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johns66
05-15-2007, 12:54 PM
Lost the brakes on my 65 cruiser, rebuilt the master cyl. and bled the brakes, still pedal goes to floor, could it the the brake booster? thanks. John

Roscomacaw
05-15-2007, 01:17 PM
Sure it could. It could be the MC didn't get put back together right as well.
Did you bleed the booster in the course of bleeding?

Miscreant adrift in
the BerStuda Triangle
http://images.andale.com/f2/115/106/906179/2006/12/7/truckonhill3.jpg

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

johns66
05-15-2007, 01:39 PM
How do you bleed the booster? doesn't look like there is any place to do that, and what is there to bleed? brakes were working good then I lost the pedal, they will come back with some pumping, the car has disc brakes. thanks for the help. John

sbca96
05-15-2007, 03:14 PM
Cruiser is just a stand alone vacuum diaphram, I think Biggs had Hawk
on the brain from the other Hydrovac posts. You are correct there is
no place to bleed. Pedal going to the floor can be caused by a number
of things. A leak is number one, make sure you done have fluid in
the rear drums. If the booster is shot you cant bleed the brakes the
old pump pump pump way. You can use a vacuum MityVac tool. That will
still not solve your problem IF the booster is bad. Check the vacuum
hose from the booster to the intake for leaks, & also the check valve
pushed into the grommet. Usually those will cause a hard pedal, not
one going to the floor.

Tom

'63 Avanti, zinc plated drilled & slotted 03 Mustang Cobra 13" front disc/98 GT rear brakes, 03 Cobra 17" wheels, GM alt, 97 Z28 leather seats, soon: 97 Z28 T-56 6-spd, Ported heads w/SST full flow valves, 'R3' 276 cam, Edelbrock AFB Carb, GM HEI distributor, 8.8mm plug wires

Roscomacaw
05-15-2007, 04:58 PM
I confess, I had a hydrovac pictured in the back of my head. It has a bleeder screw. The one in question here does not. [:I]

Sometimes there's so many threads going at once that it's possible to confuse one with another. I usually proofread what I'm about to post and THEN read it again after I post it. I didn't do that in this instance. I was in a hurry to get to town and ship some stuff I'd sold on ebay.[8]

Miscreant adrift in
the BerStuda Triangle
http://images.andale.com/f2/115/106/906179/2006/12/7/truckonhill3.jpg

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

johns66
05-15-2007, 06:27 PM
Thanks everybody, I have checked the front brakes but not the rear, I will do that tomorrow, it doesn't seem the brake booster would cause the problem. John

41 Frank
05-15-2007, 07:01 PM
Did you bench bleed the master cylinder before reinstalling?

Frank van Doorn
1962 GT Hawk 4 speed
1963 Daytona Conv
1941 Champion R-2 Rod

sbca96
05-15-2007, 08:36 PM
Bench bleeding can help. but even with air in the lines, I dont see it
sinking to the floor - though it was mentioned that the pedal DOES come
up after pumping it a while. First is to confirm there is no leaks. I
think after he checks the rear cylinders, we can offer more help.

Also check to see if its losing fluid .... is the level going down?

Tom

johns66
05-16-2007, 01:15 PM
Rear brake shoes are down to about 1/16, cylinders look good no leaks anywhere and fluid does not go down, bled front discs I will replace rear shoes and bleed the system again, sure is a puzzler as there can't be that many things to go wrong. thanks again for the help. John

StudeRich
05-16-2007, 03:07 PM
John; is it possible that you honed it too far? I am trying to remember if a bi-passing piston seal will cause no pedal, I believe it does! I do think the problem is in the Master Cylinder.:(

StudeRich
Studebakers Northwest
Ferndale, WA

johns66
05-16-2007, 04:11 PM
actually the master cyl didn't need honing, looked like new, installed a new kit anyway, funny the brakes were working good when this happened, I thought myself that it was the master cylinder, no indication that this was going to happen as the brakes were good and then bad. John

sbca96
05-16-2007, 05:25 PM
How are you bleeding the brakes? The two person pump until you get
pedal, hold, open the valve, keep pressure, close bleeder screw method
or the mityvac vacuum pump method? You mention that with enough
pumping you finally get pedal, is this when you have the other person
hold the pedal down and than you open the screw? If you havent tried
it, you might do this with the engine running, as the vacuum will make
the power assist work, and could very well speed up the process.

Tom

53k
05-16-2007, 08:53 PM
quote:Originally posted by johns66

actually the master cyl didn't need honing, looked like new, installed a new kit anyway, funny the brakes were working good when this happened, I thought myself that it was the master cylinder, no indication that this was going to happen as the brakes were good and then bad. John

You really should lightly hone the inside of any brake cylinder before installing a new piston. The new rubber needs some friction to seat and seal properly.
Regarding the no/low pedal, perhaps the replacement master cylinder kit has a shorter piston than the original. This would keep the pedal linkage from pressing far enough. If the pedal feels spongy even when it is pumped up, you still have air in the system. Bench bleeding is very important.
I went through several quarts of brake fluid one time trying to bleed the brakes on my Wagonaire (disk type). It turned out the Hill Holder has a bleeder valve on the top (where it is virtually impossible to get at). Once I bled it, the pedal came right up.
A failed booster only causes the pedal to get much harder to push. It is possible to drive the car with a bad booster, but you will need strong leg muscles.


[img=right]http://www.frontiernet.net/~thejohnsons/Forum%20signature%20pix/R-4.JPG[/img=right][img=right]http://www.frontiernet.net/~thejohnsons/Forum%20signature%20pix/64L.JPG[/img=right][img=right]http://www.frontiernet.net/~thejohnsons/Forum%20signature%20pix/64P.jpg[/img=right][img=right]http://www.frontiernet.net/~thejohnsons/Forum%20signature%20pix/53K.jpg[/img=right]Paul Johnson
'53 Commander Starliner (since 1966)
'64 Daytona Wagonaire (original owner)
'64 Daytona Convertible (2006)
Museum R-4 engine

sbca96
05-17-2007, 01:55 AM
"bench bleeding" doesnt have to be done off the car, it can be done on
the car by disconnecting the brake line(s) on the side of the cylinder
and installing the plastic fitting(s) with rubber tube(s) and run them
up into the top of the master. Then pump the brakes. Once the air
bubbles stop, reconnect the line(s) and bleed the system.

Tom

johns66
05-19-2007, 11:41 AM
Well I have the brakes back!! rebuilt the master cylinder again, that didn't help so re bled the system and that did it!! question how did air get into the system as the master cyl. was never low?? very strange, I want to thank everyone for the help this sure is a great group. John

Roscomacaw
05-19-2007, 12:31 PM
Trust me. Some things like you've just experienced simply defy understanding![}:)]

Miscreant adrift in
the BerStuda Triangle
http://images.andale.com/f2/115/106/906179/2006/12/7/truckonhill3.jpg

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe

sbca96
05-19-2007, 05:09 PM
I would guess one of two things caused you to lose brakes, either the
piston seal at the very back of the M/C allowed air to be drawn in
between the booster and the master (which will usually cause wetness
on the bottom of the booster) or if its a dual master (I dont recall
if thats been mentioned) it could have been "swapping" fluid from the
front to the rear systems instead of forcing it back to the brakes.

Tom


quote:Originally posted by johns66

rebuilt the master cylinder again, that didn't help so re bled the system and that did it!! question how did air get into the system as the master cyl. was never low??