8 replies to this topic

[Shylos]

I've had a few searches and not found anything that really answers my queries, but if anyone knows of a thread that currently exists please let me know and I'll toddle off and have a read.

Basically a lot of people talk about fibreglass for flip-fronts/bonnets etc, as well as full shells and whatnot, but is it possible to replace only certain body panels with fibreglass ones? I have several panels that need replacing (A panels, wings, door skin etc) - is it possible to replace only these with fibreglass panels?

Also, if this is possible, and fibreglass panels are lighter, cheaper and don't rust, why would anyone use steel panels?

Sorry if these are basic questions to some of you, or I have missed something obvious - any help or pointers in the right direction would be much appreciated!

[Bert]

yerah u can replace most of them from what i know...not 100% about wings though.

as for the why use steel...is good, but if it gets wet/damp it can retain the water then begin to condensate and leave plant life (had this in my gtm) which is rank
also sturdyness in driving...i'd car hit me in a car of steel than fiberglass car...

have a look at abs motorsport (google that) they do some nice fiberglass items.

hth

[p.park]

is it possible to get carbon fibre ..like the stuff they use in aero space engineering.
the stuff that's supposed to be light as plastic but strong as steel..

no?

[Ethel]

Composites, even plain old Fibreglass, have many advantages over steel but they don't weld very well

Put crudely that's the issue: you can make lighter and stronger plastic panels but there's no way of fixing them to steel that's as strong as a weld with such a small contact area. That's why the plaggy panels you can buy are the bolt on one's - and roofs, which can have a large bonding area.

[rozzer1275]

There are complete mini body shells around in fiber glass.
it is posible to have GRP car stronger than a steel one it just a question of material thickness. GRP panels can be stiffened with reinforcing.
main reson a steel front is stronger than a GRP one is with GRP there are offten no inner wings and mainly they way it is fixed to the body (a few clips is no subsitue for a welded on panel)

People keep to steel mainly because it looks better.

GRP panels are often wobbly (esp on large panels), carbon ones tend to be better I think because the material thickness is more consistant.

GRP and carbon still ages, water can get into cut edges, and the sun and air can leave the gel coat cracked and crazed.

[Shylos]

Thanks for the replies

So basically fibreglass are on the whole cheaper and lighter, but the downsides are they don't bond to steel panels particularly well/easily, aren't as strong and can suffer from damp issues?

[Ethel]

Grp is a composite so properties can vary a lot depending on the construction and plastic resin. Industrial production of car bodywork would be more expensive than steel because it's labour intensive and slow - you can't rush the resin curing. Since you only need a paint brush & a pair of scissors the opposite applies for the home botcher .

Even chopped strand/polyester layups are roughly twice as strong as pressed steel when compared weight for weight. Steel and GRP are quite dissimilar to make comparisons. Mild steel is stiffer but less elastic, you'd want stiff chassis but prefer elastic skin panels that don't dent.

GRP will bond to steel, but if all you've got is the seam that was previously spot welded it ain't going to give a big enough area so won't be strong enough.

Water ingress will cause resins to leach (dissolve) out of a moulding but isn't significant with properly cured GRP - it's used to make light transmitting roofing. UV light does degrade GRP, but it will still outlast rust susceptible steel car bodies many times.

[Shylos]

Ah ok, so fibreglass (or GRP - wikipedia tells me fibreglass is a 'common' name for what is really glass-reinforced plastic?) isn't weaker at all as a material.

It seems that you're saying the main issue is that a car primarily designed for steel panels has been constructed in such a way that makes it very difficult to make a good bond with a GRP panel, which will effect overall structural strength.

Sorry if I am just repeating things you are saying, I'm just trying to make sure I have understood it all correctly

[jaydee]

By the way if you're looking for a light and resistant material as an alternative to steel panels, alluminium is the way to go. Isnt cheap as GRP and no one build a complete alluminium front, but you can buy a lot of things like doors valance etc.. Its very strong, light and resistant, in case of crash it wont break as a piece of plastic does.