I'm making a front splitter out of ABS plastic for my CRX, will see mostly race track autoX and little street time. I see some splitter installs where they are pretty rigid mounted and that seems unsafe in the event of an accident. My idea was using nylon bolts to connect the splitter to the chassis, that way they can break away in the event of a front end collision (hopefully won't ever happen). I have some 3/8" nylon bolts, and there would be about 6-8 bolts total. In the front there will also be two support rods, so it should be rigid while racing but just weak enough during a collision. Anybody else use nylon bolts? What is your experience with front end collisions with a splitter?

 

How far forward do you plan to extend the splitter? If it extends far enough to produce any sort of downforce I can see it bending the heads right off of nylon bolts.

 

even with a "bumper" outline splitter that has to be run in H2... nylon bolts will not hold up for long.

building a splitter is a balance between being stiff enough to work but soft enough to bend/break/distort going off track. Street driving a splitter comes with risks... at best you just destroy the splitter regularly. IMHO opinion if you are set to DIY, buy PCI mounts. if you want an easier button, just buy the PCI splitter package.

 

 

I plan on having the splitter stick out up to 1-1/2", figured it might be a good starting place.

That's good to know about the nylon bolts not holding up. That's why I started this thread.

I like this idea, but any effect on the track with it flexing too much?

Thank you for all the advice

 

Nope. With the splitter attached in the rear you'll still be able to get the cable pretty tight in the front, but it allows that little extra bit of upwards deflection to hopefully help keep it from digging in.

 

I like the idea of using cables, thank you for that advice. I never liked the look of the support rods, and small steel cables will remain low key.

 

I don't think any of us have had the misfortune of breaking a splitter in a front end collision.
Most of the time the splitter blade comes off because you have an off or hit kerbs on track.
Special Projects Motorsports builds their with easy breakage in mind.
After all you don't want a blade or mounts to cause much damage if you go off course.
Nylon hardware is going to be too weak and it might take one or two whaps on the track even in a straight to lose the blade.
ABS might be equally a fail point. Most make their blades from Plywood, Marine grade plywood, or Alumalite
You cant go wrong with one of these.
HONDA CRX Splitter Kit ? Special Projects Motor Sports

 

I agree 100%.

the break away points for PCI mounts are the elevator bolts (they do a good job) and if its a hard sudden impact, the design of the two piece mounts distorts/sheers off. I"m talking about the V2 mounts FYI. the first version (1 piece mounts) are heavy duty (often knocked off) and can cause some damage. I doubt you can find V1 mounts anywhere outside of what was knocked off. dont use those at all!

I have roughly a 3 inch lip (due to rules) at the center of my lip.... at +125 i'm not distorting. i'm using 3/8 birch plywood, seal with water seal and then painted black.

 

I think you're overthinking it, no offense. Get plywood, get garden trim, get some bolts and some nuts, get some steel, and put it on the car. If your splitter bends the frame rail when you hit a wall, well, you probably hit a wall. Take the car in the garage and use a BFH to bend it back into shape

https://nasaspeed.news/toolshed-engi...-own-splitter/

 

I've used birch also. Tried thin aluminum first but I had an off that bent it and I couldn't break it off in the hot pit lane. lost that practice session at a time attack so I went to birch with smaller hardware. Only had 4 connection points and i weigh 250lbs and it was too strong even jumping up and down on it.

 

I need to send you pictures of the front splitter after my pass through the gravel in Turn 3 at summit... my birch broke before anything else

 

ABS is one the worst materials you can use for a splitter imo. Very heavy considering its strength. Birch plywood is a much better material and the budget king for sure.

 

If you are only going to have it extend an inch or 2 and you are capable of figuring out fiberglass, I would go with 5mm revolution ply with a layer or 2 of fiberglass weave over it. My first splitter blade was made out of it. It's still fairly light and very strong.

https://www.lowes.com/pd/RevolutionP...4-X-8/50121135




I had to switch birch when I wanted to extend it to 4" and the revolution ply/fiberglass blade was going to flex too much with that length and 120+ speeds at certain tracks.

 

What thickness of birch do you recommend if it will only stick out up to 1-1/2" from the bumper? Seems like the common sizes are 1/2" or 3/4"

 

i got 3/8s from Lowes