Shortening the driveshaft on your derby car has a number
of advantages. It will allow the shaft to be driven forward during the
derby without causing the trans and shaft to become jammed together and
causing a possible breakdown. Done properly the shaft should have at least
1 inch before it bottoms out on the output shaft.
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The first step in shortening your drive shaft is to
determine how much you need to take out of the shaft. Anyone can
accomplish this with a tape measure and common sense.
- Measure the distance from the rear end and the trans output
shaft -- lets say (completely hypothetically) it's 100 inches
- Then subtract 2 and 1/2 inches from that measurement -- now we
have 97.5 inches. This is the length you WANT the drive shaft to be.
- Now measure your drive shaft as shown in this picture. Lets say
(completely hypothetically) it's 101 inches
- SO.. if you measured the drive shaft as shown, and got 101
inches -- and your first measurement called for a shaft thats 97.5
inches.. then I'll want to cut out 3.5" from the shaft..
This will normally allow the shaft to be driven forward during the
derby without causing the trans and shaft to become jammed together
and causing a possible breakdown. Done properly the shaft should have
at least 1 inch before it bottoms out on the output shaft. |
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Once you have determined the length you want your
shaft to be, mark it as pictured in photo 1. Make sure your marks
follow the curve of the drive shaft so you will get an even cut that
will be easy to put back together. |
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This part of the procedure requires a good grinder or
pipe cutter. Cut the shaft on your marks taking out the length you
don't need as in this photo. You want to take this out at the top of
the shaft (the end that goes into the trans) since this will make it
easier to weld back together. In this photo you see me cutting at the
top of the shaft with the second mark down the shaft being how much I
will take out. To cut the shaft correctly: At the top or forward end
of the shaft, you will see a factory weld where the shaft is initially
welded to the insert. Cut along the edge of this weld on the shaft
side, which means cut on the side closest to the rear of the shaft.
This is *CRITICAL*, you must be careful at the top of the shaft when
cutting it. The thickness of the drive shaft is only about 1/8 inch
thick and there is an insert there. You don't need to cut to deep into
the shaft here so be careful not to cut the insert. You will see the
insert in photo 3. |
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As I said, you now see the insert I was talking about.
Using a hammer, after you've made your first cut at the top, tap out
the insert just like the photo here. Make sure your second cut is
clean and will line up with the insert. The insert will help you line
up the shaft when you are ready to weld it back together. The mark on
down the shaft is where I will cut out what I don't need. |
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In this photo I have already made the second cut and
now have the shaft at the length I need. I have lined up the insert
with the shaft and am tapping the insert in with the hammer. See how
it flushes up at the top with the insert? Now that you are at this
step you are ready to get out the welder and weld the shaft back
together. |
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Using a Mig welder, weld the shaft around the small
gap between the insert and the shaft end. I prefer the Mig welder
since it is capable of welding thin material and yet be strong enough
to hold the thicker things together. Find a temperature that wont burn
holes in the outer shaft and yet will penetrate the insert. To test
the temperature weld on the piece you cut out, raising the temp until
you reach burn through, then back off a couple of notches on the
settings. This should be right for the thicker material and the shaft
together. |
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As you can see in this photo the Mig welder does a
real clean job of welding the two halves of the shaft back together.
As a rule, I will make 3 passes on the shaft at this point. The first
being directly on the center of the shaft and the small gap between
the insert. Then the second and third welds will be on each side of
the first. For a total of three passes. Hope this helps all who need
to do this. |
