Installing Trailing Arm Reinforcement Kits | Early Classic Enterprises


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Installing Trailing Arm Reinforcement Kits

Publication Name: 
Truck Builder
Publication Date: 
October, 2003
Strong Arm Tactics

How to install Early Classic's Trailing Arm Reinforcement Kit
Story and Photography by Matt Emery

One of the best suspension designs ever to come out of Detroit came on a pickup.  The trailing arm form of rear suspension used a long swing-arm that was held aloft with a coil spring instead of the more common leaf spring.

Top - The Early Classic kit comes with all that you will need to add the strength necessary for safe, high-performance operation of a '67-'72 Chevy or GMC truck.
Bottom - Early Classic has a bunch of parts that it uses when the need arises.

The advantages of the trailing arm system over a leaf-spring design are many.  The trailing arm suspension makes for a much better handling vehicle than those with leaf springs (just ask the NASCAR guys), but the arms themselves had a not-so-hidden design flaw.

The arms are made up of two stamped pieces that are riveted together.  The problem can be that during the normal operation of the truck, the two pieces can begin to separate.  This is a two-fold problem. One is that there is the possibility of the pieces separating enough that the holes through which the U-bolts are attached become dangerously loose.  When that happens, much like an our-of-round tire, the action of the U-bolts moving back and forth within the holes exacerbates itself.  This action could begin to destroy the arm.  Another issue is that with the U-bolts coming loose in their mounting holes, the handling of the truck will become sloppy as the rearend wanders.  This will especially be evident during cornering.

To combat this, Dave Clark of Early Classic Enterprises in Fresno, California, offers a Trailing Arm Reinforcement Kit.  The idea behind the kit is to weld 1/8-inch steel plates to the upper and lower edges of the trailing arm.  These will act to integrate the two pieces of the arms into one.  In addition to simply preventing the two pieces from separating, the plates will also greatly add to the overall rigidity of the arm by preventing the arms from twisting during hard driving, thus improving the truck's handling.

The Early Classic kit not only supplies the plates, but also includes new bushings and U-bolts.  With the original arms being 40 years ld, the bushings are probably thrashed, so replacing these is a must.  Another important safety consideration is to occasionally replace the U-bolts that hold the axle tube in place.

With the exception of the time it takes to weld the plates on, this is a simple modification, and one that is important to the safe operation of '67-'72 Chevy and GMC trucks.  Follow along as we demonstrate how to install the Early Classic Trailing Arm Reinforcement kit

How To Steps and Images: 
Removing the rust
The first step is to remove all of the rust that accumulated over the years. The crew at Blast Tech handled this operation. Once the arms have been cleaned of all rust and the plates welded on, the arms will then be powder-coated at Blast Tech's state-of-the-art facility.
Back at Early Classic, the arms are clean and ready for the next step. Note that the arms are made up of two pieces that are riveted together. The problem is that they can and will begin to separate under the stress of operation.
The first step is to remove the old bushing.
This is a simple matter when one has access to a press, but those at home can use a large vise to do this job. It's just not as simple as going down to the parts house, having the bushing pressed out and the new one pressed in.
The trick is to first push the inner sleeve out. A socket that is the same size as the sleeve is placed on top, while a large socket is used to give the sleeve somewhere to go. A large set of channel locks is used to pull out the sleeve.
With the inner sleeve removed, the rubber bushing can then be pushed out.
A thin coating of lithium grease is placed on the new bushing before it is installed. Wear protective gloves so you don't get this stuff on your fingers--it doesn't come off easily.
The press is again used to install the main section of the bushing.
The cap is then installed. Make sure that the socket only makes contact with the cap and not any other part of the bushing.
Installing the plates is actually a simple matter. The important part is to get the holes lined up. They are held in place with a set of C-clamps.
Care is taken to get the plate centered on the arm.
It is then simply a matter of welding on the plates.
Be prepared to spend a good deal of time welding on the two plates. It is time well spent--the result will not only add strength to the arms, but will reduce flexing. This will, of course, help to enhance the handling capabilities of the truck.
Technical Articles
Company Name: 
Blast Tech Dept. TB
1451 N Whitney
Fresno, CA 93703
United States
(559) 251-5242
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