Coachbuilt Base Vehicle Construction Question.

[SyncroT3]

Just another camper-related question! I'm curious to know how the coachbuilt campers (Gipsy and Cheetah etc) are constructed underneath the coachbuilt body.

Considering that the original vehicle is of a monocoque construction, is there a severely cut-down panel van lower body underneath the coachbuilt floor, or did VW manufacture a special rear chassis or shallow monocoque specifically for coachbuilt conversions?

Thanks

[windysurfer]

http://www.karmann-coachbuilts.com/chas ... uction.htm
hth

cheers
Gaz

[SyncroT3]

Oh for God's sake! I've been looking everywhere for photographs and never managed to find that page. Thanks for the link.

[SyncroT3]

Hmmm, just been having a look at the photographs again. It would be interesting to find out what they did to the base chassis to strengthen it. Looking at the bottom photograph it looks as it there might be lengths of box section tacked on.

[DiscoDave]

can't see any box section tacked on?? they would buy the chassis cab and stick the gypsy or cheetah on top, same as they do with most modern coach builts!

[SyncroT3]

I was just guessing, based on that rather unclear last photograph. The dark dotted lines look as if they could be the gaps between short weld runs and I'm guessing that box sections would be good candidates for a strengthening members.

If they're starting with a cut-down (or never built up in the first place) bottom half of a monocoque body then they'll surely need to strengthen it or it would collapse when in use.

I was wondering about the feasibility of a DIY coachbuilt camper body, based on a panel van donor - and of course the obvious place to look for answers about the construction underneath is an existing production coachbuilt.

[DiscoDave]

as far as i'm aware there was no additional support other than the chassis. What is your understanding of monocoque? the t25 panel van was built from the chassis up from a number of different panels as opposed to one body shell. Have a look on the brickyard as there's loads of pictures of re builds and repairs.

as for the feasability of building a coach built you'd probably be better doing it from a pickup rather than a panel van as you would have a flat load bed, although a lot higher up than traditional coachbuilts you could utilise the locker space underneath for watertanks, gas, batteries and services so that you don't have to use up space in the main body of the motohorme!

again on the brick yard there is someone making up a demountable version on a crew cab. another one to google would be tischer.

definately doable!

[SyncroT3]

I mean monocoque as in being constructed as a single unit and getting its strength from the way it is constructed, as opposed to having a separate self-supporting chassis with an unstressed body on it.

Unless I'm seriously mistaken the T3/T25 is of a monocoque construction, and from looking at those Karmann base vehicle photographs it appears to show at least some of the standard T3 underbody and therefore only part of a monocoque, which is no longer deriving its strength from the rest of the VW body, because it's not there! It got me thinking as to how they have strengthened it as I originally thought that there might be a purpose-built chassis, which I would have expected to look completely different.

Yes, good suggestion with the pick-up. I was looking at some pick-ups that have the de-mountable camper bodies, which look quite handy.

I'm still quite intrigued about the underside of the Karmann coachbuilts and how they get the strength into the chassis with such a low floor level. The pick-ups achieve that strength by way of the load bed (taking the place of the equivalent van's roof and upper sides), which creates a shallow monocoque, the rest of which is formed by the lower sides and underside panelling.

Maybe the coachbuilt part of the Karmann bodies impart enough rigidity to compensate for the missing VW body, but having seen one with its aluminium panelling removed it didn't look as if it was designed to do that.

I'll have a look on the Brick Yard and see about that de-mountable, thanks.

[busbuddy]

the chassis is the strength, no matter whether its a panel van on top or pick-up, its just that vw in their over-engineered philosophy decided to weld the body to the chassis, the sills on a karmann are floating in mid air with none of the karmann body touching them
the floor is extended by karmann about 6 inches both sides but there are no extra chassis sections or outriggers on the vehicles, I've got a picture of a stripped one with just the floor and a few bits on my laptop I think, I'll have to dig it out

the karmann floor which is raised off the vw floor to allow for insulation and cables/pipes to run in the void has the interior units fitted to it and then the walls and roof are fitted last, as is the case with most caravans/motorhomes

[busbuddy]

at the edges of the new karmann floor they just fix some metal to give a flat edge to attach the walls








on mine you can see the sill section floating with the karmann floor (top left) a few inches above it


the chassis cab was used by most converters, not just karmann, and for those who like the numbers it was option M707

[SyncroT3]

Excellent! Thanks for the details. That answers everything.

I'm quite surprised that there is so much strength in the base chassis, but all credit to VW for that!

[busbuddy]

tischer offered mobile shop conversions as well as motorhomes

but this is reputed to be home made, cut down twin slider and fibreglass body



just shows what you can do

[SyncroT3]

Interesting idea. One of the reasons I was interested in the underside of these conversions is to see how they might be prone to rust - and also to see how difficult it might be to repair them. It looks as if it's much the same as conventional van, with regard to rusting and repairing.

[busbuddy]

I can only speak from karmann owning experience (not looked that hard at foster&day* or tischer) but they are heavily undersealed, and I mean over the top slapped on dont know if it was put on by karmann or by vw


I have only heard of one that has needed any chassis work, like I said the sill is just a floating tube so not the usual rust trap and same goes for the doors as the overhang protects them, the windscreen bottom and front panel can sometimes suffer the usual rust though





* on the subject of foster&day conversions, I believe the base vans for these were cut down over here by F&D and then the coachbuilt body constructed on top, not looked at one myself yet

[SyncroT3]

That's good news about their longevity underneath. I've read about and seen photographs of the leaks problems from the upper body, but it doesn't look too bad to pull them apart to fix them.