Rocker arm shafts

slab side and nose cone motor differences.

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chop1543
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Rocker arm shafts

#1

Post by chop1543 »

I'm about to embark on a project that may take a bit of time but would save me a pile of dough. Early rocker arm shafts have a 5/16-24 thread in one end the accept the slotted screw where the o-ring goes. Later shafts have 1/2-20 thread to take the socket head style of screw. Does anybody make the style with the smaller threaded hole? If not, I'm gonna make my own threaded inserts to reduce the thread size to accommodate the smaller thread on the slotted screws. The large-type thread shafts that I have are in way better shape than the originals, and everything fits in the original rocker boxes.


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Re: Rocker arm shafts

#2

Post by Mongrel505558 »

You might get lucky finding an early OEM set in good shape on ebay. V-Twin probably makes a repop, but they can be full of surprises :x . If you can make accurate and durable threaded inserts for the shafts you have it'll save you money and grief. Please post how it turns out. I haven't gotten really deep into my '68 motor yet. I plan to do that this summer.
chop1543
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Re: Rocker arm shafts

#3

Post by chop1543 »

Will do.....I'll take pics and see if I can post them.
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Re: Rocker arm shafts

#4

Post by Andygears »

Seems like an easy project if you have a lathe. Use the threaded part of a stainless bolt in a collet.

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Re: Rocker arm shafts

#5

Post by RUBONE »

The early shafts with the small thread are two piece, the shaft and the large block are two different pieces pressed together. The single advantage is that they can be drifted slightly to correct end play on the arms. The large screw type are one piece.
chop1543
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Re: Rocker arm shafts

#6

Post by chop1543 »

Andygears wrote: Thu Jun 10, 2021 1:21 pm Seems like an easy project if you have a lathe. Use the threaded part of a stainless bolt in a collet.

Andygears
Actually, stainless is not such a good idea. That was my first choice of material, and no matter what kind of lubricant I used when drilling the threaded piece, the hole got "work-hardened", and I had difficulty tapping the hole. I now have plain CRS bolts.
chop1543
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Re: Rocker arm shafts

#7

Post by chop1543 »

RUBONE wrote: Thu Jun 10, 2021 2:43 pm The early shafts with the small thread are two piece, the shaft and the large block are two different pieces pressed together. The single advantage is that they can be drifted slightly to correct end play on the arms. The large screw type are one piece.
Interesting, Rubone. Part of the reason for using the later shafts is because a couple of the early shafts seemed to be too short, and the rocker arms would bind in assembly. At what location do you press or drift the shaft to increase its length? Is the threaded part in the big end of the shaft removeable? There is a slot in that part which would point to it being removeable.
chop1543
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Re: Rocker arm shafts

#8

Post by chop1543 »

chop1543 wrote: Fri Jun 11, 2021 12:02 pm
RUBONE wrote: Thu Jun 10, 2021 2:43 pm The early shafts with the small thread are two piece, the shaft and the large block are two different pieces pressed together. The single advantage is that they can be drifted slightly to correct end play on the arms. The large screw type are one piece.
Interesting, Rubone. Part of the reason for using the later shafts is because a couple of the early shafts seemed to be too short, and the rocker arms would bind in assembly. At what location do you press or drift the shaft to increase its length? Is the threaded part in the big end of the shaft removeable? There is a slot in that part which would point to it being removeable.
Took another look at the old rocker arm shaft this morning. Put a 1/4" drive pin punch in the threaded hole and tapped it a couple times. Sure enough, that Lengthened the shaft so that there is no more bind on the rocker arm. Thanks for the insight Rubone.
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