Of the Fiero's I own I plan to convert one of them into a Chop Top. I have a chassis I will practice on just to get the idea of how it is done and then I can see if I can improve on the technique when I do it for real. First, What tools do I NEED, and what tools would I be better off having to do this. Currently I have a welder, cutoff saw, pneumatic metal saw, small general shop tools, what else will I need?
As I am thinking about it I will probably try my hand at lengthening the body also. In doing this type of thing, How do you get the measurements symmetrical top to bottom and side-to-side?
[This message has been edited by hcforde (edited 07-17-2013).]
Best thing I can tell you is this is a total baptism by fire! but the most important thing I can tell you is have the windows before you even make the first cut. You will find they are not only windows but also a proof of getting it right, in other words they double as a template. Tale a peak at my build thread I did mine totally at home out of a shop setting to show it can be done with minimal tools in your driveway. //www.fiero.nl/forum/Forum3/HTML/000125.html
[This message has been edited by jetsnvettes2000 (edited 07-17-2013).]
I haven't done the chop top, I cut mine right off so I will leave that advice to others who have done that work.
When I lengthened the frame. I measured 5" back from the firewall top and put a pice of tape vertical down the outside of each frame side. Make sure the tape is vertical by using a level or laser line as this line is used later for measuring. I had already taken all the engine, suspension etc. out. I also built a wood frame with rollers that fit tight under the rear frame section that would be removed. I also ensured the Fiero frame was as level as I could get it.
Once all the prep work is done, you then take your chop saw and cut along the tape line both sides. Don't forget that you have a brake line running along the passenger side lower frame rail you want to move out of the way unless you are planning on replacing that line.
Once t he cuts are made, move your frame and support cradle back the required amount for the stretch you want to do. Do a visual on the location and placement of everything. Once you have that understood, you can roll the rear frame out of the way some more to make room for addin in you frame reinforcing metal. Most folks use 2x2 square tubing top and bottom on the frames. This pretty much inserts into the frame rails quite nicely. One on top and two on the bottom. Make sure you put the metal in at least a few inches each side to make sure you have material to weld to. The lower frame is on an inward angle so I cut some wedges out of the lower frame stretch pieces so that the inserted section would go into the frame properly and the stretch section would travel rearward straight and then the rear section inserts into the rear frame properly. Also cut some welding holes into the frame pieces each side so you can do some spot welding along the inserted pieces.
Once you get the stretch pieces sorted, you can then put everything back together with the stretch pieces in place. Measure the stretch length on both sides and make sure the sides are secured. Also measure side to side. pick a location that is the same on both sides like one of the strut bolt holes and measure from one side to the strut hole and the same on the other side. i used the top frame edge where it mates to the fierewall as a consistent ref point both sides. once you have all these measurements the same, weld a small bead on each top frame to keep it in place.
Now you measure the rear cradle for vertical alignment. Theory is that the frame cut you did should have been vertical when you made the first cut so you can use that with a level to ensure the rear cradle is vertical and level. I also used the level on the top frame to make sure the stretch was also level on top.
Tack everything in place. Once it is held in place, measure several more times and places to ensure you have everything lined up. Start your welding by welding a portion of each side each frame and then switch to the other side. This helps with the natural metal deformation from the heat to keep things as straight as possible. Continue measuring all along the welding process so you maintain the proper alignment.
Does anybody have a pattern for them so they can be made from Plexiglas/Lexan? That means a greater likely-hood of scratched windows so best to have spares OR put on a film coating for protection and tint.
[This message has been edited by hcforde (edited 07-19-2013).]
Yep!!!, Years ago I was a respiratory therapist and I designed & manufactured some oxygen hoods for the neo-natal unit by gently heating some 1/4" Lexan, draping over a form and letting it cool. It was in the shape of a Quonset hut with one glued end and the other end was removable with different size openings. A 3/32" groove was cut in that end prior to the heating so when being used, the faceplates could easily snap in and out of the groove.
When sufficiently warmed, Lexan is almost rubbery.