Very Hard brake pedal!
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Freshman User
Joined: Oct 2006
Posts: 44
Likes: 0
Very Hard brake pedal!
Hi Guys,
I have a 1978 F350 2x4 SuperCab Campering Special with a 460 and C6 and power brakes. I bought the truck in October and the brake pedal seems very hard. It doesn't seem to grab until about the last 1/3 of the brake pedal's throw. And even then, you really have to put your leg into it! I want to use this truck to tow my small travel trailer, but I want to know that I'll be able to stop. Any suggestions on what to look for (or to have a brake shop look for) to improve pedal response?
Thanks,
Rod
I have a 1978 F350 2x4 SuperCab Campering Special with a 460 and C6 and power brakes. I bought the truck in October and the brake pedal seems very hard. It doesn't seem to grab until about the last 1/3 of the brake pedal's throw. And even then, you really have to put your leg into it! I want to use this truck to tow my small travel trailer, but I want to know that I'll be able to stop. Any suggestions on what to look for (or to have a brake shop look for) to improve pedal response?
Thanks,
Rod
Elder User
Joined: Dec 2007
Posts: 739
Likes: 1
Almost sounds like the power booster is failing....Basic test:
Pump the brake several times with the engine 'off'. The pedal should become higher and harder to pump each time. Next have good pressure on the pedal, and start the engine. The brake pedal should drop a fair amount (2-3 inches would be normal)
If you can't bleed out the vacuum, or can't notice a change when you start the engine with the foot on the brake? Safe bet either the check valve or booster is shot.
It's hard to tell because we are not there in person. This is just a test to verify the boosters operation.
S-
Pump the brake several times with the engine 'off'. The pedal should become higher and harder to pump each time. Next have good pressure on the pedal, and start the engine. The brake pedal should drop a fair amount (2-3 inches would be normal)
If you can't bleed out the vacuum, or can't notice a change when you start the engine with the foot on the brake? Safe bet either the check valve or booster is shot.
It's hard to tell because we are not there in person. This is just a test to verify the boosters operation.
S-
Elder User
Joined: Nov 2003
Posts: 778
Likes: 2
From: southeast Idaho
Is there any leakage from the master cylinder? Back next to the booster where it bolts on? If not it could still have some brittle cup seals inside from age and maybe a pitted wall that would allow fluid to bypass until the piston gets past the bad spot before it builds pressure to the brakes, if the above tests say the booster is good I,d say check the master cylinder next, one way to check is to take the cover off and slowly depress the brake pedal while watching the fluid level in the reservoirs, a good cylinder you will see the fluid swirling as you push the pedal down, if not the cylinder is probably bypassing internally and should be changed unless someone has a better way to do a simple easy test of it...
Last edited by wdfp; Jan 22, 2008 at 12:03 AM. Reason: description error
