One of the trickier bits of the Westfield is that the Miata engine is quite a bit taller than the one that was originally used in the Lotus 7. That’s a problem if you want to keep the original hood line. That extra height has to go somewhere. Where it goes is out the bottom of the car. And that means that the oil pan is the lowest point on the car. That’s fine for a track queen, but it’s not a great idea for a car that’s going to encounter potholes and speedbumps.
The fix for that is to add a skidplate under the oilpan. That way, if you do bottom out, you’re not going to dump all of your oil and seize the engine. Most builders slap a big steel plate underneath, but that didn’t seem like the right solution for a lightweight car like this.
A lot of rally cars now use Kevlar skidplates, so I thought I’d give that a go.
The first step is to create a mold. I glued a bunch of pink insulation foam blocks together with 3M Super 77.
Then, after a lot of filing and sanding to get them to roughly the right shape, I glued them onto a sheet of MDF. Then it was layer after layer of Bondo and primer, with lots of sanding.
Once I had that nice and smooth, I cut several layers of Kevlar so that they’d fit tightly over the mold.
You want to have the Kevlar all cut and stacked in the correct order before you start the actual assembly. In addition to the Kevlar, there are a couple of other layers you’ll need like Peel Ply.
Next you liberally cover the mold with parting wax.
Then you’re finally ready to start laying down the Kevlar with plenty of epoxy resin between layers.
After the Kevlar and the other layers are all stacked up, you stretch some vacuum bagging film over it all, and tack it down with some really, really sticky tape around the edges.
Then you connect it up to your vacuum pump and suck the air out of the bag.
This will ensure that there are no air bubbles in the layup, and it will also suck any excess resin out into the bleeder/breather layer. This will make the resulting composite much stronger than it would have been with too much resin.
After patiently waiting the better part of a day, you peel all of the extra layers off to expose the Kevlar, and then gently pry it off the mold.
It still needs a couple of stiffeners and mounting brackets added, but it seems pretty bulletproof, and it’s almost ready to fit under the nose of the car.
It was a pretty fun project! Hopefully it will do its job and prevent trouble in the future.