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How to build a Duvall style roadster windshield

Discussion in 'The Hokey Ass Message Board' started by brianangus, Oct 15, 2006.

  1. Its been a while since I've done any "how to" posts, and there is always a lot of interest in the Duvall and Hollock style of roadster windshield frames. The picture shows my old 27 roadster and the windshield frame I built for it, at the staggering cost of about $15 plus glass. These can be bought from the aftermarket for about $1000, but if your the least bit handy, then follow along.

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  2. The first step, is to find the exact center of your roadster cowl (tape measure work) and lay down a peice of 1/8" masking tape exactly in the center, from the inner dash rail to the firewall on top of the cowl. This being done, pick a point about 1/3 of the distance out from the dashrail, and drill a 1/8" diameter hole thru the cowl top. (if you have a model A with a stock located gas tank, don't do this!!!!) I then took a straight peice of wire coat hanger about 15" long and welded a 1/8" bolt to the end of it. I put the end of the 1/8" bolt thru the hole, with the coathanger stuck up verticaly, and put a nut on the end of the bolt. This allowed me to bend the coathanger back untill I had the "rake" which I desired on the frontpeice of the windshield. This is a purely visible thing, so you have to be able to stand back and look at your roadster in profile to judge this correctly.---BEWARE--the outer edge of the windshield frame is going to lean back by the same amount, so if you get too crazy with this rake you will end up with the outer edge of the windshield frame sticking out into the "doorway" and interfering with your entrance and exit from the car. At the time I built mine my roadster was still unpainted, so I actually cut a peice of 1/2" plywood and screwed it in place from under the dash. I already have a solid model of the roadster-pickup cab, so I'm going to use it for this "how to" article.

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  3. The next step is tricky. You can start out with a big peice of stiff cardboard for this step. It helps a lot to have a friend assisting you. The cardboard must be held against the front corner of the plywood "fin" that you have standing up in the center of the roadster cowl. The trailing edge of the cardboard should set about 3" in front of the door jamb at the point where the cardboard crosses the side of the cowl. The bottom must be carefully trimmed so that it conforms to the curvature of the cowl.

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  4. The next step is to "eyeball" it very carefully and determine the shape you want the outside edge of the frame to be, then trim it as shown.

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  5. The next step is to decide how much to trim away to leave the "perimeter frame". A word of warning---we are going to weld a peice of metal "glass channel" from the windshield shop to the drivers side of this thing to hold our auto glass, so get a peice of glass channel first, bend it to follow the top of the cowl, the outside of the perimeter frame, and the inside edge of the perimeter frame WARNING---do this while the template is still in place, because there will be some triangulation come into play here.. Use a pencil to trace around the inside edge of the bent glass channel, then allow at least 1/4" more---when we cut the frame, we don't want to see this glass channel from the outside of the car.---At this time, trace your cardboard pattern onto some rigid 1/8" plywood or Luan mahogany door skin--there is too much flex in the cardboard now to serve our purpose any farther. When we do this, add 1/4" to the end that was up against the side of the plywood "fin"---remember, these two frames have to meet in the center, and the plywood fin was 1/2" thick, and we were witnessing of the side not the center when we built our template.

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  6. The next step is to transfer the big template onto a peice of 1/8" thick mild steel plate and cut it out with a sabre saw and metal cutting blade (or plasma cutter). Deburr it, and set it in place. You can tape it to the wooden fin and to the top of the cowl. Next make a cardboard pattern of the end peice required (colored bronze) and tack it to the larger cut out peice of steel.

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  7. Now use your templates to make the other side---they should be exactly the same, but due to variations in fiberglass molds and old sheet metal, from side to side, you may have to do a bit of touch up welding or grinding for a perfect fit.

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  8. Next thing we do is run down to Speedy Auto Glass (or the equivalent) and buy a 10'-0 length of steel glass channel. The kind that does not have the felt inside it and I used the rigid, not the flexible. This stuff has a gap of about 3/8" in it, to accept 1/4" thick safety glass, and the 1/16" thick rubber gasket tape that holds the glass in it. I don't remember how I bent mine (other than very carefully) ---probably I made a 1/4" plywood template and "persuaded" it around the pattern with my body hammer and low torch heat in the sharp corners.--Take your time here, as the inside of this channel will be visible from the inside of the car.

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  9. This is a bit hard to see, so I have hidden the cowl and body section. This view shows the glass channel mounted in place and welded to the inside of the two windshield frames. The frames were tack welded together on the center dividing seam while still mounted to the cowl, in order to get the angle between them correct.

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  10. Using my pattern making skills (which were by now getting pretty good) I got out the trusty cardboard and glue gun, and made a swoopy looking pattern of that original plywood mock-up center fin, and cut it out of 3/16" mild steel plate. I welded the base of it onto a 1" x 1/4" flat bar, and welded two 3/8" diameter threaded studs to the bottom of it.

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  11. Then welded the center-stand to the inside of the joint between the two window frames. Remeber, all of this was tacked together with the two frames still held correctly in place on the cowl.---That is the ONLY way to get all the angles to turn out correct.

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  12. I then made up triangular 1/4" plates (dark blue) to fit into the outside corners of the frame and welded 3/8" studs to them.

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  13. Drill holes thru the cowl, set the frame in place, with the studs sticking thru the cowl. Make REALLY BIG back up washers (I used peices of flat bar) and put nylock nuts on the threaded studs, and cinch everything down tight. Do this BEFORE you make your glass templates----things will move a bit when you tighten the bolts. Make your glass templates (or better yet, get your glass cutter guy to make them) and have 1/4" laminated safety glass cut and installed. Thats how I did it---A weekends fooling around in the garage, and i was very pleased with the results. If you are a good fit and finish man, your done. If your not quite that good, you may want to use a peice of fender welt between the frame and the cowl to hide any slight gaps.

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  14. And---If you happen to be an artist---I hope that this post may be some help to you, or entertainment for you----enjoy!!!!
  15. fiat128
    Joined: Jun 26, 2006
    Posts: 1,429

    from El Paso TX

    Nice writeup, thanks. Have you written anymore of these?

    I'd like to see one about how to chop a top where you have to extend the roof of a pickup cab with sloping front pillars.
  16. Nice, lots of questions about this lately.
  17. FiddyFour
    Joined: Dec 31, 2004
    Posts: 9,019



    awesome man. i've been tossing the idea of a duvall style screen around with dawn for her roadster project... many thanks!

    T :cool:
  18. Most of the technical "how to" articles I've done have been at "" I haven't done one on chopping tops, but I can tell you that the easiest way to chop the top on a pickup with slanted A pillars is to have a second truck of the same year . When the top comes down, the top has to grow longer if you don't pie-cut the pillars at the base and lay the pillars back to match up. If you have a donor cab, you can cut a peice from it long enough to bridge the "gap", and end up with only one weld seam across the top. If you don't have a donor cab, then you have to fabricate a filler peice, and have two weld seams accross the top of the cab. Here is a quickly created model for you, showing the correct way to cut across a top if you are going to lengthen it and put a peice in. This is much stronger and easier to keep aligned than a straight across single plane cut.---Brian

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  19. Jalopy-Phil
    Joined: Nov 15, 2005
    Posts: 53


  20. Brian, got any close-up shots of that windsheild?
  21. Django
    Joined: Nov 15, 2002
    Posts: 10,196

    from Chicago

    Excellent tech post...
  22. El Caballo
    Joined: Mar 3, 2001
    Posts: 5,881

    El Caballo

    Definately tech-o-matic, mad computer skills too.
  23. Devin
    Joined: Dec 28, 2004
    Posts: 2,352

    from Napa, CA

    Thanks Brian!
    These posts are what the HAMB's all about.
  24. de-fenders
    Joined: Jul 10, 2006
    Posts: 409


    Awesome tech posting, I'll be saving this one for down the road....:cool:
  25. How close up did you want to get? I can send you the full size picture of the car that appears in the very beginning of this post.---What did you want to see???
  26. I wanted to see a large picture of just the winshield frame.
  27. Sorry my friend---I built that car 10 years ago, and sold it about 5 years ago. I don't have pictures that are specific to the windshield frame,
  28. Brad S.
    Joined: Feb 5, 2005
    Posts: 1,317

    Brad S.

    Bump so I can find this easier...

    This should be moved to the Tech Archive.
  29. Mike Duffus
    Joined: Apr 21, 2006
    Posts: 10

    Mike Duffus
    from Iowa

    Good stuff. I'm a little new here so bear with me. I know I'm off the beaten path here but I also like your CAD drawings. I was a draftsman a long time ago a would like to find a good user friendly CAD software package. I'm working on a 56 Buick Wagon and want to layout air bags before I jump in.

    Guess the bottom line is if you know of a low cost CAD package and where to get it I'd like to know that information.

    Thanks in advance
  30. Mike Duffus---"good" and "cheap" just don't go together. I use a 3D package called Solidworks. It is a wonderfull program, but with taxes it costs about $7000 and you will need a new $2000 computer to drive it.---and the annual license fee is about $1600. Do a search for "Rhino Cad"---I hear its cheap, but don't know much about it.---Brian

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