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Adding Power Brakes to a Dinosaur of a Suburban

Posted in How To: Suspension Brakes on October 24, 2018
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If you are familiar with our fossilized 1970 Chevrolet Suburban Project Vehicle known as Dino the Dinosaur then you will probably remember that our goal with this project has been to preserve Dino for the future. Not to restore Dino, or make Dino into the most capable three-door Suburban ever, but rather to make Dino better at what Dino does.

We have refreshed Dino’s suspension, added some new (and slightly larger tires), cleaned up the interior, and upgraded the fuel system on the 350 V-8 to factory GM TBI. We also added power steering and limited-slip differentials, chromoly rear axles, and disc brakes to a newer open-knuckle Dana 44 front axle. Since that last upgrade Dino has been resting (summer in Arizona can be a downright painful time to drive a classic SUV without A/C), but one aspect of Dino-ology has gone backwards rather than forwards. Once we switched Dino from drum brakes up front to discs, the old drum brake master cylinder gave up the ghost. Something inside the master failed and brake fluid began to leak.

Luckily there are upgrades available to Dino to make the brakes that much safer and more reliable. With a CPP master and booster (PN 6772-CT, $299 plus shipping) from our friends at Truckin’ Krazy Truck Parts of Mesa, Arizona, and a little elbow grease, Dino is back to stopping better than ever. Check out the install, including some tips and tricks to make everything a bit easier.

Dino’s original manual drum/drum master cylinder was displeased by our addition of front disc brakes. Maybe the larger cylinders of the calipers caused the master to travel too far, or all that new brake fluid and brake bleeding caused a seal in the master to tear? One way or another, brake fluid was leaving the system. It was time to replace it with something that would work.
With a quick call to our pal Tom at Truckin Krazy Truck Parts in Mesa, Arizona, we had a CPP Brake Master and Booster in hand. This system is designed to work with most if not all 1967-1972 GMs without drilling holes, building brackets, or much customization if any. The unit (PN 6772-CT) comes with a brand new master cylinder, a new booster, a firewall bracket, a pushrod, and a proportioning valve.
To make the install go easier, Tom recommended we drop Dino’s steering column from the dash. This gives a few inches of clearance for removing the bolt that secures the brake master pushrod to the brake pedal.
With Dino’s fossilized master cylinder out of the way we bench-bled the new master. You want to make sure the pushrod is moving all the way through the bore during this procedure. Having it connected to the brake pedal may prevent full movement. We massaged the factory brake lines over to the driver side a bit to meet the new brake proportioning valve. We also had to source a couple of brake line adapters from our local parts store to get the factory lines to fit the proportioning valve. Tom advised us that these trucks can have a few different factory brake fittings depending on year model and whether they are 1/2- or 3/4-ton rating. Truckin Krazy does keep some of these adapters on hand.
Getting the new brake pushrod the right length is critical. You will want to adjust the booster pushrod so that the brake pedal is as high as possible without preloading the brake booster and while ensuring the brake lights are off. We ended up shortening the supplied clevis bar by cutting and welding. We could have drilled another hole if a welder weren’t available.

Sources

Truckin’ Krazy
480-241-1318
facebook.com/truckinkrazy

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