Strange Brake Issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jonlopes · 06-01-2015, 12:32 PM

My truck is having a strange problem with the brakes. The main symptom is I push hard on the pedal and the truck slowly stops. I feel the brakes should have more to them, if I stand on the pedal I cannot make it skid even while unloaded. It does stop but not as good as a Chevelle/ El Camino with 9.5” drums on all 4 wheels. This truck has the huge front discs and equally large 12x2.5 rear drums on the dana 60; though it is heavier it should stop better than an A body with four 9.5" drums? In my experience this would normally be a brake booster issue but the thing is, the feel of the pedal is normal. I have driven cars with bad boosters and the pedal feels hard as a rock and the car is scary slow to stop.
Also there is no pulling to either side while stopping. I already replaced the booster check valve and hose.

My thoughts are:
1. The booster is going bad but not completely there yet. I have never seen this, I have only seen them work or not.
2. This is just how these trucks are, get used to it.
3. Something really weird not allowing either the front or the rear brakes to work.

geezer#99 · 06-01-2015, 01:54 PM

What about vacuum?
How much is your motor producing?

cdowns · 06-01-2015, 02:18 PM

I'd check your 4wheels to make sure of adequet fluid flow as somtimes these brake lines get clogged solid with crap and the fluid dont flo

cleszkie · 06-01-2015, 05:32 PM

Quote:

Originally Posted by geezer#99

What about vacuum?
How much is your motor producing?

X2. Sounds like your motor is not producing enough vacuum, or you have a faulty one-way vacuum valve at the booster. You didn't make it clear if this was a new problem that developed, or if this is the way it has always been.

Jonlopes · 06-01-2015, 05:59 PM

I have only had the truck for a couple of weeks and it was like this from the start. I will have to dig out the vacuum gauge and see. The brake booster line goes to a nipple coming off the intake manifold. There are 3 things coming off of there the tranny vacuum modulator, the brake booster and a line going into the cab (I am assuming for AC) I went ahead and removed the hose and capped the AC line.

06-01-2015, 12:32 PM	#1
Jonlopes Registered User Join Date: Mar 2013 Location: Anaheim Hills, CA Posts: 323	Strange Brake Issue My truck is having a strange problem with the brakes. The main symptom is I push hard on the pedal and the truck slowly stops. I feel the brakes should have more to them, if I stand on the pedal I cannot make it skid even while unloaded. It does stop but not as good as a Chevelle/ El Camino with 9.5” drums on all 4 wheels. This truck has the huge front discs and equally large 12x2.5 rear drums on the dana 60; though it is heavier it should stop better than an A body with four 9.5" drums? In my experience this would normally be a brake booster issue but the thing is, the feel of the pedal is normal. I have driven cars with bad boosters and the pedal feels hard as a rock and the car is scary slow to stop. Also there is no pulling to either side while stopping. I already replaced the booster check valve and hose. My thoughts are: 1. The booster is going bad but not completely there yet. I have never seen this, I have only seen them work or not. 2. This is just how these trucks are, get used to it. 3. Something really weird not allowing either the front or the rear brakes to work. __________________ 1971 Cheyenne Big Block Longhorn

06-01-2015, 01:54 PM	#2
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,707	Re: Strange Brake Issue What about vacuum? How much is your motor producing?

06-01-2015, 02:18 PM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Strange Brake Issue I'd check your 4wheels to make sure of adequet fluid flow as somtimes these brake lines get clogged solid with crap and the fluid dont flo __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

06-01-2015, 05:59 PM	#5
Jonlopes Registered User Join Date: Mar 2013 Location: Anaheim Hills, CA Posts: 323	Re: Strange Brake Issue I have only had the truck for a couple of weeks and it was like this from the start. I will have to dig out the vacuum gauge and see. The brake booster line goes to a nipple coming off the intake manifold. There are 3 things coming off of there the tranny vacuum modulator, the brake booster and a line going into the cab (I am assuming for AC) I went ahead and removed the hose and capped the AC line. __________________ 1971 Cheyenne Big Block Longhorn



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