Rear End Separation
Ah, yes, REAR END SEPARATION. Once I got this old Airstream Tradewind trailer in the yard I started looking around. Hooo boy, this ain't gonna be fun. This poor puppy has a case of rear end separation and has it BAD.
Quotes from couple of posts post on RES at Airstream Forums
Andy at Inland RV has a long post about repairing RES at:
which includes the following commentary:
The Airstream bulletin, is out of date by almost 40 years.
The steel frame kit, is designed to beef up the frame, for the axles, "ONLY".
It "DOES NOT" and will not correct or prevent rear end separation.
It does not add any additional carrying capacity for the chassis.
It does not correct bad axles.
It does not eliminate the need for shocks.
It does not eliminate the need for running gear balance.
It does not make the trailer ride any better.
But, "it does", add strength to the frame so that the frame will not buckle or bend AT THE AXLE MOUNTING PLATE, ONLY. NOTHING MORE.
Elephant ears, is a sheet metal patch at the inside lower corners of the rear quarter panels, at the rear plate junction.
That patch covers up the "INCORRECT" way to repair rear end separation.
Most of the time, when rear end separation has taken place, the rear floor channel has cracked in half, in more than two places.
The proper repair is easy.
- Remove the rear quarter panels.
- Remove most of the rivets from the rear plate, so that you can curl the rear plate upward, out of the way.
- Observe the damage to the floor channel. Remove the channel, have it welded back together.
- Add an additional gusset the outside of the frame, under the floor, for additional bolts.
- Jack up the frame to it's correct position.
- Assuming the floor is ok, and that the rear "hold down plate" is ok, reinstall the floor channel, with new 1/4" grade 5 or better hardware. Drill additional mounting holes through the gussets that were added. Use washers under the bolt heads and at the bottom of the plywood floor. Add steel plates above the floor channel at the frame and gusset areas, that will spread out the stresses.
- Add additional rivets to hold the "INSIDE" quarter panels with greater strength.
- Reinstall the quarter panels and rear plate, with olympic rivets at the sides and top. Use plenty of Vulkem sealer between the seams.
- Use 3/16" pop rivets at the bottom of the quarter panels.
- Reinstall the rub rail molding.
The above is a professional way to correct the rear end separation problem, and, at the same time, gives the rear shell to frame attachment considerable additional strength. Done properly, no evidence of repairs can be seen, other than the olympic rivets.
Keep the bikes or whatever, "OFF" the bumper.
The elephant ears is a dead give away of "short changed" repairs.
The axle beef up kit, won't do a thing for the above repairs.
and another post at:
that includes the following:
The cracked frame and axle mounting plate are a GROSS abuse of the coach, by ignoring the fact that you "MUST" balance the running gear correctly. To this day, people say "what a waste of money". Oh well, they will pay dearly later on.
Lets not blame Airstream for the frame damage caused to the trailer, because of willfull disregard for basic running gear PM.
That problem is caused by and will continue to be caused by lack of proper running gear balance, PERIOD.
Adding frame beef up plates, simply allows you to continue that disregard.
The elephant ear patch, is a "mickey mouse" method of repairing rear end separation. It's done by assuming the rear floor channel is OK, which it rarely is, and not inspecting anything. Usually the rear steel hold down plate is very rusted and must be replaced as well. But you cannot see it unless you remove the metal.
The correct way to repair rear end separation, has been and will always be to remove the two rear quarter panels and lift up the rear plate. It's amazing how many times you will find the rear floor channel, which is an aluminum extrusion, broken in several pieces. It must be removed and rewelded. Then you can reinstall the floor channel. However, you add a steel plate on top of the floor channel at the frame and add additional bolts. You "also" add a steel angle underneath the banana wrap thats welded to the outside of the frame. You install additional bolts through it and the steel plate that is on top of the floor channel. You may also have to replace the rear hold down plate, that most owners don't know it exists.
You have now substantially increased the hold down ability of the shell to the frame. This repair cannot be done using the elephant ear approach, which again, will get you down the road for a short time, and relieve your pocketbook, only to happen again, usually very shortly.
There are always at least two ways to repair anything. The right way and the "good enough" way, which is far removed from correct.
Additionally, just because the rear end separation repairs may have been done as outlined, does not avoid the need for "correct running gear balance."
Another post about rear end separation
Lyall on the old Airstreamer forum says:
I had a sagging rear in my 69 Airstream. I cut 3/4 in plywood to fit behind the toilet and under the back and under the cabinet. I then dropped the bottom pan and cut pieces of 3/4 inch plywood to fit from the skin under the bottom out to the waste tank. I put long wood screws through the floor and both pieces of plywood. I then took three inch stainless steel metal screws and put screws about every three inches through the wood, the floor and into the aluminum frame. I put a washer on each of the screws and slowly pulled the wood up against the frame. I did not cut any holes into the skin or into the inside. I have driven the trailer over many miles and over logging roads for over eight years with no problem. All Airsreams need a bead of sealer between the back bumper and aluminum sheet and the trailer skin at the back. Water off of the back tends to run under the trailer. Also I suspect that years ago, a battery many have been allowed to freeze and acid ate out the floor. This seems like the least damaging way to repair a sagging rear.
On using sign board as subfloor
There is a product called LusterBoard which is a sign board with a plywood core sandwiched between two sheets of aluminum.
I am thinking about using it for the floor in my 1969 Tradewind . It is sometimes used with success in the floors of boats.
This stuff in 5/8" is reputedly stiffer than 3/4 ply and the aluminum skin blocks the moisture from both sides. A bedding tape in the joints and around the outside edges should result in a waterproof floor. I'll have to decide if a completely waterproof floor is actually a good idea.
A product like 3M Rubber Mastic Tape. #2228 (2" wide and .065" thick) might offer good dissimilar metals corrosion protection at connection points and a moisture seal around fasteners.
Airstream Service Bulletin #146
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)
(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.
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.
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