Hard to brake - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Shane65 · 06-13-2004, 09:58 AM

My 72 needs way too much effort to stop the truck considering that it is power brakes. If I was to use the same pedal effort to stop any of the other vechicles that have power brakes I'd be locking up the brakes easily. I can't seem to get the brakes to lock up in a panic situation. I put a new m/c, porportiong valve and brake booster. With each part there has been no improvement. I don't feel I wasted money on these parts since they are replacing 32 year old stuff. All four pads have been replaced. I even took it to a brake shop for them to attempt something. They chargered me $180 to rebleed the brakes and set-up the brake pedal a little higher. No real change other then the brake pedal is higher. I intend to tow my car in an enclosed trailer but don't feel I should yet until the brakes are right. Any suggestions?

Bowtie67 · 06-13-2004, 10:13 AM

How much vacuum do you have? If vacuum is low you will be applying lots of pedal to get it to stop. I just put disk brakes and booster setup in mine and when I hit the brakes hit just about puts you through the windsheild.

neonlarry · 06-13-2004, 10:18 AM

A couple of thoughts:
Have you changed the flexible rubber lines? Its not unheard of for them to deteriorate
and clog up after 32 yrs.
You don't have a profile. What about you engine, is it modified, i.e. low vacuum.

cdowns · 06-13-2004, 10:51 AM

are you trying to compare 30+ yearold brake system to a modern day brake systems??

Shane65 · 06-13-2004, 10:53 AM

I replaced the engine 3 weeks ago. The problem has been with me before the engine was replaced. Originally it was the stock 350 but now I put in a stroker 421 to make some needed torque for the trailer. I built the engine for torque so the cam is mild for that size of engine and I use an Eldebrock Performer RPM manifold with the stock quadrajet. I just checked the vacuum and it's at 19 inches on the gauage at idle. I thought of the lines but haven't replaced them. The outside of them look good with no age cracks. Is it possible for them to be reduced on the inside diameter.

Bowtie67 · 06-13-2004, 03:30 PM

Like neon said they do sometimes have a tendency to detrierate and collapse. The hose should have an inside diamiter of 3/8 of an inch.

Bobalouie · 06-14-2004, 11:13 AM

This is a stupid question, since you changed the booster, but did you put a new check valve in the booster? I did that to mine, and it made a night and day difference. The brakes still suck (due to other issues) but at least I have some pedal travel now.

Shane65 · 06-20-2004, 03:22 PM

FINALLY!!!! My brake problems are solved. There are no check valve or filter in the booster vacuum line originally and there are none now. The brake lines are not swelled according to a mechanic that works from his 2 bay garage in the back yard of his house. If the brake lines are swelled the fluid is slow to get into the calipers and slow to get out. If this is the case then my brakes would drag when I release the pedal(they don't). He asked me about the brake pads I use. I told him I bought the best the store had but wasn't sure if they were metalic or semi-metalic. He said to go back to the store and get the cheapest set which should be organic type and put them on. He said these era of trucks never were designed for metalic brakes. I put a set on and now I have brakes that work with ease and I can actually lock up the wheels if need be. Pedal effort is reduced and now I feel confident enough to let my wife drive it.(still not sure if that's a good idea or not). Tomorrow , I've got to get over to my new mechanic friend and thank him.

06-13-2004, 09:58 AM	#1
Shane65 Registered User Join Date: Oct 2003 Location: Ontario Posts: 108	Hard to brake My 72 needs way too much effort to stop the truck considering that it is power brakes. If I was to use the same pedal effort to stop any of the other vechicles that have power brakes I'd be locking up the brakes easily. I can't seem to get the brakes to lock up in a panic situation. I put a new m/c, porportiong valve and brake booster. With each part there has been no improvement. I don't feel I wasted money on these parts since they are replacing 32 year old stuff. All four pads have been replaced. I even took it to a brake shop for them to attempt something. They chargered me $180 to rebleed the brakes and set-up the brake pedal a little higher. No real change other then the brake pedal is higher. I intend to tow my car in an enclosed trailer but don't feel I should yet until the brakes are right. Any suggestions?

06-13-2004, 10:13 AM	#2
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	How much vacuum do you have? If vacuum is low you will be applying lots of pedal to get it to stop. I just put disk brakes and booster setup in mine and when I hit the brakes hit just about puts you through the windsheild. __________________ 1967 C10 - SWBSS Pro Street 427sbc, 700R4 & 4.10 Gears 1948 Chevy FleetMaster Coupe, LS1, (almost done) 1950 Chevy StyleLine Coupe 250/6 3x2 Dueces 2009 Toyota Tundra 1996 Harley RoadKing "I maybe getting old, but I can still burn rubber with the best of them"

06-13-2004, 10:18 AM	#3
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	A couple of thoughts: Have you changed the flexible rubber lines? Its not unheard of for them to deteriorate and clog up after 32 yrs. You don't have a profile. What about you engine, is it modified, i.e. low vacuum. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

06-13-2004, 10:51 AM	#4
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	are you trying to compare 30+ yearold brake system to a modern day brake systems?? __________________ 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

06-13-2004, 03:30 PM	#6
Bowtie67 Registered User Join Date: Jan 2004 Location: NH Posts: 2,266	Like neon said they do sometimes have a tendency to detrierate and collapse. The hose should have an inside diamiter of 3/8 of an inch. __________________ 1967 C10 - SWBSS Pro Street 427sbc, 700R4 & 4.10 Gears 1948 Chevy FleetMaster Coupe, LS1, (almost done) 1950 Chevy StyleLine Coupe 250/6 3x2 Dueces 2009 Toyota Tundra 1996 Harley RoadKing "I maybe getting old, but I can still burn rubber with the best of them"

06-13-2004, 10:53 AM	#5
Shane65 Registered User Join Date: Oct 2003 Location: Ontario Posts: 108	I replaced the engine 3 weeks ago. The problem has been with me before the engine was replaced. Originally it was the stock 350 but now I put in a stroker 421 to make some needed torque for the trailer. I built the engine for torque so the cam is mild for that size of engine and I use an Eldebrock Performer RPM manifold with the stock quadrajet. I just checked the vacuum and it's at 19 inches on the gauage at idle. I thought of the lines but haven't replaced them. The outside of them look good with no age cracks. Is it possible for them to be reduced on the inside diameter.

06-14-2004, 11:13 AM	#7
Bobalouie Fetzer Valve Technician Join Date: Jun 2003 Location: Stillwater, OK Posts: 205	This is a stupid question, since you changed the booster, but did you put a new check valve in the booster? I did that to mine, and it made a night and day difference. The brakes still suck (due to other issues) but at least I have some pedal travel now. __________________ 1972 Chevy K10 SWB

06-20-2004, 03:22 PM	#8
Shane65 Registered User Join Date: Oct 2003 Location: Ontario Posts: 108	FINALLY!!!! My brake problems are solved. There are no check valve or filter in the booster vacuum line originally and there are none now. The brake lines are not swelled according to a mechanic that works from his 2 bay garage in the back yard of his house. If the brake lines are swelled the fluid is slow to get into the calipers and slow to get out. If this is the case then my brakes would drag when I release the pedal(they don't). He asked me about the brake pads I use. I told him I bought the best the store had but wasn't sure if they were metalic or semi-metalic. He said to go back to the store and get the cheapest set which should be organic type and put them on. He said these era of trucks never were designed for metalic brakes. I put a set on and now I have brakes that work with ease and I can actually lock up the wheels if need be. Pedal effort is reduced and now I feel confident enough to let my wife drive it.(still not sure if that's a good idea or not). Tomorrow , I've got to get over to my new mechanic friend and thank him.



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