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Hello all.
Posting on the off-chance someone may have a proper splitter I can either trace or take measurements off for my own car. Not after a lip style, rather an undertray style.
My issue is no place to easily do it. So anything to make it quicker is a good thing as I need to drive about 2 hours to get to my workshop at the parents house.
For reference, I have the rs factory style lip to install to act as the bridge between splitter and bumper.
Cheers all.

Located chatswood sydney btw

Get yourself a sheet of ply and then trace out the shape you need. You also need to decide on the mounting points.

Read this thread http://mx5cartalk.com/forum/viewtopic.php?p=886599#p886599

Would taking a basic shape from my stock undertray do much? Get the shape off that and trim from there?

Here is a link to my thread in building a splitter. Essentially you need a plumb bob to 'trace' the outline of the bumper onto your chosen material for the splitter.
http://mx5cartalk.com/forum/viewtopic.php?p=849484#p849484

How far it goes back depends on a few things, however mark where the jacking is if you cover up this area.

ED_MX5 wrote:Would taking a basic shape from my stock undertray do much? Get the shape off that and trim from there?

I just held my bunnings motorsport splitter up against the front bumper lip and traced a line 4inches further out..


and then cut it with a jigsaw.

^^^^ same way I did mine.

rascal wrote:

ED_MX5 wrote:Would taking a basic shape from my stock undertray do much? Get the shape off that and trim from there?

I just held my bunnings motorsport splitter up against the front bumper lip and traced a line 4inches further out..


and then cut it with a jigsaw.

Does yours extend back underneath as an undertray?
That's what I was kinda referring to.

And thanks Magpie, I'll have a read of it for some ideas.

ED_MX5 wrote:Does yours extend back underneath as an undertray?
That's what I was kinda referring .

yes, the new splitter/ undertray is a mushroom shape and replaces the fact undertray.
It goes back to just before the sump plug.

Mine keeps the factory undertray. The factory undertray does a good job of ensuring that the engine bay air goes out the back and not spilling into the wheel arches.

Like Rascal's mine goes back to just before the oil plug (and jacking point).

Aweome.
I think maybe I'll try using the factory one as a guide then plus tracing bumper.
Magpie, did that place you bought your sheet from post? Or only pickup?

Monopan? I picked it up in Brisbane. There maybe other distributors in NSW. Maybe for your first use ply, it is cheaper and easier to work with plus not expensive if you make a mistake.

If you want to make the ply last longer give it a few coats of fibreglass. The first one (fibreglass/ply core) I did lasted for ages and I still have it.

Thanks mate. I'll go with that then.
What ply did you use?
And yeah I was gonna glass and paint it

ED_MX5 wrote:Thanks mate. I'll go with that then.
What ply did you use?
And yeah I was gonna glass and paint it

I used 12mm normal ply for mine. Marine grade is overkill and heavier.
Not sure I'd bother with glassing it either. Just extra effort and weight with no real gain.
I just rattle canned mine with $3 flat black and it lasted over 2 years with several wet events, and many washes, until I I accidentally took it out on a kerb at sandown.
Replacement is also just rattle canned and i expect that last just as long if not longer provided I dont slam it head on into a kerb again..

Sounds good to me mate!
I'll give it a crack

rascal wrote:

ED_MX5 wrote:Thanks mate. I'll go with that then.
What ply did you use?
And yeah I was gonna glass and paint it

I used 12mm normal ply for mine. Marine grade is overkill and heavier.
Not sure I'd bother with glassing it either. Just extra effort and weight with no real gain.
I just rattle canned mine with $3 flat black and it lasted over 2 years with several wet events, and many washes, until I I accidentally took it out on a kerb at sandown.
Replacement is also just rattle canned and i expect that last just as long if not longer provided I dont slam it head on into a kerb again..

What he said.

These should be considered a consumable, and unless budget is not an issue I would not overcapitalise it either in cost or my time (I keep a cardboard template for ease of replacement). Don't build them to be indestructible, or mount them with over-strong structures, because that will transmit all of the loads into the car's structure, and risk damage to the car itself in a kerb strike or major gardening incident. Bunnings Racecar Supplies sell an excellent grade of ply for this purpose - cheap, easily worked and relatively light. While some minor weight saving is possible with a composite sheet, I don't think it is worth the money, but YMMV.

Check the rule set you will be running under for dimensions, some of them are quite restrictive, eg even Type 4 (Sports Sedans) limits the depth to the front of the front wheels.

I also retain the stock radiator shrouding before and after the radiator, but have sealed it up to ensure all the air coming in can only go through the radiator. Removing the undertray (the bit behind the radiator) is a no-no for good cooling.