Camshaft thrust washers

Hi I am about ready to reassemble my Norton Commando 850 lower end cases . The service manuals indicate that for bikes with serial numbers after 200,000 there should be 2 thrust washers on the camshaft. My camshaft only had one washer on it when I dismantled it and the parts manual shows 2 of the same washers. The manual both haynes and Norton manual indicate there should be a second washer that locks into the tab on the bushing. Not sure how to proceed here and would appreciate any insights from those that have rebuilt these motors before
Thx Drummer99

The cam tach drive pulls the cam into the TS case so the DS thrust washer is just a space filler w/o even a need for it. There are confusing terms of item#24-pn062601 "thrust washer" and item#25-pn061086 "cam thrust washer" that should both be installed on TS of cam. Steel bevel washer goes on cam first with wider side to the bronze washer that rubs against case face. Remove the tabs as that is well known to break off and are not needed, just smooth over the removal scar. Cam will be free to shift side to side uncomfortable normal amount when all is right of course, though held tight to TS when tuning.

hobot said:

The cam tach drive pulls the cam into the TS case so the DS thrust washer is just a space filler w/o even a need for it. There are confusing terms of item#24-pn062601 "thrust washer" and item#25-pn061086 "cam thrust washer" that should both be installed on TS of cam. Steel bevel washer goes on cam first with wider side to the bronze washer that rubs against case face. Remove the tabs as that is well known to break off and are not needed, just smooth over the removal scar. Cam will be free to shift side to side uncomfortable normal amount when all is right of course, though held tight to TS when tuning.

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What if you do not use the tach drive? I have relied on this approach until I tried the PowerArc EI units. Endplay was just to out of range for the unit to hold sync. The manufacturer calls for .020" endplay.

The internal tabbed thrust washer is not shown for the 73 750's and 850 and is called for on only some 72's. For which 72's, I have not a clue.

I now have the conical one, the tabbed one with the tab removed and a tabbed one the timing gear side. This configuration gives me cam end play within spec.

Drummer, I think this should be your approach, that is to use what you need to bring endplay into the specified range with the cam lobes nicely centered.

Drummer99 said:

Hi I am about ready to reassemble my Norton Commando 850 lower end cases . The service manuals indicate that for bikes with serial numbers after 200,000 there should be 2 thrust washers on the camshaft. My camshaft only had one washer on it when I dismantled it and the parts manual shows 2 of the same washers. The manual both haynes and Norton manual indicate there should be a second washer that locks into the tab on the bushing. Not sure how to proceed here and would appreciate any insights from those that have rebuilt these motors before
Thx Drummer99

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Drummer,
Your 850 cam should have scrolled groves for oil to lubricate the cam bushes.
In 1972 (there about) engines 200,000 where the combat engine was introduced, Norton changed the cam / bush scrolled groves to be reversed. (The scroll was on the cam bush and the 2S cam was non-scrolled.) The cam bush on these engines did not have a top hat thrust section to act against the cam wanting to wander towards the timing side halve of the crankcase. Norton solved that problem with using the tabbed washers. Which created new problems when these tabs broke off and got sucked up into the engine oil pump and jamming it. Norton then reversed their way of thinking and returned to the scrolled cam and plain bush with the top hat shape.
You should have a hardened beveled washer with the bevel facing the gear for the tach-drive output shaft. You do not need the tab washers if you have an 850, only the beveled steel thrust washer.
If someone has converted your bike to run a combat cam with out the oil grove scrolls, then you may have the bush with the scrolls in the bush.
But pictures are a good way to explain 06-2600 is for a combat non-scrolled cam. http://www.oldbritts.com/cam_bush.html But all cams with the tach drive on the timing side crankcase will use the beveled thrust washer. Only the combat used the tabbed thrust washers that fit the bent tab into the hole of the crankcase timing side.
Cheers,
Thomas
CNN

Like Pete says just mix and match washer to get cam centered well on the lifter bores when running. If no tach drive cog to pull cam to TS then put DS washers in to limit cam bouncing side to side too much. DS cam end can have one long grooved bush or a pair of shorter one used to form oil reservoir gap between the 2 bushes. I reverse the bevel steel washer to put more surface area on the softer bronze face than the cam. Done this in 2 Combats so far w/o issue after some horrendous testing events and later inspections. Both my Combats had lost both washera tabs but only 1st Combat showed gear pump evidence of tabs being chewed up and spit out, with some chipped cog teeth but not really bothering the oil pump supplying sufficient oil pressure/flow. Second Combat tabs stayed in sump broken/mooshed w/o pump processing any significant size or hardness. My Peel needs the Powerarc programing so appreciate the warning to steady up the cam shifting. Similar can be done to rockers too if tedious attention enough.

Just for information sake,

You can run a scrolled cam with a non scrolled bush,
a non scrolled cam with a scrolled bush,
a scrolled cam with a scrolled bush,
BUT, not a non scrolled cam wtih a non scrolled bush.

I run a scrolled cam with the scrolled 06-2600 bush. I swapped out a 200xxx set with a newer 210xxx set. This set had these 06-2600 bushes in place and were like new, although there was evidence of some sort of catastrophic failure within the confine of the cases. The cam I got from JS fit as well as could be expected. This was fortunate.

These 06-2600 scrolled bushes are only "x"ed at the oil hole and not pronouncedly scrolled. If circumstances warranted, one could do this with a ball bit in a Dremel tool

pete.v said:

Just for information sake,


These 06-2600 scrolled bushes are only "x"ed at the oil hole and not pronouncedly scrolled.

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Ok true enough.... not scrolled but relieved to allow oil to get to the plain journal on the SS or 2S Combat Cam. There were a lot of things that were changed during that era. Oil pickup placement, tabbed washers, not using the large oil filter plug. Bad engineering practice or bean counters muddying the waters. Not too sure but history was made.
CNN

CanukNortonNut said:

There were a lot of things that were changed during that era. Oil pickup placement, tabbed washers, not using the large oil filter plug. Bad engineering practice or bean counters muddying the waters. Not too sure but history was made.
CNN

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I find 2 things particularly amazing about the 72's. How many are still around and how desirable they are.

Yep Combats can be Cream of the Commando Crop any way you can measure, hi performance potential to smooth endurance to minimalist mass and legal equipment configuration. Might give a look at the tiny drool fed bush oil supply holes and consider grooving case walls to direct more oil layer to aim at widened funnel holes. Don't groove bushes to very end that faces the cam to help hold some oil layer inside and remember nil oil slinging flowing anywhere at dead idle rpms.