Best Materials for Repro Body Parts

Drbrown

Drbrown

Well-known member
After looking for metal reproductions and searching salvage yards, sometimes it may not be possible to obtain metal ones and one may need to consider ABS or fiberglass reproductions.

Based on my (limited) experience with newer vintage cars (i.e. say 1970's-1980's) that have ABS body parts, they seem to have aged and become brittle especially when exposed to near or below freezing temperatures, even tho they may still be somewhat flexible at room temperatures.

My question is .... in comparison, is either ABS or fiberglass better in cold temperature zones ? I notice that owners of vintage Vette's in my area that have fiberglass body parts typically store their cars in winter (due to possible cracking ?).

Appreciate any input !
 
I used to live in your area and drove my Corvettes all year. Cracking of fiberglass was not a problem. The salt did create havoc with the metal parts, so that is why many Corvette owners will park them for the winter.
 
My process is when I need a part my first choice is a OEM NOS part. I usually can't find/afford the NOS stuff if I can find it soooo my next option is good used followed closely by usable/repairable used parts. High quality repro parts are my next choice.
If I strike out on all of the above my last resort is 'glass/plastic. I'm always on the lookout for parts I can use to upgrade whatever I can on my cars.
As far as storing cars is concerned, my cars are off the road for the winter because of a number of reasons. Salt on the roads mostly and the lack of tops or heaters.
The lack of car shows and cruises limits activity in general anyway.
 
Dan: having owned two Corvettes in the past, a '78 and a '95 neither one was great in the snow, so they remained parked for most of the winter. The '78 did have stress cracks in the fenders, I suspect as the fiberglass was just plain older, and maybe Chevy learned how to make fiberglass better by '95. As you know it's the salt that's the killer in our area. I remember growing up only 20 miles south of here and once the roads in our development got snow covered they stayed that way until spring. Now even my dead end street gets salted, if they even think it's going to snow. It's funny to see deer tracks on everone's lawn leading to the street( they like to lick up the salt in the road). I even complained to my town that they didn't need to use so much salt on a dead end street, that lasted for about half the winter. Sure makes you wonder why we still live in the Northeast.
 
ABS is a thermo-plastic. It is heated to soften it and then formed. This process is relatively cheap and uses low cost tools. The problems are that it is not nearly as stable over time as a good thermo-setting plastic, tending to become hard and brittle with time. The forming action also introduces micro-cracks similar to when steel is formed across a tight radius.

Fiberglass, in contrast, is a composite of glass fibers and a thermo-setting resin. A thermo-setting plastic becomes solid by chemical action and cannot be significantly formed after curing. Fiberglass is very labor intensive and so relatively expensive to manufacture. Tooling costs are variable for production needs, low production is often low cost, high production equivalent to steel stamping dies. Due to the relatively long fibers normally used fiberglass does not like tight corners, and trim finishing times become excessive for small parts.

Corvette tended to have a stress cracking problem the first year of a new body style... 1963, 1968, 1978, etc. Fixed when the older generation of engineers slapped the newbies and got them to put adequate steel reinforcing internally in the body.

The "gold standard" for restoration is to use the material that was original, subject to all the deficiencies of the original. When switching materials you have to be technically astute, as each has its own strengths and "gotcha's"
 
So simply .... if the original was metal and one cannot find an original, one should become a blacksmith/sheet metal worker. Not hard to do. Learn the trade, experiment, improvise and do it. Anything is possible.
 
Dunno what you have over there, but here in OZ, the better fibreglass body manufacturers are using vinylester rather than polyester.

Only a little bit dearer but much better.

Our legal minimum thickness is 3.5 mm for body panels.

I suppose a good start would be to ask Wescotts what they use.
 
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