Beginning in 1988 GM revised the door hinge system on their medium duty and full sized pickup trucks. 

The biggest change was the elimination of traditional “bolted on” hinges, and the introduction of welded hinges. The hinges were no longer attached to the door or body with bolts, but were now robotically MIG welded to the door and body from the back side of the hinge. The doors were then attached to the body using a replaceable pin and bushing design. 

This same system was first used on 1982 S-10 series trucks. The primary purpose of the changes was to simplify production of these vehicles, and improve serviceability of the hinge pin and bushings.

This hinge system worked very well while these vehicles were relatively new, but with the passage of time some significant problems began to appear.

1)   The flange of the top bushing in the upper door hinge would wear away and allow the bushing to fall out of the hinge.

2)   The hinge pin could then begin to wear away at the bushing bore in the hinge - or the pin would wear completely through the bushing wall, and then against the hinge itself.

3)   The replacement of the worn out bushings and pins was often made more difficult because the new bushings would not stay firmly fixed in the hinge since the bushing bore in the hinge had become oversized from wear.

4)   The locations where the hinge pin “anchors” in the hinges would also become worn to the point where they were unserviceable and would no longer firmly hold the pin in position.

These problems eventually lead to a condition where the door(s) will not close properly even with new hinge pins and bushings installed. This problem is further aggravated where the vehicle is used in a commercial application. 

One of our customers has a fleet of beverage delivery trucks that experience in excess of 150 open/close door cycles per day. To keep some of these vehicles in operation the hinges themselves must be replaced. A ghastly and very time consuming process even for the experienced professional or fleet garage technician, the old welded hinges must be cut from the body and door, and then the new hinges bolted in place. This also involves readjusting the door position within the cab door opening. Not to mention the fact that the replacement hinges are attached with bolts, and they cannot match the structural integrity of the original welded hinges. 

If the worn out hinges are not replaced they will eventually cause cracking of the door and in some cases, the cab itself. We have witnessed several situations where the entire cab was replaced on a municipal vehicle due to cracking, and wear of the cab at the hinge, and striker area. On this particular vehicle the sagging door had actually worn a hole in the cab.

At the heart of this problem is the fact that the hinges cannot be properly lubricated.  Aerosol lubricants are commonly used to lubricate these hinges, but these only lubricate the exterior of the hinge joint. 

Engines last hundreds of thousands of miles because they have “pressure lubrication”.

Our repair system includes a provision for “pressure lubrication” to ensure the hinges can actually last the life of the vehicle.  In order to do so, we have designed a system of hinge repair that make no compromises in design or manufacture.  We have utilized every bit of currently available aerospace, and machining technology to manufacture bushings that can be installed and “pressure lubricated” in a very easy to follow method.

We have use a custom made step drill to drill the hinges precisely accept our bushing as a press fit, and a custom made mechanical press to do so. We even make a special “Anchor Repair” (AR) bushing the replace the area of the hinge where the hinge pins are fixed into the hinge.

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Our unique GMC medium duty truck hinge repair system