fade on my part, and trusting that purchased equipment advertised to do a specific job, will actually do what it says it will do, I ended up fabricating new pedal linkage to give the full 1.5"+ stroke.
What do you know, all kinds of pedal pressure.
Actually drove the car around the block a couple of times.
Now, I need to work on shoe adjustment.
Thanks to everyone for your advice, I was totally frustrated yesterday.

Ken