Chevelle Brakes - Whoa Down

Installing a Hard-Stopping, Hydroboosted Four-Wheel Disc Brake System

John Nelson Feb 26, 2008 0 Comment(s)

It was a given that we'd be upgrading the brakes themselves when we showed up at Performance Online, ditching the old B-body discs for a pair of 13-inch platters clamped by two-piston PBR calipers and excising the drum rears in favor of 12-inch discs with matching PBR calipers. We also knew we'd be swapping out the master cylinder and prop valve, converting from manual to power assisted brakes. The easiest route would have been to install a typical engine vacuum-fed power brake booster unit behind the new master. The problem, as Chadick points out, is that the booster has to see enough vacuum to boost to be effective. POL considers 15-22 inches of engine vacuum to be the optimal level. The mondo-cammed 396 in our test bed was only pulling 5 inches at idle, which just isn't enough for the job.

The solution was to install a Hydroboost hydraulic brake assist unit in place of the typical power booster. Rather than relying on engine vacuum for its boosting capabilities, the Hydroboost relies on hydraulic pressure from a car's power steering system to provide assistance in braking efforts. In this case, that meant that Becker had POL convert his Chevelle to power steering before we arrived on the scene to document the brake installation--the Hydroboost system was then plumbed into the new system as part of the brake conversion. It took some extra effort and expense on Becker's part, but was it worth it?

Taking it solely by the numbers, absolutely. The new binders cut 10 feet off the Chevelle's 60-0 stopping distance, taking us down to 145 feet. Fade was nonexistent--our top-three average was 147 feet. But there's also the nature of the improvement to consider, and suffice it to say that the effort it takes to make this thing stop has been significantly reduced. Pedal response is immediate--when we say these brakes really bite, we mean it in a good way. We quickly learned to develop a light touch on the pedal--that was all we needed to produce consistent, short stops.

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This is the front brake we found as we got to work on Jeremiah Becker's '66 Chevelle. Given that B-body spindles and disc brakes were installed in between the Hotrods to Hell upper and lower control arms, this Chevelle was in better brake shape than when it rolled off the line, but it still had plenty of room for improvement. Performance Online's Mike Wheeler capped the brake line to keep fluid from getting all over the works before doing anything else.

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Wheeler wanted to use the ball joints and tie-rod ends already bolted into the '66, so he eschewed the pickle fork and relied on a dead-blow hammer and copper mallet instead. The ball joints were released by loosening--but not removing--the castle nuts, then striking the spindle with the dead-blow hammer until it dropped. For the tie rods, a copper mallet was inserted so that the tie-rod end could be hammered out without damaging it.

Now you can stop this thing hard-without limping away.


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