Thread: Question for Dave S. or Pat M. on brakes.

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Ever since I had my 70 Ford pickup catch fire the brakes have not been up to snuff.
I thought it was from some glazing on the front rotors after towing all the weight up and down the mountains on the way out here. Anyway the rear brakes have been totaly re - done. New Drums, new wheel cylinder's new pad's. The front's I just did,
New rotor's new pads. It stops but you really have to get on them. The peddle is hard not spungy at all and it hold's brake pressure. Could the vaccum booster or proportioning valve have gone bad??? What's this sound like to you guy's???
Thanks Kurt

Do you have a brake pressure gauge to check the pressure at the calipers/wheel cylinders???? Most folks don't bother with one, but I've found them to be an invaluable tool when diagnosing brake problems as it will tell you what the pressure is at each wheel.

Another possibility, Kurt... When it had the fire, was it in an area that would have heated up the master cylinder and the brake fluid a lot? Could the master cylinder maybe be bypassing the fluid because of some seals that have deteriorated from the heat???

Could be the combination valve, but again, hard to say for sure without knowing what the brake pressure is at the wheels........

Hey Dave;
The fire was at the right rear axle. When it caught fire the bearing had gone out and melted the seals.
Then the fluid caught fire and drained out passed the bad seals. Just how hot the brake fluid got is anyone's guess.
The axle got the steel rim hot enough the pop the tire and catch fire, then it warped the axle which had to be replaced.
I am not sure how hot the fluid got near the master cylinder though since it all drained out on the ground.
I have never used a brake pressure gage, how do you hook that up Dave???

The one for checking brake pressure just screws in where the brake bleeder goes, remove the bleeder, screw in the gauge to check the pressure, re-install the bleeder and bleed.

Here's a link to a kit Summit sells;

http://www.summitracing.com/parts/SSB-A1704/

at least you can look at it and know what I'm talking about.....

Kurt it sounds like your booster isn't working.If you have a hard pedal. With the booster it should be easy. Just my $0.02

Thanks Dave and Cffisher;
I went and bought a new master cylinder today but didn't have time to install it.
If it still does not act right I will go and get the booster.
I hate throwing money at things, but the Master cylinder looks old.
So I figured for $14 dollers I can't go wrong, when it comes to stopping.
Just the front pads cost $17 dollers.
Kurt

Originally Posted by Dave Severson

The one for checking brake pressure just screws in where the brake bleeder goes, remove the bleeder, screw in the gauge to check the pressure, re-install the bleeder and bleed.

Here's a link to a kit Summit sells;

SSBC A1704 - SSBC Sure Stop Brake Pressure Gauge Kits - Overview - SummitRacing.com

at least you can look at it and know what I'm talking about.....

Thanks Dave! I knew there was something I needed to add to the new tool box. It'll help me on Dustin's Elky.

David

Just adding information:

I would not think fire in the back would cause anymore damage up the line. But one never knows, you can check the booster. Put your foot on the pedal and start the motor it should go down some when the motor fires. Sorry to use that word but it was funny, then take your foot off and reapply the brake, it should get pressure at the top of the travel.

Your description sounds like the booster, not the proportioning valve. There could be a proportioning valve problem if the line blew out and the rear lost all pressure. It might have forced the valve to go off center and all the braking is now being done up front. There is an internal valve that will or can get off center, it can be reset go to master power web site and look for the procedure.

Say Kurt you said the fire was in the rear did you replace the hose in the back it maybe blocked.

Thanks for the help Dave; Cffisher, David, Angrystroker.
I did some more reading on it last night, looking for my exact problem on the net.
So this morning I went out and with my doctors stethoscope started listening for vaccum leaks
around the brake booster. I could not hear anything even with the motor running.
So I followed the vaccum line from the brake booster to a vaccum bar that
is tucked away on the fire wall behind the brake booster on the inside.
Unless your 2 feet above the engine on the passanger side you really can not see it.
And guess what, thats right where I found the problem.
A 2 cent vaccum line plug had either vibrated off or dry rotted and fell off.
I check the other one's and they are all still soft so I think it just vibrated off.
Photo's on the link below, Thanks for all the help and input guy's.
The truck stop's on a dime now!!!
Kurt
Flickr: kurtvara's Photostream

Good to hear you have it back working correctly, Kurt! Sometimes the simplest things take the most time to find!!!!!

Thanks Dave; I went ahead and replaced the master cylinder too because it had lot's of rust around the back.
When I took it off it was rust inside the back too, plus it had a bolt that held the fluid cover on it.
So anytime I wanted to check the fluid level I had to go hunt down a 1/2 inch wrench.
Now I have the clip, I can just pull to the side, to take a quick peek when topping off other fluids!!!
Thanks for for help again.
Kurt