Lotus Elan

Fiberglass

PostPost by: kayenney » Thu Dec 29, 2005 11:32 pm

There is an interesting article in the January '06 issue of Auto Restorer entitled "Learning Fiberglass Repair", in which the author states that FRP panels never stop shrinking and that this is the cause of surface cracks in vintage Corvettes. Has anyone heard this before and does it also apply to Loti?

Ken Evans
NW Florida
'69 Plus 2, '71 Plus 2 (in pieces), etc.





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PostPost by: Rob_LaMoreaux » Fri Dec 30, 2005 1:38 pm

There is an interesting article in the January '06 issue of
Auto Restorer entitled "Learning Fiberglass Repair", in which
the author states that FRP panels never stop shrinking and
that this is the cause of surface cracks in vintage
Corvettes. Has anyone heard this before and does it also
apply to Loti?

I don't think it is that the panels shrink so much as the resin gets more
brittle especially if it is exposed to UV and such. On a Lotus it will
always be worse than a vintage Corvette because the panels on a vintage
Corvette are around twice as thick as those on a Lotus and therefore the
panels flex more causing the gelcoat to crack easily.

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PostPost by: grat » Sat Dec 31, 2005 12:45 am

On Thu, Dec 29, 2005 at 03:30:31PM -0800, Ken Evans wrote:

There is an interesting article in the January '06 issue of Auto
Restorer entitled "Learning Fiberglass Repair", in which the author
states that FRP panels never stop shrinking and that this is the
cause of surface cracks in vintage Corvettes. Has anyone heard this
before and does it also apply to Loti?

Well yes and no. FRP does shrink over time but it is
asymptotic, most of the shrinkage occurs in the first few days or
weeks (depending on how hot the cure was) diminishing over
time. Initial shrink is about 1/16"/foot, hardly measurable after
that. This can cause a crazing in the gelcoat and with
impact/vibration could become cracks in the surface coat. Vettes were
laid with blown in chop, rather than hand laid up matting. So Vette
FRP tended to be not real uniform in thickness and be very thick in
some areas, all this combined would make the above statement 'more
true' than it would be for a lotus. Combine the FRP process with the
low frequency vibrations of a big V8, minor impacts along the
way... wouldn't be surprised.
While possible I don't think it would be a common occurrence in
lotuses, as they are all hand laid and from my experience done well,
and fairly uniform. So unless there was a defect/void in the FRP I
wouldn't expect cracks in a lotus finish simply from shrinkage.

fj..
1969 S4 45/9297
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