The Ford Barn

CSArno · 05-17-2017, 06:44 PM

A few times now I have taken my '49 F1 for a ride and the brakes were fine out of a cool garage but as things warm up, the brake system pressurizes so much that the brake switch is activated and the brakes drag. I have loosened the brakes twice and it still does it. This is a totally stock setup and all 4 wheels drag. Only thing I have replaced is all new brake lines and 2 front wheel cylinders.
Thanks for any help,
Chris

TJ · 05-17-2017, 07:08 PM

Do you have at least 1/2 inch of free play at the pedal and a good strong return spring?

CSArno · 05-17-2017, 07:17 PM

When I start, I have about half the pedal travel for free play. New return spring last year.

Art Newland · 05-17-2017, 07:20 PM

Probably time for a new master cylinder.

V8 Bob · 05-17-2017, 07:46 PM

Pedal "free play" can sometimes be deceiving. You really want to measure the actual pedal push rod to master cylinder clearance, with the pedal fully retracted by it's own spring. This should be close to 1/16".

Talkwrench · 05-17-2017, 07:48 PM

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Sounds like something is failing in the master cylinder ...?

Kube · 05-17-2017, 08:49 PM

First things first... One of three things is happening...
1) The rod at the cylinder is adjusted too long and thereby not allowing the master cylinder plunger to return far enough for the fluid to return. If you let it sit say, overnight, the fluid will return and you start this process the next time you use the brakes.
2) the brakes are adjusted too tight to the drums. the drums heat up, close in on the shoes and you get drag.
3) You state you replaced the front wheel cylinders. Many new cylinders are incorrectly made. the return hole is drilled too far forward and as such, the fluid can't return.
Next time the brakes start locking, pull over, jack up the front wheel(s) and see if they spin. Do the same at the rear. If the rear spin and front ones don't, bad wheel cylinders.

My guess? Either bad wheel cylinders or that adjustment rod at the master is incorrectly adjusted.

Did you mess with that rod since the brakes last operated correctly? If not, front cylinders no doubt...

05-17-2017, 06:44 PM	#1
CSArno Senior Member Join Date: Feb 2015 Location: Maine Posts: 378	Brake system pressurizing A few times now I have taken my '49 F1 for a ride and the brakes were fine out of a cool garage but as things warm up, the brake system pressurizes so much that the brake switch is activated and the brakes drag. I have loosened the brakes twice and it still does it. This is a totally stock setup and all 4 wheels drag. Only thing I have replaced is all new brake lines and 2 front wheel cylinders. Thanks for any help, Chris

05-17-2017, 07:08 PM	#2
TJ Senior Member Join Date: May 2010 Location: Napa,California Posts: 6,037	Re: Brake system pressurizing Do you have at least 1/2 inch of free play at the pedal and a good strong return spring?

05-17-2017, 07:17 PM	#3
CSArno Senior Member Join Date: Feb 2015 Location: Maine Posts: 378	Re: Brake system pressurizing When I start, I have about half the pedal travel for free play. New return spring last year.

05-17-2017, 07:20 PM	#4
Art Newland Senior Member Join Date: Mar 2016 Location: Lynden, WA Posts: 1,564	Re: Brake system pressurizing Probably time for a new master cylinder.

05-17-2017, 07:46 PM	#5
V8 Bob Senior Member Join Date: May 2010 Location: Granger (Northern) Indiana Posts: 1,520	Re: Brake system pressurizing Pedal "free play" can sometimes be deceiving. You really want to measure the actual pedal push rod to master cylinder clearance, with the pedal fully retracted by it's own spring. This should be close to 1/16".

05-17-2017, 07:48 PM	#6
Talkwrench Senior Member Join Date: Aug 2012 Location: Perth, Western Australia Posts: 2,687	Re: Brake system pressurizing Sponsored Links (Register now to hide all advertisements) Sounds like something is failing in the master cylinder ...? __________________ *"Came too close to dying to stop living now!"*

05-17-2017, 08:49 PM	#7
Kube Senior Member Join Date: May 2010 Location: Wisconsin, USA Posts: 9,001	Re: Brake system pressurizing First things first... One of three things is happening... 1) The rod at the cylinder is adjusted too long and thereby not allowing the master cylinder plunger to return far enough for the fluid to return. If you let it sit say, overnight, the fluid will return and you start this process the next time you use the brakes. 2) the brakes are adjusted too tight to the drums. the drums heat up, close in on the shoes and you get drag. 3) You state you replaced the front wheel cylinders. Many new cylinders are incorrectly made. the return hole is drilled too far forward and as such, the fluid can't return. Next time the brakes start locking, pull over, jack up the front wheel(s) and see if they spin. Do the same at the rear. If the rear spin and front ones don't, bad wheel cylinders. My guess? Either bad wheel cylinders or that adjustment rod at the master is incorrectly adjusted. Did you mess with that rod since the brakes last operated correctly? If not, front cylinders no doubt... __________________ "I can explain it for you. However, I can't understand it for you".