Why so pessimistic regarding coachwork rebuild ?

[keitholivier]

I have read through a several postings here and on the Yahoo site. The general consensus is that failure of the coachwork is considered the death blow for one of these units. It seems like there is no real alternative on the market for anyone wanting a small and economical RV and I also note that the later model Toyotas (91-93) have very steep price tags (have seen a few in the $14k range).

Given this background, is it simply considered too big a job to rebuild the coachwork on one of these rigs ? Time has moved on and we are no longer stuck with the materials available when these units were originally built. My investigations into the aluminum honeycomb panels show that a new shell is going to cost around $4000 in material + labor. If one were to use the same material on the interior "furniture and cabinetry", it may be feasible to make a substantial weight reduction, which will improve performance and fuel economy without requiring expensive engine/trans swaps.

Granted, if one were to sell the vehicle, one may not be able to recoup the cost, but I think many of us would prefer to keep running these units until the frames rust out....

I have also considered composite, but to fully utilize this material one would need a mold, a rather large one at that. The later model units that are fiberglass have a more streamlined profile that I'm sure is beneficial to performance and by not having a flat roof many of the joint issues and leakage are eliminated. Using "moldless" methods (as used in experimental aircraft) eliminates the mold, but adds an enormous job of finishing the exterior to an acceptable degree (filling and sanding) and kills the excellent weight potential inherent in composite design.

Am I crazy to be considering rebuilding the coachwork ? It looks to me like the alternative is to spend $20-30k on a 6mpg gas gazzling Class C RV. Or alternatively, $10-15k on a 3500 series diesel pickup cab & chassis + buildng a custom coach for that.

Regards

Keith

[86rader]

here's another alternative.

www.skoolie.com

This is a great site, composed of a bunch of crazy folks that have done school bus rv conversions. Many live in them. They make fantastic RVs and are built like a tank. If I was single, I'd get one and live in it in a heartbeat.

[Gulfstream Greg]

I have read through a several postings here and on the Yahoo site. The general consensus is that failure of the coachwork is considered the death blow for one of these units. It seems like there is no real alternative on the market for anyone wanting a small and economical RV and I also note that the later model Toyotas (91-93) have very steep price tags (have seen a few in the $14k range).

Given this background, is it simply considered too big a job to rebuild the coachwork on one of these rigs ? Time has moved on and we are no longer stuck with the materials available when these units were originally built. My investigations into the aluminum honeycomb panels show that a new shell is going to cost around $4000 in material + labor. If one were to use the same material on the interior "furniture and cabinetry", it may be feasible to make a substantial weight reduction, which will improve performance and fuel economy without requiring expensive engine/trans swaps.

Granted, if one were to sell the vehicle, one may not be able to recoup the cost, but I think many of us would prefer to keep running these units until the frames rust out....

I have also considered composite, but to fully utilize this material one would need a mold, a rather large one at that. The later model units that are fiberglass have a more streamlined profile that I'm sure is beneficial to performance and by not having a flat roof many of the joint issues and leakage are eliminated. Using "moldless" methods (as used in experimental aircraft) eliminates the mold, but adds an enormous job of finishing the exterior to an acceptable degree (filling and sanding) and kills the excellent weight potential inherent in composite design.

Am I crazy to be considering rebuilding the coachwork ? It looks to me like the alternative is to spend $20-30k on a 6mpg gas gazzling Class C RV. Or alternatively, $10-15k on a 3500 series diesel pickup cab & chassis + buildng a custom coach for that.

Regards

Keith

Re you actually going to rebuild one using the honeycomb. It sounds like a cool materiel's. How do you fasten it together and what about fastening such things as windows and cabinets to the shell etc?

[keitholivier]

Greg: Since I hope to have the rebuild be next summers project, I am presently considering my options. It seems that using material that will not rot would be a good idea. Avoiding the exterior/marine grade materials with their preservatives (toxic) would also be a good idea. Besides which they are not exactly cheap either and very heavy.

The aluminum is the least expensive "off the shelf" option. I would also be biased to using it for interior trimming because it is more fire resistant and has perfect surface finish (easy to apply veneers etc). I am also looking at 1" PVC foam (not eps or other "soft" foams) with 2 layers of unidirectional glass on both sides. I would have to build a LARGE workbench to do that (the laminated panel needs to be flat and straight since it is very stiff once set). For flat panels, the laminating is not terribly complicated. It is also easy for flat panels to use a shop vac to apply clamping pressure (with vacum bagging) to get a really strong bond. The benefit of the foam core is that insulation is integrated and the weight is further reduced. According to my calculations, the shell would be 580lb with the aluminum honeycomb and 380lb with 1" PVC foam and the 0/90 uni laminations.

Typically,when joining aluminum panels, the edges are joined by bonding a small angle to the interior 90 degree corner and a larger angle to the outside corner. This is done for the full length of the joint. The surface to be bonded is "de glazed" with a scotchbrite pad prior to bonding with an industrial adhesive. Sometimes, for redundancy, one can set rivets at a certain interval. If the adhesive has a long curing time, the rivets can help supply the required clamping pressure.

With composite panels, one typically would apply "peel ply" to the edges to be bonded, (the last layer in the laminate) which one peels off before bonding to leave a rough checked surface that needs no further prep before bonding. The corner joins most likely would be reinforced with an additional laminate outside and a foam gusset with additional laminations inside. This type of glass construction would really need siding, because one does not have a polished mold to impart a perfect finish to the outside.

For external openings, one would typically embed "hard points" into the laminate into which one can set screws etc. A moisture resistant wood or one of the synthetic woods used today for decking can be used for these areas. I haven't yet had a look at things like windows to work out those details.

One of the things that is a little irritating is that most of the roofs are flat. I don't like a flat roof because of the possibility of water pooling. Going to an arched roof does complicate the construction quite a bit, but I think it will increase the longevity of the camper quite a bit by eliminating one of the systematic reasons for leaks. All the vent holes can be built up a little so that NO water can get into the joint. This way, none of the gasketed surfaces has to be perfectly watertight (something that inevitably fails).

Maybe following a logical sequence would be stripping everything down to the truck frame, then redoing the floor including the various tanks. Then raise up the sides and finally bond on the roof. Once everything is sealed up and tight work on the inside (and now the workshop will be "free" again).

Regards

Keith