Damage from stones getting thrown into underside of fenders

[kgreen]

Is there valid concern for damage to the underside of fenders when stones are flipped up from tires.  I suppose undercoating can reduce possible damage, but I don't want to undercoat.  What experience with this sort of damage can you share?

[TTR]

For what it’s worth, but for 100+ years, hundreds of millions (billions ?) of cars, some with undercoating, some without, have been and continue to be subjected to this everyday.

I imagine vast majority of drivers or owners (including me) do not nor have ever considered  it a “concern”.

Edited September 20, 2021 by TTR (see edit history)

[CHuDWah]

17 minutes ago, kgreen said:

Is there valid concern for damage to the underside of fenders when stones are flipped up from tires.  I suppose undercoating can reduce possible damage, but I don't want to undercoat.  What experience with this sort of damage can you share?

I've driven pre-WW2 cars on gravel as well as paved roads and never incurred damage.  Most if not all old cars have fenders heavy enough to not be damaged other than maybe paint chips.  I know some coat the underside with spray-on truck bed liner but I have no experience with it.

[Walt G]

When I restored a 1931 Franklin ( painted in nitrocellulose lacquer even under the fenders) the fellow who did the pint work and taught me how to paint as I was working side by side with him - suggested that after we paint the fenders, to then spray on a coat of a clear covering used on the lower body panels of G.M. cars of that era ( early 1970s say 1971-72) . It was used on Cadillac's of the time ( and other GM cars???) to prevent just that, stones coming up and damaging the paint. Do not recall what the name was nor the manufacturer . It made it easy to  wipe off when you wanted to clean the underside of the fenders of any dirt , even tar that would be thrown up from a repaired road surface.

I drove that car thousands of miles and never ever had a stone come up hard enough to dent a fender.

[ramair]

Has anyone applied that clear plastic that you see around rear fenders and front sheet metal on some of the new sports cars , probably after market, it would look better than the tar coating and may be easy to remove?

[nickelroadster]

There is a clear textured coating that is available at any body shop supply.

[jrbartlett]

I saw some Duesenbergs on tour with the ACD Club a couple years ago that had removable hard-plastic liners inserted under the fenders. It was a really neat job and unfortunately I never had an opportunity to ask how the liners were formed or of what materials.

[Rusty_OToole]

This is a real problem with fibreglass fenders on cars that get driven on gravel roads. Stones make a star shaped mark that is  very hard to get rid of.

The spray on material used on the lower parts of cars in the 80s is called "stone guard" or Shutz sprayed on with a Shutz gun. It is quite durable and does deflect stones without damage. After a long period of time it can shrink and crack but never saw it peel or cause any problems.

[prewarnut]

I used "Lamin-X" on the head-lights on our new SUV a few years back (since sold it). I was trying to protect our investment. I bring this up as their film is a little thick and spongy so it could protect against smaller rocks. It will probably give off a slightly different sheen when applied over paint but probably not bad. It can be cut to fit into corners and obviously is stretchable and made to go around convex designs. Their company actually does market sheets for this purpose and for industrial applications too. At issue is just what rocks or type of road conditions are you going to experience? It may or may not help. Probably mostly it would prevent chipping, not dents.

[Guest]

 I have a 57 Corvette that had star shaped cracks on top of the fenders so I ground them down and repaired them with Radom wove fiber glass. Then placed two layers of the random wove glass over the whole top of the fenders,

 I doubt that any stone would be strong enough to damage the fenders again.

[ejboyd5]

If you a fortunate enough to have an aluminum or alloy bodied car stone damage can be a real concern.

[TTR]

1 hour ago, ejboyd5 said:

If you a fortunate enough to have an aluminum or alloy bodied car stone damage can be a real concern.

Could also mean it may not be a right car for that person…

… or perhaps that person is not a right owner for such a car ?

 

One of the coolest things I've ever seen was over 50 years old lightweight alloy bodied race/sports car still with its original paint and other finishes and each of its fender had small upward pointing dings and dents in various sizes. And mind you that this was a multi seven figure car, one of the only handful ever made and last one existing in it's original form and finishes.

Unfortunately, I've heard rumors it having changed hands within last few years and also having been subjected to a complete restoration.

Probably now doesn't look anything like when it was new, but instead just another over-restored trailer queen intended for pathetic existence of static display trophy wh**e. 😞

Edited September 21, 2021 by TTR (see edit history)

[Joe in Canada]

I used a plasticized spray on stone guard than the paint color on top. You have to look to see it.