Rocker Spindles

Not looking for answers just find this interesting and hope others do so "pub talk".

When I rebuild Commando engines, I often find one or more rocker spindles scored and often visibly worn on the bottom. Sometimes the corresponding rocker is OK and sometimes rough inside. When the rocker appears good inside, it usually will run smoothly on a good spindle. I see this on engines with no damage to the big-end shells, so I don't think it is dirty oil causing it.

I'm no metallurgist, but it seems like the rocker should wear before the spindles. I assume that the rockers are cast iron of some sort and the spindle are some sort of hardened steel.

Fortunately, spindles are inexpensive - rockers are definitely not!

I have never tried it but have toyed with the idea of having the flat in the spindle point down. This should still stop over-oiling but put the oil where the most stress exists. Of course, it would require different end plates and modified spindles to let the oil into the end. There might a small increase in oil going through the rockers to the pushrods but for the exhaust a little increased oil flow shouldn't hurt since the pushrod tunnels can easily drain much more than required. Might never try it on the intakes - IMHO, that area gets too much oil with the spindles properly installed and any increase that enters there could be bad.

Sounds interesting .... pointing down .... wonder if the flow could be metered to compensate ??

Would scoring the spindle like the bearing area on a cam be better, easier? It still leave oil flow as it was designed.

mean gene said:

Would scoring the spindle like the bearing area on a cam be better, easier? It still leave oil flow as it was designed.

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Don't know but if scrolled wider than the area where the rocker resides, I assume that would increase the oil flow. Would be a simpler thing to do and might be OK for the exhaust spindles.

Grandad said:

Sounds interesting .... pointing down .... wonder if the flow could be metered to compensate ??

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Maybe. And maybe there would be no need for the exhaust spindles. The intake oil return is just a small hole on the timing side at about 4 o'clock when looking at the timing side intake valve. That why I considering idling on the side stand to be a terrible thing on a Norton - lots of oil pools on the drive side.

The other thing I've wondered about is why the problem doesn't exist on Triumphs. On most, their oil feed is return pressure (small takeoff from the oil return line) and the materials seem similar to Norton. Their rockers and spindles seem to last MUCH longer - in fact, I've never had to change either.

marshg246 said:

I have never tried it but have toyed with the idea of having the flat in the spindle point down.

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Won't that place the rocker spindle flat (with the oil hole and less bearing surface) in the area that needs the most bearing surface?

L.A.B. said:

Won't that place the rocker spindle flat (with the oil hole and less bearing surface) in the area that needs the most bearing surface?

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Yes, and that's probably a showstopper. Just wondered if it's a lack of oil film causing it. I certainly wouldn't recommend doing it without some serious testing. Another possibility would be rotating them 135 degrees from standard which would put the oil closer to where needed and still preserve the bearing surface. That probably would be OK for the exhaust but might put way too much oil through the intake rockers.

I once had the bright idea to open up the slot in the spindle, so it didn't partly cover the oil feed hole - bad idea - way too much oil in the intake rocker area.

Interesting ideas. I found scoring on my intake reoker shafts a few years back. Repla9ced them and also drilled them as per Comnoz. Had them out last winter for valve seals a nd saw noscoring