Back Hatch Screw Replacement

Our intention was to repaint this vehicle before we brought it back north from Arizona.  The screws in the back hatch however were so rusted up that it was not possible to even tell if they were Phillips heads or some other species of screw.  Any attempt to paint them would result in new rust almost immediately. 

 

           

We ordered new screws from Cooperative Motor Works and had them drop shipped to a friend in Mesa where we were picking up the coach.  This was one of our mistakes in the project, Jim advertised these special screws on his web site for about $1.50 apiece but when we got the bill he charged us $2.50 apiece.  Also there was nothing special about them.  The screws were actually a 3/4in long 1/4 inch Truss head SS machine screw available at any good fastener supply house for less then 30 cents each and an aluminum insert used to put machine screws into particle board.  The inserts are also available at fastener supply houses and I also found them at the local ACE hardware store in Gila Bend for 49 cents each. No instructions came with this set of screws and inserts and their use was a little tricky since the glass that the inserts needed to be put into is considerably harder then particle board so the inserts could not simply be screwed in.  I was a little perturbed with the charges for these parts.  I don't mind a supplier making a reasonable markup, but even at the marine stores 40% is typical, but my real complaint is the increase in price above that advertised on the web site.

When we started this project we soon found that getting the original screws out was next to impossible, of the 25 screws we were only able to unscrew 3 of them.  We found that our trusty battery operated drill was mans best friend for this project, and using a 1/4 inch bit we drilled the heads off the screws.  When all the heads were off the screws it was easy to lift out the hatch, or so we thought until we found that the tire carrier was in the way.

 Getting the tire carrier off turned out to be a three man job since the bolts were so rusted on.  Most of the bolts ended up in two pieces.

With the tire carrier removed then hatch popped right out.

     

Now that the hatch was out of the way we had access to the remains of the screws and using vice grips it was possible to get a good grip and back them out, including the original insert that was imbedded in the glass.  The inserts and the original screws were so corroded that they were essentially one part.

     

With the screws and inserts removed the holes were drilled a little deeper for the new inserts which were much deeper then the originals.

The new inserts were designed for use in soft materials such as particle board and they really have no ability to cut threads into the hard glass.  We had two choices, either drill the holes big enough so the new inserts would slide into the new holes and the use a high strength body filler to keep them in place or find a way to modify them so they would screw into the hard glass.

We actually chose a solution that was a little bit of both.  We used a flat file to take down the teeth on the inserts leaving only points sticking out.  This created an insert that would screw into the hole, we then used a high strength bonding compound around each of the inserts as it was screwed into place. The result is a new insert that is part of the body.

The following picture shows the various pieces used to do the job. Top left is the original screw and the insert that came out in one piece.  The remains of the screw head is just below this.  Second from the left is the new 1/4 x 3/4 inch SS machine screw that replaces the original screws.  Third from the left is a screw and insert combination and on the far right top row is the new insert by itself.  Below the screw and insert combination is an end view of the insert and just to the right is an end view of the modified insert. Note how the tops of the threaded teeth have been filed down. At the bottom is the insert with an Allen wrench used to screw the insert into the hole after it has been smeared with high strength body filler.

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The screws along the bottom were #14 3/4 inch truss head sheet metal screws.

The final result was great and it was easy to remove the back again when I got home. 

There is a seal that appears to be a round gasket used to seal the rear hatch that I will try to replace before completion of the project.