brake problems

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Jan 21, 2001 | 11:10 PM

rick

Thread Starter

Senior User

Joined: Jun 1999

Posts: 288

Likes: 1

brake problems

Hi all,

'78 F100 400/C6 2WD. Front brakes disk w/ drums in the rear. My initial problem was that the brake pedal was not returning enough to engage the brake light switch to turn the brake lights off. Went out and purchased a new master cylinder (from AutoZone, I know, I know) and put it on last weekend. Well, at first it did solve the problem albeit not as well as I hope for. But, today I went out to drive the truck and my front brakes were locked up. So, I disconnected the brake line to front brakes, it relieved the pressure and they were free and fine. So, my dilemna, when free and fine the brake pedal does not travel back far enough to engage the brake light switch and turn the brake lights off. However, when pressure builds up, the brake light switch works fine but my brakes are staying engaged. Is this problem solely the master cylinder or am I missing something here? Thanks, Rick

Jan 22, 2001 | 06:24 AM

jowilker

Fleet Owner

Joined: Jun 1999

Posts: 24,552

Likes: 74

From: Creedmoor, North Carolina

brake problems

Rick, I can feel yo pain, had the same problem. You need to shorten the rod from the booster to the master cylinder (screw it in). It is keeping the brakes applied just enough that they are getting hot and expanding and appling themselves harder.

Hope this helps.

John
jowilker
Club FTE since 01 01

66 F100s
In the still cool hours of the night,
you can hear chevys rusting away.

Jan 22, 2001 | 07:44 AM

goodfoot

Senior User

Joined: Sep 1999

Posts: 151

Likes: 0

brake problems

Yep, the rod needs to be adjusted to allow the Master Cylinder to fit flush to the booster or fire wall. Make sure that the rear brake shoes are adjusted out properly. There should be enough adjustment in the switch to make the brake lights function if everything else is correctly adjusted

Jan 22, 2001 | 10:19 PM

rick

Thread Starter

Senior User

Joined: Jun 1999

Posts: 288

Likes: 1

brake problems

Hey all, thanks for the response, but, my rod is not adjustable. I have manual brakes and the rod from the master cylinder just "snaps" into the cylinder and has no thread adjustment. I thought about the proportioning valve but am not sure how that plays into all of this. My options now are to put another reman master on or try a new one... If I go that route, which parts suppliers would be the best? Around here we have NAPA, AutoZone, Advance, and FORD. Also, check my newest post...I just may scrap it all and go to power brakes and work on it from there...

Jan 27, 2001 | 08:04 PM

Trail_Rider

Fleet Mechanic

Joined: Nov 1999

Posts: 1,415

Likes: 0

From: Lower 48

brake problems

When I first put my '72 on the road after it had been sitting quite a while, I experienced almost the same thing. When I would first take off brakes were fine, then as I drove (and applied the brakes in normal driving) they would build up pressure to the point there was no play in the pedal. My problem turned out to be bad rubber brake lines at the front wheels. The rubber was detoriating from the inside and wouldn't let pressure bleed back from the wheels.

Trail Rider