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Splitting
Shovel Rocker Boxes
David
“Englishman” Gregory
I’ve been a fan of
the ‘split look’ on Shovelhead and Ironhead XL rocker boxes for some
time now. I’m sure it was first done back in the ‘day’, as most
things were by some enterprising artist, probably out in Southern
California somewhere, but they seem to have been experiencing a bit of a
comeback in recent years. People like Fred ‘Krugger’ in Belgium,
Chica in SoCal, Indian Larry on NYC and Hank Young in Georgia have all
recently fielded bikes with split rocker boxes. Recently I saw a nice
example of split XL rocker covers on a Ron Finch Sportster..the rest of
the bike was way off the weirdo scale, but the top end looked good.
So,
how hard could it be? As most of you know, my mechanical aptitude is
about as scary as riding a Boss Hoss at full throttle across Deals Gap,
but I figured I’d give it a shot, and if I can do it…
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The original plan was to obtain a spare set of Shovel rocker boxes (in case I
really hosed them up), and either hacksaw or sawsall the things apart. I
solicited opinions from a few people and the
consensus
was
that it would be better to try
and leave the middle mount in place.
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If the boxes are truly split in two, that eliminates the middle mount and
there is a greater chance for leaks from the pressure of the pushrods working
against the rear mounts.
I’d like to take the opportunity here to thank Steve Broyles of Stevenson’s
Cycle in Warren, MI for coming up with a pair of rocker boxes for me for
attempting the procedure. In hindsight, I wouldn’t have gone wrong using the
ones already on the Shovel.
I was heading to Detroit to do some more work on the Triumph project, so I asked
Eric if I could use the Bridgeport mill to do the ceremonial hacking. He said it
was OK, and I figured I could get him to do the necessary welding on them at the
same time
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The
area to be cut out on the rocker boxes is pretty much solid. You can put your
fingers through the pushrod holes and feel where the ‘wall’ is, and I
wasn’t sure how much material I could safely take out in the middle. I
called Hank Young to find out how much he’s removed when he did the rockers
for his Discovery Channel bike, he measured the gap
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and
told me it was 5/8”.
Eric just happened
to have a 5/8” mill bit, so that greatly simplified the work. We measured
the center of the rocker box, then 5/16” each side of the center and
scored a line for a guide. Then it was mill(er) time!
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I
took cuts of .100” at a time; it took about 15 minutes per side to complete.
It probably would have taken considerably longer using a hacksaw/sawsall/bandsaw
and it’s WAY easier keeping the cut straight on the mill. |
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In
the first picture, you can see where the mill cut through the oilway
that linked the inlet and exhaust rockershafts. This brings up the other
problem with this deal, when the boxes are split, you have to plug the
oilways between the split, and figure out an alternative method of
delivering the oil to the rocker shafts, more on that in a minute.
With
the mill it was a simple job to leave the center mount boss intact, but
like I say, lots of people have just sliced the whole thing out. After
they were milled, it was up to Eric to plug the oilways with the TIG
welder. He wanted to drill the passage out a little wider than it was so
as to be sure he was welding uncontaminated aluminum, and then he zapped
the holes shut. This operation would be a lot easier if the boxes were cut
in two, it’s tough to get into a 5/8” gap and weld!
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Back
at the kitchen table it was time to do some shaping. I took a hand file
and rounded off the corners at the top of the split, and blended the shape
a little until I was (sorta) happy with the overall look. Then it was time
to figure out the oiling for the rockershafts. People like Krugger and
Hank Young utilized systems linking the rockershafts from the end of the
shaft itself,
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coming up with some kind of banjo device to oil the shaft and continue
to the next.
I
decided I liked the look of the uncluttered face of the rocker boxes, so
what I plan to do is; run the stock feed almost to the first stock
oilway on the rear rocker cover, but put a T just before it connects,
then run another line to the inlet rocker, entering the box from below,
similar to how the stock system is for the Exhaust rockershaft on the
rear, but have another T in the line so I can run oil to the exhaust
rockershaft in the front. Then I can utilize the stock crossover from
the rear to front. |
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It’s
probably hard to see what I’m getting at here, especially since
it’s not done yet and I can’t show you a picture, but the original
plan just called for a single line running below the boxes, and T’s
in place under every shaft, feeding them oil. However, I want to keep
the carb mount under the front inlet shaft, which is why I am opting
for the stock crossover at that point.
So
I had to drill and tap holes under the rear inlet, and front exhaust
shafts.
I
picked up a drill and a 1/8” taper tap and had the holes drilled and
tapped fairly quickly (considering I had to use a hand drill).
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All
that was left was to polish the boxes, and then await the reconditioned
shafts and rockers from Dan Roedel, Shovelhead specialist
extraordinaire. I say ‘all’ as I was kind of dreading polishing the
things, but I got to it anyway. Starting out with 400 grit and working
my way up to 600 before squirting light oil on the boxes and making all
kinds of mess. Then, the hand drill-mounted buffing wheel came out, and
I was soon in an all-out cuss session trying to keep the wheel on the
piece. Hey, I’m no Bradley da Polisher, but I don’t think they came
out too bad. |
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details and photographic evidence of the oiling system will be on these
pages soon. I am in the middle of a full-scale facelift for the Shovel,
which include new tank, seat, fender etc. Together with the split rocker
boxes and magneto I’m hoping it’ll look pretty cool!
Thanks
again the Steve Broyles of Stevenson’s Cycle: 734 641 2200 or www.stevensoncycle.com
and Eric Gorges of Voodoo Choppers: 248 601 3000 or www.voodoochoppers.com
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What happened next??
Click here! |
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