Do you guys think there would be problems with flex by taking an oem front spoiler lip and molding from it? I want the replacement part to fit the car. Think the new carbon part will flex enough for fitting and aligning the new part to the car?
This isn’t the rear bumper project car btw.
well,you could always make a metal or wood structure that mimics the mounting points of the bumper and bolt the spoiler on that , if you are worried about flexing…
personally, i would say such parts are flexible enough. i have a front spoiler on my car that is 6 layers of 300 grm carbon and there’s no problem in flexing it (i know, 6 layers are too much but i was young and foolish…two years ago)
I second Aga’s suggestion, we often use some real ugly looking jigs to hold parts as we take moulds off them. They also can hold the part in a manner that will be easy to work on.
Have you thought about using a outer skin of carbon and then the rest glass? It would take the knocks that it is bound to get without cracking and provide the flex you might need when fitting. We just did a front bumper and splitter for a race car and we used 1 layer of 300gsm glass each side of 5mm Nomex with carbon straps to stiffen it in places, it will be painted so finish wasn’t that important.
Install it on the vehicle as it’s supposed to be.
Reinforce the back side so it holds the shape when removed.
Make a mold with any necessary parting lines.
Thank you guys 
The final part will be 2 layers of carbon 3K, and 4 layers of 6oz glass cloth. I have to bolt a splitter to the bottom of it, but the splitter will have struts from it to the actuall bumper. So I may just use plastic fasteners to hold the splitter flush to the bottom of the front lip.
I was just thinking how thick the part should be? I’d like to use all cf construction but it’s not a real high end part.
1200 grams of reinforcement sounds a bit overkill to me. even csm bumpers can only be like 2x 300csm and are fit for purpose. i figure if its too strong or too well fastened when you have a bit of a nudge more of the car gets damaged = bigger deal to repair.
i would say, for best fitment, i would make it as thick as the original part, if that doesnt add up the cost much. i always bear this in mind when copying plastic accesories.
did this recently using the standard plastic lip.abraded the back of the part and layed some layers of csm on to it while on the car.Ended up stiff enough for a perfect replica out of the mold.
Hi Zac, remember - csm is much thicker and takes up a lot more resin than woven cloth.
I will probably make the lips with top layer 6oz cf, 6oz glass, 6oz cf, 6oz glass, 6oz cf. run the glass on opposing 45 degrees.
It will get vacuum bagged, possibly infused.
fair enough, and i agree, however if its a shiny carbon part and it takes a knock its a throw away item anyway really, repairs look gay. too strong and it can start damging other parts of the car too.
good luck though, look forward to seeing the results.
It should end up being just 1mm thick part after i lay them up. carbon and epoxy resin flex pretty well, and I won’t be using polyester gel coat. If they damage the lip they can buy a new one, or repair and paint it.
I hope to get this done quick…i’m waiting on a customer to send me an oem part. I also have a car coming tuesday to make a template for a race splitter.
1mm! Even using unidirectional prepreg carbon I couldn’t produce a part that thin that would be any good aerodynamically!
Let’s not mislead people that come on the forums and read that they should make 1mm thick parts!
That’s why we used 1 layer of 300gsm e-glass cloth on each side of 4mm 48kg/m3 nomex for the race car front bumper and splitter we just made. That made it plenty stiff enough for the aerodynamic loads at 200km/h.
Interesting. That’s about 10oz glass, and a 4mm core is very very thin for a splitter. Somehow that doesn’t sound like it would work. A 300gsm skin, of weak e-glass no less, will not contribute much strength at all. Even a little pebble at speed would puncture it!
Got pics?
It is prepreg glass so is better than infused or wet laminated wrt resin system and consolidation. The underside is kevlar to help with the off track excursions and there is 100mm sq patches around the mounting points. They have had a few days testing complete with a few off track moments and the bumper is fine with a few scrapes on the underside. The full underbody tray is 4 layers of 300gsm uni with 10mm nomex and kevlar.
I have pictures but need to check with the owner of the car first.
1 300grm layer on each side and honeycomb… sounds flimsy to me too… well if you say it’s held up, then ok… my own is 5 layers of 200 to 350 grm carbon, so i can feel confident enough to put it on…
1mm hmmm sounded thick enough, but i guess i was not considering the wind forces.
Ok… i’ll aim for 2mm thickness. and i’m changing from 3K to 6K carbon.
Sounds almost like i need a few layers of biaxial fiberglass if i am to use f/g in the laminate. these guys won’t pay for full cf parts prices.
whats the lip look like? if its really small piece and has a lot of shape with no flats 1mm might be strong enough to prevent any deflection of the part. However if it large than certainly more laminate or even core is needed. Its difficult to give recommedations of a laminate for something that is not seen. pictures would help
The lip is 3" tall and has many contours.
best thing you can do is make a part and see how it feels. You dont want any deflection in the shape of the part. The lip I was making was little over 1mm thick. made from prepreg twill and uni-carbon. once bolted to bumper it was much stronger than the bumper itself and had zero deflection. Of course most of the strength came from the shape of the lip, however was very durable and was difficult to break.