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commando cam thrust washer help #69237 03/28/07 5:11 pm
Joined: Mar 2007
Posts: 2
goat Offline OP
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Posts: 2
In asembleing the bottom end of my combat commando engine(about 208,000) I put in one chamfered thrust washer #06-1086, as is shown in the parts page. I did this even though the parts list shows to use 2 of this same 06-1086. I didn't do that as it didn't make sense looking at them to put 2 stacked, both on the timing side of the cam. It can't go on the drive side as you are up against a cam lobe there. After puting the cases together I noticed how much cam end play I had. It must have been 1/8" to 3/16" slop. I then read in the Shop Manuel section c29 paragraph 2 that you are to use the tab thrust washer in addition to the chamfered washer. I have that washer and can put it in also with one chamfered washer but that stil won't take up the end play I have.
What is the proper assembly here. This is a 72 motor.
Thanks
Goat

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Re: commando cam thrust washer help #69239 03/28/07 8:02 pm
Joined: May 2004
Posts: 556
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jangg Offline
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Joined: May 2004
Posts: 556
Hi there,
One thrust washer is correct - "Camshaft Thrust Washer" (bit 22 in my parts manual valid for 750 engine # 212278 on, and 850 engines). The workshop manual are warning for NOT having endplay. When warm the camshaft will expand taking up endplay - then you better have some room... As for the cam it is held in place by the cam chain, and so aligned right. This shaft has big tolerances. It's just the CRANKSHAFT that is spec-ed for "Permissible endfloat". Not the camshaft - has to have endfloat - under no circumstances it must stick.

Mine has considerable endfloat when not under load from camchain cool ...

regards
jangg


'73 Commando Basket - new aluminium cyl
'93 Ducati 900 SS

"Better lit a light than cursing the darkness"
(Confucius)
Re: commando cam thrust washer help #69240 03/28/07 9:41 pm
Joined: Aug 2001
Posts: 1,341
D
Dave Comeau Offline
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D
Joined: Aug 2001
Posts: 1,341
1. All 20M3S and up use (1) 06-1086 thrust washer (rotating). Small side against the gear.

2. All 2xxxxx came with "2" 06-2601 (stationary) thrust washers. One inside the cases and one outside. These are the "KISS OF DEATH" washers where the tabs break off and lock up the oil pump.
This system is to be avoided at all cost. The normal remedy is to use any of the 850 style bushes/thrust washers. Pre combat bushes are larger in diameter and won't work.

3. Stack-up of cam components give a 1.135" shaft length from thrust washer to gear..... and the cases and thrust washers are normally 1.105" total giving .030" end float/clearance. Case thickness vary a little but I have never seen properly assembled cases that are to tight and bind, and the sloppy ones have always had worn out thrust surfaces.

IMO avoid the 06-2600/06-2601 system at all cost, if you have a "plain bush" cam then get it scrolled, or scroll the later bushes.


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: commando cam thrust washer help #69241 03/28/07 10:56 pm
Joined: Mar 2007
Posts: 2
goat Offline OP
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Ok. So what I've gathered so far is with the components I have which are as follows:

1. SS cam non-scrolled
2. Timming side cam bush #06-2600 ( the one with the internal X-shaped oil recess passage)
3. Thrust washer with chamfer/bevel, #06-1086

I'm not to use, in addition to the chamfered washer, the flat tab washer which the shop manuel says to use, and I'm to let the camshaft end play be taken up with the cam timing gear when it is installed. Is that correct?

One more thing. Since this SS cam does not have the hole in the flange between the second and third lobe will this still allow the timed breather to work?

Thanks for your help.

Re: commando cam thrust washer help #69242 03/29/07 1:26 am
Joined: Aug 2001
Posts: 1,341
D
Dave Comeau Offline
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Joined: Aug 2001
Posts: 1,341
"IMO avoid the 06-2600bush /06-2601washer system at all cost, if you have a "plain bush" cam then get it scrolled, or scroll the later bushes."

Actually I look VERY VERY HARSHLY on ol brits for even offering to sell the 062600/062601 bush/washers. shame on them if they actually sell them.

What this means is...666 666 666...don't use this system at all, get them out and squish them in a vise and throw them away. OR never drive the bike any faster than you want to fall off when the motor locks up.
What this means is buy and install later model cam bushes from 73-75(at least do the timing side). and mod the cams or bushes to allow oiling.

Since you are assembling a 208xxx motor you DO NOT HAVE cam breather cases. Therefore no cam breather issues. The cam breather system WILL NOT FIT in your engine without extensive custom machining.


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: commando cam thrust washer help #69243 03/29/07 9:55 am
Joined: Dec 2002
Posts: 706
B
beltdriveman Offline
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To even suggest that the cam is located in position by the drive chain is rediculous...if thats what the writer meant. Yee gods chain sprockets are supposed to be lined up to within thous but I dont suppose many even bother to check their primary drive sprocket alignment let alone that of the cam sprockets....As a friend said decades ago regarding the BSA/Tri 3 motors he tuned fir customers for racing..'I can take the average owners motor and obtain on the dyno a noticable power increase simply by aligning the primary drive sprockets correctly'.
The torsional loads shoved on that poor olde chain by the cam are rediculous as it is without the sprockets being incorrectly aligned causing excessive wear and tiny bits of metal getting into the oil supply some of them so small they are not picked up by even a decent oil filter thus they circulate around the motor adding to the wear. To quote Motor Cycle Sport Jan 77 page 27...
'It did not go unnoticed that the mileage was the distance at which the mains failed in many cases, and that failure of the advance unit happened much more quickly with the super-sports camshaft. This was because of the fierce nature of the new cam which driven as it was by chain, used to thrash about within the slack allowed by the chain adjustment. This too was giving problems. Many engines seemed to be wearing out cam chains excessively, and this fault was compounded by the difficulty of regulating it. To do this the timing had to be disturbed and the complete timing cover removed. Dealers were suppossed to adjust the chains at the first service but you can imagine how many of them did so. The torsional vibration of a 4 lobed camshaft driven by a slack chain are tremendous, especially when it is remembered that the cams were not evenly spaced and so for two periods in each turn of the cam(4 at low speeds where inertia effects are less) the cam is actually trying to turn the engine because of the pressure of the valve springs on the downhill side of the ramp. MISTAKE No 7.'

The cam is located by the bushes at its D.S.end. There has to be just a tad of clearance to allow it to rotate. Any expansion is taken up at the non drive end.
Most cam bush failures are the result of owners incorrectly assembing the bushes or not giving them any lubrication when assembling them allowing them to run dry when the motor is turned by hand and later at engine start up causing metal to be picked up (galling) which leads to quick failure of both the bushes and cam surfaces. Bet lots have noticed how the bearing surfaces are well worn and blued up due to heat. (Been there seen it done it got the T shirt AND LEARNT) Just As Norton camshaft and follower wear is due to lack of correct lubrication in most cases..
The problem with the original bushes was that they required fitting correctly and line reaming in my experience.
This resulted in all the different types of bushes in an attempt to overcome the need for reaming. Norton once put out a document listing all the different combinations of bushes. Personally I have always employed the old type.

As for the thrust washers with the lugs breaking off and knackering the oil pump....if you are silly enough to use those crankcases then you deserve the problem. Dont know who the lack of brain was who 'designed' the cases but they should of been shot. They were, in the way of British business, probably promoted... Its The Peter Principal that states everyone rises to their own level of incompetence. When Norton finally closed these cases were available at less than 20 a set, for cash, from the cellers of MCE and there were 3 std mods anyone with a brain did to them before using them. 1 Replace the camshaft oil bath so the cam and followers are lubricated correctly just as Mr Hopwood had originally designed them to be. 2. Blank off that stupid so called breather ..even the NOC Commando service notes are a tad scathing about that stupid idea. 3. Replace the gauze oil filter into the bottom of the cases... as Norton eventually did on the later cases.Its really not hard to do.

Decades ago I converted a set of timing gear to duplex chain using 17 t Tiger Cub engine sprockets....Renold didnt stock 1 1/2 link bits for the duplex chain so they bought some from a German chain manufacturer for me....well a duplex chain solved most of the Leyland engines timing chain rattle problems so why not on a Norton... never completed the mod for use but it fitted into the timing chest..just... and with 17t sprockets gave cam timing changes in about half degree increments.

Probably the biggest problem these days is finding some Reynold 'Made In England' real chain. Personally I have a few new lumps but cannot for the life of me find those very nice Made in England rivit links with the shouldered pins...... Anyone still got any spare???

NO SPELL OR GRAMMER CHECKS.


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