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Senior Charter Member
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710 Posts
Discussion Starter · #1 ·
This is OT but it has come up before when discussing aluminum panel attachment. Unfortunately, I seem to be search-challenged.

I have a Lotus Esprit. The frame is a bit of a noodle. It's a backbone-style chassis with a big hole in it for the shifter. In '95, about 20 cars after mine, Lotus started adding a stiffening plate around that hole, welding in nuts while assembling the chassis. I want to install the plate but welding nuts in is not possible. It has to be removable (it's OK if it's difficult) so I can't just weld the whole plate in. Welding would be a big pain in the interior anyway.

I've received some advice that a structural adhesive in conjunction with cherry-Q rivets might be a way to go. I had thought rivnuts might work but the feedback I'm getting is they won't be strong enough.

Any thoughts on a specific material? I need something strong in shear that I can still theoretically remove if necessary.

Here's what an Esprit frame looks like:
 

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Junior Charter Member
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791 Posts
I'm sure someone with aircraft engineering could be more specific but you might try starting with Aircraft Spruce http://www.aircraftspruce.com/
There may be some bonding agents that may come near what you're looking for, I think their catalog is free also, it's huge I know that. Jon
 

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Senior Charter Member
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Discussion Starter · #4 ·
Originally posted by Eric the Red:
shear is not the problem, it is torsional stifness is what I think you need to carry the load across the whole tunnel. You might be well off with a large doubler that is installed on all three sides.
The entire problem is one of torsional stiffness but I'm pretty sure a flat plate on one side of the tunnel will only see shear.

I agree a more elaborate solution would probably be better but it would involve either taking the entire body off the frame (no way) or cutting the fiberglass tunnel apart inside the car (rather not).
 

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FFCobra Master Craftsman
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8,694 Posts
There was a post very recently about an adhesive to bond aluminum to aluminum that is used by the aircraft industry. I believe the original topic of the post was on riveting footboxes. Apparently this adhesive is so strong that it is impossible to separate the aluminum once the pieces are bonded. Sorry I can't be of more help. Maybe try a Forum search on aluminum adhesive, adhesive, aircraft, or footbox.
 

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Charter Member
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If you have a lot of surface area to work with, look into double sided tape. I was give a partial roll of 6" wide 3M Scotch Brand Tape - Core Series 2-1300. The machinist told me that it will hold just about anything. They use it sometimes for prototypes instead of other bonding techniques.

Robert
 

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Premium Member
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1,902 Posts
I asked one of my engineers and this is what he wrote back:

I see him needing a saddle type doubler surrounding the cutout. He would still have to determine the size, thickness and shape of the doubler. If he can take a look at the strap Lotus added then the Engineering is done. He can fasten the doubler in place with Cherrymax rivets. (requires a special tool) http://www.peerlessaerospace.com/pub/Productimages/TAF_CHERRYMAX.pdf

This is the quickest and easiest way to install the doubler with fasteners that will do the job. These are used in Aerospace all the time.
 

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Senior Charter Member
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Discussion Starter · #9 ·
Thanks guys. Good stuff.

BTW, I ordered the Lotus piece already. That part is done - I just want to be comfortable with my attachment method.

[ December 22, 2004, 11:40 AM: Message edited by: MikeyRide ]
 
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