Longbed, No! - Shortbed, Yes! | Early Classic Enterprises

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The premier manufacturer and distributor of quality suspension and restoration components for 1960-1972 GM pickups, blazers, panels and suburbans.

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Longbed, No! - Shortbed, Yes!

Publication Name: 
Custom Classic Trucks
Publication Date: 
April, 2003
Section: 
Early Classic Long To Shortbed Conversion

With the popularity and prices of '67-'72 GM trucks currently going through the roof, it's nearly impossible to find a good, clean shortbed truck to restore. Anyone lucky enough to own one has a dozen stories of enthusiasts trying to buy their ride. These popular trucks usually produce a few windshield notes and business cards left by prospective buyers as well.

ple supply of longbed models floating around, and many savvy hot rodders are building the truck of their dreams by acquiring a longbed and shortening the chassis. Now this seems like a giant undertaking, but truck frames are shortened and lengthened everyday to accommodate different applications in the big truck industry. The same techniques can be applied to the light truck market with great results.

Loyal readers have been following along as Early Classic Enterprises has converted a 1971 C-20 ¾-ton truck using their new C-10 conversion spindles and rear air- suspension kit. Now with the suspension finished, it's time to shorten the frame and make this longbed truck about 20 inches shorter than the factory made it.

How To Steps and Images: 
The '60-'72 GM light truck series had several wheelbase options. The two most popular are the (115-inch) shortbed and the (127-inch) longbed. Over the years, many longbed chassis' have been shortened, and the process isn't that complicated. Shown here are two bare frame examples. You can see that the length is different. Also, the location of the various crossmembers aren't the same.
The rear frame rails can simply be cut off, and do not require any welding or other modification. The rear of the frame needed to be shortened 8 inches, and a sharp blade in our Sawzall made quick work of the job.
Shortening the center of a chassis is substantially more involved. The frame needed to be cut in half - one foot removed of length removed - and the front and rear frame sections welded securely together. In other words, it's not a project for the novice welder. Proper alignment of the frame sections is also a critical procedure; it can mean the difference between a sweet shortbed chassis and a pile of junk.
The secret to success is cross-measuring on a level and flat section of concrete floor. After the frame was fixtured on a level floor with jackstands underneath, the cab mount bolts were removed to allow the cab to be raised up from the frame for clearance. Remember, all plumbing and wiring needs to be removed before any cutting begins.
The center of the frame had to be shortened by exactly 12 inches under the cab area. After ECE scribed a 45 degree line, they cut the front scribe line with the Sawzall. Because ECE blocked the front and center of the frame, the rear section was able to roll away from the cab to make access to the rear cut easier.
Early Classic offers these trick frame supports to help brace the center of the chassis. Custom- formed from 3/16-inch steel to exactly fit the odd inside dimension of the frame, these inserts are welded in place to help support the center of the chassis after it has been re-welded.
After ECE carefully re-aligned the front and rear frame sections and made certain that everything was in place, the seams were welded with maximum bead penetration. Once again, this is not a job for a novice welder. If you are uncertain of your abilities, seek professional help. After welding both the inner and outer seams, the guys at ECE chose to grind off and smooth the outside of the frame. It's imperative that the inside of the frame be welded for added strength if you plan on smoothing the outside surface. The ECE frame support can be seen in the background.
After a one foot section was re-moved from the frame, the rear cab- mount brackets had to be moved rearward by pre-cisely the same amount to re-align with the cab bolts. The original mounts are riveted to the frame, and have to be removed with a cold chisel or drilled out. The new holes were marked exactly 12 inches behind the old ones and drilled. They can also be welded in place on the frame. Here again, caution needs to be taken to prevent drilling into any wiring, brake lines, or fuel lines.
One common goal is to relocate the fuel tank from behind the seat. Not only does it eliminate the gasoline fumes in the cab, it allows the seats to slide farther back for more legroom. The additional space increases the storage area of the cab, and it’s a great place to mount stereo speakers and equipment. Early Classic now offers a custom-built fuel tank that can be mounted behind the axle and between the rear frame rails with little modification. This 23 gallon tank is made from puncture resistant 16 gauge stainless steel, and will never rust or corrode.
In order to fit the fuel tank, the rear crossmember and spare tire brace had to be removed for clearance. Like the cab mounts, they were riveted to the frame and had to be removed in the same fashion. The front of the tank will bolt to the frame on either side, and a new channel-brace crossmember will be formed to give support to both the frame rails and the rear of the tank.
Because this truck will do some towing in its new life, an ECE hidden receiver hitch kit is the perfect addition to the project. This Class 4 receiver mounts totally behind a factory chrome rear bumper, and also lends a great deal of support and protection to the frame and new fuel tank.
The hitch kit also includes an extended ball-mount to clear the bumper, a flip-up license plate frame, and a no-splice wiring kit for the trailer light connector.
To provide a mounting surface and support for the new tank, Early Classic formed a new rear crossmember using the same 3/16-inch material as the frame supports. Since the rear brace, fuel tank, hitch, and bumper brackets all come together in the same area, ECE’s Stan Hammond decided to mount the bumper brackets to the frame before the rear crossmember was installed. A little creative maneuvering was necessary in order to make everything fit. But once everything was in place, all of the components work well together well. The next hurdle will be assembling and installing the new reproduction Fleetside bed assembly. Stay tuned.
Category: 
Technical Articles
Sources: 
Company Name: 
Early Classic Enterprises
Address: 
5843 E. Clinton Ave.
Fresno, CA 93727
United States
Front Slide: 
no