Lotus Elan

Body Crack Near Headlight Pod

PostPost by: 1969Plus2 » Thu Jun 06, 2019 4:05 pm

Any advice on how to sort out a crack like this without sanding down, re-doing the fiberglass and re-painting the whole thing?

The crack runs about an in inch to the left of the right (looking at the car) headlight pod and then goes 45 degree clean through the shell to back side. When the headlights are up, or if they have been up for awhile, the crack stays together but if you have the headlight pods down and go for a drive, the vibration separates the crack.

I am OK with a visual blemish but I just want to seal the crack together so that it doesn't get worse but I am reluctant to take on the hard work of sanding down repairing and repainting until I decide to take on a full paint job! Maybe I am just looking for the easy solution that doesn't exist though...
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PostPost by: Slowtus » Thu Jun 06, 2019 5:15 pm

Can't help with a quick fix here but this serves as a reminder to never (if possible) pop the lights up when travelling at speed. I am reliably informed that doing so will cause exactly what we see here.
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PostPost by: 1969Plus2 » Thu Jun 06, 2019 5:22 pm

Why would popping them up at speed cause this issue? If anything, I would have thought that popping them up would provide more support.
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PostPost by: Matt Elan » Thu Jun 06, 2019 6:14 pm

As a quick(ish) fix I would do this:

1. Take out the pod.
2. You can then get to the underneath of the body shell. Grind out around the crack from the underneath but don't break through, just get rid of the old paint and the first layer of old glasss fibre. This will give a good bond to the existing body work to the repair.
3. Now lay some cut to fit matt (or better still some woven roving cloth) underneath the body where you've ground away the old matt. The difficult bit here is to get the new cloth/matt to stick - its often better to do lots of small pieces rather than one big bit. Leave it to go off, this will stabilise the crack.
4. Option 1 - Once the underside is set, you can grind out the crack from the top. For a quick repair and to minimise paint damage you can do a quite steep sided groove, then fill it - I'd use P40 which has glass fibre reinforcement. Then paint, but the repair will probably reappear in a few months as it won't be that stable.
5. Option 2 - Grind out the crack from the top with a narrow angle - say about 30 degrees, so you end up with a strip an inch or 2 wide. Lay matt (not cloth as the weave will likely show through) and top off with glass fibre tissue, then sand back. This will give a better, more stable repair which should last a lot longer than Option 1, but will need more paint rectification and blending in.

Looking at body design, I can see how putting the lights up at speed could cause this sort of damage. However, I think that it's more likely caused by the top of the pod hitting the bodywork when it opens, which it shouldn't.

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PostPost by: 1969Plus2 » Thu Jun 06, 2019 6:28 pm

Thanks. That is very helpful and sounds like the right course of action.

I guess I was hoping there was something even easier, like a dose of fix all JB Weld but I should know better...
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PostPost by: 1969Plus2 » Thu Jun 06, 2019 6:30 pm

What is the P40 you are referencing?
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PostPost by: Matt Elan » Thu Jun 06, 2019 8:37 pm

Isopon P40 body filler - it's a body filler with fine chopped glass fibre in it. This gives it a degree structural strength greater than plain body filler. Available from Halfords in the UK.
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PostPost by: Slowtus » Thu Jun 06, 2019 8:44 pm

1969Plus2 wrote:Why would popping them up at speed cause this issue? If anything, I would have thought that popping them up would provide more support.


There was a great deal of debate about this back in the '80s and greater minds than mine - including that of Graham Arnold (where is that name drop smilie when you need it?) - much discussion about physics, car/light design, component wear and tear, fiberglass, etc

Don't want you doing a repair and next time you pop 'em at speed...crack!
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PostPost by: 1969Plus2 » Thu Jun 06, 2019 8:49 pm

And what was the conclusion of this great debate?!?! What does one define as being "at speed"?
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PostPost by: Matt Elan » Thu Jun 06, 2019 9:47 pm

The body cracking at the top of the headlamp pod hole is obvious when you look at the body design at that point.
Each pod hole has a glass fibre plate either side of the hole, which carries the pod hinges and strengthens the opening, but the top of the pod hole has no additional strengthening. So you turn on the headlamps, the pod snaps open, and at speed the wind will help it up. As the pod stops, with the headlamp up, there is a downward force applied to the plates which forces them down. This will flex the body panel along the top edge of the pod hole. I've just looked at my Plus 2 body, and there is no reinforcement along the top edge of the pod hole, and each corner will be a stress point. Once there is a starting point, such as a crack in the gel coat in one of the corners of the top of the pod hole, a crack will tend to propagate from the top corners into the body shell.
Fix? Well you could laminate a rib or vertical plate of glass fibre along the underneath of the rear edge of the pod hole, and join it to the two vertical plates to stiffen the top edge of the pod to begin with. If that was not enough then maybe glass in a pair of ribs to extend or continue the vertical ribs towards the bonnet shut line as well. These should remove the stress concentrations from the corners of the pod holes and dissipate the force of the pods snapping open over a larger area, hopefully eliminating any weak points.
Just my thoughts on the matter....
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PostPost by: MarkDa » Thu Jun 06, 2019 11:26 pm

If you are going to do a temporary repair that includes some work on the outside then drilling a hole at the end might help stop further propagation.
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PostPost by: Slowtus » Fri Jun 07, 2019 3:25 am

1969Plus2 wrote:And what was the conclusion of this great debate?!?! What does one define as being "at speed"?


I'm trying to help here. :o

Take the advice I passed on - or don't.
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PostPost by: Old English White » Fri Jun 07, 2019 6:13 am

Slowtus wrote:
1969Plus2 wrote:And what was the conclusion of this great debate?!?! What does one define as being "at speed"?


I'm trying to help here. :o

Take the advice I passed on - or don't.

I'm with you, Slowtus.
This, and added to the build process and the -too- flat design of that surface.
These are all things that make such a problem.
Apart from doubling the thickness (Corvette's don't get such issues), and maybe trying to make it stronger by putting a little cardboard profile under glassfiber (the same as on an ?lan bonnet), the years will always sign your body ...
Christian. :mrgreen:
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PostPost by: vxah » Fri Jun 07, 2019 7:27 am

For reinforcement I have used glass fibre rope (intended for stove sealing). It's very light, can be soaked in resin and matted over to provide a strong structure around curves where needed. One issue you will have is trying to work upside down! Gravity is against you and resin can get messy!
Maybe you could take the pod out, set the bodywork to close up the crack and then reinforce from behind to keep the crack minimal. when cured touch up and see how it goes? Use the given advice to get as good a bond as possible. What do people think about soaking the old gfrp surface with acetone to soften it for a better bond?
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PostPost by: Matt Elan » Fri Jun 07, 2019 8:05 am

Re soaking in acetone - I'd not risk it. A quick wipe over after physically cleaning the surface you are bonding to may be OK, but if you've removed the dirty top layers and are bonding onto a clean virgin surface there's not much point. Soaking risks two things - softening too much of the surface (and under the surface) beyond that which you want to bond to, and when adding the new matt etc sealing in some acetone which will work its way out over time - usually in the spot where it is most visible!

Re drilling a hole at the end of the crack - no need if you are repairing it properly, by grooving the sides of the crack top and bottom then glassing it in. Mr Wilkins in his book recommends running a hacksaw blade down the crack before grooving to clean up the edges and ensure you've got to the end of it.
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