Lotus Elan

Woven may fiberrglass to apply on top of existing fiberglass

PostPost by: tdskip » Thu Sep 05, 2019 2:05 pm

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.
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 363
Joined: 13 Sep 2012
Location: SoCal

PostPost by: nmauduit » Thu Sep 05, 2019 2:20 pm

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...
S4SE 36/8198
User avatar
nmauduit
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1529
Joined: 02 Sep 2013
Location: France

PostPost by: tdskip » Thu Sep 05, 2019 2:39 pm

Good morning/afternoon.

Here is the boot floor area in question - it is currently thin enough to see through!
Attachments
2569301b-7f88-41c8-90cf-3edd1366fa72.jpeg and
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 363
Joined: 13 Sep 2012
Location: SoCal

PostPost by: tdskip » Thu Sep 05, 2019 3:26 pm

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?
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 363
Joined: 13 Sep 2012
Location: SoCal

PostPost by: steve lyle » Thu Sep 05, 2019 3:38 pm

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.
Steve Lyle
1972 Elan Sprint 0248k @ https://www.mgexp.com/registry/1972-Lot ... 48K.30245/
1972 MGB Roadster @ https://www.mgexp.com/registry/1972-MG- ... 842G.4498/
2007 BMW 335i Coupe
User avatar
steve lyle
Second Gear
Second Gear
 
Posts: 181
Joined: 15 Jun 2015
Location: Tulsa, OK USA

PostPost by: tdskip » Thu Sep 05, 2019 4:08 pm

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.
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 363
Joined: 13 Sep 2012
Location: SoCal

PostPost by: gjz30075 » Thu Sep 05, 2019 5:49 pm

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.
Greg Z
45/0243K Sprint
36/5727 pre airflow coupe
User avatar
gjz30075
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 3000
Joined: 12 Sep 2003
Location: Roswell, Georgia, USA

PostPost by: David1953 » Thu Sep 05, 2019 7:30 pm

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
David1953
First Gear
First Gear
 
Posts: 37
Joined: 10 Apr 2018
Location: Wiltshire, England

PostPost by: tdskip » Thu Sep 05, 2019 9:26 pm

Thanks gentlemen, great advice and that is how I will proceed.
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 363
Joined: 13 Sep 2012
Location: SoCal

PostPost by: vxah » Thu Sep 05, 2019 10:34 pm

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!
vxah
Third Gear
Third Gear
 
Posts: 326
Joined: 08 Nov 2012
Location: Cambridge UK

PostPost by: tdskip » Fri Sep 06, 2019 2:55 am

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
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 363
Joined: 13 Sep 2012
Location: SoCal

PostPost by: 512BB » Fri Sep 06, 2019 7:05 am

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
512BB
Fourth Gear
Fourth Gear
 
Posts: 893
Joined: 24 Jan 2008
Location: Cambridgeshire, UK

PostPost by: tdskip » Fri Sep 06, 2019 11:57 am

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.
SoCal
1969 Elan DHC
tdskip
Third Gear
Third Gear
 
Posts: 363
Joined: 13 Sep 2012
Location: SoCal

PostPost by: Mike Ostrov » Fri Sep 06, 2019 11:57 pm

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]
[email protected] or (5l0) 232-7764
Mike Ostrov
Second Gear
Second Gear
 
Posts: 123
Joined: 20 Sep 2003
Location: Richmond, CA

PostPost by: h20hamelan » Sat Sep 07, 2019 5:59 am

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.
W. Kootenays B.C. Canada
Born, and brought home from the hospital (no seat belt (wtf)) in a baby!
Find out where the limits are, and start from there
User avatar
h20hamelan
Fourth Gear
Fourth Gear
 
Posts: 532
Joined: 25 Sep 2010
Next

Total Online:

Users browsing this forum: mosler and 8 guests