How do you keep from eroding fiberglass bodywork with race tires?
 

So I got some fiberglass front fenders that I might use on my SM2 FC.

I noticed that on the stock fenders lower rear wheel arch the paint and now bare metal has been sandblasted and dented from rocks thrown off the tires. Our couse has a LOT of gravel on it.

Won't the same sandblasting wear the fiberglass fenders much more quickly than the steel ones?

Has anyone found something to place over the fiberglass to protect it?

I remember once seeing some heat formed sticky backed plastic sheet in a Grassroots Motorsports for race repairs but can't find it online yet.

Let it wear and then just "rebuild" it with more fibreglass when it's worn?

Yes the fglass will get the same damage and get it faster. You might dig on the web for clear protective plastic, I had a friend cover the nose of his Cobra replica with the stuff and you could barely see it.

How about a small piece of aluminum formed and riveted in the area that will take the most beating?

I remember it as well - http://www.rubbnrepair.com/

A couple layers of a clear bra might work - http://www.invisiblemask.com/clear_bra_protection.html - there are multiple manufacturers or clear bra material

Thank you! Thank you! That is it.

The closest I could find in my searches was people heat forming Kydex for sheaths and holsters lol.

I was thinking I would have to paint the area with several coats of black vinyl plier handle dip....

I have used paint on vinyl before on steel and it resists sand blasting well, but tends to peel from an edge over time.

I also thought of using that really thick electrical splicing tape.

I remember seeing an article about the old CART racing teams using "leading edge tape" on the nose cones and suspension arms. It is a very tough aircraft tape that is designed to protect leading surfaces from debris damage. Though with everything aircraft I believe it is expensive.

I've heard of people using spray on truck bed liner type stuff to help protect the underside of such panels.

Alright! More good ideas to check out.

Do you know if the plasticized spray on bedliner comes in a can or is this professionally applied only?

I know from experience I don't want to mess with the soft style tar based bedliner as the vinyl plier dip works better than that goop.

Found that leading edge tape and it looks promising. I have also used wrestling mat tape before, but it yellows fairly fast.

The guys who build the various glass-bodied kit cars, specifically the Factory Five Cobra clones, are always fighting the issue with rocks kicked up by the wheels striking the underside of the fenders and creating cracks and "stars" in the paint. A lot of them use the spray on bedliner products. You may want to go look through their forums for thoughts on what works and what doesn't.

http://www.ffcobra.com/forums/

Good luck,

-b

We use that tape on the leading edges of our c130 blades to protect the de-icing boots. They hold up well during flight, and on some dirt landings. It would prob work well for a car. Just clean the surface, lay it on, heat gun it, done.

Spray on bed liner works best its light and stops the spider webs from forming in the clear coat. just put the fender well on and spray away

i know a guy that used "Rhino Liner" for truck beds... its a little heavy but unless your running F1 id bet it would wrk for ya.

I have a fiberglass fendered IMSA GTU race car, and the most damage is caused by small rocks slinging off the sticky race tires and hitting inside the fenders, particularly where the tire is closest to the fender (right above the tires.) These small rocks slinging off the slicks at 140mph will crack the fiberglass, and look like small stars on the outside of the fiberglass. Spray on rubber bed liner did not 100% stop the star cracks, plus it added a lot of weight to the light weight fenders. I finally bonded some .030" thick sheet aluminum inside the fender in the few areas that took most of the rock hits. I glued it on with a few blobs of RTV silicone, leaving a small air gap between the aluminum and the fiberglass. This makes it like double layer tank armour. I now do not have any new star cracks in my fiberglass.

In road racing, you will get a LOT of damage to the paint on the front of your car from sand and small rocks being thrown off the cars in front of you. On external surfaces, particularly forward facing surfaces, I use the clear stick on tape that comes in 12" wide rolls. Put it on before you race, while your paint is perfect, and then your paint will stay perfect.

Could you use a urethane flexy plastic (like a mudflap) liner, or even a hard waxy plastic liner? (they're both pretty lightweight).

One thing the rally cars do is get some kevlar mat and epoxy and wet lay up under body protection from the gravel. You could lay up a few layers on the inside of your fender. Kevlar is also pretty light, so it shouldnt counter the effort that much.