roller Posted May 12, 2006 Share Posted May 12, 2006 i'm getting a fiberglass 6" cowl scoop and trying to decided if i should go with the stock hood or a fiberglass replacement? i kinda think if i use the metal hood and the fiberglass scoop it may crack off? Quote Link to comment Share on other sites More sharing options...
AK-Z Posted May 12, 2006 Share Posted May 12, 2006 It would if you put stress on it when mounting (making it fit). Its shouldn't be bended to fit. IMO I don't think it matters, but saying some extra weight is always a plus. Quote Link to comment Share on other sites More sharing options...
Bartman Posted May 12, 2006 Share Posted May 12, 2006 Some people will tell you that fiberglass bonded to metal will always crack eventually (different rates of thermal expansion), but there are also quite a few people that have done it without any problems so far. If you really don't want any cracks your best bet is to bond fiberglass to fiberglass. Anyone have a fiberglass scoop bonded to a metal hood (say for a few years or more) without any cracks? On a similar issue, I saw a Z that had the rear spoiler blended into his car. I would imagine that would crack eventually as well. I would be very interested in anyone that has discovered a process to bond fiberglass to metal that will not crack. Quote Link to comment Share on other sites More sharing options...
AK-Z Posted May 12, 2006 Share Posted May 12, 2006 Don't really know because I haven't done it before, but I would think that using epoxy and roughing the metal would make it bond better. I used epoxy on the crank shaft of my go-cart when I was in junior high when the key groove on the shaft broke on one side. Still have the motor and same epoxy. Slightly discolored but still on there tight. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted May 12, 2006 Share Posted May 12, 2006 Fiberglass to fiberglass it the best bond in this situation (be sure to rough up the bonding surfaces with some 40 grit (or similar) sandpaper to get best adhesion. 3M makes some great bonding compounds for attaching fiberglass or plastic parts to steel panels, and this may be what you want as well. As for using fiberglass to bond onto steel, it will look fine for a while, but you'll see cracks develop between the glass and metal within two years (probably less if the car sits in the weather much), which leads to rust, discoloration, and the whole notion of wondering if you should have done this in the first place. Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted May 12, 2006 Share Posted May 12, 2006 This is my 5" fiberglass cowl to a metal hood that was cracked about 1/2" when I bought this car and the crack keep spreading until we secured a hood pin over it . The crack has not spread since we did this 2 years ago. I've had the car for 4 years and sometime this year I will change to a new hood but not fiberglass to metal...... LARRY Quote Link to comment Share on other sites More sharing options...
Guest ViZ Posted May 14, 2006 Share Posted May 14, 2006 look into "kitty hair", alot of the mini truckin guys use it to shave body lines.. i guess its really strong and hard and doesnt crack even after years of use.. Quote Link to comment Share on other sites More sharing options...
Guest manntis Posted May 18, 2006 Share Posted May 18, 2006 Some people will tell you that fiberglass bonded to metal will always crack eventually (different rates of thermal expansion) ...added to which, hoods on anything but Detroit Iron tend to be thin, lightweight affairs. They twist slightly every time you open them. Not permanently, mind, but hoods have crummy torsional rigidity. Fibreglass bonded to a hood will, over time, develop subtle or not-so-subtle stress cracks whereas an all-fibreglass hood will flex as a unit. The downside to fibreglass hoods is mounting. If you add metal inside the substructure as mounting points for hinges, latches, and prop-rod snags, you're re-adding weight; and the difference in weight between metal Japanese hoods and their FRP counterparts of similar strength is mimimal to begin with. If you don't add metal, and instead bolt directly into the 'glass, you'll again experience stress cracks but now at a structural point rather than nuisance cosmatic cracks. Having your hood fly off its hinges whilst cruising down the highway makes for an unhappy drive. That's why many composite hoods are mounted with hood pins. Quote Link to comment Share on other sites More sharing options...
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