Panzer Pulling Tips
from Bill Janitor
July 23, 1998
Panzers are unique, moody, and incredibly powerful machines for their
size. I used to pull with a lot of success in the stock 700# and 900# classes
in Southwestern Pennsylvania. My friends Randy and Tom also pulled with
me, but for some reason my tractor, "Bad Company" or "B.C.", always seemed
to run better than theirs (especially when Randy was on it!) All 3 were
T65's and I have yet to understand what the differences between them are/were.
I guess that's what got me into Mechanical Engineering...
Between the 3 of us, we have a dozen or so of these tractors being used
for various tasks, so we have some idea of what makes them run. I quit
pulling about 9 years ago, and my old competitors have since discovered
some of my tricks and either used them or made them illegal…
Here is a list of suggestions in no particular order. Remember
that some of this stuff is against the rules, so don't blame me if you
get caught...
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Don't use the rulebook's allowable hitch height to determine your tractor's
optimum hitch height. B.C. pulled best with a 8" hitch, even though the
rules allowed 9" or sometimes 13". (I used the holes in the stock hitch)
The rules limited the front weights to be no more than 12" in front of
the front axle, which heavily influenced how much weight was transferred
to the rear wheels when the front end began to lift. A higher hitch created
more of a moment arm (twisting force) around the rear axle, resulting in
more weight being required at the front to balance the tractor (keep the
front end just touching the ground during the pull).
Think of this as trying to turn a nut with a ratchet. The further
away from the nut you hold your hand on the wrench, the easier it is to
turn the nut. You create a higher 'moment' around the rear axle by raising
the hitch relative to the axle center line height, and by moving the weights
in front further away from the rear axle. This moment is a force that governs
how a tractor behaves as it travels down the track. With a limited total
weight and tractor length, you need to experiment to find the right hitch
height for your tractor.
-
Move your hitch point as far towards the center of the rear axle as possible.
This trick was given to me by someone in the Tri-County Mini Pullers while
I was at one of my first pulls in Sharon, Pa. many years ago. It will put
just as much downward force on your rear end without wanting to lift up
on your front end, given the same hitch height. This results in you being
able to put less weight out front and more weight over the rear axle where
it belongs.
-
BALANCE and TIMING: You don't want the tractor to dig in all at once and
lift the front end at the end of the track. Both timing AND balance are
important to a successful pull. If you're carrying the wheels off the line,
you're too light on front. The tractor should show it's best balance (front
just light enough to leave the ground) at the END of the pull. Too much
weight transfer can also cause you to fall into soft ruts dug by other
tractors. As you go up the track, your tractor is balanced well if it 1)
has the front wheels lightly touching the ground at half track, and 2)
lifts the front wheels just off the ground (about 2") about 2 feet before
it finally stops. It MUST NOT lift the front end high enough to touch the
wheelie bars at ANY TIME! Doing so is equivalent to dropping an anchor
or hitting the rear brakes.
-
If you use barbell weights on the front of the tractor and orient them
horizontally, put the smallest one on the bottom. This will concentrate
the static force exerted on the end of the rod and effectively give you
"more weight further out". A large weight has more surface area and distributes
some of the weight rearward on your mount. If you have access to the internet
and look at the pictures of my tractor, Bad Company, you'll notice that
the weights in picture 1 are BACKWARDS of how I'm describing them. Hidden
under the bottom weight is a small platform that concentrated the load
on the bar (one of my secrets).
-
Weight above the rear wheels should be placed just forward of the center
of the rear axle. Think of it this way, if you drop a straight line from
the center of the weight to the ground, it should touch about an inch in
front of the axle. As the front end rises, the point that touches the ground
moves back toward the center of the axle. If it goes behind the rear axle,
you loose traction effectiveness.
-
Make certain that your brakes don't drag in the drums. Back them out as
much as possible, or squirt some WD40 on them. Friction robs horsepower.
-
We couldn't lock the rear end because of the rules, so I pumped the rear
end full of regular grease. It provided enough friction to lock the spiders,
but allowed the independent brakes to work. DON'T do this on high speed
tractors, though.
-
Don't use high octane (Cam2, Turbo Blue) in a stock engine. It'll give
you expensive exhaust. Use straight Amoco Premium 93 octane. You need to
make major modifications for flow and compression ratio in order to take
advantage of higher octane race gas.
-
Adjust the mixture on a stock engine at FULL THROTTLE. It will run rich
at idle, but you are never at idle during the pull (hopefully). You will
probably need to change the spark plug more often.
-
Use a gas torch tip cleaner to enlarge the nozzle holes in your carburetor
(particularly the Briggs Flo-Jet). It's hard to pick up that trick in a
stock class.
-
Run the chain on the rear sprocket loose. It does no good to have it tight,
other than adding friction. The links on the opposite side of the big sprocket
are just along for the ride. Make sure your chain is new, a non-O-ring
type (friction) and is well lubricated.
-
Adjust, adjust adjust the belt tension. Do this before EVERY hook. Use
steel split collars instead of the aluminum collars. Split collars don't
mark the shaft with a set screw making it difficult to slide the collar
off. They are available at Bearing Service (see parts souce section of
the web page) for about $4 each, or I found them at my local Sears Hardware
store.
-
Remove the reverse wheel if the rules permit. You may need to buy a slightly
smaller belt.
-
Speaking of belts, Gates Power Belts (green) worked best for me. Gates
6934 for stock setup with the reverse wheel, 6933 for maximum belt adjustment
with rubber puck removed.
-
Replacing the bearings in the drive shaft will keep the grease from flying
out all over the pulley. They are a standard size. I use the 3/4" oil impregnated
bronze bushings in mine. Bearing Service part number FF1014-2.
-
Paint on a garden tractor makes it look good, but it doesn't make it run
better. Paint weighs a lot - have you picked up a quart of paint, lately?
Polish those remarkable and unique aluminum castings if you have a Copar
Panzer- it will make your Panzer a show-stopper. This is the reason the
external fuel tank on the space shuttle is not painted - saves weight.
-
From experience, the bigger Copar Panzers don't do well in stock tractor
pulls. They have a lot of weight in the front end from the cast iron casting,
so it's hard to transfer weight. If anyone has success with a T102 or similar
model, please let me know!
-
You may notice in the pictures on the web site that my 22x10.50-12 Carlisle
rear tires have a groove cut down the middle of them. Part of the reason
is that they have been cut so many times they wore out, but the other part
is that they don't dig into loose dirt. About 15 years ago, the big tractors
started shaving almost all of the tread off of their rear tires. This was
done for the same reason. If you take the tread off, it allows you to not
dig in or fall into holes made by others. The thing you need to do to compensate
is to increase tire speed (so that's why the do that...).
-
Remember that Force = Mass multiplied by Acceleration. Sir Newton made
this fundamental connection, supposedly, when an apple fell on his head,
and we have dubbed it 'Newton's Second Law'. Since our tire speeds are
generally constant, this integrates to become Kinetic Energy = 0.5(mass)(velocity
squared). Kinetic energy is simply energy in motion. The square of velocity
is the key. If you get the velocity of the tires to go faster (with a higher
gear ratio), you increase the kinetic energy by a squared factor. Run the
highest gear ratio you can without stalling the engine, remembering that
it is replacing the energy lost from the tires slipping and friction in
the driveshaft/axle. You'll need to change engine pulley positions for
loose or packed tracks, and lose a few hooks before you get it right (I
did!). It's easier to find bigger sprockets for the drive shaft (and cheaper)
than to get the big one that fits the pinion. Increasing from 10 to 12
teeth will make a big difference!
-
Never, ever, ever run weights in your rear wheels, or fill them with liquid.
It takes horsepower (force) to get the mass accelerating (and to maintain
it!). Lighter tires/wheels will allow you to increase their velocity without
increasing the horsepower required to turn them.
This list of tips was taken from the Panzer Page web site. For more
information, please check out the site at http://www.oocities.org/MotorCity/5702
Other Pulling Resources:
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Brian Miller's tractor pulling tips. http://members.aol.com/BMiller211/tips.html
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Bill Marrison's National Garden Tractor Pulling Association site. http://www.oocities.org/MotorCity/4795/GTINDEX.HTM
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