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Mon Mar 07, 2016 8:26 pm

Okay ...this may sound a bit odd: I was watching the British TV show "Wheeler Dealers" and they were fixing up a Caterham drift / track car for re-sale. This custom-built car was constructed with a body-on pan structure, and used floor pans that look very similar to VW floor pans. Thing is, the pans are held on by 'panel bond' (the Brits call it mastic) and pop-rivets ...really. So, that got me to thinking, has anyone used this method to replace VW floor pans? Eastwood panel bond (or 3M equiv.) is readily available, as are pop rivets. The built quarter-million dollar supercars using ONLY panel bond to hold them together ...so why not on the 'lowly Beetle'?? Sure would save a LOT of welding ...and, if done correctly, could be as strong, or stronger than welding ....
Comments??

Mon Mar 07, 2016 8:43 pm

I don't think I would feel save riding around In my car if the floors where glued in maybe I just chicken shit but I feel the same way about fiberglass floor pans

Mon Mar 07, 2016 8:44 pm

After removing the body, replacing the floor pans is probably the easiest panel replacement you will do to a rusty Beetle . . .and the welding is actually a pretty small portion of the job!

Mon Mar 07, 2016 8:59 pm

Aston-Martin, Ford GT, Mclaren ...just to name a few. Google: bonded panels on supercars.

Mon Mar 07, 2016 9:12 pm

full frame cars I would bet

Tue Mar 08, 2016 4:41 am

Digger89L wrote: Okay ...this may sound a bit odd: I was watching the British TV show "Wheeler Dealers" and they were fixing up a Caterham drift / track car for re-sale. This custom-built car was constructed with a body-on pan structure, and used floor pans that look very similar to VW floor pans. Thing is, the pans are held on by 'panel bond' (the Brits call it mastic) and pop-rivets ...really. So, that got me to thinking, has anyone used this method to replace VW floor pans? Eastwood panel bond (or 3M equiv.) is readily available, as are pop rivets. The built quarter-million dollar supercars using ONLY panel bond to hold them together ...so why not on the 'lowly Beetle'?? Sure would save a LOT of welding ...and, if done correctly, could be as strong, or stronger than welding ....
Comments??

These supercars have been designed to be built like this, with stresses and strength built in different ways. The beetle wasnt.....stick to welding and do the job properly

Tue Mar 08, 2016 6:18 am

Quote: So, that got me to thinking, has anyone used this method to replace VW floor pans?
Yes many have tried to repair rusted floor pans this way. While it may work initially, the repairs failed shortly afterward. I have had many beetles that had this repair done and they all leaked. Also have seen screws used to equal failure. The spot welded floor pans are an integral part of the structure of the car. Not repaired correctly it can affect the passenger compartment safety. Ie: a rear end impact can eject the driver into the back seat when the floor tears away from the surrounding structure.
Have a great day.

Tue Mar 08, 2016 7:13 am

I have seen a Caterham without it's body panels, they could be bought as kits. Their strength comes from a welded tubular chassis similar to a sand rail,you don't have anything like that. A beetle needs everything it has to hold together tunnel, floors,heater channels and body.

Tue Mar 08, 2016 7:32 am

Digger89L wrote: Okay ...this may sound a bit odd: I was watching the British TV show "Wheeler Dealers" and they were fixing up a Caterham drift / track car for re-sale. This custom-built car was constructed with a body-on pan structure, and used floor pans that look very similar to VW floor pans. Thing is, the pans are held on by 'panel bond' (the Brits call it mastic) and pop-rivets ...really. So, that got me to thinking, has anyone used this method to replace VW floor pans? Eastwood panel bond (or 3M equiv.) is readily available, as are pop rivets. The built quarter-million dollar supercars using ONLY panel bond to hold them together ...so why not on the 'lowly Beetle'?? Sure would save a LOT of welding ...and, if done correctly, could be as strong, or stronger than welding ....
Comments??

properly done rivets and adhesive can work fine, however i prefer original type construction just for originality. i went thru a lot of effort to replicate the weld patterns exactly on a floor replacement, just because. i dont see why rivets snd adhesive could not function good. just not my style for my ride.

Tue Mar 08, 2016 11:33 am

Digger89L wrote: Sure would save a LOT of welding ...and, if done correctly, could be as strong, or stronger than welding ....
Comments??

I am pointing out that the biggest portion of the job is all the necessary prep work . . . it MUST be done before welding OR super-glue/rivets!

I doubt that what you are suggesting is going to save you much of anything!

This is my pan . . . only maybe an hours welding time per side! Will rivets and glue look like this when you are done? NO!

Tue Mar 08, 2016 1:04 pm

That's a super looking job, 57blitz ...no argument there. And, of course, I wasn't suggesting that a person should try to pass off a panel-bonded floor pan job as a 'restoration' ...far from it. I'm just suggesting that it 'may' be a viable option for some of us take a shot at ....if not for the floor pans, perhaps for other panel replacement work. I'm thinking some of the nay-sayers may be thinking of examples were guys may have used silicon or seam-sealer and sheet metal screws, instead of the actual professional 2-part epoxy panel bonding products. Wow ...seem to have stirred up some strong emotions out there!!

Tue Mar 08, 2016 1:43 pm

Digger89L wrote: That's a super looking job, 57blitz ...no argument there. And, of course, I wasn't suggesting that a person should try to pass off a panel-bonded floor pan job as a 'restoration' ...far from it. I'm just suggesting that it 'may' be a viable option for some of us take a shot at ....if not for the floor pans, perhaps for other panel replacement work. I'm thinking some of the nay-sayers may be thinking of examples were guys may have used silicon or seam-sealer and sheet metal screws, instead of the actual professional 2-part epoxy panel bonding products. Wow ...seem to have stirred up some strong emotions out there!!

Ive been in the body trade for more than 30 years.I have used panel bond as well as various welding and brazing techniques. Panel bonding has its place but it isnt on structural floors. Here in the UK that would fail annual inspection. On non structural external panels or where heat distortion on roof and door patching is a risk the panel bond works well

Tue Mar 08, 2016 1:57 pm

Interesting. So, in the UK, how does this Caterham vehicle get away with being built using "mastic and pop-rivets"? Just curious. Here's the Wheeler Dealer episode on youtube: https://www.youtube.com/watch?v=V34SmthqYFo

Tue Mar 08, 2016 2:45 pm

the catheram is a lightweight construction. the floor pans and the outer skins collaborate with the square tube frame to the structural integrity of the car. the issue is, the panels are aluminium and the frame is steel. welding the two together is, if not completely impossible, surely beyond the capabilities of an amateur building one in a shed. the rivets keep them together and they are good enough because of the car's structure, similar to a small airplane's fuselage. mastic is just there for waterproofing.

Now what large automakers like audi use to bond steel and aluminium is structural adhesive. it can be immensely strong but it's all in the preparation and curing processes. Surfaces must be flawlessly clean (think clean rooms), the glue stored and applied at the correct temperature and the whole left to cure in an oven at a specific temperature for a given time. then the joint is as strong as a continuous weld.

if the question is: can you pop rivet the floor pans on a beetle like on a seven? the answer is, yes but it won't work. It will just be another bad repair

if the question is: can you use structural adhesive to bond a beetle's floor pans on the chassis? the answer is yes, theoretically it can be done and be as good as a weld but you have to do it the right way, with the right preparation and with the right equipment or it will be much worse than using pop rivets.

Tue Mar 08, 2016 3:16 pm

Thanks GArBa for the 'less than completely negative' reponse.

I'm a LOT older now, but I was one of those kids who stuck paper-clips in wall plug-ins, and jumped off the barn roof with an umbrella ...so, when someone tells me "it won't work ...it can't be done.." etc. etc. ...it just makes me more curious and more determined to check it out for myself.

If, as VW enthusiasts, we aren't willing to check out ALL the possibilities, maybe we should just give up and make Disneyworld models out of toothpicks.

Tue Mar 08, 2016 4:46 pm

Digger89L wrote: Interesting. So, in the UK, how does this Caterham vehicle get away with being built using "mastic and pop-rivets"? Just curious. Here's the Wheeler Dealer episode on youtube: https://www.youtube.com/watch?v=V34SmthqYFo

its because its designed that way, the floors are not structural in the same way as the Beetle and all load bearing structures are part of the space frame chassis. In the same way as some older cars had wooden floor boards even new ones like the Morgan. Basically for UK inspection, any corrosion that weakens the structure within 12" of a body mount, load bearing structure, suspension or steering mount or seat belt mountings will be a fail. Any repairs must be seam welded if patch panels are used, or welded in accordance with the original construction, ie spot welds if full factory replacement panels are used. So basically if you patch in a battery pan repair into the floor it has to be seam welded, the whole pan though can be spot or plug welded. Hope that makes sense

Appendix C in the following pages explains...
https://www.gov.uk/government/uploads/system/uploa...hicles.pdf