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F.A.Q.'s
Wheels & Axles
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A: Split rims are used to describe
a style of wheel popular up until the early 1960's. The wheel consisted
of a 2 part ring on the
outside rim of the wheel. This was to allow easy replacement of the
tire and inner-tube. The only catch was that if the ring was not seated
correctly,
as the tire was inflated it could fly-off with explosive force, injuring
the person standing over the wheel. There are special cages to inflate
such wheels, but most shops just have a blanket policy of no split-rims.
The fix is to replace the rims with new solid steel conventional wheels.
Click on image to enlarge below image. You can see the spit rim
ring seam at the bottom of the wheel.
A: The standard for all single axle
Airstreams, except the Bambi, is a 15"x6",
zero offset with a 6 lug pattern on 5.5" spacing, rated at 2600#. A
properly rated Chevy truck wheel will meet this sizing, too. Don't
use underrated car wheels. The desired color for originality is a
black wheel.
A: Depends on your year trailer.
If it still had the split-rims wheels, the moon style hubcap
has spring-clip that slipped
inside the wheel center - these are no longer available and
are hard to find. If you have conventional wheels, the style up to 1971
was a
baby
moon style of hubcap. 15" wheels use a 10 1/4" ID and 14"
wheels use a 9 1/8" ID style. You can find them at any utility trailer
dealer or on eBay. The later style
hubcaps show up on eBay all the time.
A: Best bet is to get the trailer
to a dealer, provide them with as much information as you
can, and let them match, mount and
then install the tires. That way if there is an issue, they
are responsible for making the tire fit. Generally, the tire used on
the older trailers
were 7.00 x 15 LT (Light Truck) 8 ply bias ply tires of the era. Some
exceptions are the small 16 to 18 foot trailers, which used
a 6.70 x 15 LT tire,
as did some early tandem axle trailers.
ST type (special trailer) tires weren't available back then - the same
with radial tires. The ST has a stiffer sidewall than a passenger car
radial and has UV inhibitors in it - not really an issue if you use the
trailer at least 6 times a year to release the friction activated inhibitors,
and protect the tires from the sun while in storage. Radials were used,
usually the 225SR15 and 205SR15 sizes once they came out in the '70's.
You can retrofit
radials in some cases where clearance is not an issue, but it is recommended
to use the ST type, as the average radial sidewall flexes too much when
used on a trailer.
A: Until 1962, axles used on airstreams
varied greatly, from the cast cross member leaf-spring “Model A” type axles
of the ‘40’s and early ‘50’s, to the heavy duty
leaf-spring tubular type specialized trailer axles of the mid and late
‘50’s, usually by Hadco. In 1961 Airstream introduced their
own unique suspension assemblies which were called Dura-Torque.
Later, the suspension manufacturing unit was sold along with the
design and
rights.
It became Henschen Mfg, and is located in an old building several
blocks from Airstream in Jackson Center.
This new design was a square tube (axle) with a smaller square
steel shank with two 90 degree angles (suspension arm) inserted
into the larger
tube.
Cushion and support is provided by four approximately 12" long round
rubber rods of approximately 1/2" diameter inserted between
the flat side of the suspension arm and the corners of the
square axle tube.
The
rods are temporarily placed in a super cooling freezer beside
the work station, using liquid nitrogen to shrink the rubber
rods.
The rods are
quickly removed from the freezer, placed by a gloved hand against
the suspension arm, and the arm with rods are shoved into the
axle tube.
The
weight ratings of the Henschen Dura-Torque axles are determined
by the diameter and hardness of the rubber rods. To this durable
but smooth
riding
system, conventional shock absorbers are then added for additional
ride dampening.
A: Yes. The rubber rods
eventually will take a set from their own weight and just sitting. High-mileage
trailers, or those left out in the elements can suffer from deterioration
of the rubber rods will wear out even faster. There isn't
any hard and fast rules. There are early ‘60’s trailers
with plenty of spring left, and 1970’s trailers that
are shot. When the 'spring' goes from these axles, going over
bumps and pot-holes can
result in the
torsion arm coming up and hitting the stop there to prevent
the wheel from contacting the wheel-well or the rubber rods
from
being displaced.
This jolt and not only shake up your packing, but can weaken
the frame and trailer structure and skin joints.
A: This is going to vary
depending on who you talk to. A good rule of thumb is that the
trailing
torsion arm shouldn’t
be angled upwards past horizontal when the trailer is fully
loaded. A good second opinion verification is to put masking
tape or sealant
on
the up stop. If the stop gets hit during routine travel, you
will be able to tell, and your axle is a candidate for replacement.
A: If you have a pre-1967
axle with non-tapered inner bearings, I would recommend replacing the
axle. More
info in this restoration topic section. Also, any axle
older than ~1978 is going to have the rubber rods pretty much
worn out and should be evaluated for replacing anyway.
A: Henschen no longer repairs the
older Dura-Torque axles, replacement is the only solution (Airstream
Dealer). For experienced restorers, you can spec out a new torsion axle
from Dexter
or Axis Products,
but you cannot order, say “an axle
for a 1968 Safari”. More
info in this restoration topic section.
A: Here you have many more choices.
The axle components can be replaced or repaired using conventional auto/trailer
parts, such as leaf springs, brake drums and brake parts, shocks, hubs,
bearings and wheels. If an axle is too far gone (rusted or broke) a
new Dexter or Hadco axle can be attached, or a new torsion axle can
be retrofitted. See this Restoration
Resource section for alternatives and the replacement
we did on our Flying Cloud.
A: These wheels were actually low
cost 4-lug Ford Mustang/Falcon wheels of the era. Replacements are usually
made using Dexter wheels and
moon hub caps just like the bigger trailers. As an option, you can usually
go up to 14” wheels and use P185/75R14 tires and have just enough
wheel-well clearance.
A: Replace the axle with one from
Dexter. The old axles have a 10" brake drum with 4 bolts. That pattern is no longer available.
Use the 10" drum with 5 bolts and get the new Dexter matching wheels
and Moon hubcaps. The new axle actually fits the frame better than the
old one. Installation only requires that new holes be drilled in the
frame
rail. The new install is actually cleaner than the old one.
A: "Pipe frame" Airstream
trailers were built from 1947 to 1950, and usually have both or one end
rounded with a single
wide oval window on that rounded end. Travel trailers back then were
built very light with few appliances and furnishings, so their frame
could be
relatively lightweight. The pipe frame was strengthened slightly in 1949
by adding another 3' section of pipe inside the front most 3 feet near
the hitch. But the frame soon became insufficient for the added weight
of larger trailers with more stuff installed and loaded inside.
The "pipe frame" was also called a "Centerpole" by
Airstream. The frame is like a fish skeleton: a longitudinal center rib
with outriggers to both sides. The outriggers are not all that strong
and cannot take too much weight being placed on them, other than above
the wheels, which has some additional framing to attach the axle. You
will typically see the appliances mounted in the center of trailers,
usually
above or just forward of the wheels, as that is best for weight distribution.
If the small brackets that secure them to the centerpole become detached,
you can (it has been done!) pull the centerpole right out the front of
the trailer.
The first ladder frame Airstream with a "A" frame up front appeared
in mid 1949. It was the 24' "Unlimited", soon to be renamed
the "Cruiser." By late 1950, all new Airstream trailers were
built using the ladder frame.
The pipe frames are still OK if not rusted inside the tube, the outriggers
have not become detached, if the trailer is kept light and not overloaded,
and if you avoid using weight equalizing bars. To see what a Pipe-Frame
looks like, check this '48
Liner page.
A: More than likely the axle was
made by Hadco
Engineering, a supplier to Airstream in the 1950's. You can either
maintain the brakes as hydraulic, which can be done with the use of
a hydraulic actuator mounted somewhere on the trailer, or you can replace
the axle. Both hydraulic and electrical components
are
still available
from Hadco. The
old Stromberg slave cylinder, parts and fittings are not made anymore,
though. Hydraulic actuators are available from Carlisle.
A: It is a chassis to shell separation on longer Airstreams,
usually Ambassadors and Sovereigns prior to 1982. It was caused by the
installation of gray (1973+) and black water tanks, along with the battery
and weight of the bathroom fixtures in the back end of these long trailers.
This combined weight, especially when the trailer was towed with the tanks
left full, caused the shell to separate from the frame in the back from
all the dynamic flexing, and ultimately bent the frame just aft of the
wheel wells.
The fix is to install Airstream bulletin #29. It consists of two perforated
plates, notched and pre-drilled to fit over the axles on both sides.
You
need to go through an Airstream dealer or authorized repair service
to have the work done. If the shell is detached from the frame or the
frame
is bent, that will have to be corrected also. The bulletin is in the VAC
Online Library if you wish to see if the mod has been done to your
trailer. Ways to recognize the condition is to stand on the bumper
and see if the frame moves and the shell doesn't. Other sure signs
are
loose interior
partitions and cabinets, or a 45 deg bulge in the side of the skin
just aft of the wheels.
It can occur on other models of trailers, but is usually caused by the
floor rotting in the rear of the trailer, and the C Channel that attached
the upper and belly skins to the wood floor coming loose from the floor.
A: Use a loaded backing plate, replacing
the entire brake assy at each wheel. It consists of the magnet, brake
shoes, springs, etc.
mounted on the "backing plate". There are several advantages
to loaded backing plates. Often the cost of the individual components
meets or exceed the cost of the complete unit. The process for replacement
is: undo the 5 (or 4) bolts and two wires. Reinstall, connect wires,
which
do not need to be connected in any certain way, reinstall hub/drum and
adjust. You're done. You will now have all new springs, brake shoes and
a current style magnet.
It also makes sense to repack the wheel bearings at the same time. A tip
for removing the grease seal. Pry off the dust cap, cut and remove the
cotter pin, remove the castle nut and washer, remove the outer bearing,
replace the washer and nut, pull the hub/drum toward you allowing the
washer to bear against the inner bearing, pulling with a sharp movement
nearly always dislodges the inner bearing and seal with no damage to the
bearing. Pack the bearings per this Champion
article.
Another area that you need to be aware of are the different grease seals
available. Many RV outlets have a simple single lip seal that will fit
in Airstream axles. Airstream does not use nor do they recommend the use
of single lip seals. Their recommendation is to use double lip seals only.
They may be a little harder to find is a small price to pay for the added
security.
The original P/N was a National 291148 felt seal and 292100 in the ‘60s
Henschen axle. The 292100’s are available from OasisRV.
The TCM 21325TB is a good substitute for the 291148. It is a double lip
seal, also.
A: Except for later model tandem
axles, conventional heavy-duty auto and light truck shocks are correct.
Take a shock to an
auto parts store so they can match the ends, stroke & length.
With the big body style change in 1969, Airstream changed to a horizontal
mounted (trailing arm) shock absorber configuration. They can also be
found on some later '60's dual axles.
What makes the new shock special is: "The shock used in the horizontal
mount is a specialty shock built for Airstream by Gabriel. The difference
is a bladder is used to hold the oil on the piston. The typical design
of shocks would allow the oil to pool away from the piston leading to
premature failure." This shock is the one you need to get from Airstream
dealers. While a conventional shock can be made to fit, you can see it
may eventually fail.
A: Either in the tow vehicle, under
the bed if you have an external access compartment, or by one of these
ideas:
http://www.airmarktools.net/services/airstream-parts/index.html
http://vintageairstream.com/archives1/59WorldTraveler/59WorldTraveler.html (This was original from Airstream)
http://vintageairstream.com/myrtle_tour_details.html This
last one was made from C channel used to hang ceilings in commercial
buildings, and
was bought in 1965 (commercial made) from the Airstream dealer.
A:Depends. Modern trailers usually
always have 2 for a couple of reasons. Manufactures can
use 2 lower cost, lighter weight axles, wheels & tires than
the more expensive heavy duty single axles. 2 axles are more
stable and the trailer tracks straighter. A tire blowout can
result in a easier to manage condition, you can even remove
a blown tire and proceed slowly on the remaining tire to a service
station. The downside? You
have 2 of everything. Twice
the cost of maintenance - tires need to be replaced
every 7-8 years, bearings repacked every 3 years. When fixing
up an older trailer you may have to replace the axles - again twice
the cost. Single axle trailers are more maneuverable and
have more interior storage (less wheelwell size). As you can see,
there is no clear answer.
