Rear bumper aero

[meanmx]

Cut it!!!!!!

[deviant]

For 20 - 50grams, I'd much prefer the look of an intact bumper

It's for aero not weight. The rear bumper on an MX5 is like a parachute.

[22Silver]

For 20 - 50grams, I'd much prefer the look of an intact bumper

It's for aero not weight. The rear bumper on an MX5 is like a parachute.

I know. But filling the parachute with something so it's just a 'block' rather than a hollow parachute has much the same effect, right?

[Rasputin]

Being a Cabinetmaker/Joiner - I have inherited godlike skills in using a tape measure, and sighting if things are level/plumb/in-line with other things.

I found relative points on both sides. I believe I used the start of the brake lights as reference points. Held a spirit level on the inner-most point on the brake light, plumbed it vertically and Marked a few dots here and there, used a small spirit level to verify my dots were in-line, and plumb ; then just drew a random curve on an a4 piece of paper to use as a mirror image curve template. I Made a few more dots on the rear bumper using the curve template, grabbed some masking tape and joined up all my dots. The edge of the tape was my "cut line".

Put the tip of my box cutter against the bumper, jabbed it through using the palm of my hand ; then went ape sh*t. Literally. It took a fair bit of strength to cut it and so primal noises may or may not have been heard. (I didn't score it over and over again, I literally "sliced" the bumper in a single stroke).

By no means was it a perfectly straight cut, but the cut was clean. I wasn't worried about this anyway, as I was going to buy some rubber U-Channel from clark rubber to go over the raw edge to give a professional finished look.

Cost me about $18 all up, and was the best mod I've ever done to a car.

[Rasputin]

For 20 - 50grams, I'd much prefer the look of an intact bumper

It's for aero not weight. The rear bumper on an MX5 is like a parachute.

I know. But filling the parachute with something so it's just a 'block' rather than a hollow parachute has much the same effect, right?

Not sure if it WILL, but it MAY create lift on the rear. Rather than letting air escape; you're forcing the air downwards and under the bumper.

Unless you're planning on using the foam on the whole underside of the car.

I'd also be wary of it catching fire from exhaust heat.. This whole scheme is a big no no in my books...