The stock stance and factory drum brakes on '55-59 GM pickups may have been enough to handle the job a half century ago, but today's style and driving demands require something much more contemporary. Classic Performance Products (CPP) has been ahead of the game for years, producing parts to make early GM pickups (as well as many other makes and models) stop, steer, and handle better. So we went straight to them with our needs.
While CPP can supply anything from factory replacement pieces to a complete, new street rod-style chassis, our project was looking for a mild drop and better stopping power that could all be handled at home without much more than basic hand tools. CPP had the answer with its 3-inch dropped axle and disc brake conversion kit. Everything was included to complete the conversion. While we were shopping, we picked up a few more things to freshen up our frontend, like new shock mounts and a brand-new drag link.
Follow along as we transform our front underpinnings from outdated to state-of-the-art in solid-axle technology. We'll dress it up in the end with some fresh rolling stock from Wheel Vintiques and Coker Tire. Stay tuned for the next issue when the back half gets a similar treatment.
Everything you need to drop...
Everything you need to drop and stop your '55-59 GM pickup comes complete from Classic Performance Products. CPP's disc brake conversion kit fits all stock or dropped axle-equipped GM pickups from '47 to '59.
The original wheels and mile-high...
The original wheels and mile-high stance leave much to be desired if you're looking for something cooler than stodgy stocker.
After removing the original...
After removing the original six-lug wheel, this rusty and neglected drum brake assembly is not what you would want to entrust with your and others' safety.
Because of the new CPP axle's...
Because of the new CPP axle's additional drop, the tie rod needed to be relocated from the top of the steering arms to mount from the bottom in the position shown to allow the new tie-rod end to clear the leaf springs.
CPP owner Jim Reis got started...
CPP owner Jim Reis got started on the disassembly of our spindles from the axle by removing the frozen backing plate hardware. Be prepared for stuck hardware when dealing with a vehicle of this vintage.
Next to be removed was the...
Next to be removed was the kingpin lock pins. These must be taken out before the kingpin can be disassembled from the axle.
GM pickup spindles from this...
GM pickup spindles from this era use a plug on each end of the kingpin to seal in grease and seal out road debris.
A trick Jim showed us to ease...
A trick Jim showed us to ease the removal of the kingpin plugs is to dimple them inward with a large punch.
After dimpling the kingpin...
After dimpling the kingpin plugs, they could easily be removed with a small screwdriver.
A soft metal punch works well...
A soft metal punch works well to get the kingpins moving in the removal process. The softer brass is used because if the ends of the kingpins become "mushroomed" they are very difficult to remove.
For exceptionally stubborn...
For exceptionally stubborn original kingpins that have rusted themselves in place, a press may be required to remove them.
After removing the kingpins,...
After removing the kingpins, note the bearing placement on the bottom side of the spindle with the thin metal shims on the top. This same combination will be repeated in the reassembly.
Once the spindles were cleaned,...
Once the spindles were cleaned, a special tool was used to remove the original kingpin bushings from the spindles.
The bushing removal tool pushes...
The bushing removal tool pushes the bushings evenly out of the spindles.
Using the same tool, new kingpin...
Using the same tool, new kingpin bushings were installed into the center of the spindle.
Another Jim trick for reinstalling...
Another Jim trick for reinstalling the kingpin plugs is to reverse-dimple them using a socket and a metal punch before inserting them in the axle.
Before installing the new...
Before installing the new bearing adaptors, the spindles were tuned up and smoothed with emery cloth.
Using a proper-sized piece...
Using a proper-sized piece of tubing, the bearing adapters were installed onto the original spindles.
Since we were using new tie-rod...
Since we were using new tie-rod ends with a bolt-on design, the original ball-style inserts must be removed from the steering arms. The first step was to grind off the swedged end of the steering ball.
After grinding, the center...
After grinding, the center of the steering ball was drilled out to remove the press fit's mechanical pressure.
After drilling, the steering...
After drilling, the steering ball was easily knocked free of the steering arm.
Comparing the new Classic...
Comparing the new Classic Performance Products dropped axle to the original unit, it's easy to see the 3 inches of lowering to be gained from the new unit.
The heavy-duty forged dropped...
The heavy-duty forged dropped ends of the new CPP axle are equally super strong and very graceful.
A new shock mount kit from...
A new shock mount kit from CPP would replace the rusted and broken original factory pieces.
The new axle installed just...
The new axle installed just like the original unit. Note the new lower shock mount tucked in close to the axle for additional clearance.
With the shim pack on the...
With the shim pack on the bottom side of the axle, the new kingpins slid right in the re-bushed spindles.
The new caliper bracket installed...
The new caliper bracket installed on the spindle with the supplied shims and hardware.
The new bearing was loaded...
The new bearing was loaded into the rotor followed by a fresh dust seal.
The new cross-drilled rotor...
The new cross-drilled rotor slid right onto the spindle and mated up to the installed bearing adapter.
After loading the new outer...
After loading the new outer bearing, the new spindle nut and washer locked the whole assembly in place.
The new caliper was installed...
The new caliper was installed toward the rear of the vehicle with the bleeder facing up. Make sure the special caliper bolts are secured tightly.
As mentioned earlier, the...
As mentioned earlier, the new tie rod now installs in the bottom side of the steering arm to clear the leaf springs.
The finished assembly needed...
The finished assembly needed only the new supplied flexible brake lines and some bleeding to complete the installation.
A new dual master cylinder...
A new dual master cylinder and power booster setup from CPP is a huge improvement in both braking and safety over the original single non-power unit.
The original brake pedal mounted...
The original brake pedal mounted up to the well-designed CPP master cylinder unit gives a factory appearance inside the cab.
For ease of illustration,...
For ease of illustration, this mock-up shows how the new master cylinder and booster mount to the GM pickup frame.
With the much-improved front...
With the much-improved front stance, a fresh pair of shoes was certainly in order (and required because of the swap from the six-lug to five-lug passenger car bolt pattern). Nailing the retro look is a pair of beautiful chrome-reversed wheels from Wheel Vintiques wrapped in a pair of U.S. Royal wide whites from Coker Tire.
With the front half now under...
With the front half now under control with pieces from Classic Performance Products, Wheel Vintiques, and Coker Tire, we will handle the rear half next time with pieces from the same suppliers.