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Vintage Snowmobile Tunnel Restoration

While this tunnel is for the 1972 Polaris Charger, a lot of the procedures will work on any steel tunnel.

What we started out with is a tunnel that didn't look that bad in the beginning.  As we tore into it, it kept getting progressively worse.  None of you have ever been there!

Initially this was not going to be torn down this far.  I decided to fix this, well if you fix that then this won't be good enough, etc. 

Ok, on with the project. This page will deal only with the tunnel.

I am going to try and lay this out so that someone can use it as some reference material so it will be a little more in-depth than some of the pages.  Please remember that everyone has their methods, these are some of mine.

The tunnel at the start

The tunnel had some pretty nasty gashes and other damage from rocks, stumps and who knows what all it had hit.  I had already roughed out the belly pan damage prior to these pictures.  The metal was quite "stretched" due to the sharpness of the dents.  There were also quite a few tears in the metal that needed to be welded up.

Doing some "metal shrinking"

When metal stretches, the metal becomes thinner, but larger than required.  We now need to "shrink" it.  We do this by heating the metal up and hammer and dolling it and then quickly cooling.   Many small shrinks are more controllable than one large shrink.  Notice that I have tried to get my body lines where we want them so that we minimize the amount of any filler used.

A overview of the tunnel with metal work roughed in and ready for the sandblaster.

The tunnel sand blasted. 

Ran into a minor snag.  Some rust under the fuel tank/seat area.

Some people would have used dura-glass or fiberglass, but I elected to cut it out and weld it up.

The first picture shows the metal cut out and the procedure of "flanging" the metal.  This way the metal lays into the step and stays flush.  This also give the metal more stability.  You will also notice that I rounded the corners rather than leave them square.  I find that they finish up nicer this way. 

The third picture shows some copper weld through primer.

The forth picture shows the metal patch laid in place. 

The fifth picture shows the metal welded into place and the weld cleaned up.

The sixth, seventh and eighth picture show placing the gas tank bracket into position and welding that into place.

And the tunnel in one piece again.

The bodywork begins

this is an industrial epoxy that I put down before I do body work.  It gives corrosion protection that plastic filler would not applied directly to steel.  It also goes on quite heavy and minor imperfections will be sanded out with it.  It is sanded before filler is applied.

Where there is a weld I applied a think coat of Duraglass or equivalent in case there are any pin holes.  This will keep moisture from coming through.  I then just roughly cut that down making sure that it was lower than where any other finish material would be.

A 3 inch and a 6 inch DA.  Used quite a bit throughout this process.

Last two pics show the filler finished off in 180 grit.  Blocked with a hard block and lightly hit with sponge pads and da's to minimize the scratches.

The Paintwork begins.

The tunnel with "primer filler" applied where necessary.

Picture 1, 2, and 3 show how when you start to block you can see imperfections.  As you sand further they go away.  I started here with 240 by hand and finished with 400 grit by hand and then lightly went over it with 400 on a DA.  400 by machine will leave a less severe scratch than by hand.

A single stage paint could easily go as coarse as 320

Picture 4 shows how when you start to cut through the primer it is time to stop.  You will just have high spots if you continue.  If severe enough you might have to use a glaze or some other means of creating more fill.

Picture 5 and 6 shows the tunnel ready for paint.

Paint Day

The first photo is the tunnel hanging ready for paint.

The second and third show the tunnel in "sealer".  I used a automotive epoxy and applied 2 coats in critical areas.  I allowed it to dry overnight to allow plenty of flash time.

Picture 4 is with the first coat of basecoat.  I originally was going to use single stage but since this is a metallic I opted to go with basecoat.  I am glad that I did with all the nooks and crannies.

Picture 5 and 6 are the finished product.

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