Disaster...

[brainbug007]

I was working on drilling out the holes in one of my side panels for the front suspension and it was going well until I got to the last hole. About halfway through drilling the hole with a holesaw, the drill kind of jammed/got stuck on the grp and there was a nasty kickback which made the drill twist in my hands. The grp inbetween all of the holes then cracked and practically broke off. It's only hanging on really by a few threads so to speak so I'm wondering what my options are going to be now. I can't really afford to replace the whole panel at the moment so I guess that only leaves me with 2 options that I can think of. 1) I try to repair the grp but never have worked with grp I'm worried I will just make an even worse mess of it and I can imagine trying to get the right color will be quite difficult.. 2) I just cut the whole section out and have a sort of square shaped hole (I'm sure I've seen a picture of a companys side panels on here somewhere like that). Granted this wouldn't look as good but I'm also thinking it will make IVA harder as won't the tester try shoving his 100mm sphere in there which means everything will need the 2.5mm curves? I'm thinking things like suspension brackets and the water inlet pipe bracket, and alternator are over there for example and these definately wouldn't pass any 2.5mm rules I'm guessing?

Any suggestions would be very welcome!

[AshG]

stick a picture up lets see how bad it is, then we can suggest the best way of fixing it

[MarkB]

Don't panic is the first thing. Then what you need to do is clean up the edges where it's broken, feather them so the new repair has a chance.

Then clamp the side panel gel coat face down to as smooth a surface as you can find making sure all the damaged area is over this....then gel coat the missing bits and lay up two layers of 450gm....leave it to go till it feels rubbery then trim any oddness off with sharp knife. Leave it over night and pop it off your board and bingo you have repaired your panel.

Make sure there are no gaps between the side panel and the board though as the gel coat WILL bleed through no matter how thick and gloopy it looks.

As for matching colours well that is all but impossible unless the gel used is from the same batch that was used to make it in the first place, and then that only applies to ready pigmented gel coat as mixing it yourself leads to variations.

Hope that helps in some way but like Ash said, pictures of the damage would help.

[MarkB]

Also you should never use sharp drill bits or holesaws to cut grp as it snags and chips plus it tends to "drag itself" thru just as it's breaking through.
The best way is to chain drill then open up using a whizzy(dremel type thing)

[robo]

Trouble with a large hole saw in grp is the pilot hole getting bigger as you drill then the hole saw starts to walk, thats when they start to snag. The method I use is to rivet a small plate in the middle of the hole <anything will do> mask the area you are drilling and drill from the gel coat side inwards. Never had a problem doing it this way even with a 130mm saw. The masking tape is enough to stop the plintering of the gel coat and the small plate will stop the drill walking. Oh and go slowly with a variable speed drill.

Bob

[shh120m]

If you know the ral code, i can have a look see if there is any pigment kicking about. Might not be the same batch and there may be a slight variation but its better than nothing. If ive got the same colour il pop a bit of gel/resin/pigment and a bit of matting in the post.

nathan

[alga]

The prototype car in the book did not have the front wishbone area covered at all, and it's barely noticeable. So I'd bet any reasonably tidy repair won't be noticeable unless you're looking for it.

You could buy a glossy sheet of Lexan or some other plastic as a background for the repair. MarkB, what are good plastics for that purpose?

[MarkB]

The prototype car in the book did not have the front wishbone area covered at all, and it's barely noticeable. So I'd bet any reasonably tidy repair won't be noticeable unless you're looking for it.

You could buy a glossy sheet of Lexan or some other plastic as a background for the repair. MarkB, what are good plastics for that purpose?

No need to buy anything expensive, an old double glazing unit will do the job these can be found in most skips or down the dump as long as it's big enough of course. Wax it to make sure gel won't stick then clamp side panel to it and off you go....simple really.

[brainbug007]

Thanks alot for all of the suggestions guys. In the end I took your advice and repaired it instead of just cutting the whole section out as I figured trying to make it IVA compliant would end up being more hassle than trying to repair it. As it turned out my neighbor was quite handy with GRP and did a clever repair by kind of re-enforcing it from behind with some metal strips then applying more GRP the back. Luckly where it had cracked in a majority of places you could line the pieces back up and the crack wasn't that noticeble when you look at the shiny side so to speak. The only bit that wasn't fixable was a section along the top kind of between the holes for the top wishbones and the shock absorber so i've got a strip cutout basically between the front hole and the rear hole that kind of looks like an upside down T but at least none of it is over 100mm so once the rubber u channel strips are put on it should be impossible for the IVA man to shove his sphere into the engine bay anywhere so to speak.

[MarkB]

Sounds like you got away with that then, well done:)

[baz-r]

i have found that grit faced tools for tiles are brillent for cutting grp (jigsaw and hole cutting tools).
minimal chipping of gel and i use blades in my jigsaw free hand without touching the shoe on the panel if i need to do cuts from the outside.
finally opening out to the finished line with a sanding drum or disc.

[tex]

you could of made a flared side panel instead - if you cut the panel out from where the scuttle lower front touches the side panel - chop out the engine bay sides then either replace with ally but make the rear edge further out from the body allowing air out - front sits in same place

like this

http://forum.wscc.co.uk/forum/index.php?/topic/75872-carbon-side-panels/page__hl__%2Bflared+%2Bpanels__fromsearch__1

looks really cool - if you use ally you can leave it bare - looks pretty
or carbon - :cool:
or - - - grp? needs a mould which shouldnt be hard to do - maybe then sell them on to other haynes users? could be a little earner

[shh120m]

thats got me thinking, i could quite easily churn out a 'locost' version of these for the haynes, using prepreg backed with grp to keep costs down. Would certainly consider making some up if the demand was there. Would have to add a radius to the rear vent to keep them iva freindly.

[MarkB]

prepreg isn't locost though

[shh120m]

It is if youve got the facility to prepreg the twill;) granted its not cheap, but its certainly not mega bucks, thats why there would need to be interest first.

[MarkB]

So are we to see a full Roadster in carbon fibre soon then?

[chrisponter]

I'd certainly think about buying carbon bodywork when the time comes. Depending on price and weight.

Anyone know what the weight difference between GRP and Carbon Fibre is?

[shh120m]

theres two ways of doing it:

1 layer of carbon fibre twill matting at 120g/sm impregnated with epoxy is mega strong (at least as strong as 2 or 3 layers of polyester and chopstrand glass) and also very light for exanple a side panel would weigh about 500g. This is 'proper' structural carbon fibre like f1 parts etc. This is pretty expensive because epoxy is a pig to work with and because its so sticky and horrid the only way to get a perfect finish is to vac-bag everything, the tape and bags cost a fortune, and there is alot of wasted materials, another way is to use an autoclave which again pushes up the cost to the customer.

or

1 layer of carbon fibre twill impregnated with polyester, but due to the structural properties of polyester resin with cloth it would have to be backed up with chopped strand matting to give it some rigidity, so cosmetically its real carbon fibre, but its reinforced behind. This is the cheaper way to do it because no expensive epoxy is required, its alot easier to work with than epoxy and there is no need on most items for the vacumn pump. The weight works out about the same, if not a little lighter because you are replaceing say 1kg of gelcoat with the equivilent of 120-150gram of twill.

[MarkB]

You don't get waste or mess or even a nasty stink with vac bagging and it's far superior than hand lay up as it ensures an even spread of the resin.

[PorkChop]

I'd be up for flared side panels (but not necessarily in CF; I reckon FG would be fairly popular too).