Vacuum Forming Splitter

[Eagle7]

how is your splitter mounted? we use a "L" shaped bracket bolted to transport tie-down locations on the bumper horns, the bottom of which has a slot at the front, opening to the rear, and a pin hole at the back. the splitter plate has mounts which capture the brackets in double shear, so the slotted mount "hole" never has to come undone. use a small bolt for the fixed mount and a 3/8" or so up front. one mount on each side. if you hit something, the rear pin shears and the splitter falls off, most if not completely intact. make it from good plywood covered in a thin layer of GFPR for toughness.

Do you have any pics you'd be willing to share? My methods sound somewhat similar, but I've not yet figured out how accomplish the graceful departure.

What's GFPR?

[Chip42]

Do you have any pics you'd be willing to share? My methods sound somewhat similar, but I've not yet figured out how accomplish the graceful departure.

What's GFPR?

shorthand for fiberglass(glass fiber reinforced plastic)

I have some CAD I could screenshot and post, on car is not possible right now. hard part is a pin with enough strength to hold the splitter and "desired" loads while failing in a collision. also, if you add stays, they have to be able to give way OR allow the movement of the splitter plank.


the shape is structurally compromised to allow MR2 coolant hose routing, but you can see the top bolt locations which allow this to replace the OEM tie-down hooks, then the forward slot and rear pin-hole - that's 3/8" now and probably doesn't fail as intended (well, not without ancillary damages) but as is it certainly makes installation and removal easier. high hole on the front is to add a stay if needed, like a steel cable X across the radiator to the bumper mounts. the bottom part is pretty universal once you have a place to mount it. I'm happy to help draw or make one if you like.

[Z3_GoCar]

I had a combination of carriage head bolts and screws to the ABS bumper cover and the aluminum under tray. It wound up breaking into three parts. The center peeled the aluminum undertray into a ball under the car and moving the oil cooler line into the alternator pully. The two corner stayed some what bolted on, except the drivers side finder liner was part of the aluminum ball, along with my unharmed wired transponder. Since I have to install a new bumper cover, I could bolt some mounts with break-away points onto the aluminum bumper bar, but was thinking of swiss cheesing the bar for nose weight reduction. What I want is something that's easy to replace, and doesn't take anything else (bumper cover, under-tray, or finder liners) out when it goes away.

[Chip42]

plywood, attached from the top up to something like I showed will allow the splitter plank to break/break off without taking the bumper and other bits with it.

treat the splitter plate as disposable / expendable and you are halfway there.

[Eagle7]

Conceptually, that's exactly what I've got now, except I've got the front slot facing forward - which of course eliminates the possibility of a clean break. It took a big hit last summer and didn't fare well.

Do you have ideas for a rear pin that will shear when you want but not when you don't? Maybe something non-metalic and brittle? Or plastic?

[Chip42]

Whatever you choose it has to be strong enough to support the aero load and light dings but break free at a somewhat limitted contact force.

Pins dont really cover those criteria if you are making good aero use of the thing, ive been thinking about T6 aluminum flat stock, notched. But i have to run the math to see how much to notch and what cross section does best. Its not as easy to use as a bolt, but should give the desired results.

[Greg Amy]

What about shear bolts from a snowthrower? Made to shear under sharp force and you can buy them in six-packs at Lowe's. Just gotta design it so the shear plane is in the right location. - GA