Woven may fiberrglass to apply on top of existing fiberglass

[tdskip]

Good morning gentlemen-happy Thursday to everyone ( or Friday to our friends in AUS ).

I receive some great coaching on how to repair the body panels on the new to me asked for, I have a related question that seemed like it was worthwhile to break out into a separate topic however. Looking at the repairs I need to make, as well as the booth floor where it starts coming up to the vertical surface, I am going to need to add some fiberglass to reinforce those areas. I am assuming that I would use a woven mat material for that, but I wanted to ask what thickness and resin would be the correct choice to make sure it?s compatible with the original materials that Lotus used.

Thank you in advance for the replies, trying to make sure I?m being a good custodian.

[nmauduit]

repairing is one thing, reinforcing is an other...

woven clotch is likely to show a lot more than matt, you'll find that in any introduction to fiberglass work document you may gather before embarking in mixing chemicals. For a race car that is likely to have a short but fast life that may be perfectly acceptable - for a road car that one may eventually be willing to sell at some later point one may want to double check in what exactly this reinforcement would be better and not worse than the original design...

[tdskip]

Good morning/afternoon.

Here is the boot floor area in question - it is currently thin enough to see through!

[tdskip]

Just spent some time staring at that area with a torch ( any bonus points for using the correct UK term ?) and it looks like chopped strand.

Would that then be the better choice of material to reinforce that area?

[steve lyle]

If you're fanatical about originality, use chopped strand mat - that's what the factory used.

If you're more utilitarian, and want max strength, use woven cloth.

IMHO, hey, it's a boot floor. Strength counts for a lot more than looks there.

The factory used polyester resin, that would certainly do a fine job in your case. Epoxy resin is stronger, but is, again IMHO, overkill. The strength in the laminate is primarily from the mat/cloth, not the resin. What you need out of the resin is adhesion, and both will do the job, or not, depending on preparation and cleanliness.

[tdskip]

Thank you Steve.

Any real difference in how easy/hard the various materials are to work with?

This will be my first time but I figure if I can MIG weld this is doable.

[gjz30075]

I think the mat is easier to work with, as it, seems to me, do compound curves better than woven. Your area
is small so it may not matter there.

[David1953]

I would go with mat, that was original and is easiest. Cloth can be a pain on the slightest complex curve.
For strength the important thing is a good bond to the existing, get in there with a sanding disc on an angle grinder and remove all the surface muck to clean mat. Do not worry about going right through it in places, you are going to rebuild that. then 2 or 3 layers of 300gm mat will be stronger than original. (Which is good that was always a weak area)
David

[tdskip]

Thanks gentlemen, great advice and that is how I will proceed.

[vxah]

Of course grinding gfrp in the depth of the boot is going to be a nasty job dust wise! I strongly recommend a good set of goggles and a proper dust mask, not one of the crappy paper type things as they still let dust in around the edges and, if it?s a bit cold will cause your goggles to mist up!

[tdskip]

I am duly concerned about inhaling this stuff, I am, as you?ve suggested, I?m going to be very careful about protecting my lungs.

Thank you for the reminder sincerely

[512BB]

Whilst I had the engine out of my Sprint recently, I wanted to renew the rear seal on the gearbox at the same time. It soon became obvious that the hole in the tunnel had not been enlarged enough from new, as I was not able to remove the large nylon gearstick retaining thingy. So I set about the hole with a dremel, with a mate following the tool around with an industrial hoover. This worked a treat in preventing dust being flung around the interior of the car and from being inhaled. We did not even bother wearing masks, there was no dust. The hoover dealt with it all. You might want to do something similar.

Leslie

[tdskip]

Good tip Leslie, thank you.

On a related topic to this, should the boot floor be a matt or satin black finish once the repair is made?

Thanks and happy Friday to everyone.

[Mike Ostrov]

If you have any questions, I might have some answers as I have done decades of composite repaire on all types of Lotus cars. Just give a call: Cheers. Mike Ostrov, Richmond, CA (near Berkeley) 510-232-7764 or [email protected]

[h20hamelan]

I would simply lay some mat, after meticulous cleaning. Any oil or grease, it will just not bond.

Two techniques
1 is a roller, specifically for fibreglass. The reason you roll out the resin after you have wetted the cloth/mat. Is, that there is zero strength in resin (spend time removing wet resin or grinding after dry). The strength is in the wetted fibres. If the fibres are white, or yellow if your Kevlar. Then they will absorb atmosphere, and fail. If the resin kicks prior to absorption, you will need to start again. Work when it is cool and not in direct sun.

2 is a medium plastic sheet (or a bag, as your going to throw it out anyway) Most plastic can withstand the heat, but more importantly is the solvent (mekp). Biodegradable bags dissolve i bet. The plastic allows you to squeegee out the resin. So, if you prepreg the mat between two plastic surfaces, squeegee out the excess resin. And remove the resin onto paper or the neighbours lawn, you are able to remove the top layer of plastic. And adhere the mat/cloth matrix to desired area. This then allows the moving (use your gloved hands ((i always wear two pair of gloves with talcum powder because if the outer glove gets resin) of the fibres into the crack. Also desirable.

When working with cloth, cloth does not bond to cloth or anything other than mat. So always use a layer of mat first. You can finish with cloth.

I believe Lotus used chop strand gun, rather than mat. Of course they would have used mat in certain applications. This is why some areas are thick, and some are thin.