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I'm putting a front splitter / undertray on my car and I was wonder if anyone has good ideas on how to attach it. For now, I've cut it out of 12mm plyboard that I will paint black but later I might make it more exotic once I have the final design.

I have an excellent mount point mid way along which is my radiator bracket/ hanger already in the car. The front I plan to hold up with some adjustable stays from the main front cross member. It should be strong enough to stand on which I think is the main test for a splitter.

How do people mount them at the back on the subframe? Do you just use the two small m10 bolt holes or do you make something new? I figure it needs a bit of strength at the back from the high pressure air in the engine bay pushing down.

The rally car we used to run had a CF/Kevlar sump guard that had a slot in the rear that keyed into a stud hanging from the subframe. This made it very easy to remove as you could just undo the two front bolts and slide out the sump tray without jacking the car.

Here is what I used http://miataroadster.com/kazespec_engineering/kazespec_engineering_splitter_hardware_kits/kseshk/i-1680573.aspx.

I would suggest that you leave the undertray on even with the splitter as it will keep the air going through the radiator and not under it.

I have done a write up of the install http://mx5cartalk.com/forum/viewtopic.php?p=730055#p730055

Splitter V2 is here http://mx5cartalk.com/forum/viewtopic.php?p=764135#p764135

I'm planning Splitter V3 at the moment, more than likley it will be out of 5mm aluminium composite.

Without reading through your whole thread, how did you mount it at the rear? I can see the brackets mounted off the power steering point.

I can't fit the stock undertray as it clashes with my custom radiator bracket. I have completely boxed the front mount opening to direct the air to the radiator so there is no risk of it getting out there.

I was thinking of using some 8mm aluminium honeycomb and covering with a thin layer of stainless on the bottom for protection. I'll see how the ply version fairs first though. The one we made for the rally car was a 10mm thick combination of stainless, carbon and kevlar. You could sit the whole car on a rock and it would hardly bend! Not very light though.

Yes brackets off the steering rack. I thought I linked just the install post.

I mounted my 12mm ply splitter using the two rear 10mm boltholes. (as well as two 3mm aluminium stays hanging from the side stock undertray mounts, another two 3mm metal mounts hanging from the radiator support panel and finally 2mm wire stays at the front to the baby teeth.

Solid as a rock, I can stand/bounce on the front, and its survived several hi speed off track excursions, numerous contacts with kerbs and two meetings in pouring rain.
Still as good as new, has just needed some more paint underneath where it wore off from contacting things. (bitumen, kerbs, loading ramps)

My splitter is now all mounted up. Been a bit of work but it's nice and strong and made in a way where it's very easy to remove.

Apologies for the bad phone pictures!



I machined some hanger bolts with large spacers that are mounted to the subframe either side of the sump. Slots in the back of the splitter key into these which mean I can drop the splitter off or put it back on without having the jack the car.




Holding up the front are three collapsible hangers mounted from my custom radiator bracket. I have also fixed some lightweight support brackets to the back of the splitter to make it a bit more rigid.




I also have two hangers at the front to help hold up the front lip. It feels nice and rigid when all bolted up so hopefully it has some effect. It's quick to remove as I just have to drop off the two front hangers, undo the 3 bolts at the front and pull the splitter off.

I have also made it so any front impact will put the load into the subframe pins. Any major vertical impact will hopefully squash the front mounting brackets and not damage my radiator support. I'll be running in a few weekends time so I'll get to see if it's made any difference on the track.