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Randy Pflanzer
Technology Professionals Consortium
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  02/01/13 - Reformatted web page.

 

Cooling Shroud

The problem to be solved is how to fill this area between the nose and the radiator?  One can buy the shroud offered by Lone Star but I don't care for it because it has a series of bends in it and it's not smooth.  I first considered shaping one out of a sheet of stainless but quickly abandoned that due to the difficulty involved.  Then I planned to install a series of flat panels across the bottom and up the sides.  I started to move in that direction but eventually decided I didn't care for the appearance of it.  So I ultimately decided to create a single piece out of fiberglass.

The first step was to build a male mould upon which I could lay up the fiberglass.  I cut the two ends out of plywood and stuck them on the body and the radiator.  I took a couple of measurements and cut a couple of framing pieces to connect the ends.  The critical measurements at this point is to get the angle of the parts correct relative to one another.  If not, then the finished part will not fit the nose opening on the body properly. 

Next, I used block of blue foam and my glue gun to fill in the spaces between the front and rear forms.  This is a time consuming effort that must be done properly or else the form will loose shape when the excess foam is cut away.

I decided that rather than sand the part to shape, I would fabricate a hot wire cutter and use it to cut around the plywood shapes to get the foam into its final shape.  This worked pretty good although it's hard to control the temperature of the wire and it gets a little too hot.  The result is that it melts a little too much of the foam but that's not a big issue to correct.

Once the blue foam was cut to shape, I covered it with body filler until it was smooth.  When I was done with the body filler, I painted the part with three coats of enamel paint to provide the final surface.  I also mounted the part in a jig so I could rotate the mould while I was glassing it.  The blue foam glued to the front edge is to provide a lip to the front of the finished part so it will slip over the front opening in the body.

Prior to glassing the part, I covered the mould with mould release agent.  A couple of coats was sufficient to provide a good barrier.  I then laid up two layers of 9 ounce glass on the part.  I kind of guessed on the number of layers.  I wanted the part to be stiff enough to hold its general shape but also flexible enough to bend and fold so I can install it through the nose.

To get the part off the mould, I split the part at the top where the cleco clips are in the picture.  This is where I will glass an overlay of 4 layers for a nut plate and screw.

This is the trial fit of the part to the car right off the mould without any trimming.  It fits very well and only minor trimming will be required to finalize the fit.  In this picture, the radiator and rock guard have been removed so I don't have to worry about the rear trim lines just yet.  It turns out that the 2 layers of glass was just about right.  I probably could have added one more but that's not a big deal.  Now I need to figure out how to secure the part to the frame so it is rigid enough to stand up to the vibration and heat.

My first step was to weld a couple of mounts on the bottom.  In each location where I place a mounting, I laid up a 4 layer reinforcing lay up to provide abrasion resistance and so I could countersink the mounting holes for the stainless screws.

On top, I riveted some aluminum tabs to the shroud and drilled mounting holes for screws and nut plates in the frame of the rock guard.  What's not shown in this picture are two slots that I cut into the top of the glass shroud to allow the hood hinges to close.

I decided that the sides of the shroud were still a little too flexible so I added a couple of mounting tabs to the frame to secure the sides of the shroud.  Missing in the picture are the nut plates riveted to the mounting tabs.

The final bit of reinforcing was a couple of aluminum angles riveted along the edges of the openings.

This is the final fit.  The part lines up nicely with the opening and is square to the radiator.  The six mounting points appear to provide a nice solid mounting for the part so I think I can consider this difficult part completed.  All that's left is to fill the pin holes and paint.  I still haven't decided on the color for the shroud so I may wait and consult with the painter before deciding.

Next, I plan to build a mould and install a shroud for the lower opening for the transmission cooler.  That work begins on the next page.