I've got a '77 31 footer with the sags. I'm thinking that instead of trying to patch up the old frame, to instead fabricate a brand new frame for it. I'd like to build the new one ahead of time, so that basically once I lift the shell, I can roll out the old and roll in the new.
Where could I get an accurate drawing of the original frame? Is that something I could get from Airstream? I'd like a top view and a side view, both with some dimensions.
I've got the service manual, and it shows a couple drawings, but nothing accurate enough to build from.
Jim, too many variances in frames of that vintage to be able to make an accurate frame from a drawing.
You have 3 tanks and the associated plumbing inside the frame rails, and also a bunch of other variables to consider.
Best to either repair or duplicate the old frame, in my opinion.
a completely new frame for a 35 year old trailer....wow that's a noble undertaking.....no doubt the factory has specs for the frame....but would you really want to trust them?
i mean that having seen how the trailers are constructed, there is ALOT of individual, hand work for fitting....and i imagine the early 70s models were no exception. perhaps even moreso.
inland andy might have wisdom to share on frame rebuilds...
if going to the extreme and building a complete frame i sure would want it to fit. not sure i'd trust even original drawing/specs.
do you really need a complete frame? seems if you're going the full "shell off" route, that the orginal could be inspected, derusted, reinforced, painted. maybe add new axles, a segments, underbelly, insulation, flooring and so on....while still having the benefits of any original factory frame mods....that may not show on the original frame spec drawings.
dave schuman (sp) who is the customer service/service dept big boss, has been restoring 2 70s units, i think, so he might be the best factory person for frame related issues.
If you want a roll-in replacement, I assume you are putting new axles under it.
If that's the case, you don't need to be super accurate, all you need is the general dimensions, like the distance between the frame rails, location of the wheel wells, and spacing of the crossmembers and outriggers. After all, its the floor that attaches to the shell, not the frame.
Tucker and Ultradog are building a frame right now for a '60 Tradewind. They are building the new frame right on top of the old one. It's hard to make a mistake if one is built right over the other.
I haven't been to his site in awhile, but if you go to http://www.tompatterson.com and check out the trailer section, he might have some specs there. I know he's got a bunch of TSB's (or whatever Airstream called them) and some other miscellaneous paperwork there. Good luck to in your endeavor.
Maybe in the distant future, I will replace the frame. If I do, I will fabricate a new one with taller 6" channels instead of the 4" rails it now has. This would create a greater GVWR and allow for bigger gray and black water tanks, put an end all tail sag and, and, and,.
It would be "overkill" but I like "overkill". Good luck with your project.
Ernie
'58 Traveler, 18ft.
Getting accurate shop drawings is extremely unlikely. But what is to be saved doing it the way you propose? You have to take the shell off anyway. Why not either modify, reinforce and rust proof your original once its out or use it for an ABSOLUTELY ACCURATE template to fabricate a new one?
I can't see where you would save even a minute building it in advance and why take a chance. It will take HOURS and HOURS to make up for any mistake.
Markdoane and Atzlanco have hit the nail upon the head exactly!
After reading on these forums a lot and doing some math, I've come to the conclusion that the original frame design was very marginal. I feel that patching it would only be a bandaid.
My plan is to use at the very least a 6" deep section, but more likely an 8" deep section for the frame. I'd also plan to put a metal perimeter around this for the channel to attach to. This will end the sag/separation problems forever. It might add a few pounds, but not much in the scheme of things. An eight inch deep frame section would give about seven times the strength of the 4" deep one. I could mount whatever I wanted to the back bumper as long as it didn't mess up the hitch weight and never need to worry. The bottom line is that the weak link of the trailer would be fixed better than new.
I would be using brand new axles so Markdoane's post was right-on. I've formed some opinions about some of Airstream's design featues. I think most of what they did was really great. But, I think some of what they did was not so great. I'd like to duplicate what I think are the great parts and change out what I think are the not so great parts.
I have a friend who is an OEM frame supplier to the RV industry. When I looked into buying the steel to do the mods to the original frame, it didn't cost a whole lot more to actually have a brand new one made (by my friend...as a favor type deal), but with a deeper section. And to Markdoanne's point, the only really crucial dimensions then are the wheel well locations, hitch location, main frame rail spacing, etc.
This would then make my trailer better than new. A lot of work, yes. But I don't think it would be as much as trying to fix up the old frame. As Atzlanco said, it would be overkill, but I like overkill. I could add a place to put a genset out front (say lengthen the tongue a foot) and maybe even a real bike carrier out back. I kind of like the "Frankenstream" idea. Strong is good.
Anyway, that's why I was looking for the print. I'm sure I will have to do some minor fitting/fabbing, but a good engineering drawing showing the plan view and elevation views should get me well within the ballpark.
I could go ahead and rip the interior out and just measure the original. And, I'll do that if I can't get good drawings. But I thought I'd throw the question out of where I might be able to get the drawings first. It's a rear bath '77 Excella 500 31 footer. I really like the coach. I want to redo it right the first time.
Since you have an OEM friend - perhaps you can discuss a better coating for the "NEW" frame. Electro-coating or Galvanizing would be the hot ticket. You most likely know that RV frames rust from the inside out. Both of the above suggestions can really prolong the life of the frame and are economical when you consider the advantages. Both are dip procedures that coat the inside and outside of the steel. The salt spray test results that I have seen (while working in RV Engineering for about 15 years) favor the galvanizing - but E-coat still yeilds excellent results and costs slightly less. The new axles can be done as well through Dexter/Al-Ko/Henschen or Axis!
I'll look into those coatings. I don't know if my friend could do those or not.
What do you think of the epoxy primers like they use for aircraft? That's what I was leaning toward. I've used them on some cars I've restored. It's really heavy stuff.
When I bought this Excella, I really hadn't planned on going to these lengths. But, I did get it pretty cheaply, enough so that I could put some money into it and still come out OK in the end. If I go to this effort, I'll probably keep it forever. I've always liked this model. My grandpa had one 20 years ago and I still like it the best of all the Airstreams he's had (he's had eight of them I believe). Basically, I'm considering that I got a shell with some appliances.
I'm thinking that I can get it redone (not counting my labor of course) and on the road as right as rain and still have less than $12K in it total. Last time I saw, the new 31's were in the $63K range, so that doesn't sound too bad to me.
My ideal wish list would include:
New 8" frame
New axles
new disk brakes
new E over H controller
Lengthened tongue
room for genset on tongue
bike rack on back bumper (capable of carrying KLR650...350lbs)
new floor
new upholstery
new fridge and toilet
new TV and central sterero
Anyway, if things pan out, I'll document the whole process and put it on here. At least people can see one crazy engineer's idea of a way to do it.
I am not familiar with the epoxy primers that you speak of – sorry.
What I can tell you though is that E-Coating is becoming more and more common on RV frames. This process is a series of dip tanks where the completed frame is electrically charged and dipped into a series of “baths” that provide a multi-step coating process that is tough. There seem to be two common forms, one is UV stable and one is not. I think that Volkswagen had something to do with progressing this technology to its current state.
The coating is thin but tough. The US Government specifies this on some, if not all, military Hummer frames. I have visited a local facility that E-Coats frequently and the process is awesome. Additionally – I have been involved in some testing of the product and recommend it highly. I happen to own 2 E-Coated axles and they are both several years old and look brand new. What might surprise you is that one is on my boat trailer. Hose it off after a trip to the lake and the scum disappears leaving the factory look every time – and I do fish a bit.
I am sure that you will be impressed as you look into both E-Coating and Galvanizing. One benefit of the galvanizing is that it is silver and I know how the Airstream crowd loves it’s silver.
My plan is to use at the very least a 6" deep section, but more likely an 8" deep section for the frame. I'd also plan to put a metal perimeter around this for the channel to attach to. This will end the sag/separation problems forever. It might add a few pounds, but not much in the scheme of things. An eight inch deep frame section would give about seven times the strength of the 4" deep one. I could mount whatever I wanted to the back bumper as long as it didn't mess up the hitch weight and never need to worry. The bottom line is that the weak link of the trailer would be fixed better than new.
Jim
You will also change the ride height of the trailer and the coupler height to the hitch. And the entry step height. This will create more wind resistance for a harder pull.
And a whole lot of effort to make it.
As a previous poster wrote, the frame does not hold up the shell. It holds up the floor. The floor holds up the shell. Remove the belly pan. Disconnect* the old frame from the floor. And as long as the wheel wells were cut correctly, the rest could be done later.
* Propane lines, heater duct work, refer venting, sink/shower/toilet drain lines go through the floor. And may be some electrical.
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Well, right now she's riding LOW-LOW. My axles are shot. Plus, I'm pulling it with a 4x4 pickup and I'm having to really use a lot of drop on the hitch. If I raised the whole thing up 6-7", that'd probably get it about where I wouldn't need the drop hitch anymore. Granted, it would be higher, but she looks like a low-rider right now. The new axles would raise it about 3" from where it is now, and if I go to the proposed bigger frame, that'd set it up another 4".
I've read that the design is supposed to be a semi monocoque like an airplane, and that is a really good way to save weight (my degree was Aerospace Engineering and I used to work for Boeing...and I really like a lot of the planes Glenn Curtis built {P-40s are simply beautiful}, which I understand Wally Byram worked for him for a period). But I have to admit I'm dubious as to whether that length needs to be gone to for a road going travel trailer for weight reduction. I ran the numbers, and the difference in weight between a 4" channel frame and an 8" channel frame for this trailer would be only about 160lbs, on a trailer that weighs about 5900lbs empty. The 8" frame would net you a frame that is over five times as stiff (I misquoted in my earlier post...a 10" frame gets you one that is 9.2 times stiffer...I must have been quoting a 9" section...I looked at a bunch of them...). If I made an 8" frame for it (or rather, have my friend make it for me in his factory) then the requirement for the aluminum shell to carry any flexural load at all is basically gone.
I really wish I'd read these forums more in depth before I bought this trailer. I might have held out for a post '84 model with the deeper frame. I have to admit that I'm a bit disappointed that they used such a flimsy little frame on a trailer that length. But, this one at least, is only beginning to show the signs of sag, and no separation. So I think I caught it early enough that the shell wasn't damaged. Besides, I just plain like this model.
I'm getting into more work with this project than I'd originally figured, but it's a worthy cause and kind of fun. Airstreams are cool. And I can take the whole family (four of us). I'll bring this ol' gal back to life and better than she was when she came off the line in February of 1977.
Thanks to everybody for all the guidance. I truly do appreciate it. It is absolutely amazing the information on these forums.
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