Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 09-09-2012, 12:00 AM   #1
Richard in Anaheim CA
Senior Member
 
Richard in Anaheim CA's Avatar
 
Join Date: May 2010
Location: Anaheim California
Posts: 551
Default Hydraulic Brakes

I know I should post this on the V8 or Hot rod forum but I thought I would ask among friends first.

A prospective new member to the club told me he had hydraulic brakes and after driving some miles they build up so much pressure they lock the wheels. I had a little experience with hydraulics 50 years ago but never ran across anytning like this.

Is this something common? Is there an easy fix? I already offered a complete set of mechanical brakes but he turned me down.

Thanks,

Richard
Anaheim CA
Richard in Anaheim CA is offline   Reply With Quote
Old 09-09-2012, 12:30 AM   #2
Geo. H
Senior Member
 
Join Date: May 2010
Posts: 374
Default Re: Hydraulic Brakes

There's something radically wrong with his master cylinder if pressure does indeed build up.
Geo. H is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 09-09-2012, 12:31 AM   #3
Pete
Senior Member
 
Pete's Avatar
 
Join Date: May 2010
Location: Wa.
Posts: 5,373
Default Re: Hydraulic Brakes

Adjust the link between the pedal and master cylinder.
It sounds like the piston is not coming back far enough
to clear the port.
Pete is offline   Reply With Quote
Old 09-09-2012, 12:32 AM   #4
Bob Johnson
Senior Member
 
Bob Johnson's Avatar
 
Join Date: May 2010
Location: California
Posts: 976
Default Re: Hydraulic Brakes

It is possible that there is a problem with the residual (check) valve, if there was one installed. The purpose of the residual valve is to keep a little hydraulic pressure on the wheel cylinders when the brakes are not applied. This prevents the wheel cylinders from "sucking" air back into the wheel cylinders. If the residual valve is faulty or is not the correct one for the application then it could cause the brakes to drag or even lock up. It could also be some foreign matter in the system that plugs up the system that blocks the fluid returning back to the master cylinder.

Just my 2 cents.

Bob
Bob Johnson is offline   Reply With Quote
Old 09-09-2012, 12:53 AM   #5
Mike V. Florida
Senior Member
 
Mike V. Florida's Avatar
 
Join Date: May 2010
Location: South Florida
Posts: 14,054
Send a message via AIM to Mike V. Florida
Default Re: Hydraulic Brakes

Quote:
Originally Posted by Richard in Anaheim CA View Post
I know I should post this on the V8 or Hot rod forum but I thought I would ask among friends first.
Can't hurt to post on both of the other sites as well.
__________________
What's right about America is that although we have a mess of problems, we have great capacity - intellect and resources - to do some thing about them. - Henry Ford II
Mike V. Florida is offline   Reply With Quote
Old 09-09-2012, 01:14 AM   #6
Dodge
Senior Member
 
Join Date: Nov 2011
Location: Sonoma, CA.
Posts: 1,491
Default Re: Hydraulic Brakes

Sponsored Links (Register now to hide all advertisements)
make sure the brake pedal hasn't been adjusted with no free play. there should be
some play in the pedal to give the fluid a place to expand.
If all that is ok I would suspect bad front brake lines colapsing on the inside and acting like a one way valve causing the brakes to drag.
Dodge is offline   Reply With Quote
Old 09-09-2012, 02:26 AM   #7
BILL WILLIAMSON
Senior Member
 
BILL WILLIAMSON's Avatar
 
Join Date: Dec 2010
Location: FRESNO, CA
Posts: 12,560
Default Re: Hydraulic Brakes

If all 4 brakes lock up, it has to be master cyl. related. Check all the things that the others have posted. Bill W.
__________________
"THE ASSISTANT GURU OF STUFF"
BILL WILLIAMSON is offline   Reply With Quote
Old 09-09-2012, 09:17 AM   #8
'29wagon
Senior Member
 
Join Date: May 2010
Location: H.B. California
Posts: 451
Default Re: Hydraulic Brakes

dot5 i'm told with it's silicon may heat up and expand.
'29wagon is offline   Reply With Quote
Old 09-09-2012, 09:39 AM   #9
Tom Wesenberg
Senior Member
 
Tom Wesenberg's Avatar
 
Join Date: May 2010
Location: Mpls, MN
Posts: 27,582
Default Re: Hydraulic Brakes

Quote:
Originally Posted by '29wagon View Post
dot5 i'm told with it's silicon may heat up and expand.
Dot 5 silicone is the only thing I use on my old cars that have hydraulic brakes. I don't know that it expands with heat, but even if it did, it would simply raise the level in the reservoir. I'd bet the problem is the master cylinder piston isn't coming back far enough to uncover the hole.
Tom Wesenberg is offline   Reply With Quote
Old 09-09-2012, 11:53 AM   #10
Charlie Stephens
Senior Member
 
Join Date: May 2010
Location: Southern California
Posts: 7,017
Default Re: Hydraulic Brakes

Quote:
Originally Posted by Richard in Anaheim CA View Post
I know I should post this on the V8 or Hot rod forum but I thought I would ask among friends first.

A prospective new member to the club told me he had hydraulic brakes and after driving some miles they build up so much pressure they lock the wheels. I had a little experience with hydraulics 50 years ago but never ran across anytning like this.

Is this something common? Is there an easy fix? I already offered a complete set of mechanical brakes but he turned me down.

Thanks,

Richard
Anaheim CA
Everyone has had good suggestions so far but I would like to ask if this is a newly installed system on an older one? If it is new it is possible the linkage is not allowing the master cylinder piston to retract far enough.

Charlie Stephens
Charlie Stephens is offline   Reply With Quote
Old 09-09-2012, 12:09 PM   #11
bbrocksr
Senior Member
 
Join Date: May 2010
Location: Yakima Washington
Posts: 913
Default Re: Hydraulic Brakes

Quote:
Originally Posted by Charlie Stephens View Post
Everyone has had good suggestions so far but I would like to ask if this is a newly installed system on an older one? If it is new it is possible the linkage is not allowing the master cylinder piston to retract far enough.

Charlie Stephens

Pete's post nailed it! The piston is not returning far enough to uncover the port and as the heat builds up and expands the fluid it applies the brakes.
Shorten the pushrod until the piston uncovers the port allowing the fluid to return. Bill
bbrocksr is offline   Reply With Quote
Old 09-09-2012, 12:44 PM   #12
Richard in Anaheim CA
Senior Member
 
Richard in Anaheim CA's Avatar
 
Join Date: May 2010
Location: Anaheim California
Posts: 551
Default Re: Hydraulic Brakes

Thanks everybody. Thats great information and reallly quick.

I have printed all the replies out and will deliver them to him this morning

Thanks Again,

Richard
Anaheim CA
Richard in Anaheim CA is offline   Reply With Quote
Old 09-09-2012, 01:37 PM   #13
Marco Tahtaras
Senior Member
 
Marco Tahtaras's Avatar
 
Join Date: May 2010
Posts: 3,099
Default Re: Hydraulic Brakes

The guys got it right. A car I owned for a short time did that. In my case the bleed back passage in the master cylinder plugged. When the piston retracted the passage was at least mostly uncovered. That car hadn't been driven for a couple years.
__________________
http://www.abarnyard.com/
Marco Tahtaras is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:17 AM.