Hi,

I'll be making some CF wheel arches for my Caterham shortly and would like your recommendations as to a durable (lots of travel will hit them) resin. The arches will remain unpainted and the process I will use is vacuum infusion.

Ta in advance :-)

For resin infusion I would go with our IN2 infusion epoxy resin which is a very good quality strong resin.  For stone chip protection, you might want to add a layer of Diolen or Kevlar to the inside face.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

if you were going the prepreg route I would suggest sticking a bit of kraibon rubber into the laminate to help for impact protection, but as you are going infusion / wetlay I would agree with warren and add some kevlar or even glass fibre as its better for impact.

I highly doubt, that a thin Kevlar layer will give the laminate any protection. The problem is load distribution. A sharp stone transfers a force on a very small area. A thin Kevlar layer will not change that. If the local force is too high for your layup, it will crack. Kevlar holds everything together, if it fails, and has a better abrasion resistance, but it will not prevent any damage (except abrasion). At least not better than any other material. A thin rubber sheet is a different story, as it distributes the force.
That's  the first thing I wanted to say. The other is: I've done quite a few sets of carbon wheel arches for seven like cars. I never used any protective layer, and never had any complaints. Some customers took them to the racetrack including some distance at high speeds through the gravel trap.
The standard arches are made of chopped mat, which is exceptionally weak against chipping and cracking.

Cheers guys.

The 'protection' that I am looking for is on the Outside of the arch (oekmont spotted that).

I'm not concerned for he matting getting damaged here, as I am sure the resin 'faces' the product and it is this that I'm trying to find a solution to.

Oekmont, when you made yours, did you use prepreg? If not, what resin did you use please?

Ta.

Have you made an infusion, yet? Just a question, to get an idea, what might be the background of your question.
There is no actual resin layer outside. Well, there is, but a really thin one, which you will never really see chipping. Stones will either damage the structure (didn't happen so far) or scratch the lacquer.

Not yet.

Thought so.
Are you worried  about spider cracks? That won't  happen with woven fabric and infused parts. These defects are caused by the thick gelcoat, and the low stiffness of chopped mat reinforced composites.

Not worried about that at all, I'm seeking the most impact/abrasion resistant resin for infusion.

As I said, impact resistance of the resin really isn't a problem here. And when looking for abrasion resistance, the one thing to worry about is your choice of lacquer, as you almost certainly going to lacquer the parts.
I infused all the wheel arches, and used the standard infusion resin from hp-textiles. Although I never used it, I am 100% sure, that the infusion resin from ec will perform just as good.