Floor damage repair

[MartinH]

I have started the planned repairs, upgrades, etc for this winter. Dual circuit brakes, move the coil from under the carbs, tidy up the under dash areas, etc. I noticed what looks like a tear in the underside of the passenger floor on my 1967 S3 DHC (re-bodied by a PO with an S4 body)
Please see the attached pictures, I pulled out what looks like filler from the tear to the point where I could see the bottom of the trellised metalwork that runs along the side of the car.
I then stripped out the interior to see if this had gone all the way through the floor.

The photo of the interior shows there is no damage to the inside of the floor and the trellised metal work is in good condition.

Please give me your thoughts/advice on the best way to fix up the underside. I was thinking grind it all back and lay up some new fibreglass and then skim it to a smooth surface for painting. I am no expert in this so any input will be very welcome especially re the type of fibreglass to use.

Thanks in anticipation
Martin

[webbslinger]

Hi Martin. I would use regular old polyester resin as that's what the rest of the car is made of. There are two types, lay-up and finishing resin. The lay -up type remains tacky so you can build up another layer without having to rough it up to get a good bond. That said, I usually just use the finishing type for these small jobs. Besides the resin (and catalyst) you will need some glass material and acetone for clean up. The acetone can also be used to soften a cured surface to put get a good bond for another layer. Lotus used just mat, but in most all of my repairs I try to use some roving as well, or better yet, biaxle for more strength. The biaxle is thinner and actually stronger than roving so that's what I favor now. Biaxle has mat on one side. The mat is good for bonding multiple layers. Anywhere you do repairs that will be on the outside of the body you should finish your work with thin vail to keep the pattern of the glass fabric from printing through the paint.
Yes, cut and grind out the damage and taper the edges. The taper should be about three times the thickness of the piece you're repairing. You can use taped or glued in thin cardboard for forms to glass to and just leave it there, or you can cover the form with plastic so it will pull away after the glass sets.
There isn't much strength in puddles of resin or glass that isn't wet out all the way so try to get the mix right.
If this is your first glass job you may want to seek out someone who has done it before. Not because it's hard to do, but there are lots of ways to get the stuff to do what you want. There are form release agents and additives to make lay up resin set like finishing resin. Also, before you do the repair, test it out on something outside the car so you see how long you have before it sets and what working with it is like. It is a lot easier to do a neet job than fix a mess after it cures. Resin spilled anywhere on your paint will wreck it.

[webbslinger]

A. Ouple more things Martin. What works well for wetting out your material is to do it on a big piece of cardboard. Use a cheap disposable paint brush and wet the cardboard with catalized resin and then lay the glass material on the wet spot. Paint the top of the material with more resin and work it in with the brush until it is saturated. Then gently peal off the wet material and put it in place being careful that it doesn't drip anywhere you don't want it to. Work out air bubbles with your brush or with a serrated roller for that purpose.

[bill308]

Hi Martin.

I can't tell if the exposed lower rod of the lattice surface is affected by rust scale. If it's a spot here and there, it's probably no big deal, but I would treat it with some rust converter before covering it over with glass and resin. If it is more severe, I think you have to expose and treat it all.

Bill

[MartinH]

Hi Martin.

I can't tell if the exposed lower rod of the lattice surface is affected by rust scale. If it's a spot here and there, it's probably no big deal, but I would treat it with some rust converter before covering it over with glass and resin. If it is more severe, I think you have to expose and treat it all.

Bill

Bill you are right about this, The exposed lattice is sound but has surface rust.
My intention is to grind out the tear and expose the lattice until I have clean metal and then apply the rust treatment before repairing the fibre glass. Thanks
martin

Webbslinger, thanks for the very detailed reply I PM'd you