How to make fiberglass GRP parts.
Discussion
I looking for advice and help on how to make my own fiberglass parts for a project I'm about to get started.
It's a 1990's Fiat Coupe and I'm hoping to replace the outer door skins, boot lid, bonnet and wings with fiberglass ones to reduce the weight of the car so tuning is more effective.
GRP bonnets are available but they have chav vents cut into them and cost far too much to take seriously.
I'm a welder and the use of filler is alien to me so any ideas, tips or advice is more than welcome.
All the best Liquid Knight.
It's a 1990's Fiat Coupe and I'm hoping to replace the outer door skins, boot lid, bonnet and wings with fiberglass ones to reduce the weight of the car so tuning is more effective.
GRP bonnets are available but they have chav vents cut into them and cost far too much to take seriously.
I'm a welder and the use of filler is alien to me so any ideas, tips or advice is more than welcome.
All the best Liquid Knight.
If the items aren't already available in GRP you'll need to make a mould using the existing panel.
Then you'll need to make the panel using the mould you've just made.
You'll need to make a mould of each panel you want to make.
Huge amount of work & materials including gelcoat, grp cloth, mat, resin/hardener/catalyst, acetone for cleaning up, release agent to stop adhesion to the original part & then the mould.
Resin is heavy, the panels will need bracing to stop them flopping around & I'm not sure how much weight you'd actually save.
Have a read through this:
https://www.ecfibreglasssupplies.co.uk/t-MakingMou...
I have made moulds when a part wasn't available (motorbike mudguard was the last one & that was some years ago) but I've also made boats & canoes so have a fair bit of experience working with GRP.
Then you'll need to make the panel using the mould you've just made.
You'll need to make a mould of each panel you want to make.
Huge amount of work & materials including gelcoat, grp cloth, mat, resin/hardener/catalyst, acetone for cleaning up, release agent to stop adhesion to the original part & then the mould.
Resin is heavy, the panels will need bracing to stop them flopping around & I'm not sure how much weight you'd actually save.
Have a read through this:
https://www.ecfibreglasssupplies.co.uk/t-MakingMou...
I have made moulds when a part wasn't available (motorbike mudguard was the last one & that was some years ago) but I've also made boats & canoes so have a fair bit of experience working with GRP.
As per that really. I've made a few small bits and it does get rather expensive. Doing most of a car like that will likely cost thousands. If it were carbon you'd save a lot of weight, but GRP isn't that light for large parts as stated above. And the amount of work is massive, especially after you've thrown a few parts away while learning.
Plenty of youtube vids on it though, it's not too hard in concept though I imagine something like a wing or bonnet will be very difficult just from a handling point of view.
Plenty of youtube vids on it though, it's not too hard in concept though I imagine something like a wing or bonnet will be very difficult just from a handling point of view.
This thread in Readers' Cars may be of some use if you haven't already seen it: http://www.pistonheads.com/gassing/topic.asp?h=0&a...
I know he makes the parts in carbon rather than GRP, but most of the processes are the same and he also started from scratch using, IIRC, www.easycomposites.co.uk. I've bought a couple of their starter kits, but haven't got around to using them yet, however they seem to offer quite a lot of info on their site and after-sales support if needed.
I know he makes the parts in carbon rather than GRP, but most of the processes are the same and he also started from scratch using, IIRC, www.easycomposites.co.uk. I've bought a couple of their starter kits, but haven't got around to using them yet, however they seem to offer quite a lot of info on their site and after-sales support if needed.
Complete waste of time effort and money i'm afraid.
The wings on a Coupe weigh about as much as a bag of crisps so the weight savings are practically zero, ditto the bootlid. Forget putting a composite doorskin on an existing door as that won't work either.
If your incompetent with filler then it's also a non starter as the old panels will need making right before you take moulds from them.
Moulds are for multiple items, not just one, by the time you've fathomed out how to do it you'll be into hundreds of hours and £££.
OE style bonnets are available and the only part of a car which is worth saving weight as it's huge and 27kgs. A lightweight FG bonnet will suffer from distortion due to the temps of the turbo engine, a heavy stable one, well.....
You're just trying to reinvent the wheel and failing.
The wings on a Coupe weigh about as much as a bag of crisps so the weight savings are practically zero, ditto the bootlid. Forget putting a composite doorskin on an existing door as that won't work either.
If your incompetent with filler then it's also a non starter as the old panels will need making right before you take moulds from them.
Moulds are for multiple items, not just one, by the time you've fathomed out how to do it you'll be into hundreds of hours and £££.
OE style bonnets are available and the only part of a car which is worth saving weight as it's huge and 27kgs. A lightweight FG bonnet will suffer from distortion due to the temps of the turbo engine, a heavy stable one, well.....
You're just trying to reinvent the wheel and failing.
No matter what you do to a Coupe it's a big heavy (about 1350kg) car with a massive front weight bias (heavy engine) and a long legged 'box, there's FA you can do about it apart from shave a few kg off, even then the lighter cars will show you the way home. The only tracks it can really get into its stride are big flowing ones like Donington.
It's a great motorway cruiser, 5th is good for 160+ if you've got the power. Buy a MR2 Roadster or MX5.....
It's a great motorway cruiser, 5th is good for 160+ if you've got the power. Buy a MR2 Roadster or MX5.....
To give yourself the idea of what's involved you could look at the bonnet and boot lids of a manufacturer's fibreglass car such as a Daimler SP250, a Jensen 541 or a Lotus Elite or Elan. You will find an inner skin with lots of closed channels formed between inner and outer skins, all necessary to give stiffness and resulting in quite heavy panels.
Adding lightness to thin metal panels is difficult unless you use even thinner metal.
Adding lightness to thin metal panels is difficult unless you use even thinner metal.
The glass window, sunroof, air conditioning and so on are already on my "skip" list. As are the seats, carpets, interior trim and original wheels. That would get the weight down to about 1,100Kg instead of 1,250 at best.
I am competent with filler but as I was learning to weld and do bodywork I was told...
"The instructions suggest you need a pea of hardener for every golf ball of filler; but if you ever need a golf ball of filler and you're doing less than the whole side of a car you should give your tools away and never touch a car again".
...by a specialist at the time and have stuck to it ever since.
I chose to start with the wings because they are the smallest part. I know they barely weigh five kilos and the benefit would be minimal but it's a learning curve. I fitted a Sebring kit to my MGB and the amount of bracing to fit the rear arches safely made any weight loss futile. I love it when other people hack away stuck the kit on and wonder why the car handles like crap and bends as soon as they hit a pot hole.
So...
Cost + Faff + Time = not worth it
...thank you again for all of your grounded and balanced advice.
I am competent with filler but as I was learning to weld and do bodywork I was told...
"The instructions suggest you need a pea of hardener for every golf ball of filler; but if you ever need a golf ball of filler and you're doing less than the whole side of a car you should give your tools away and never touch a car again".
...by a specialist at the time and have stuck to it ever since.
I chose to start with the wings because they are the smallest part. I know they barely weigh five kilos and the benefit would be minimal but it's a learning curve. I fitted a Sebring kit to my MGB and the amount of bracing to fit the rear arches safely made any weight loss futile. I love it when other people hack away stuck the kit on and wonder why the car handles like crap and bends as soon as they hit a pot hole.
So...
Cost + Faff + Time = not worth it
...thank you again for all of your grounded and balanced advice.
LK,
To counteract the doom & gloom above, I did what you intend on a Triumph Herald Estate, to great effect.
For instance; roof, 30kgs unbolted, 9 kgs in GRP
Doors, can't recall wreight in steel, with glass windows, winders etc. but in GRP complete with hinges and handles, 5kgs
I made a rear hatch, but that wasn't so successful as I used polyurethane foam and that soaks up resin.
The roof and doors were far from floppy, in fact the roof was many times stiffer than the original metal one.
The secret was honeycomb. Not the vastly expensive aluminium, but paper honeycomb, available as a compressed mass of card, that opens up into the cells when pulled apart. The roof comprised a skin of one gel-coat with tissue and one layer of random matt. Under that the honeycomb, stuck down with polyurethane foam, the space filler in an aerosol loved by bodger builders. And under that, to form the inner skin a half-thickness layer of random matt.
The entire car, originally 1250kgs, was 850kgs with the commercial bonnet.
I wrote the project up for a Triumph magazine - I'll gladly send you a copy, if you pm me with your email address.
To counteract the doom & gloom above, I did what you intend on a Triumph Herald Estate, to great effect.
For instance; roof, 30kgs unbolted, 9 kgs in GRP
Doors, can't recall wreight in steel, with glass windows, winders etc. but in GRP complete with hinges and handles, 5kgs
I made a rear hatch, but that wasn't so successful as I used polyurethane foam and that soaks up resin.
The roof and doors were far from floppy, in fact the roof was many times stiffer than the original metal one.
The secret was honeycomb. Not the vastly expensive aluminium, but paper honeycomb, available as a compressed mass of card, that opens up into the cells when pulled apart. The roof comprised a skin of one gel-coat with tissue and one layer of random matt. Under that the honeycomb, stuck down with polyurethane foam, the space filler in an aerosol loved by bodger builders. And under that, to form the inner skin a half-thickness layer of random matt.
The entire car, originally 1250kgs, was 850kgs with the commercial bonnet.
I wrote the project up for a Triumph magazine - I'll gladly send you a copy, if you pm me with your email address.
tapkaJohnD said:
LK,
To counteract the doom & gloom above, I did what you intend on a Triumph Herald Estate, to great effect.
For instance; roof, 30kgs unbolted, 9 kgs in GRP
Doors, can't recall wreight in steel, with glass windows, winders etc. but in GRP complete with hinges and handles, 5kgs
I made a rear hatch, but that wasn't so successful as I used polyurethane foam and that soaks up resin.
The roof and doors were far from floppy, in fact the roof was many times stiffer than the original metal one.
The secret was honeycomb. Not the vastly expensive aluminium, but paper honeycomb, available as a compressed mass of card, that opens up into the cells when pulled apart. The roof comprised a skin of one gel-coat with tissue and one layer of random matt. Under that the honeycomb, stuck down with polyurethane foam, the space filler in an aerosol loved by bodger builders. And under that, to form the inner skin a half-thickness layer of random matt.
The entire car, originally 1250kgs, was 850kgs with the commercial bonnet.
I wrote the project up for a Triumph magazine - I'll gladly send you a copy, if you pm me with your email address.
You're comparing apples with oranges.To counteract the doom & gloom above, I did what you intend on a Triumph Herald Estate, to great effect.
For instance; roof, 30kgs unbolted, 9 kgs in GRP
Doors, can't recall wreight in steel, with glass windows, winders etc. but in GRP complete with hinges and handles, 5kgs
I made a rear hatch, but that wasn't so successful as I used polyurethane foam and that soaks up resin.
The roof and doors were far from floppy, in fact the roof was many times stiffer than the original metal one.
The secret was honeycomb. Not the vastly expensive aluminium, but paper honeycomb, available as a compressed mass of card, that opens up into the cells when pulled apart. The roof comprised a skin of one gel-coat with tissue and one layer of random matt. Under that the honeycomb, stuck down with polyurethane foam, the space filler in an aerosol loved by bodger builders. And under that, to form the inner skin a half-thickness layer of random matt.
The entire car, originally 1250kgs, was 850kgs with the commercial bonnet.
I wrote the project up for a Triumph magazine - I'll gladly send you a copy, if you pm me with your email address.
I would definatly recommend starting with a relatively flat panel of a reasonable size,this will give you a good idea of handling material and resin coverage required. It will also mean you wont have to worry just yet about weiring the panel for a split mould(which would be required for front wings etc) as once laminated the mould will crack off in one piece.
The mould materials are the cheap bit for wet laminating (gelcoat,glass and resin) even the panel materials arent too expensive either for the main reason you'll be using less. Its the time that costs
You could use an epoxy resin for mould manufacture (Sike composites or Huntsman) and woven glass material instead of chopped mat,meaning once you've taken the first panels you can reuse the mould(s) again and try with carbon at a later date.
Hope this helps fella.
The mould materials are the cheap bit for wet laminating (gelcoat,glass and resin) even the panel materials arent too expensive either for the main reason you'll be using less. Its the time that costs
You could use an epoxy resin for mould manufacture (Sike composites or Huntsman) and woven glass material instead of chopped mat,meaning once you've taken the first panels you can reuse the mould(s) again and try with carbon at a later date.
Hope this helps fella.
Evoluzione said:
Liquid Knight said:
Evoluzione said:
You'd be surprised to learn they are just a whisker over 1kg.
Not very much at all. Shame the donor car I bought is a pile. I would have liked to have done something about the bonnet. I got the whole car for less than what I was going to pay for the exhaust and inlet cam' so anything else is a result.
Getting cross threaded here chaps. The Fiat Coupe's in question are in the Italian section.
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