Sandblasting

Obviously, when you tear external parts from a 15-year old car they are not going to look like new but realistically the brakes and hubs from my MX-5 were not in a bad state and could have been used as-is. But where is the "fun" in that? I had originally planned to either buy myself a small sandblasting cabinet (more expense) or nip down to a friend's workshop and us his, however, the discovery of a hand-held sandblasting gun and a huge compressor at work unleashed the inner cheapskate in me. A few things I have learned:

• Sandblasting without a cabinet is not pleasant
• Doing it after work, in winter, in the dark, is worse
• No matter what you try to keep it out, sand will get into your eyes, ears and nose...
• ...and down your back, and in your shoes, and your hair
• You can quite easily turn the area directly outside a fire exit into a small beach

Front caliper piston removal

Before anything can be sandblasted though, it must be stripped down to its constituent parts. The brake calipers were fairly simple, the fronts just needing some compressed air to get the pistons out and a screwdriver to prise out the seals. The rears were a bit more complicated, with the pistons needing to be unscrewed from the handbrake adjustment mechanism, but once done blasting could commence. Considering they are relatively small, these parts take a while to blast as they are a very complicated shape with a deceptively large surface area. They also start to rust immediately afterwards, so they need painting or powder-coating pretty quickly. I painted mine and am very happy with the results. I used a brush-on caliper paint, which is very thin and tends to run easily, but with patience and multiple coats, the finish is very nice.

Before, after and painted

The rear hubs were a little more work. I wanted to replace the bearings, so the wheel hubs had to be removed from the main uprights. This was a simple case of placing an appropriately sized impact socket on each hub shaft from the rear and hitting them repeatedly with an FBH (... Big Hammer). The hubs came out, but unfortunately with the inner races of the bearings still attached to them.

Impact socket from behind

Now, I was prepared for this, having done plenty of research (well, watching a couple of YouTube videos and reading some forum posts) and the wisdom of the internet surmised that you could remove this half of the bearing with a hammer and a flat bolster of some kind to get in the join between the two parts and prise them apart. Well, I think I need to correct the internet on this point, because two ruined bolsters and a lot of swearing proves you can't. A little lateral thinking is actually required: A wheel bearing is made of hardened steel and whilst very strong, it's also relatively brittle, so a score line with a grinder and then a single whack with a hammer and bolster splits it like butter. The outer races still in the main uprights were then removed in much the same way as the hubs, just with a slightly bigger impact socket.

This does not work

This does though

At this point I also cut off the old dust guards as they spoilt the look of the hubs. The only other parts to remove were the old wishbone bearings, which was simply accomplished by bodging a 51mm hole saw and G-clamp together to push them out.

Bush removal - simples

Old bush and it's replacement

Once sandblasted, I used an etch primer to get a good bind to the metal and then a gloss black finish to match the wishbones. Reassembly was straightforward; luckily for me a colleague at work owns a hydraulic press, so he inserted the new bearings for me and I fitted some nice new strongflex poly bushes to the top mounts. The only other modification required was the addition of a length of tube to reduce the size of the bolt holes on the bottom of each upright as the GBS wishbone system is based on 10mm bolts whereas the original Mazda was 14mm.

Before, after and painted

I think the finished result is rather good.

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...