Tough Brake Question
Thread Starter
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Senior User
Joined: Oct 2004
Posts: 342
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From: Gainesville, Georgia
Tough Brake Question
HERE's WHAT I GOT:
1967 F-100 4X4 with four wheel drum brakes, originally manual brakes. 35 inch all terrain tires.
HERE's WHAT I DID:
Have upgraded to power brakes... Rebuilt Master Cylinder (1967), New Brake Booster (for a 1971 F-100), All new brake lines everywhere, all new wheel cylinders, All new brake pads, springs, drums, etc., New fresh fluid thru out. All air is bled out of the system. Have retained the original distribution block and the original brake pedal assembly.
HERE's THE PROBLEM:
My brakes are still very spongy and have to press almost to the floor to get it to stop. While the brakes will stop the truck, I am concerned!!
Please advise. Thanks.
1967 F-100 4X4 with four wheel drum brakes, originally manual brakes. 35 inch all terrain tires.
HERE's WHAT I DID:
Have upgraded to power brakes... Rebuilt Master Cylinder (1967), New Brake Booster (for a 1971 F-100), All new brake lines everywhere, all new wheel cylinders, All new brake pads, springs, drums, etc., New fresh fluid thru out. All air is bled out of the system. Have retained the original distribution block and the original brake pedal assembly.
HERE's THE PROBLEM:
My brakes are still very spongy and have to press almost to the floor to get it to stop. While the brakes will stop the truck, I am concerned!!
Please advise. Thanks.
Postmaster
Joined: Apr 2002
Posts: 3,613
Likes: 6
From: Coal country
Did you bench bleed the master cylinder before installing it?
If you didn't then you still have a lot of air in it.
If you did, then look at the following:
1. Brake pedal play - is it normal before engaging the brakes? If not, make sure the play is not under the dash, see the next point.
2. The rod between the master cylinder and the booster may need to be adjusted. It can be screwed out, but make sure it isn't engaging the master cylinder when the brake pedal is at rest.
3. Finally, did you change out the rubber brake hoses? If not, you may be in for a world of hurt.
The rubber lines are over 35 years old if original. They eventually swell shut on the inside. They will usually swell shut before bursting, by the way. The swelling may not have been too noticable with manual brakes, but a hard stop or two with the booster may have pushed them over the limit.
If you didn't then you still have a lot of air in it.
If you did, then look at the following:
1. Brake pedal play - is it normal before engaging the brakes? If not, make sure the play is not under the dash, see the next point.
2. The rod between the master cylinder and the booster may need to be adjusted. It can be screwed out, but make sure it isn't engaging the master cylinder when the brake pedal is at rest.
3. Finally, did you change out the rubber brake hoses? If not, you may be in for a world of hurt.
The rubber lines are over 35 years old if original. They eventually swell shut on the inside. They will usually swell shut before bursting, by the way. The swelling may not have been too noticable with manual brakes, but a hard stop or two with the booster may have pushed them over the limit.
Thread Starter
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Senior User
Joined: Oct 2004
Posts: 342
Likes: 0
From: Gainesville, Georgia
Hey thanks Picker,
Yeah all hoses are new as well. Wentr with the stainless braided ones.
The master cylinder was bench bled. But I did not know about the rod adjusting from the pedal to the booster. I am sure that's what the problem is. If I can bring my pedal up a bit, it should give me more stopping power.
I'll see how that works this weekend.
Thanks again.
Yeah all hoses are new as well. Wentr with the stainless braided ones.
The master cylinder was bench bled. But I did not know about the rod adjusting from the pedal to the booster. I am sure that's what the problem is. If I can bring my pedal up a bit, it should give me more stopping power.
I'll see how that works this weekend.
Thanks again.
Postmaster
Joined: Apr 2002
Posts: 3,613
Likes: 6
From: Coal country
Careful!
You said this: "But I did not know about the rod adjusting from the pedal to the booster."
I am referring to the short rod between the booster and the master cylinder - not the one you mentioned!
You said this: "But I did not know about the rod adjusting from the pedal to the booster."
I am referring to the short rod between the booster and the master cylinder - not the one you mentioned!
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
John, Line bleeding should remove any air from the master cylinder. My thinking since you have to move the fluid from the master cylinder to the wheel cylinder bench bleeding is a waste of time. IMHO
All 4 wheels need to be bled starting from the furthest away to the closest.
John
All 4 wheels need to be bled starting from the furthest away to the closest.
John
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