Bodywork Problems
Discussion
Apologies to those who get the Pre 1980 listing too, but the more advice the better!
We've spent the last year doing bodywork on the M, and we're so so close, but yet again we've come across little things that will spoil the overall effect unless we attempt to rectify them now.
This time we've got a 'common' fault, stress cracks just on the inside of the headlight mounting hole as it curves up to the main bonnet itself (difficult to describe, but i'm sure you know it yourselves), and we've now ground the cracks out to leave a 5-8mm gap, and filled in with plenty of solid P40, left to dry and skimmed over with P38, yet we've once again given it a coat of primer and found the crack back in exactly the same place.
Don't think the GRP itself is under any stress where it's sat (front on a workmate, back suspended from the ceiling) but in less that two days it's back and as obvious as ever right through the new P40.
Can anyone offer any guidance as to what we can do about this? This is the third time we've tried to sort it, and each time, we're thwarted at spraying time....
Any advice appreciated before I throw it somewhere in a fit of late night rage!
Finally, to those sprayers amongst you, has anyone experienced a bizzare phenomenon with a air spray gun, where the paint seems to irregularly pulsate out of the gun? Doesn't seem to matter what the pressure is, how big a fan i'm using, or how much paint is coming out, but it has the effect of an uneven painted surface, which we have to flat back unnecessarily before the top coat can go on. Ideas anyone?
Thanks,
Tony (& exasperated Chris) & '76 3000M
www.tvr-3000m.co.uk
We've spent the last year doing bodywork on the M, and we're so so close, but yet again we've come across little things that will spoil the overall effect unless we attempt to rectify them now.
This time we've got a 'common' fault, stress cracks just on the inside of the headlight mounting hole as it curves up to the main bonnet itself (difficult to describe, but i'm sure you know it yourselves), and we've now ground the cracks out to leave a 5-8mm gap, and filled in with plenty of solid P40, left to dry and skimmed over with P38, yet we've once again given it a coat of primer and found the crack back in exactly the same place.
Don't think the GRP itself is under any stress where it's sat (front on a workmate, back suspended from the ceiling) but in less that two days it's back and as obvious as ever right through the new P40.
Can anyone offer any guidance as to what we can do about this? This is the third time we've tried to sort it, and each time, we're thwarted at spraying time....
Any advice appreciated before I throw it somewhere in a fit of late night rage!
Finally, to those sprayers amongst you, has anyone experienced a bizzare phenomenon with a air spray gun, where the paint seems to irregularly pulsate out of the gun? Doesn't seem to matter what the pressure is, how big a fan i'm using, or how much paint is coming out, but it has the effect of an uneven painted surface, which we have to flat back unnecessarily before the top coat can go on. Ideas anyone?
Thanks,
Tony (& exasperated Chris) & '76 3000M
www.tvr-3000m.co.uk
There was a book by Miles Wilkins on grp repairs, i think it is available through Club Lotus, detailing exactly what to do.
Your problem i believe is that the crack is being filled with filler which is not providing any strength. The crack is a "stress crack" therefore there is a weakness in the grp. You need to grind back an area, glass it then apply the filler.
Your problem i believe is that the crack is being filled with filler which is not providing any strength. The crack is a "stress crack" therefore there is a weakness in the grp. You need to grind back an area, glass it then apply the filler.
I just posted the following note on the general forum, and then I saw a very similar post here, so I'm reposting it here. (Same stress crack issues and paint finish)
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Years ago in my 2500-M I was closing on a car that hesitated waaay too lonng to turn and get out of the way, and I miss judged the situation and tapped the rear of the car. It didn't appear to do any damage to the car, however, there was a certain amount of force that was transmitted back to the windshield and bulkhead area, and the entire front end of the car (fiberglass body parts) must have flexed a bit. The result are some cracks in the paint on the top part of the front tilt up engine enclosure. I figure I'm going to have to strip the paint all the way down to the glass, reprime, and repaint. Does anyone have any other considerations to offer, such as any potential structural damage that may have been done to the fiberglass itself. At this time it just looks like cracks in the paint, but I guess it could be cracks in the actual glass and polyester too.
Just tossing this out to anyone who has worked with fiberglass a lot who may have some tips, council, or observations.
regards, Dogsharks
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Years ago in my 2500-M I was closing on a car that hesitated waaay too lonng to turn and get out of the way, and I miss judged the situation and tapped the rear of the car. It didn't appear to do any damage to the car, however, there was a certain amount of force that was transmitted back to the windshield and bulkhead area, and the entire front end of the car (fiberglass body parts) must have flexed a bit. The result are some cracks in the paint on the top part of the front tilt up engine enclosure. I figure I'm going to have to strip the paint all the way down to the glass, reprime, and repaint. Does anyone have any other considerations to offer, such as any potential structural damage that may have been done to the fiberglass itself. At this time it just looks like cracks in the paint, but I guess it could be cracks in the actual glass and polyester too.
Just tossing this out to anyone who has worked with fiberglass a lot who may have some tips, council, or observations.
regards, Dogsharks
The first problem is that body filler has no strength. The second problem is that (usually - depending on type) the paint is less brittle than the polyester / glass body. So, if you've got cracks in the paint then (unfortunately) you've probably got cracks in the gelcoat bodywork.
Having wrapped my Tuscan V6 around a tree many years ago I had the bonnet in about 12 pieces. I used metal straps to re-assemble the jigsaw back together, glass up the inside, grind back all of the joins on the outside and lay new glass into the joins. Once that was back to about the right shape I re-tissued the whole bonnet (having taken all the paint off), put a thin scree of filler over it and started to flatten it off........
I found a 'How to repair Glass Fibre' book (Osprey press from memory) very useful and well worth getting if you intend to do any glass work.
Having wrapped my Tuscan V6 around a tree many years ago I had the bonnet in about 12 pieces. I used metal straps to re-assemble the jigsaw back together, glass up the inside, grind back all of the joins on the outside and lay new glass into the joins. Once that was back to about the right shape I re-tissued the whole bonnet (having taken all the paint off), put a thin scree of filler over it and started to flatten it off........
I found a 'How to repair Glass Fibre' book (Osprey press from memory) very useful and well worth getting if you intend to do any glass work.
Thanks folks, I had hoped that with the use of P40 instead of P38 things would be a lot stronger. The traditional filler is more for the top layer and reshaping more than strength, although I use it for pits in the surface too. With the P40 I use a mini-tool cutting disc and as well as the main area, cut into the surrounding areas in the hope that this will provide a good enough key to hold on to. It certainly seems strong enough when set....
I'll take a look at that book too - thanks for that.
Tony
I'll take a look at that book too - thanks for that.
Tony
Tony
I have a copy of the Miles Wilkins book + the one in the same series on Paintwork. Mail me offline if you want to do a deal (no use to me at present as no plastic cars and I can't spraypaint children (well not legally anyway!!!), got to able to beat Amazon
davidy
PS both mine are hardback (better for the garage!!)
>> Edited by davidy on Monday 13th October 19:25
I have a copy of the Miles Wilkins book + the one in the same series on Paintwork. Mail me offline if you want to do a deal (no use to me at present as no plastic cars and I can't spraypaint children (well not legally anyway!!!), got to able to beat Amazon
davidy
PS both mine are hardback (better for the garage!!)
>> Edited by davidy on Monday 13th October 19:25
Paintwork book
www.amazon.co.uk/exec/obidos/ASIN/085045557X/qid=1066127845/sr=1-3/ref=sr_1_0_3/026-2014526-5927647
Only the wishful joker wants £95 notes for it!!!
I've made Tony an offer, if he refuses I'll send you an email
davidy
www.amazon.co.uk/exec/obidos/ASIN/085045557X/qid=1066127845/sr=1-3/ref=sr_1_0_3/026-2014526-5927647
Only the wishful joker wants £95 notes for it!!!
I've made Tony an offer, if he refuses I'll send you an email
davidy
Just a note to confirm what others have mentioned above. Firstly forget the filler. Secondly you will have to feather the crack out for about 3" or 4" either side (ie above the bonnet and below) and reglass with 200/250 matting finishing with tissue on top. Miles Wilkins was the bodywork engineer at Lotus for a long time (20 years?) and his book is excellent, though out of print. The area that you have highlighted is a weak point with Ms but you should get maybe 10 to 15 years OK. If you glass in some aluminium gauze you should get a longer life. Don't forget the dust mask and good luck.
I've got the same cracks and feel sure the advice given will solve the problem. It's cause is the tight radii formed by the shape of the bonnet in that area. The only mechanical strength from GRP comes from the reasonable proximity of the matting within the resin. Too thick an area of gel coat will put the matting too far into the depth and so leave it unable to support the brittle finish.
This area in the moulds would have been tricky to keep consistent and difficult to lay up. Grinding out and laying up with tissue will, I feel, cure it for good.
This area in the moulds would have been tricky to keep consistent and difficult to lay up. Grinding out and laying up with tissue will, I feel, cure it for good.
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