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

leatherhead63 · 12-24-2008, 06:19 PM

Hello

I have a 1972 K10 with disc up front. It has been awhile since I have owned an older truck. The brakes were terrible. Replaced the booster with much improvement. The peddle is a little harder than I would expect. If I get on the brakes hard the rear locks up. Am I looking at a problem in the front as in too little braking or am I looking at a problem in the rear with too much braking

thanks

*Dylan · 12-24-2008, 06:22 PM

Your rears will generally always lock up before your front will. Just due to the fact of there being less weight in the rear. I don't think your dealing with a problem just a standard issue that everyone has with our trucks. One question I would have though, is it pulling to either side when you brake?

69halfton · 12-24-2008, 06:22 PM

sounds like it could be a bad master cylinder to me. that would be my next thing to swap, or inspect.

leatherhead63 · 12-24-2008, 07:45 PM

no pulling, stiff pedal I was thinking to replace the master cylinder

Longhorn Man · 12-24-2008, 07:51 PM

sounds to me like they are working right.
Since there is no way to tell through words on a screen, I would recomend taking it to a brake place, or a person who would know.

cdowns · 12-24-2008, 08:47 PM

learn the technique of braking that was used prior toABS brakes//for hard braking it isnt effective to just slam on the brakes its alot more effective to use a pulsing type of motion to avoid locking the brakes up// having a heavy load in the bed will also reduce the brakes tendencies to lockup

bootlegger · 12-25-2008, 11:11 AM

you possibly have a problem with the metering or purportioning valve .it distributes presure from front to rear more in rear less in front .also ck brake adj in rear check vacum at boster and check valve on boster . a big cam wont give good vac at idle . new on sight just giving info

Shyguy · 12-25-2008, 11:25 AM

If I remember right disc brakes are not supposed to lock up the way they are designed.

As stated before it would be a good idea to replace the master cylinder just because of the age of these old trucks and check the proportioning valve

Danny

leatherhead63 · 12-26-2008, 02:04 AM

You have sold me. A new master cylinder it is

thanks

12-24-2008, 06:19 PM	#1
leatherhead63 Registered User Join Date: Jun 2008 Location: Yuma, Arizona Posts: 43	Brake logic Hello I have a 1972 K10 with disc up front. It has been awhile since I have owned an older truck. The brakes were terrible. Replaced the booster with much improvement. The peddle is a little harder than I would expect. If I get on the brakes hard the rear locks up. Am I looking at a problem in the front as in too little braking or am I looking at a problem in the rear with too much braking thanks

12-24-2008, 06:22 PM	#2
*Dylan Mean Buzzin' Half Dozen Join Date: Mar 2008 Location: Orlando, Florida Posts: 1,081	Re: Brake logic Your rears will generally always lock up before your front will. Just due to the fact of there being less weight in the rear. I don't think your dealing with a problem just a standard issue that everyone has with our trucks. One question I would have though, is it pulling to either side when you brake? __________________ "War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself." MY TRUCK (Now for sale) 1967 C10 SWB *Dylan* IIMY? Last edited by Dylan; 12-24-2008 at 06:23 PM.*

12-24-2008, 06:22 PM	#3
69halfton Registered User Join Date: Apr 2007 Location: King City, Ontario, Canada Posts: 974	Re: Brake logic sounds like it could be a bad master cylinder to me. that would be my next thing to swap, or inspect. __________________ - Jason If you can turn, Youre not going fast enough. Favorite caption: first car to 200 mph in the 1/4 mile, no parachute, drum brakes all the way around.. ..back when men were men.

12-24-2008, 07:45 PM	#4
leatherhead63 Registered User Join Date: Jun 2008 Location: Yuma, Arizona Posts: 43	Re: Brake logic no pulling, stiff pedal I was thinking to replace the master cylinder

12-24-2008, 07:51 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Brake logic sounds to me like they are working right. Since there is no way to tell through words on a screen, I would recomend taking it to a brake place, or a person who would know.

12-24-2008, 08:47 PM	#6
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Brake logic learn the technique of braking that was used prior toABS brakes//for hard braking it isnt effective to just slam on the brakes its alot more effective to use a pulsing type of motion to avoid locking the brakes up// having a heavy load in the bed will also reduce the brakes tendencies to lockup __________________ 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 Last edited by cdowns; 12-24-2008 at 08:49 PM.

12-25-2008, 11:11 AM	#7
bootlegger Registered User Join Date: Dec 2008 Location: syksville md Posts: 3	Re: Brake logic you possibly have a problem with the metering or purportioning valve .it distributes presure from front to rear more in rear less in front .also ck brake adj in rear check vacum at boster and check valve on boster . a big cam wont give good vac at idle . new on sight just giving info Last edited by bootlegger; 12-25-2008 at 11:16 AM.

12-25-2008, 11:25 AM	#8
Shyguy Junior Member Join Date: Dec 2006 Location: Southeast Missouri Posts: 2,436	Re: Brake logic If I remember right disc brakes are not supposed to lock up the way they are designed. As stated before it would be a good idea to replace the master cylinder just because of the age of these old trucks and check the proportioning valve Danny __________________ '67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E.

12-26-2008, 02:04 AM	#9
leatherhead63 Registered User Join Date: Jun 2008 Location: Yuma, Arizona Posts: 43	Re: Brake logic You have sold me. A new master cylinder it is thanks



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