A Bit of Panelling

Progress hasn't been as fast as it could have been recently (damn these small children and their ridiculous need for Birthday parties!), but I have made a start on some panel work. The most sensible panel to start with seemed to be the large piece that sits behind the seats which, along with keeping the water out, provides a fair amount of strength to the torsional rigidity of the rear of the Zero.

Panel ready for drilling

To get it right, the panel work is slow and a bit tedious. Each panel is cut-to-fit, but doesn't quite, as most seem to foul on a weld or overlap the edges of a support by a few millimetres, so each has to be carefully sized up, marked, filed down a bit, re-fitted, marked, filed down a bit, and so on. Once the correct shape, it can be clamped in place and all the beams and cross-members can be marked out, ready for drilling. It's then removed again and all the hole positions measured out and drilled (I've been using 1/8" rivets, so a 3.5mm drill bit works well) and then de-burred afterwards. The panel can then be clamped back in place again and the holes used as a template for drilling the chassis. Some people seem to only want to drill the square section tubing and not the round tube diagonals for fear of drilling off-centre, but I didn't seem to have any issues with it.

Because the chassis is mostly constructed of box-section steel and the car cannot be made entirely of right-angles, the panel wouldn't sit flush against the top and bottom rails. In these cases I either bent the panel slightly on the workbench whilst it was clamped between two straight edges or I just used a soft mallet to form it around the chassis itself. The finish is relatively neat but as this particular panel is going to be covered in carpet, it doesn't really matter too much.

Cleco pins in place

To be sure of drilling the chassis holes in exactly the right place, and to assist with fitting the panel later on, I purchased a set of "Cleco pins" and their respective tool. I had not heard of these little marvels before starting this project, but they are used extensively in metalwork and the aviation industries. They are basically a temporary rivet that is insert and removed with a special set of pliars, with each size of pin a different colour for ease of identification (1/8" is copper, 5/32" is black, 3/16" is brass etc). After each hole was drilled, I inserted a Cleco, therefore making the panel rigid very quickly. I should also point out here that a right-angled drill attachment is very useful, if not invaluable, for getting into some of the tighter corners of the chassis.

Riveting finished

At this point I may have gone a little over-the-top, but I decided to paint the insides of the holes in the chassis with a bit of Hammerite, to help protect against future rusting. Whether this makes any difference or not, I doubt I will ever know. The final stage in the panel preparation is the removal of the protective film, which is a pain. Where the film has been burnt by the laser cutter it's edges are melted and stuck to the aluminium, so it takes rather a long time to pick it off. Again, as this panel will be covered in carpet, the final finish is not too important, so I experimented with a few things such as wire wool, a knife, solvents and sand paper. Nothing really worked as well as my thumbnail, although I may try a hot-air gun or some IPA next time.

Along with being held in place with rivets, each panel is bonded with the notorious (in these circles anyway) GBS-supplied "Black Stuff", otherwise known as polyurethane sealant. This stuff is very tough and I would strongly suggest you apply it wearing gloves, as if you get it on your skin, it won't come off for weeks unless you bathe in white spirit. Before applying the glue, I cleaned both the panel and all the chassis parts with a degreasant to make sure the bond took well, then it was just a case of applying a bead of glue over every chassis part, making sure to cover every rivet hole, and re-fitting the panel, hopefully for the last time. Now, you could be quick with the rivet gun and hope for the best, but the easiest solution is to use the Cleco pins again. Once the pins are in you can have a cup of tea and replace each one with a permanent rivet at your own pace. After all the rivets were in, I applied a bead of Black Stuff along all the chassis rails in an attempt to make the panel water-tight. It's just like using silicon sealant on your bath, except you need to dip your finger in white spirit rather than soapy water!

Dynamat installed

I had also recently been thinking about some sound-deadening within the car, to try and make the finished product feel a bit more well-built and a little less tin-canny and after experimenting with different types of foam my mind wandered back to my in-car hi-fi days and the wonder that is "Dynamat". It's basically a squidgy, sticky rubber bonded to an aluminium skin and is designed to dampen the ringing of large metal panels and therefore tighten up the bass frequencies within a car when you install a ridiculous great sub-woofer. It's quite expensive and relatively heavy, but you don't need to use much and a few extra kilos doesn't really bother me. It's very easy to apply, you just cut it to shape with a knife (careful, the edges can be sharp) stick it to the panel and then for maximum effect squeeze all the air out with a wallpaper seam roller. Once finished, the result is really quite impressive, with a loud clang being replaced by a dull thud, just the result I was looking for.

First panel finished, bring on the rest...