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Rocker Panel Question

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stevebn2bj7

Jedi Warrior
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Here is a question about installing the rockers. I have done it twice before using the traditional method of welding them to the sills as the factory did. This leads to the obvious future problems of rust should you not get rustproofing or a coating of some kind inside the rocker once it is installed.

The question is, has anyone used any method of bonding them to the car using epoxy or other similar product? I have used epoxy for many other applications and find that it is an excellent product with excellent bonding properties.
 
There are many structural adhesives available today that people never dreamed of 30 years ago. I work in aviation and believe me, these adhesives are being used in lieu of many traditional fasteners. I am sure there are some that would work well for the purpose you have asked about. I would not necessarily recommend that you use someting you buy at Home Depot, but seek out information on the web that will find you a product you might be able to purchase in small quantity, through an aviation supplier like Aviall. One thought might be using some of the newer sealants, rather than adhesives. Some of these are incredibly strong and chemical resistant. (check out www.actechaero.com ). I never considered it when I rebuilt my car, but now that I think about it might not be a bad idea. I would probably still want to weld them in a few spots where they tie into parts other than the outer sills. Hope this helps.
 
Both 3M and Lord/Fusor make specialized bonding products specifically for the automobile repair industry.

Specialized application tools (guns) are required, as the two (2) components are mixed as they're squeezed out.

Likely similar to the aircraft variety, but without FAA testing and certification, so probably less expensive to experiment with.

As for me, well, I've got these two (2) really swell welding machines, and I trust them explicitly.

You can start your research here:

https://solutions.3m.com/wps/portal/3M/en...BbeBR9SN82MTGgl

https://www.lord.com/Home/ProductsService...00/Default.aspx
 
The people at SEM came out with a lot of the panel adhesives for the bodyshops, and the testing on some cars showed a more ridged seam than factory welding could achieve. The bodies on most cars have a built in flex factor that may disappear when glue is used as apposed to spot welds. The lack of flex in certain areas may show up as cracks in others...... Just a thought.
 
jsfbond said:
The people at SEM came out with a lot of the panel adhesives for the bodyshops, and the testing on some cars showed a more ridged seam than factory welding could achieve. The bodies on most cars have a built in flex factor that may disappear when glue is used as apposed to spot welds. The lack of flex in certain areas may show up as cracks in others...... Just a thought.
Click to expand...
If the original poster does his homework (recommended) he'll read lots of stories on using the adhesives on cars nor originally built that way.

The story that sticks out most in my mind, was on how much stronger (not entirely sure that's the scientifically correct term, but...) the bonded panel was than when a replacement was welded; it was considered to be a detriment by not absorbing the energy of an impact, and therefore not recommended.

I do not remember the type of car (only that it was a rear quarter panel on much more modern car than our Healeys), nor the source, though likely one of the half-dozen or so trade publications I receive, so it should be taken with a grain of salt...
 
Part of the reason I suggested sealants instead of adhesives is that many of them remain flexible, but are ridcuously strong in shear and tension. Years ago, I was removing an hydraulic servo mount that had been installed with such a sealant, from the main gearbox deck of a helicopter. We couldn't get it to break loose so we attached a hoist to it (after removing all the mount bolts) and it would have lifted the whole helicopter (about 3000 lbs) so we backed off.
We were actually afraid of ripping the aluminum skin off the honeycomb panel the mount was attached to. That stuff would glue the crack of dawn.
 
Steve, I have used two part bonding adhesives many times, usually to attach patch panels. I have used 3m and Sems products. Both with success. But also to try to match the right product for the job. I do not have the product numbers handy right now, but one such 3M product is black in colour and maintains some flexibility even after curing. the product can also be feather edged alittle to help blend into a repaired section. But the product I like the most is a SEMs product and it is clear or a translucent amber. It sets very hard and if you ran a bead of this product and then a bead of weld and primered them you could not tell which one was weld and which one was adhesive. But so far all the products I have used advise not to use it in a structual strength area. The one from SEMs says it can be used to attach quarter panels.(rear fenders). But that if using it in that manner some welds should also be applied to ensure strength.
So, is the rocker attachment to the inner sill to be considered a structural strength area??? Maybe not, but could road jostelling around brake it loose??
After welding on my rocker panels, I bought a spray wand from Eastwood Company.
Used it to spray 2-part epoxy inside the rockers. Loaded it up till it dripped out everywhere.

Dave C.
 
Just another thought. Recently I was reading a brochure from Factory Five Racing about the specifications and material provided to build one of their cobra replicas. It seams the status of the chasis that they send has verical upright aluminum panels already installed for things like the toe boxes, rear bulkhead, lower fire wall , etc. All these aluminum panels are attached to their frame at the factory using epoxy and of all things, guess what? Rivits. So here they are reenforcing the epoxy's integraty with rivits.
When I bought my Healey, it had fibre glass fenders, rear trunk lid and of all things rocker panels. The rocker panels were attached to the inner sill with Rivits. Those rocker panels were surprisingly well attached and they looked very good from the outside and did not move or affect the seam gaps at all. But I don't think I would put my foot on them to apply any weight.
Rivits, just a thought.
 
Having built a Factory Five roadster a few years ago let me clarify the above post. There are now "basic kits" similar to mine, "complete kits" available now which I am not familiar with, plus another two or three body styles.

However, the basic roadster kits came/come with the alum panels temporarily attached with a few rivets just to hold the panels in place during shipping. The actual build of the kit required ALL the alum panels to come off and be reassembled with the sealer / adhesive / caulk of your choice. My car was built using GE silicon sealer.

The entire aluminum structure is NON-LOAD BEARING although it is held together with somewhere around one thousand rivets to itself and the tubular steel chassis.

Bob
 
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