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Which resin and body filler to use

5117 Views 8 Replies 4 Participants Last post by  LotusManDan
My auto body guy's supplier has him unsure on which products to use. Which resin and body filler should he use to repair fiber glass on a lotus Elise?
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· Registered
297 Posts
I just recently fixed my front clam with the following parts order from:

Fiberglass Supplies For Aviation, Boat building, and Automotive

4 yards of 4oz cloth

4 yards of 3/4 oz matt
FGM.75x50 FIBERGLASS MATT 3/4 OUNCE $2.10 4 $8.40

1 jar (1 lb) of 1/8 milled fibers
FIL18 1/8 Milled Fibers $6.40 1 $6.40

1 gallon of resin
RHSG Premium Polyester Resin
60cc hardener
$30.98 1 $30.98

I have a *bunch* of everything left over. (ordered extra to have some to practice with and, because it is so cheap, just to ensure I had plenty) Yours doesn't look like it would take but a fraction of that.

The repair is lovely. I had no idea what I was doing prior, but a friend who has been working with fiberglass for years and years told me what to buy and how to go about it.

I took this:

to this:

For some of the fill-in work, I loaded up the resin with the milled fibers, added some chopped up matt and used it as a sort of fiberglass putty. Do that and sand it back a couple/few times and it gets close and then a light dusting of bondo to perfectly level it out prior to paint.

Good luck with the front clam repair you have there. It looks like the body line is going to make it a pita to get right. :(

· Registered
1,539 Posts
I would not use polyester resin products on Elise/Exige bodywork. The panels are polypropylene and should be repaired with a suitable resin that will bond properly.
Shrinkage can occur with any repair, some products exhibit more shrinkage then others. The important part is that the shop that does the work account for the fact that there is shrinkage and allow the material to stabilize before continuing on with topcoat/paint.

· Registered
297 Posts
Have you guys had and issues with shrinking, cracking or repairs being visible after paint?
My experience base is small, but, nope.

I would not use polyester resin products on Elise/Exige bodywork. The panels are polypropylene and should be repaired with a suitable resin that will bond properly.
Can you elaborate? Interested for next time I have to do this...

· Registered
35 Posts
From Section BQ of the Service Manual:

The composite body panels of the Elise are manufactured by one of several processes dependent on the requirements of the panel concerned:
- The front and rear clamshells, sill panels, windscreen frame, door outer panels, hard top roof outer panel and front crash structure are produced by Injection Compression System Resin Transfer Moulding (ICS-RTM), whereby a mix of polyester resin and glass fibres is injected into a heated, chrome steel surfaced, closed mould. After filling, the gap between the two halves of the mould is then reduced in order to compress the moulding and ensure complete material flow and consistent structural quality. Panel thickness is a nominal 2.2 mm. The absence of the 'gel coat' used with other processes results in much greater resistance to surface damage, and minimum surface preparation for before painting.
Page 4
Lotus Service Notes
Section BQ
- The front access panels, engine cover lid, door hinge panels, door and roof inners and rear window shroud are produced from Low Pressure Sheet Moulding Compound (LPSMC), whereby flat sheets of composite material are formed using heated, chrome steel surfaced moulds to produce panels with a nominal thickness of 2.5 mm.

- A third process is used for the cabin rear bulkhead, bootbox and radiator mounting panel where the panel surface is not primarily visible. These panels are produced by a Polyurethane Structural Reaction Injection Moulding (PU SRIM) process.
- Body panels unique to the Exige model, including front and rear clamshells, door hinge cover panels and tailgate panel, are 'hand lay' composite mouldings with a nominal thickness of 2.5 mm.
Whichever production process applies, conventional composite repair techniques can be used to rectify structural or surface damage whenever repairs can be determined as being more economic than panel replacement

So the way I see it, the clam shells themselves are polyester, the access panels appear to be somewhat different and could be polyurethane and some non visible parts are in fact polyurethane. But most repairs can be done with conventional polyester resins and fiberglass.
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