Reese Dual-Cam Hitch
While I was familiar with both the goal, and general
appearance of a weight distributing hitch, I had never actually laid hands upon
one until it came time to tow my Airstream home from the previous owner’s
house. But since I somewhat live for
mechanical challenges, hooking up the spring bars and figuring out how many
chain links to drop seemed rather straightforward, and I was on my way in short
order. The groaning & popping of the
Reese Dual Cam Anti-Sway hitch while on the road did initially catch me off
guard, but seeing as the whole works had sat unused & rusting outside unprotected
for the last 23 years I was not alarmed.
Since
my Overlander had been towed behind a ¾ ton Suburban similar to mine for the
last seven years of its previous camping life, I thought no adjustments would
be required for me to open up another chapter in the trailer’s life. If nothing else, I knew the previous owner
had had all his hitch work done at an Airstream
dealership. So other than sandblasting
& painting all the hitch’s components, no adjustments were made although I
continued to read what others had to say about the setup, and maintenance of
this particular hitch.
While
it might make sense to some for me to stop and write out a few equations with
corresponding free-body diagrams as an aid in understanding the words &
pictures below, I believe I will spare you.
Although I enjoyed my Statics and Kinematics
classes, that stuff appears to have low general appeal to most. Unless a lot of people email me begging for
[even more] dry detail, I will just stick to the high points of how I arrived
at having a properly set up hitch.
There is an Airstream guru in
Now,
up until that point, it had not occurred to me that there was more than one
flavor of spring bar. In response to
further questioning, the guru shared the secret to determining what size spring
bar one might have, “Measure the thickness of the bar at the trunnion. A 1 inch bar with cam follower has a 550
pound rating, 1-1/8” = 750, and 1-1/4” = 1000.”
After
reading this, I went out to the shop and determined that I had 1000 pound
spring bars. Coupled with my Suburban’s
¾ ton suspension, I too apparently qualified as over-hitched. The Dealer went on to share some other
disheartening (but accurate) observations about why this condition was not a
good idea, and wrapped up his statements with a remark that he was going to
write a magazine article on the topic.
Unfortunately, many months have elapsed, and the article has yet to be
written.
Although I continued camping unabated for the rest of
the season, the thought that I could be towing
smarter never left my mind. Reading
from additional sources, it became clear that Suburban’s suspension did not
need spring bars that stiff to distribute weight as its rear springs really
don’t settle that much under the unadjusted load. In fact, it needed the lightest ones made. I believe the reason the previous owner had
1000 pound bars in spite of having less than 500 pounds tongue weight is
because those particular bars would have been suitable for his original tow
vehicle – a soft-sprung 1966 Oldsmobile Delta.
When upgrading to a Suburban, the fact that he needed to switch to the
smallest spring bars made was either unknown or lost on the dealer who
installed his hitch.
The
immediate effect of over-rated bars is that there is no “give” at the
hitch. If, for example, the tow
vehicle’s rear wheels should want to drop into a pothole, they might not
actually drop all the way down because the over-rated bars are strong enough to
keep “axis of towing” level. Since the
Airstream’s frame is not as stiff as the Suburban’s, the Airstream will suffer.
Reese changed the spring bars’ style at some point. Doing away with the bolted-on cam follower,
they elected to make a bend in the steel.
Other than the bar being a bit longer than the old style, the new style
looks like it would do the job. But at
$300 a pair new, I turned to eBay for some used ones.
Odd
story there: It took very little effort
to find an item with “Reese 550 Weight Bars” in the title. The two, used spring bars pictured appeared
to be what I was looking for, and they were complete with cam followers. So I bid on, and won them for not much money.
Measuring
the bars after they arrived, I found them to be 750 pound bars. Alerting the
seller to this fact, I asked her how she wanted to proceed. Advising me of her current credentials in the
RV business, she tried to tell me the bars would work just fine. This statement was especially interesting
because I was never asked what kind of truck or travel trailer I had.
I
replied back that no, I would like to have the purchase price & shipping
refunded PLUS the cost of shipping the bars back to her. She said okay EXCEPT just keep the bars
and/or throw them away as she was not supplying return shipping fees. A satisfactory email from PayPal arrived soon
thereafter so I logged on to eBay and left the seller positive feedback.
Renewing my search for the
proper spring bars, a just-listed auction presented itself. While the spring bars pictured had no cam
followers, I knew that the ones on the 750 pound bars would work on them. To be on the safe side, I decided to email
the seller & ask for a measurement.
Guess who the seller was? Yep! -
The one who had just refunded my money.
After thinking about it a minute, I went ahead and posted my
question. Getting the answer I wanted to
read, I bid on & won this pair too… for a few bucks less than the last set.
And yes, this time the seller shipped me 550
pound bars.
An interesting thing about both the 750 & 550
pound bars is that both sets had a gentle bend in the loaded axis in each bar
that does not exist in my 1000 pound bars.
An unloaded bend in high-grade spring steel means the metal has yielded,
and is pretty much done for. But it
takes a tremendous force to accomplish that.
All four of these bars just looked like they had been left in a loaded
position for an extended period of time, and had acclimated to their present
condition. Since Reese Australia allowed
that spring bars can, over time, develop a gentle bend that does not hurt
anything, I decided that the bars are not made of a high-grade spring steel and
there was no reason to go in search of an unbent set.
A
properly loaded spring bar, i.e. a bar installed on the hitch & under a
weight distributing load, should deflect at least one to two inches according
the guru. The bend is measured by
placing a straightedge on top of the bar & measuring the distance between
it and the bar. The bar can apparently
be deflected up to five inches without suffering damage. The whole concept of a visible bend was new
to me as my 1000 pound bars were never anything but perfectly straight. I even adjusted it too tight once to see if
the bars would deflect, and the only thing that happened was the back of the
Suburban sat too high.
Around
the time all this eBay activity was being conducted, we headed out on a long
distance trip to the beach with the Airstream in tow. The Overlander seemed to suffer a lot of
vibration issues on the trip. Deciding
the bulk of the blame was probably attributable to the original axles I was
still using; new, complete axles were installed
while the “new” 550 pound spring bars were being painted a “Sixties Airstream”
color.
If
I had wanted to be a good scientist, the new spring bars would have been
installed and reported on before the new axles were installed; or
vice-versa. But with another long
distance trip scheduled for only a couple of weeks away, it was more important
to have the Airstream in the best possible towing condition. So the two were installed back-to-back.
In a properly set up Reese
Dual Cam hitch, both the tow vehicle & Airstream will ride level, and
the spring bars, except for their prescribed bend, will be parallel to the
trailer frame. The picture at right shows
the original drawbar with the new 550 pound spring bars. As you can see, the spring bars are far from
parallel to the trailer frame. Also
notice the adjustment chain near the left of the picture dangling free. While only slightly less than an inch of
deflection was required to level the Suburban, I ran out of links which would
safely hook. What the picture does not
show is the Airstream nose-diving somewhat due to the additional 1-1/4 inches
of height picked up after the new axles were installed.
Adjustments
obviously needed to be made, but they had to occur at the drawbar, and if you
look closely, you will notice my drawbar is welded-together. I assume custom making a drawbar used to be
the only way to get one. While eBay
sells the necessary piece-parts, it does not appear to be done much
anymore. Luckily, I had another drawbar
that could be used, and it was fully adjustable. Following Reese’s setup directions, I arrived
at the configuration shown in the picture at the top of this page.
Two
things uncovered during the set up I was previously unaware of are worth
mentioning. One of my original 1000
pound spring bars is about a ¼ inch longer than the other. Since the relative positions of the cam
saddles are fixed, this would make a difference in the anti-sway function if
the bars were interchanged. Upon further
inspection, one of the bars is either a very old Reese bar or another brand
altogether, although I have no idea of who it would be, because it has only one
hole in the end instead of two like my other five bars.
The
other thing noticed is that my Overlander’s A-frame is bent upward. After thinking about it, I believe this was a
direct result of running with too-stiff spring bars. Since, like I mentioned earlier, the
Airstream’s frame is not as stiff as the tow vehicle’s, the Airstream will be
the loser when bad road conditions are encountered. A bent A-frame is the manifestation of the
damage. Fortunately, I believe ‘bent’ is
all it is as much time was spent working on the Overlander’s front frame during
the refurbishment, and no cracks in either the steel or welds were found.
The results of going to lighter-weight spring bars
were remarkably noticeable, and could easily be differentiated from the new
axles’ contribution to an improved ride.
On our first trip, I had barely made it out of town before noticing that
the Suburban had a gentler feel overall, and my teeth were not jarred when
going over railroad tracks or potholes.
Allowing the Airstream to move independently of the Suburban while
negotiating adverse road conditions was definitely the right thing to do. On the interstate, the anti-sway capabilities
of the hitch showed improvement – I had apparently been riding around for some
time with the old bars swapped.
And
now that it is all said & done, I am the only one I know who has a complete
collection of Reese spring bars.