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MG MGF Technical - Group buy: GRP body panels
|Another spin off from Project Shed - I chatted to Mike at Smith and Deakin yesterday, who has agreed to make panel moulds for MGF and TFs - specifically doors, bonnet and bootlid.|
The doors and bonnet will be 150 quid each if purchased as single items - but for a purchase of 5, that will drop to 100 quid per panel (quite a saving on usual ebay prices for second-hand, standard metal bonnets for example).
My guess is that there will be more interest in the bonnets (crash repair, or even those considering ducting the rad through the bonnet, a la mgtf200HPD) - but hopefully there will also be interest from those track-day and competition fanatics for the doors too...
Let me know - add your name here and state the panels you'd be interested in :o)
If order placed in the next month or so, we'd be looking at delivery in the new year.
|Just a warning - |
don't expect S&D bonnets and the like to be of road - going quality.
In fact, I paid more than twice as much again to get my bonnet on the midget fitting so it actually looked like a bonnet.
and make sure the panels you give S&D are top notch - the previous plan used separate wings, when they arrived they came with cast in faux rust bubbles
|Rob, what weight saving do you estimate to achieve by fitting the panels?|
|Will, I suspect that the quality of the original panel was suspect if it came complete with re-production bubbling ferrous oxide! LOL|
Erik has dealt with S&D for the Trophy spoiler, and following some initial snags, got a good quality product, so I think we can be reasonably confident. :o)
Davey, GRP panels are not always lighter than the steel items they're meant to be replacing - it depends on how they're made, and how light the steel original was in the first place. I can't say how much weight will be saved by going GRP for the doors and bonnet, but the bootlid I have (from a TF converted MGF Cup car) is about 50% lighter than the steel original as a guestimate, and of course, I am deleting the hinges for the track car...
I guess if we aim for around 20% less weight, that'd be achievable in a functional panel.
|Mais oui, those boot hinges & springs are the thick end of 3 kilos between 'em, and that's high-up weight too - absolutely the worst sort for high speed cornering ;o) and the crumple zone element of the underside of the bootlid makes the OE panel fat & very heavy. There is slightly less impact protection with a skinny GRP panel, but the engine bay makes an excellent crumple zone in the statistically very rare event of shunt intrusion with that degree of force. Much more likely to come from in front of you!|
Having done some calculations based on a single skin GRP bonnet, which worked out about 2kg, and from what I've gathered speaking to S&D in the past, their finished product is likely to show a 40% saving (ish) provided they don't over-do the rigidity - it's supposed to give up easily in a potentially painful frontal intrusion (ooer!) and be soft & bouncy if a body lies on it at high velocity having been bowled over by the front bumper knee-capping them...
Rob, are there discussions of a ducted version and the reworked front panel entering production? Am presuming S&D will only want to do the original panel?
Doors might well not show so much saving, if the side impact protection is spec'd the same then you may save a kilo, maybe not even that much if you want it in 'road' trim; if S&D made it more of a race/track-day spec you'd get the best saving. The steel door once stripped of its glass, motors, runners, linkages & lock is actually not particularly heavy, just this week one bounced off my toes without causing much profanity. Strangely doors are very cheap secondhand, so S&D's price might need to reflect that, perhaps persuade them to make the bonnets the cash cow and do the rest at slimmest margins, when crash repairers are shopping around and it's cheaper than a steel one & the owner is happy to have a better lightweight version in order to un-shorten their car quicker, they'll enjoy steady business. As Will says, it would have to be a very good mould & finished to as close to steel panel basis i.e. shut line accuracy (which can be quite hard to achieve on a large panel) and needing nothing more than painting & fitting. Still, a little time spent fettling can be therapeutic I find, so long as it only involves sandpaper, and it doesn't stop being 'a little'...
|This might be the route to go when supply of steel panels dries up, but it's probably premature at present.|
Composites are not very good at offering both flexibility and stiffness at reduced weight, especially when executed in "fibreglass". I would suggest you ask S&D about the alternative materials and lay-up methods they might use. You could also ask them whether there are any issues around copyright we need to know as well.
|The savings in weight from GPR-panels is close no nothing when they are tidied up (putty) and finally look acceptable.Know this from my Porsche roadsport project years ago.|
A much better approach is vacum forming in ABS-plastic. Can be done from sheets.Only drawback is that there can be a slight deforming during excessive heat.Normally retain their shape after cooling.. / Carl.
|OOops! Should of course be "GRP", i.e what we normally call "glassfibre".|
|If a decent laminate is used in a good mould, then there is no reason GRP panels will need ANY finishing besides a quick sand a spray. Only poor quality moulds and lack of veil cloth in the laminate will lead to poor quality panels. If your GRP panels are not significantly lighter than the standard steel ones I'd be taking them back and asking for my money back.|
Ask them if they can use resin infusion to impregnate the laminate, it will give a better B side finish and will give higher volume fractions (and hence specific strength and stiffness) than wet hand lay up or vacuum bagging. Combined with a closed-cell foam core of say 5-10mm will give excellent stiffness and be very light. Try and get them to steer clear of random mats, they're cheaper but they result in heavier products with lower volume fractions than can be achieved with woven or stitched fabrics.
I doubt you will be able to get after market GRP panels to meet pedestrian impact standards very easily.
|>> Rob, are there discussions of a ducted version and the reworked front panel entering production? Am presuming S&D will only want to do the original panel? <<|
I mentioned this possibility to Mike - and you're right he's only interested in the standard panels at the moment. But there does seem to be a lot of interest in 200HPD panels, which potentially could change Mike's mind if I can show him that's there a market for them... Or perhaps get one of our MGF suppliers to take the plunge on getting the moulds made?
Incidentally, I am not too concerned about the surface quality for a track and sprint car - but would love to have a black gel-coat finish! Would save on paint!
Points taken - it's well known that GRP panels aren't necessarily lighter than steel. I'll be adding lightness with an electric drill! But others may want the production-levels of rigidity, particularly for 200HPD repro panels...
Actually, do people want faithful reproductions of the 200HPD bonnet? To align the bonnet vents successfully would involve additional work narrowing the bonnet closing panel, as well as removal of the front wall of the spare wheel well...
This thread was discussed between 24/09/2008 and 30/09/2008
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