Brake issue on the 69 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Kw69 · 09-22-2016, 03:08 PM

Hey guys I had all the brakes done about a year ago and replaced the rubber lines. The metal ones are still original. Truck has non power assisted drum brakes. Anyway the last few weeks I have noticed that the pedal would lose pressure, like I had air in the system. But I should not have any air cause I can't find a leak and they were bleed a year ago. Funny thing is you can pump the pedal after you lose pressure one time and you have pressure again. This symptom comes and goes a few times if you drive it. So I checked the fluid and its full! Anyway being the original brake master cylinder, I'm thinking it's going bad. After all it's from 1969 so I figured it's time. Does my thought sound right? Or am I missing something ? If I replace it should I also just go for the power assisted as well? And if so where is a good power unit available?mauto zone, advanced auto, or ? Or would it be worth to convert the whole truck to five lug and disc? eBay about 1100.00 ...... Seeing what you guys think. Thanks in advance

custom10nut · 09-22-2016, 10:23 PM

The quick answer is yes, your my temps suggest a worn out MC. Easy to replace, and if your favorite APS doesn't stock them, they can have it for you in a day or two. I wouldn't be driving the truck if I were you, because once that fails completely you won't stop till you hit something big. I converted mine to PB by getting the complete setup from another truck, and then used that MC and booster as the core for a new one. I used the prop valve and all the brackets (which are not reproduced). Far as the conversion goes, that's entirely up to you, and if you can justify the cost, then it's a good upgrade.

Myoldtruck · 09-22-2016, 10:35 PM

I bought my replacement master/booster from advance auto for 125.00. I was manual before i changed over. I bought the adapter bracket on ebay to mount the booster. Well worth the 200. 00 i have into it.

Kw69 · 09-23-2016, 04:05 PM

Thinking that I will do the same. I will leave it original 6 lug and add th power booster. Not familiar with the adapter bracket will need to look that up. Yep I'm not driving it for sure, don't want to not be able to stop. Thanks guys

Kw69 · 09-23-2016, 04:26 PM

Ebay is good, just ordered the power brake booster assembly for around 200.00. Will work for what I need, and it will also work if I ever go to disc brakes. Not sure about that since I may not want to convert to 5 lug. It gets pretty expensive. I am thing of just leaving the drums and buying a nice set of rally wheels instead. Any ideas where to get those in 6 lug pattern? Thanks

Myoldtruck · 09-26-2016, 07:51 AM

One more thing, buy the rubber gasket that goes on the fire wall for the power brake booster. One of those things that i forgot and had to jury rig after the fact.

I also had to make new lines from the master cylinder to the porportional valve. Your going to need the vacume fitting for the intake manifold also.

09-22-2016, 03:08 PM	#1
Kw69 Registered User Join Date: Sep 2015 Location: Florida Posts: 111	Brake issue on the 69 Hey guys I had all the brakes done about a year ago and replaced the rubber lines. The metal ones are still original. Truck has non power assisted drum brakes. Anyway the last few weeks I have noticed that the pedal would lose pressure, like I had air in the system. But I should not have any air cause I can't find a leak and they were bleed a year ago. Funny thing is you can pump the pedal after you lose pressure one time and you have pressure again. This symptom comes and goes a few times if you drive it. So I checked the fluid and its full! Anyway being the original brake master cylinder, I'm thinking it's going bad. After all it's from 1969 so I figured it's time. Does my thought sound right? Or am I missing something ? If I replace it should I also just go for the power assisted as well? And if so where is a good power unit available?mauto zone, advanced auto, or ? Or would it be worth to convert the whole truck to five lug and disc? eBay about 1100.00 ...... Seeing what you guys think. Thanks in advance __________________ 2009 GMC 2500HD 6.0, 6 speed auto, stealth grey, 4x4 Z71, Bilsteins, Black Bear Tuned. Pulls the 10k fifth wheel all so easy. 1969 CST 350 black long bed, 3 on the floor, PS, AC, drum brakes, old school and love it. Last edited by Kw69; 09-22-2016 at 03:23 PM.

09-22-2016, 10:23 PM	#2
custom10nut Registered User Join Date: Apr 2015 Location: East Tn (In the heart of the Smoky Mtns) Posts: 1,887	Re: Brake issue on the 69 The quick answer is yes, your my temps suggest a worn out MC. Easy to replace, and if your favorite APS doesn't stock them, they can have it for you in a day or two. I wouldn't be driving the truck if I were you, because once that fails completely you won't stop till you hit something big. I converted mine to PB by getting the complete setup from another truck, and then used that MC and booster as the core for a new one. I used the prop valve and all the brackets (which are not reproduced). Far as the conversion goes, that's entirely up to you, and if you can justify the cost, then it's a good upgrade.

09-22-2016, 10:35 PM	#3
Myoldtruck Registered User Join Date: Sep 2015 Location: Mohnton pa. Posts: 208	Re: Brake issue on the 69 I bought my replacement master/booster from advance auto for 125.00. I was manual before i changed over. I bought the adapter bracket on ebay to mount the booster. Well worth the 200. 00 i have into it.

09-23-2016, 04:05 PM	#4
Kw69 Registered User Join Date: Sep 2015 Location: Florida Posts: 111	Re: Brake issue on the 69 Thinking that I will do the same. I will leave it original 6 lug and add th power booster. Not familiar with the adapter bracket will need to look that up. Yep I'm not driving it for sure, don't want to not be able to stop. Thanks guys __________________ 2009 GMC 2500HD 6.0, 6 speed auto, stealth grey, 4x4 Z71, Bilsteins, Black Bear Tuned. Pulls the 10k fifth wheel all so easy. 1969 CST 350 black long bed, 3 on the floor, PS, AC, drum brakes, old school and love it.

09-23-2016, 04:26 PM	#5
Kw69 Registered User Join Date: Sep 2015 Location: Florida Posts: 111	Re: Brake issue on the 69 Ebay is good, just ordered the power brake booster assembly for around 200.00. Will work for what I need, and it will also work if I ever go to disc brakes. Not sure about that since I may not want to convert to 5 lug. It gets pretty expensive. I am thing of just leaving the drums and buying a nice set of rally wheels instead. Any ideas where to get those in 6 lug pattern? Thanks __________________ 2009 GMC 2500HD 6.0, 6 speed auto, stealth grey, 4x4 Z71, Bilsteins, Black Bear Tuned. Pulls the 10k fifth wheel all so easy. 1969 CST 350 black long bed, 3 on the floor, PS, AC, drum brakes, old school and love it.

09-26-2016, 07:51 AM	#6
Myoldtruck Registered User Join Date: Sep 2015 Location: Mohnton pa. Posts: 208	Re: Brake issue on the 69 One more thing, buy the rubber gasket that goes on the fire wall for the power brake booster. One of those things that i forgot and had to jury rig after the fact. I also had to make new lines from the master cylinder to the porportional valve. Your going to need the vacume fitting for the intake manifold also.



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