Mk111 Project

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The Tensioner ! Thank god I read the primary chain tensioner system should be held together with tape ( on dismantling the primary ) to prevent both springs from sending the 2 plungers across the room. There was no such action and both plungers stayed in place within the body. After thinking about it before sleep I decided to take it all apart and have a look the next day. Bad news , the body bores were scored ( the lower worse than the top bore ) .
No smooth free movements with the 2 plunger units , jerky and sticky movements only. On inspection there were tiny black rubber bits blocking the tiny oil holes in the bottom of the bores. The tiny pin hole lubrication hole in the lower plunger was restricted by a tiny aluminum body piece and a bit more black rubber . There were 3 groove marks into the outer body where the primary chain had been flopping about and striking the body. This would explain my "Pushrod Rattle " thread in the main "Classics section Forum ". The rattle would disappear between 3000 and 3700 R.P.M. , which just happens to be the smoothest running point of most Commandos.
I can only conclude that : The tensioner assembly had siezed up from lack of lubrication due to the very tiny holes becoming blocked from rubber plunger debris build up.
From this point forward I will be thoroughly cleaning the NEW tensioner assembly every time the primary cover comes off . The interior will be wiped down with shop towels as clean as I can get it an fresh 20W50 used.
As an aside note , the 2 brand new punger assemblies in the 2 AN packets , well the first one that I cut open the rubber foot was about to fall off /separate from the steel plate that holds it. Looked to me like it was glued on and the glue failed ? Don't know. The other one looks O.K. but today I'll test it by finger pulling and see if it's solid.
Imagine if I had installed it and it fell off on the road and got slurped into any moving parts ?
 
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Inspected the brand new plunger unit that fell apart in my hands from A.N.
Not only had/did the rubber fall off in the brand new package , it allowed me to inspect why.
Normally you can't see how the rubber tensioner piece is attached to the plate but now I could. There is a short central post (not unlike a large lipped rivet ) that is the central support/attachment point for that rubber block primary chain contact point. It was crooked and was not hammered in or pressed in flush or home in it's position.
So that's why the rubber block which has it's own cast in attachment lip did not take and hold tight to to the plate.
To add insult to injury I looked down the steel bore and there were drops of yellow glue -like stuff , adhering to the interior bore . This bore should have been clean of that glue nonsense , to let the plastic/ teflon plunger spring piece move in conjunction with the long spring. I'm not even going to try fitting the white plunger to that bore as a test because visually it won't even go into place. More money.
 

gortnipper

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Send them pictures in email. They should send you a known good/inspected replacement FOC.
 
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snipped
I can only conclude that : The tensioner assembly had seized up from lack of lubrication due to the very tiny holes becoming blocked from rubber plunger debris build up.
snipped
Paul,
Odds are that all the oil that is supposed to be retained in the oil reservoir of the assembly had drained out during an extended period of non use. Upon start up, the slack primary chain bounced repeatedly, causing excessive wear of the rubber pads on the two plungers. There is supposed to be a paper gasket between the plunger body and the flat steel outer plate. It's not mentioned in the original manual or parts catalog. Andover Norton now shows it in their parts list.
It appears to have been added after the fact. Probably was an after the fact add on, to cure this issue. Without the gasket, the oil in the reservoir leaks out between the plunger body and the outer steel plate. I've made a note about this in my edited Mk III manual with the appropriate part number for the gasket.
 

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Inspected the brand new plunger unit that fell apart in my hands from A.N.
Not only had/did the rubber fall off in the brand new package , it allowed me to inspect why.
.... More money.
Who supplied the duff bits?
 
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Who supplied the duff bits?
06-5341. Genuine Andover Norton. No one else makes the plungers that I'm aware of.
I've been buying a lot of MK111 new parts during Covid winter to rebuild this primary to better than new.
Can't say as I've used Andover , RGM ,Walridge and CNW to supply me recently with all the parts.
Shouldn't much matter as the plunger assemblies came in small sealed plastic bags with AN logos and a sheet describing the correct way to fit the white plastic push-bobbin . The correct way is as described : Long thin spring goes into the aluminum body , the white plastic bobbin mushroom head end fits touching the head to that inserted spring, The hollow plunger fits over this , the narrower longer end of the plastic piece will be pointed towards the rubber block end. It's possible to accidentally reverse the white bobbin as the parts manual illustration does not show the mushroom head .
 
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Paul,
Odds are that all the oil that is supposed to be retained in the oil reservoir of the assembly had drained out during an extended period of non use. Upon start up, the slack primary chain bounced repeatedly, causing excessive wear of the rubber pads on the two plungers. There is supposed to be a paper gasket between the plunger body and the flat steel outer plate. It's not mentioned in the original manual or parts catalog. Andover Norton now shows it in their parts list.
It appears to have been added after the fact. Probably was an after the fact add on, to cure this issue. Without the gasket, the oil in the reservoir leaks out between the plunger body and the outer steel plate. I've made a note about this in my edited Mk III manual with the appropriate part number for the gasket.
Normal wear on the rubber blocks of the Skate plungers.
The tensioner body is scored and the skate plunger tubes that drop into those bores are rough too. I believe they stuck in a semi-retracted position which would negate more wear to the rubbers seeing as they were no longer resting against the triplex chain and doing their job.
The paper gasket was in place albeit quite old ,black and thin. The new one I have looks much healthier and thicker.
It will be fitted behind the new body and torque values adhered to.
Yes it could be all the oil drained out before a start-up. This rattle issue arose in spring after a long winter sleep.
 
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Simon of Andover said sorry and will send me 2 new skate plungers (free).
I let him know the block support ( on the bad one) was put in crooked , causing the block to fall off.
I didn't want to trust the second one so asked for both to be replaced please.
 

L.A.B.

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The paper gasket was in place albeit quite old ,black and thin. The new one I have looks much healthier and thicker.
It will be fitted behind the new body and torque values adhered to.

Hopefully, you meant the gasket will be fitted between the body and the plate?
 
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snipped I believe they stuck in a semi-retracted position which would negate more wear to the rubbers seeing as they were no longer resting against the triplex chain and doing their job.
The paper gasket was in place albeit quite old ,black and thin. The new one I have looks much healthier and thicker. It will be fitted behind the new body and torque values adhered to.
Yes it could be all the oil drained out before a start-up. This rattle issue arose in spring after a long winter sleep.
While the chain does not touch the retracted plunger heads at rest, that chain will slap furiously once the engine is started. Gasket goes between the plunger housing and the steel outer plate. You can apply a thin coating of your favorite sealant between the plunger housing and the inner primary cover. Sealant only needs to be applied in the area of the oil reservoir.
 

L.A.B.

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While the chain does not touch the retracted plunger heads at rest,

The plungers should always be in contact with the chain as they are constantly being pushed outwards by the springs.

that chain will slap furiously once the engine is started.

Yes, because the plunger movement is undamped until the tensioner has reprimed.
 
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Hopefully, you meant the gasket will be fitted between the body and the plate?
Yes , I have it's proper placement now noted in the exploded diagram , which does not have the omitted gasket illustrated (drawn ) .
 
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The plungers should always be in contact with the chain as they are constantly being pushed outwards by the springs.



Yes, because the plunger movement is undamped until the tensioner has reprimed.
Yes indeed. Unless the 2 plungers have seized , retracted in their bores . I must now fit a new Tensioner body , with 2 new plunger assemblies and the gasket in it's proper placement. Let the fun continue. I'm deeply into this primary rebuild now financially. CNW , A.N. , RGM ,Jason the Chain Man and Walridge all helping to take my credit card. There will be a decision coming up , when I mock fit the endless double row IWIS chain to the inboard 2 rows of the CNW sprocket and the stock chainwheel. I'll be eyeballing how this narrower high quality endless German chain will sit on the skate plungers. If I feel there would be side pressures of any sort on them I'll abort and fit an endless Reynolds triplex chain as per stock.
 

grandpaul

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Yes indeed. Unless the 2 plungers have seized , retracted in their bores . I must now fit a new Tensioner body , with 2 new plunger assemblies and the gasket in it's proper placement. Let the fun continue. I'm deeply into this primary rebuild now financially. CNW , A.N. , RGM ,Jason the Chain Man and Walridge all helping to take my credit card. There will be a decision coming up , when I mock fit the endless double row IWIS chain to the inboard 2 rows of the CNW sprocket and the stock chainwheel. I'll be eyeballing how this narrower high quality endless German chain will sit on the skate plungers. If I feel there would be side pressures of any sort on them I'll abort and fit an endless Reynolds triplex chain as per stock.
I have a known good tensioner body on the shelf. Pretty sure I know right where it is. Yours for the asking, plus postage.
 
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I have a known good tensioner body on the shelf. Pretty sure I know right where it is. Yours for the asking, plus postage.
Wow. Sweet , I'll P.M. ya.
Our largest postal facility in Toronto is called Gateway. It was shut down recently due to an outbreak of Covid in it. It will re-open one day but until then the news says many parcels and letters are piling up. Our mailman is carrying a noticeably smaller bag these days.
 
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Wow. Sweet , I'll P.M. ya.
Our largest postal facility in Toronto is called Gateway. It was shut down recently due to an outbreak of Covid in it. It will re-open one day but until then the news says many parcels and letters are piling up. Our mailman is carrying a noticeably smaller bag these days.
Today temperatures rose to +2 C.
So I installed the black brand new 21 T. and screwed the retainer ring down tight. Covered her up well before the howling winds snow storm , -5 tomorrow. No work foreseen. Very quiet here , thanks Covid. Stocked up on food and booze.
 
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Today temperatures rose to +2 C.
So I installed the black brand new 21 T. and screwed the retainer ring down tight. Covered her up well before the howling winds snow storm , -5 tomorrow. No work foreseen. Very quiet here , thanks Covid. Stocked up on food and booze.
Today watched the storm and wrote in some necessary revision and omission notes in my MK 111 workshop manual and Parts listing manual.
 

grandpaul

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Tensioner strapped to the back of a turtle and pointed towards Canada...

Maybe I should have used a carrier pigeon? (they can tolerate cold better)

It includes the stud with nut and washer, the angled plate, and the old/worn shoes with springs.
 
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Tensioner strapped to the back of a turtle and pointed towards Canada...

Maybe I should have used a carrier pigeon? (they can tolerate cold better)

It includes the stud with nut and washer, the angled plate, and the old/worn shoes with springs.
Thank you so much. I have all Covid winter to wait . Carrier Pigeons trained to carry messages I believe might be extinct ( Most shot dead for sport by early N.A. hunter sportsmen types.). Apparently the sky over America was black with them before the white man showed up. Buffalo same issue. Anyways , I'm thinking of the mock up now for the IWIS double row primary chain and how to get it to fit with the skate plungers . I'm thinking the tensioner body may have to be thinned out to the visual max. , inboard side , about 1/8 " removal of aluminum material , in order to achieve a more centralized pressure/running the inboard double row chain as opposed to the stock triplex which runs very centralized. It could be a non-issue and simply fit the tensioner and IWIS duplex chain. It's a beautiful chain if a chain can be called so.
 
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