rocker shaft not "tight"

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One of the rocker shafts is a slip fit, rest are "heat to press" fit. Wonder if this is significant. Will it rotate? Do the tangs on the cover plates work to restain rotation well?
I was thinking about zinc plating a few tenths of a thou on the end(s)
Thanks
Doug
 

eskasteve

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Colorado Norton Works used to show them on their web site. Not sure if they're still available. A quick call to Matt would be my suggestion. 970-882-7163
 

Fast Eddie

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One piece alloy plates are available from JS, NYC Norton, Holland Norton Works, and others, they’re a much better idea than the stock design which, frankly, is a bit of a botch job.

But the RGM ones LAB showed actually use a grub screw which can tighten up hard against the rocker spindle and physically clamp it into place rather than rely on alloy tags to hold it, so are a better fix for a loose rocker IMHO.
 
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better idea than the stock design which, frankly, is a bit of a botch job.
Easy to blame 1949 norton's design for (2 brain cell) ham fisted mechanics bang them in and out cold, which they probably do to their valve guides also and complain then too?
Fire the mechanic...heat the head
 

Fast Eddie

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Easy to blame 1949 norton's design for (2 brain cell) ham fisted mechanics bang them in and out cold, which they probably do to their valve guides also and complain then too?
Fire the mechanic...heat the head
That’s not my point, it’s the use of two plates and two gaskets on each shaft that I think is a botched design aspect.
 
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One of the rocker shafts is a slip fit, rest are "heat to press" fit. Wonder if this is significant. Will it rotate? Do the tangs on the cover plates work to restain rotation well?
I was thinking about zinc plating a few tenths of a thou on the end(s)
Thanks
Doug
Is this a Commando head or an ATLAS head. Earlier heads had less material to support the rockers and they were prone to wallowing out. Later heads had wider aluminum bosses to receive the rocker shafts.
 
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I have similar issue (right hand intake spindle) and to be honest while fiddly getting slots orientated and fitting the "botched" design it does not turn. As long as there is no play and the rockers are a good fit you probably do not need to worry (for now). I just spent the winter trying to sort an oil burn issue out, one of the potential culprits I looked at was this.
 

Tornado

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I JUST (like yesterday) realized I had this problem with a head I'm working on. I really liked the RGM solution with the grub screws, but didn't want wait to get it from England, so I ginned up my own version in the afternoon. Here's the story...https://www.doovsprojects.com/projects/norton-rocker-spindle-fix. I
Nice job!
I guess this could also be achieved by drilling/tapping a suitable grub screw hole in stock plates?
Not all of us have a milling machine handy :)
 
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Pete Lovell told me quite a few years ago that with a loose rocker spindle, he places a large ball bearing over the rocker spindle hole(s) and gives an appropriately weighted tap with a hammer to spread the aluminium. I assume the amount of "welly" to give it comes with experience.
 
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That's what he advised me too. Ball bearing is 3/4" with a flat ground on it. Don't hit it too hard The long fat nail punch pictured allows the inside spindle sockets to be addressed.
20170723_150827.jpg
If it's really worn then he advises to bush it.
 
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robs ss

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I copied this from Jim Comstock some time ago (look for the thread if you like)
It worked well for me.
I think it may be superior to the ball bearing method because I believe the ball will cause only very localised deformation compared with comnoz's method.

Cheers
Rob

Re: Fixes for loose rocker arm spindles?
Postby comnoz » Thu Dec 08, 2011 6:41 am

"A cheap and dirty trick if the outer hole is only slightly loose is to use a 1/2 inch grade eight bolt-fully threaded- along with a couple hard washers and a nut. Put it through the outer hole and torque it guten-tight. I squeezes the metal and shrinks the hole a couple thousandths. Jim"
 
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I copied this from Jim Comstock some time ago (look for the thread if you like)
It worked well for me.
I think it may be superior to the ball bearing method because I believe the ball will cause only very localised deformation compared with comnoz's method.

Cheers
Rob

Re: Fixes for loose rocker arm spindles?
Postby comnoz » Thu Dec 08, 2011 6:41 am

"A cheap and dirty trick if the outer hole is only slightly loose is to use a 1/2 inch grade eight bolt-fully threaded- along with a couple hard washers and a nut. Put it through the outer hole and torque it guten-tight. I squeezes the metal and shrinks the hole a couple thousandths. Jim"
That's ok for the outer hole, I agree.
I was swapping a scrolled spindle for a plain one when I pressure fed the head on my Dommie and the drive side inlet spindle seemed to locate just a little too easy in the inner socket. The ball bearing method worked a treat.
 
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robs ss

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That's ok for the outer hole, I agree.
How true - my mistake in not considering the inner one.
I suppose the smart procedure would be to use the ball method on the inner (check for success) then use comnoz's method on the outer.
Cheers
Rob
 

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