Are all Speedster manufactures exterior bodies the identical in exterior shape? For instance is a old CMC exterior shape the same as a new Intermacanica. If not, what would the differences be?
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Are all Speedster manufactures exterior bodies the identical in exterior shape? For instance is a old CMC exterior shape the same as a new Intermacanica. If not, what would the differences be?
I believe all "classic" bodied speedsters are based on the 356A speedster. Some use the older behive lights with top down plate light. Others use the tear drop lights with shine up plate light.
The flared kits are quite different. Some like the CMC have a flared lip around well. The VS is very wide and is widened through the full fender.
I think the VS Flared body is the best wide body shape.
The flared kits are quite different. Some like the CMC have a flared lip around well. The VS is very wide and is widened through the full fender.
I think the VS Flared body is the best wide body shape.
There is no body difference in the bee hive or tear drop, it's just a change where the holes are. The actual body mold is the same. VS has two wide body molds, there is a medium fender version and a very wide fender version, (I think the one Eric is talking about). Since, JPS uses the VS molds, I'm sure he has access to the extra wide version as well.
-=theron
-=theron
Intermeccanica has its own molds and its own process which differs from VS. As mentioned, JPS uses VS bodies. Don't know about anybody else.
I'm curious, what is the difference in process between IM and VS?
Bruce, the difference is in the type of fiberglass layup and resins used, plus IM heat cures the bodies prior to prep for paintwork. The curing process stabilizes the fiberglass and prevents shrinkage which may otherwise occur.
Not to forget.
IM sets the engine and tranny 3" forward in their superb tube frame that is fused to the body, making a very fridged framed unibody with a better center of gravity.
Add the adjustible coilover shocks and the Golf rack and pinion, and its got to be Outstanding.
IM sets the engine and tranny 3" forward in their superb tube frame that is fused to the body, making a very fridged framed unibody with a better center of gravity.
Add the adjustible coilover shocks and the Golf rack and pinion, and its got to be Outstanding.
From what I remember Herny telling me on my visit to his shop (see bruceclement.com/356/imvisit.htm), the kind of fiberglass they use is not "regular" fiberglass, but the kind generally used for fiberglass molds; their fiberglass fabricator, who they have been using for many years, uses a chopper gun rather than hand-laying and hand rolling (no bubbles); after the body comes back from the fiberglass shop, IM cures it under a huge heating device (seen here bruceclement.com/356/images/IM013.jpg). I don't recall all of the details of Henry's explanation, but I do recall being left with the impression that he had fine tuned the fiberglass work to a fine art. I think that feeling is borne out in the end result.
From personal exsperence with laying cloth, reguardless of the resin a cloth lay is 5 time as strong as a chopper shoot job.
Especially if its overlapped in at least three layers. and you can be sure thats the IM way.
Especially if its overlapped in at least three layers. and you can be sure thats the IM way.
Sorry Barry, but you're wrong. Fiberglass strength is related to the multi-directional glass fiber orientation in the layup; a chopper gun provides multi-directional fibers instead of the uni-directional fibers in conventional cloth layups (this is why fiberglass mat is stronger than cloth).
The problem with chopper gun layups used to be keeping consistent thickness, but this has been overcome with modern chopper gun methodolgy and techniques.
The problem with chopper gun layups used to be keeping consistent thickness, but this has been overcome with modern chopper gun methodolgy and techniques.
Then I stand corrected. But where sections are joined it is still nessary to lay muliple layers of cloth to reinforce the build correct?
I don't know George, all my research shows otherwise. Eddie
The strength of a fiberglass product is determined by the type of resin used and the layup of the fiberglass.
Is the laminating resin a strong Vinylester and Isothalic type, or a much less costly general purpose Ortholthalic type?
The actual thickness of a laminate is not quite as important as what's actually there. Is it 1/8" thick from a resin rich chopper gun or 1/8" thick from multiple layers of hand laid mat and woven roving? Thick chop will be heavy and brittle. Layered mat and roving using Kevlar and knitted Biaxial fabrics will be very strong.
Cloth fiberglass on flat areas will be generally stronger than mat, and mat in tight or hard corners will be stronger than cloth.
Is the laminating resin a strong Vinylester and Isothalic type, or a much less costly general purpose Ortholthalic type?
The actual thickness of a laminate is not quite as important as what's actually there. Is it 1/8" thick from a resin rich chopper gun or 1/8" thick from multiple layers of hand laid mat and woven roving? Thick chop will be heavy and brittle. Layered mat and roving using Kevlar and knitted Biaxial fabrics will be very strong.
Cloth fiberglass on flat areas will be generally stronger than mat, and mat in tight or hard corners will be stronger than cloth.
David, technology has prevailed - chopper gun layups are no longer "resin rich". Obviously the type of resin will be a factor in strength with epoxy resins being the strongest (and most expensive and difficult to work with).
I'm with Eddie and Dave - Chopper guns have their place, but they have their drawbacks, too.
It's interesting to note, coming from Rhode Island where a LOT of fiberglass boats are made, that NO ONE here is using a chopper gun to lay up high performance, high strength boat hulls. The reason is that they all know that the hand lay-up with mat/cloth and resin (they are using some pretty advanced resins around here) properly squeegied and rolled out is far superior in strength to a chopper gun lay-up, which, given its relatively short lengths of randomly placed glass fibers (generally, 1 - 2 inches long and blown in every direction), simply can't provide the latitudinal and longditudinal strength of glass mat, properly set, pressed and evacuated.
In fact, the guys at BOTH Total Composites Inc. and Hall Spars in Bristol, RI, (the hull and mast makers for a LOT of Americas cup boats who have now gone to advanced carbon fiber techniques for mega-bucks yachts) tell me that NO ONE doing high performance lay-ups use chopper guns on hulls and masts - choppers are only used by the low-cost, volume guys doing mass-market hulls and decks, or to provide a binder layer between layers of mat (a very common use of choppers in high perf. boat hulls).
Fiberglass gets it's strength from the bond between the resin and the glass strand. Inherently, both the resin and glass fibers are brittle, but when combined properly, they form a strong bond for two reasons: 1. the very fineness of the strand means that, if contacted, it will just bend out of the way, rather than resist and break. 2. there is a minimum size of crack which a glass strand will tolerate without its very high natural strength being affected. Although that minimum size is very small, it is generall larger than the diameter of a single fiber, so the fact that the fiber is intact in one peice means that it probably doesn't contain any flaws above the critical size.
Three things are important here: The strand diameter (smaller is stronger because a crack will be bigger than the strand), the resin bond (which essentially shields the strand from scratches and binds multiple strands together) and the number of perpendicular strands nearby. A crack has to sever a strand perpendicularly, so the anti-crack mechanics depend on a weak bond between the resin and strand: As the crack progresses, the bond breaks between the resin and strand, effectively forming a barrier similar to drilling a hole at the peak of a crack in metal, thus halting it's progress. Having many long strands nearby in perpendicular directions gives crack resistance in multiple directions. The more perpendicular stands nearby, the stronger the area (just makes sense).
(see next post >>>>>>>>)
It's interesting to note, coming from Rhode Island where a LOT of fiberglass boats are made, that NO ONE here is using a chopper gun to lay up high performance, high strength boat hulls. The reason is that they all know that the hand lay-up with mat/cloth and resin (they are using some pretty advanced resins around here) properly squeegied and rolled out is far superior in strength to a chopper gun lay-up, which, given its relatively short lengths of randomly placed glass fibers (generally, 1 - 2 inches long and blown in every direction), simply can't provide the latitudinal and longditudinal strength of glass mat, properly set, pressed and evacuated.
In fact, the guys at BOTH Total Composites Inc. and Hall Spars in Bristol, RI, (the hull and mast makers for a LOT of Americas cup boats who have now gone to advanced carbon fiber techniques for mega-bucks yachts) tell me that NO ONE doing high performance lay-ups use chopper guns on hulls and masts - choppers are only used by the low-cost, volume guys doing mass-market hulls and decks, or to provide a binder layer between layers of mat (a very common use of choppers in high perf. boat hulls).
Fiberglass gets it's strength from the bond between the resin and the glass strand. Inherently, both the resin and glass fibers are brittle, but when combined properly, they form a strong bond for two reasons: 1. the very fineness of the strand means that, if contacted, it will just bend out of the way, rather than resist and break. 2. there is a minimum size of crack which a glass strand will tolerate without its very high natural strength being affected. Although that minimum size is very small, it is generall larger than the diameter of a single fiber, so the fact that the fiber is intact in one peice means that it probably doesn't contain any flaws above the critical size.
Three things are important here: The strand diameter (smaller is stronger because a crack will be bigger than the strand), the resin bond (which essentially shields the strand from scratches and binds multiple strands together) and the number of perpendicular strands nearby. A crack has to sever a strand perpendicularly, so the anti-crack mechanics depend on a weak bond between the resin and strand: As the crack progresses, the bond breaks between the resin and strand, effectively forming a barrier similar to drilling a hole at the peak of a crack in metal, thus halting it's progress. Having many long strands nearby in perpendicular directions gives crack resistance in multiple directions. The more perpendicular stands nearby, the stronger the area (just makes sense).
(see next post >>>>>>>>)
Look at the difference between an inexpensive, 1/8" thick mat with, say, 250 strands per inch in each direction (making a total of 500 perpendicular strands) saturated in resin and properly cured, versus a chopper gun spewing, maybe, 150 - 200 randomly oriented strands per inch, imbedded in typically twice the thickness of resin and little or no squeeging of the form (in fact, you CAN'T squeegy chopper jobs, you have to rib-roll them, and the gun introduces a LOT of air into the mix resulting in possible air bubbles in the final product - that's why many boat (and car part) houses bake their product or vacuum bag when curing - to out-gas any air bubbles) and you can see that the strength premium (and quality of final product) will go to the mat/cloth version for the same volume of resin.
The VOLUME coming out of chopper gun is consistent, but the movement of the operator isn't, meaning that the thickness of the resin coat varies with the operator. That's why the roving (the rope-like glass fiber stuff the chopper is chopping up) has a tracer strand (usually red) that gets spewed out so the operator can visualize thin and thick areas as it's being sprayed. Also, 30% - 35% resin reinforcement is required for chopper applied coatings, whereas only 10% - 20% (or less in carbon fiber) resin reinforcement is needed in mat/cloth procedures and you just run subsequent layers.
Now, make that a premium mat/cloth of 350 - 500 strands per inch (1,000 perpendicular strands) and you've REALLY got some strength - typically 10X that of a chopper job for the same amount of medium thickness or weight. Why? Look back - more and smaller diameter strands which are more crack resistant.
Think of a cheap fiber glass (high resin-to-strand ratio) as thickness without strength, which causes "Crows feet" or cracks over time because of fatigue in the thicker resin (or gel coat) at stress points.
Chopper guns give you good (read that, acceptable) quality for lower-cost, mass produced products. They're also the only good way to make pre-forms - essentially a custom-shaped piece of glass mat. For higher quality and longer lasting product, around here at least, everyone does hand lay-up of proven cloth/mat techniques. However, you have to look closely at the final product application, expected stresses on that product, expected torsional strength and so forth, and weigh that against the cost of hand lay-ups - usually a 30% - 50% premium over chopper gun applications - to decide what makes good economic sense for your product.
If you're REALLY curious about this stuff, a friend of mine, Forbes Aird, wrote a book entitled "Fiberglass and Composite Materials". It's not a textbook, but more like an enthusiasts guide for automotive and marine uses.
This was long, but I hope it causes less confusion.........gordon
The VOLUME coming out of chopper gun is consistent, but the movement of the operator isn't, meaning that the thickness of the resin coat varies with the operator. That's why the roving (the rope-like glass fiber stuff the chopper is chopping up) has a tracer strand (usually red) that gets spewed out so the operator can visualize thin and thick areas as it's being sprayed. Also, 30% - 35% resin reinforcement is required for chopper applied coatings, whereas only 10% - 20% (or less in carbon fiber) resin reinforcement is needed in mat/cloth procedures and you just run subsequent layers.
Now, make that a premium mat/cloth of 350 - 500 strands per inch (1,000 perpendicular strands) and you've REALLY got some strength - typically 10X that of a chopper job for the same amount of medium thickness or weight. Why? Look back - more and smaller diameter strands which are more crack resistant.
Think of a cheap fiber glass (high resin-to-strand ratio) as thickness without strength, which causes "Crows feet" or cracks over time because of fatigue in the thicker resin (or gel coat) at stress points.
Chopper guns give you good (read that, acceptable) quality for lower-cost, mass produced products. They're also the only good way to make pre-forms - essentially a custom-shaped piece of glass mat. For higher quality and longer lasting product, around here at least, everyone does hand lay-up of proven cloth/mat techniques. However, you have to look closely at the final product application, expected stresses on that product, expected torsional strength and so forth, and weigh that against the cost of hand lay-ups - usually a 30% - 50% premium over chopper gun applications - to decide what makes good economic sense for your product.
If you're REALLY curious about this stuff, a friend of mine, Forbes Aird, wrote a book entitled "Fiberglass and Composite Materials". It's not a textbook, but more like an enthusiasts guide for automotive and marine uses.
This was long, but I hope it causes less confusion.........gordon
Oh, I almost forgot......a lot of places (both marine and automotive) use a combination of mat lay-ups and chopper applications. For instance, they may spray in a color gel coat of, say, 60 thousandths thick over a mold release, then lay up mat/cloth at known stress points and then spray a layer over everything with a chopper giving a generally strong piece with mat/cloth reinforced stress points - Voila! The best of both worlds.
gn
gn
Gordon,
Wow, now your post should be the milepost on this topic. I hope Theron
inserts it in the technical area. Great job!
Bruce
Wow, now your post should be the milepost on this topic. I hope Theron
inserts it in the technical area. Great job!
Bruce
That is a really good write up. I will add it to the knowledge area when I get a few minutes.
-=theron
-=theron