Replacing floor pans

George, the reason I commented on this issue is that I deal with this on a daily basis. The companies I represent supply welders (Mig and resistance spot) to the automotive industry be it to the assembly plants as well as for collision repair. In recent years OEMs have found that adhesives can speed up assembly and repair and have used it in certain part of the vehicles they manufacture (Ford F150 has over 100" of bonding). Body shop technicians think that if bonding is good for a sail panel why not every where else and see this use of bonding agents as a way to cut down on repair time. This is a dangerous practice and I see this every day. You maybe right that on the E-Type floor pan this would not be an issue. But it gives me the chills when I hear people say to "Just bond it".

Bill thanks for the respect--I myself had a hard time with this issue years ago when I first tried it--I did it on my own car for a test and found that the process works well. There is no issue with fire and heat distortion from the welding--the undercoat and brake lines and on 1970 on E types the return lines etc need not come into play. The question posed was how big of a job is it and if you insist on welding (melting metal together) it becomes a much larger job. As far as the flex the floor pans are part of the stressed strructure of the E body but if properly applied the bond with modern adhesives is more than sufficient. The major stress is through the sills and trans tunnel and I would never suggest epoxy there. I was also only talking about the floor pans and not the floor surround. Jaguar themselves did not weld the pans to the floor structure in a 360 degree manner--one of the problems with rust. Not trying to get into a contest but I carefully worded my response--If he only has to replace the pans it matters little how it is fastened but matters greatly if the car is burned.

Bob,
With all respect to George Camp, automotive adhesives are not that easy to work with and are not recommended for use by itself in structural areas or where there is a lot of flex. Since we don't know the particular flex, or how this panel affects the structural rigidity of the E-Type, I would not recommend it. Just because an auto maker recommends adhesive in one part of the car, it does not mean that it can be used everywhere in the car. If that was the case there wouldn't be anymore welding being performed at the assembly plants. Bonding is meant to minimize rattles, noise and water intrusion. Where adhesive is used in conjuction with resistance spot welding (weld bonding), it is used for the same reasons as stated above as well as for additional rigidity. If the floor pan was originally spot welded in, I would recommend that you do the same if possible. If you do not have access to a spot welder that can reach the area to be welded, than you can Mig plug weld mimicking a spot weld. Pannels for older cars are all mild steel and you should not have any problems with heat affected zone. Once you weld the panel in place apply some seam sealer to prevent water intrusion. If you decide to install the floor pan using weld bonding, than you must use a spot welder as mig welding is not recommended in conjunction with body adhesives.

With the proper welding equiptment it is not a difficult job. Those pans were welded in with a resistance spot welder as the rest of the tub. Yes, a modern body adhesive could also be used. 3M and Valvoline both make excellent panel adhesives . The only catch is you have to beg, borrow buy or steal the special application gun to apply.
Make sure you pull back the carpets and inner sill covering to check for rust there as well.

Bob in the days when you needed to weld the new pans in it was a huge task--now with the new body adhesives it is not too bad. You must cut out the old pans and make a good clean mating surface--then epoxy in the new pans (if all it needs are pans!). Please note I am not speaking of normal glue but modern materials that the car companies use to assemble panels. Best of luck.