Fibreglass Repair

[duncx]

What's the plan Paul, reinforce inside and then feather/glass the joins on the outside?

[DeanB]

14 hours ago, duncx said:

Blimey that looks like a right bodge job, and who the blazes would be so stupid as to keep driving a car in that sort of condition?

Who the blazes says who the blazes in 2025? 🤣

I thought I'd stumbled onto a Biggles forum by mistake! 😁

Edited July 16, 2025 by DeanB

[DeanB]

1 hour ago, foxy76 said:

Where did you get the repair piece from? An unfortunate donor?

The repair piece was made and supplied by Elise Spares in Norwich. A really helpful outfit. They supplied my clutch and clutch cylinders too and were a lot cheaper than Eliseparts.

[PaulH]

22 hours ago, duncx said:

What's the plan Paul, reinforce inside and then feather/glass the joins on the outside?

Yes, exactly that.  Here's the first of those steps.

 

Episode 4

With the repair piece held in place with the pop riveted plates on the outside, the inside of the joins can be fibre glassed.

I used a vacuum cleaner to get rid of all the dust on the inside.

I'm going to use two layers of chopped fibreglass mat.  Here are the pieces, about 25 to 30 mm wide, cut to lengths to suit the joins.

I've bought a very small quantity of resin (250 ml) plus the hardener which is more than enough for this job.

I mixed 75 ml, which was just about correct, only a little left over.

Brush the resin around all the joins, then place the first layer of mat and wet it thoroughly with the resin, then apply the next layer and again wet it with resin.  The resin is applied with the brush using a stippling motion to get rid of air bubbles.

With a lamp inside you can see the fibreglass on the inside

When this has hardened the pop rivets can be drilled out and the plates removed, then the joins can be worked on from the outside.  More about that in the next exciting episode.

[DeanB]

This is tremendous stuff Paul. So neat.

 

[PaulH]

Episode 5

Now that the resin is hard (after 24 hours in this case) the pop rivets can be drilled out and the plates removed.  You can see I made a mistake when I pop riveted the plate onto the existing bodywork and it has cracked the fibreglass.  I should have put a washer over the pop rivet to spread the force.  So I'll have to make sure the crack is dealt with in the next steps.

However this is not quite the invisible repair we are looking for.  So, you may have noticed the grinder in the picture, so it's time to look away for those with a nervous disposition.  

Yes, we have to grind away the outer surface either side of the join lines so that the surface tapers into the join.  Keep going until the join line disappears.  The wheel arch liner is back in and the cardboard and cloths are back to protect the car from dust, and I've got close fitting goggles, dust mask, ear defenders and thick gloves to protect me.

Lots of dust, so I did this outside.

Notice that the join lines are more or less gone.  I've ground it until I've reached the new fibreglass laid up yesterday on the inside.  Brutal isn't it.

I've also ground out the crack caused by the pop rivet.

You can see the grinding marks, which have to be removed.

It's out with the 60 grit sand paper again, this time to sand out all the grinding marks.

Next I've cut the fibreglass so that there is a narrow piece which will go on first, then a wider piece, and this time there is also tissue. 

I mixed up 100 ml of resin.  I used less than half that amount.

I painted on resin then placed the narrow piece and full wetted it with resin using a stippling motion, then the wider piece and wetted it, then finally the tissue.  

Here's what it looks like with a lamp behind the bodywork to illuminate the new fibreglass.  I'm pretty happy that there are only a few air bubbles and they are on the part inside the wheel arch  

Here's what it looks like without the lamp

Ideally this repair would be very close the the finished surface shape, but it doesn't want to be proud of the surface because we don't want any exposed fibres that might let moisture in if it had be be sanded back. 

Once the resin is hard (I'll give it another 24 hours) there is a choice of continuing to build up the the finished shape with resin, avoiding bubbles, or using body filler. I can confirm that the original Lotus Elan bodies had quite a lot of filler applied by Lotus. 

I'll make a decision about that tomorrow. 

 

Edited July 17, 2025 by PaulH

[Elisemadray]

looking spot on

[duncx]

Looking good, super neat work as always Paul   

I'm curious about one thing, why did you bother to remove the grinding marks? They would surely be buried under the first layers of resin so of no consequence, and arguably give a rougher/better surface for the resin to key onto (not that it needs it in this case).

Edited July 18, 2025 by duncx

[DeanB]

It looks great Paul.

I'm loving tuning-in nightly for the next instalment 😊

[PaulH]

5 hours ago, duncx said:

Looking good, super neat work as always Paul   

I'm curious about one thing, why did you bother to remove the grinding marks? They would surely be buried under the first layers of resin so of no consequence, and arguably give a rougher/better surface for the resin to key onto (not that it needs it in this case).

Good question.  I've not experimented with leaving the grinding marks in to see the outcome, and it doesn't take that long to sand them out with 60 grit.  I've blindly followed the instructions (or my memory of them) in this book which was very definitely seen as 'the' reference book for fibreglass repair when I started the work on my Elan +2 in the 1980s.  If anyone if contemplating carrying out fibreglass repair work and you want a reference book, then get hold of a copy, they are available 2nd hand. 

[Oakman]

Will the provider be able to place his trusty trolley jack straight under the repair Paul ? 
 

😉😉

[PaulH]

4 minutes ago, Oakman said:

Will the provider be able to place his trusty trolley jack straight under the repair Paul ? 
 

😉😉

Please, no, never!  😅

[PaulH]

Episode 6

Not too much extra today.  The resin has had 24 hours to harden, so it was rubbed down with sandpaper.  60 grit (very carefully) for the drips and very high points, then 80 grit.  There is something a little odd with the chemistry of resin, in that the very outer skin always seems to be very slightly tacky, so it tends to clog the first piece of sandpaper.  Once that's gone it's fine.  I seem to remember that it is bad practice to add more hardener to try to resolve that because it weakens the resin (goes off too quickly).

After initial sanding this is what it looks like.

The darker patches are where the surface is a little lower and the sandpaper hasn't touched it.

There are areas where the surface is still lower than the required final surface shape, so definitely room for another layer of tissue and resin.

The wheel arch edge needs building up

So, tissue pieces were cut to shape and resin mixed (30 ml) and applied.

Another 24 hours to wait for it to harden.  Hopefully it will be close enough to the final shape that I will used body filler once it has been sanded back to give a good key.  I'm pretty sure that's what a commercial body shop would do at this point.

I'm very happy with the quality of the repair.  The section thickness will be a little thicker than the original, due to the internal fibre glassing work, but not too much, and the strength of the panel will be pretty much as good as the original.  

If you have a cracked panel to repair the procedure is as I've described, including pop riveting the plates if the crack needs holding together.  If the crack is bad and is holding the surfaces out of alignment, it would make sense to get a hacksaw blade and cut along the crack so the surfaces either side can then be properly aligned.

More to follow on this repair in the next episode.

[DeanB]

Tremendous work Paul. Thank you!

[PaulH]

Episode 7

Sanded back the fibreglass resin, this time with 80 grit.  Again is has the annoying tacky surface which clogs the first piece of sandpaper.

It's not far away from the final shape, so I decided to use filler.  Once the filler is set (I gave it an hour) I sanded it with 120 grit for this first application.

 

 

You can see a few low points.  So on with another application of filler.  Here it is applied.  I'm not the neatest at applying filler, but it will rub down OK.  

Can this really become an invisible repair I'm sure you're thinking, including me 😄

Edited July 20, 2025 by PaulH