rear bumper question

[milesmason]

I have an '71 Overlander that I'm in the process of fixing up. I've read some members talk about the rear end seperating from the frame. Just for fun, I pulled up and down on my bumper and observed very slight movement (less than a quater of an inch) Is this normal, or could this be a problem?


Thanks,

Miles

[Sneakinup]

You may not have it yet. Check your plywood floor between the frame and the shell in the bathroom area, and if it is rotted away... it won't be long. It is a "must do" repair. Also, check in your back compartment to see that your blackwater tank supports are not rusted through. I am not sure a 71 is the same as a 72, but it can't be much different... he says with no confidence.

A link to my anxiety---> Separation Anxiety

[milesmason]

Are you talking about the floor that is the rear access area? I do observe areas of rot in this area? When will I know it is time for the repair, and how much do most airstream repair shops charge for it?

[Sneakinup]

Yes, the wood flooring that will be running through your bathroom and up to the back bumper area inside the back drop down door.

Just moving the trailer down the road will facilitate the start of RES. If you see the aluminum skin on the back of the trailer starting to bunch up a bit just over the frame rails that extend in to the bumper compartment, the process has already begun. That is the shell bouncing up and down without the wood between it.

Perhaps someone else that has had an outside party do the work can chime in. I did mine myself, and at my labor rate of a $1.50 an hour (plus food) it would have cost thousands! Kidding.

[bdlwet]

Yeah, the little known reaction to moisture in a AS tail is wet rot/dry rot that can make life a horrible surprise or just a dreaded re-build....I have placed on my calender a stretch of time this coming winter/spring to drill out the bottom rear and re-build from bed back. I am not looking forward to it, but I am not afraid to tackle it. What I cannot figure out afterward is.....black/grey water -one tank? //blind rivets, should I get a pneumatic riveter, is it worth the cost?//Do I re-plumb like oriiginal, or put in an additional gate valve to lessen the mess?? In the meantime I am headed out to Rocky Mountain National Park this weekend to listen for elk and do some fishing with my 10 year old. Tradewind is running dry right now because I haven't found all the points of leakage in tank, (run grey water out to ground when I can.)
I just keep figuring it will get better, Electric system came through pretty good and I still use old univolt set up. ( I took janets husbands advice and bought backup battery charger too). Sleeps well, needs some cosmetic help, but a great little trailer.

[tphan]

hi- am in the middle of this process, and can tell you it isn't exactly fun but agree that it is a MUST DO if you want your coach to be safe, reliable, and structurally sound. Much of my bath floor was rotted partially or entirely from previous neglect of leaky tub, totilet flange, and water heater. This rusted out the bolts that sandwich together the frame members, plywood floor, and the u-channel that holds the bottom of the wall "studs". (sorry-I'm a carpenter) Some of this rust can permeate down to the chassis, and the angle-steel holding up the black-water pan and tank. So out with everything in the bath, away with the old plumbing lines, heater duct, electric panel- and eventually, out with the bad plywood, chipping it all out of any channels it may be hiding in. Get rid of all old remaining elevator bolts, screws, anything in the way of the new sheet of nice clean plywood. This means also drilling out the rivets holding any lower interior skin on, and taking it off or bending it up out of the way to access the inside of the U-channel. Dropping the belly pan is highly advantageous too. Now is a good time to scrape off the big chunks of rust on the frame below and give it the por-15 treatment (very nasty stuff- wear gloves!!) I had a local mechanical shop make me up a new black-tank pan out of galvanized sheet metal (your old one may be ok), and new angles to hold it up. I also have ordered a gasket-kit from Thetford for the dump valve. I made a cardboard pattern for the new sheet of plywood, and gave both sides and the edges a coat of wood sealer. Temporarily get your black tank where you want it, measure, mark, and cut all holes in the plywood for the toilet flange, dump-valve, and vent pipe. Drop the tank out of the way, and slide the new sheet in from the outside, side. Put in new bolts through the u-channel , ply, and frame, and around the curve, and you're in business. Between the skunky black-tank and the dead rodents in their fiberglass nests, it is unpleasant at best. But I know now that the rear end of my overlander is at least as strong as when she was new, and ready for the road for lots of years. WORTH IT!! Next: to take a break from belly-pan dropping and gut out the kitchen. BDLWET- I live in estes, come to my garage sale! -tim

[milesmason]

Upon further investigation, I've determined my "71 Overlander is a victum of RES. I've scheduled an appointment for structural reinforcements. I'll keep you posted. The wood rot is isolated mainly to the right rear section between interior wall outer shell. The right side of bumper is lower than the left side by approx .5 to .75 inch. Can the plywood be patched and still reinforced to the c-chanel with a metal sheet? Advise please? I don't want to gut the bathroom.



Thanks,

Miles

[TomW]

Originally Posted by milesmason

... Can the plywood be patched and still reinforced to the c-chanel with a metal sheet? Advise please? I don't want to gut the bathroom.

In my opinion, No.

An Airstream's frame, at either of the two C-channels, is tied to the shell at the aft-most points by steel hardware. If RES occurs, it means that one or both of the bolts has rusted apart. Since this requires water intrusion, there is no reason to think that the plywood in the area is in good shape.

Put another way, you could patch the identified soft areas, but unless the steel fasteners in the previously mentioned area are replaced, you will still have RES.

You may want to check member Sneakinup's web page for more insight into a possible repair.

Tom

[milesmason]

According to Airstream Service Bulletin: New bolts can be added with a piece of sheet metal (see below) I'm not sure this will work if I only patch small area of wood rot? How can this be done and still maintain structural integrity?


AIRSTREAM SERVICE BULLETIN # 146

SHELL TO CHASSIS SEPERATION

Frame separation at the rear of the trailer is indicated by the chassis of the

trailer dropping away from the shell or body.

- To correct 1969 - 1970 - 1971 - 1972 - Models -

(1) Remove rub rail from rear of trailer.

(2) Cut 3" square hole directly above main frame, starting at bottom of rear sheet.

(See figure # 1B) Be sure not to cut floor channel.

(3) Remove rivets from sewer hose carrier pan bottom, (using a # 30 drill) and remove

pan from trailer.

(4) Place floor jacks under the main frame at the rear of the trailer and jack

frame up until it is back in corrected position.

(5) Jack frame up to correct position. From underside of trailer, drill. a 3/8"

hole through the main frame floor and floor channel into the area between

walls of the trailer.

(6) Use a 3/8" bolt, 3” long. with a large 3/8" flat washer on the head and place

from bottom side up through the hole.

(7) On the top side, place piece 1/4" thick steel plate 1 1/2" wide, 3” long, with

a 7/16" hole drilled in the center onto the 3/8" bolt which was pushed through

from bottom of frame (See figure # 1C).

(8) Steel plate should fit down in floor channel, place 3/8" lock washer nut on bolt

and tighten You may wish to use a ratchet wrench to tighten from bottom side.

(9) After bolt is tight, place a 3 1/2" wide X 3 1/4" high patch over the 3” X 3"

hole, cut at rear. Apply vulkem to patch before applying and using AD54BS pop

rivets, rivet over hole.

(10) Apply a bead of vulkem seal across rear of trailer between bottom edge of rear

panel and hose carrier top.

(11) Reinstall sewer hose pan bottom.

(12) Around rear wraps and across rear of trailer, drill through side sheets and floor

channel every 1 1/2" with a #20 drill and install AD54BS pop rivets.

(13) Reinstall rub rail.

(14) Install an oblong red reflector over patched hole at rear.

NOTE :

On 1972 models, the bolt may be installed, but not the 1/4" steel plate. Follow

above steps to allow installation of plate. It will not be necessary to remove

sewer hose carrier bottom.

[milesmason]

In my previous posts I referred to a piece of sheet metal. I actually meant a solid steel plate to bridge the two pieces of plywood as well as mount to the c-channel. Is this advisable?

Thanks,

Miles