[VAC] Re: offlist wheel bearings

[Jim Dunmyer <jdunmyer@xxxxxxxxxxx>]

Scott,
I'm going to copy this to the List, I think it's pertinent.
 
 My recent long-haul experience was during our Winter trip, and it
wasn't all that warm most of the time, usually in the 40s. In that
situation, our tires and hubs didn't get even slightly warm at 60 MPH.

Now, here's something I learned a couple of years ago, just before our
first trip with the A/S:

I had a bad drum, it went out of round when it got warm. Sooo... I
called around and found a local trailer builder who got me a drum
overnight. It was a 12", and he included a new grease seal, telling me
that "there are 2 different IDs on those seals, I gave you the one
that's most common". Well, after packing the bearings and installing the
seal, I found that it wouldn't slip onto the hub. Did some checking and
found that the seal ID was too small. Fortunately, I hadn't damaged the
"old" seal (just replaced as part of my initial tuneup on my 'new to me'
A/S) and was able to install it in the new drum. Your local RV place
might only carry the more-common seal.

I had gotten that "old" (new) seal at the local NAPA store, just took it
in with me. I did the same thing when I got the Avion, including getting
a spare seal and both inner and outer bearings as spares to carry along.

As far as trusting a local RV "mechanic", I won't, period. Packing
bearings is a low-end job and is likely going to be done by the kid who
decided to work there, instead of McDonald's. It's really an easy job to
do right, but it's also easy to screw it up. Perhaps you remember the
story on the VAC list a couple of years ago about the poor fella who had
the local RV place install the bearings backwards or inside out or
something. The wheels rattled around and ruined the bearings; he was
lucky that he didn't have REALLY serious problems.

As far as tightening the bearings, I described it pretty well in my
other message on the List: snug it up pretty good using a Channel-Lock
pliers. Don't get right up on it, just good and snug. Spin the wheel to
make sure that the bearings are seated and the nut is still snug. Then,
back it off and re-snug so you know exactly where all the slack is taken
up, but you haven't really tightened the nut. I'll go back and forth 2
or 3 times to be sure. Then, back it off to the very first hole that
lines up and insert the cotter pin.

Something I didn't mention is the need for CLEANLINESS, you want
everything to be absolutely CLEAN. If you have no parts washer, use a
brush (an old toothbrush will work) and gasoline. When I was a kid,
that's all we used for parts cleaning. You don't really need compressed
air, the gas will evaporate all by itself. After getting everything
clean, including all the way through the hub, pack the bearings, install
the inboard bearing, pack a bit of grease over the top of it, then tap
the seal into place. Use your finger to wipe a bit of grease around the
seal and on the surface of the spindle where the seal rides. This is
very important, if you neglect it, the seal will be gone in short order.

Seals do wear out, plus if they fit very tightly in the drum, you'll
destroy them while removing them. That's why I always figure on
replacing them when packing the bearings. As you've found, the bearings
will probably last "forever" if properly maintained.

Proper tire pressure is important, underinflation will cause excessive
heat and will destroy a tire very quickly. However, "proper" doesn't
mean "the pressure printed on the sidewall", that's the "maximum safe
pressure". Your owner's manual will tell you the correct pressure.
Lacking that, I'd start off at about 50 or 55 PSI (cold) on a
single-axle A/S and about 45 PSI on a double-axle unit. Monitor the tire
temperature during travel, bearing in mind that the "sunny side" will
get a lot warmer than the "shady side", and they'll all run warmer in
hot weather. Personally, I'm going to drop the pressure to 40 PSI on the
Avion and see how warm the tires run as compared to the 45 that I ran
during the trip. Harder tires will make the trailer ride a lot harder,
causing damage from the shocks and vibration. You also need to bear in
mind that the "cold" pressure will vary depending on ambient
temperature. I forget the exact ratio, it's something like 1 PSI per 10
degrees or somesuch. Always check the tires after the vehicle has been
sitting for several hours or has been driven less than one mile.

Dragging brakes, due to misadjustment of the brakes or controller will
cause heating, as will excessive use in hilly country. The latter is
pretty much unavoidable, that's what the brakes do, change the momentum
of the trailer into heat. Putting your left foot on the brake pedal,
just enough to cause the brake lights to come on, but not enough to
apply the tow vehicle's brakes, will cause heating of the trailer brakes
if you use the typical pendulum controller. The "proper" adjustment of
them puts a slight amount of current to the trailer brakes when the
brake lights first illuminate.

Hope it helps!!

                                       <<Jim>>