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opinions of the Commando cam tensioner? #527104
02/08/14 10:45 pm
02/08/14 10:45 pm
Joined: Sep 2009
Posts: 632
SEATTLE WA
S
SEATTLE GS Offline OP
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SEATTLE GS  Offline OP
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Posts: 632
SEATTLE WA
I am looking for reviews of the timing chain tensioner spring loaded wedge shaped devise on the market. Has this shown improvements? The stock system seems micky mouse but has worked for the last 70 years. I even took three sets down to the local machine shop to see if the gears/sprockets had been machined poorly and they all checked out very well. What is the source of the radical slack/tight/slack/tight that goes on when the motor turns over? It is scary to watch. I close the timing cover and try not to think of all the chain whipping going on inside. I am surprised it holds up, but it has done so and very well over the years. THE QUESTION...What is the performance gain using the tensioner?

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Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #527149
02/09/14 5:48 am
02/09/14 5:48 am
Joined: Dec 2004
Posts: 9,551
Scotland
kommando Online content
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kommando  Online Content
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Joined: Dec 2004
Posts: 9,551
Scotland
There have been a couple of reported issues with the wedge tensioner, trouble was the maker was not interested in engaging with the buyers to sort out the issues which rules it out for me as an option.

There are 3 further options to better control chain tension.

1. Go for a uprated chain from Andy the Chainman in the UK, under testing these do not wear out so look to be a fit, tension and then forget option. No wear means no variations in tension from uneven wear.

2. Go for the Cork tensioner, these are no longer made but you can replicate yourself using Cloyes 9-5047, see pics below.

3. Go for a Hydraulic tensioner supplied with the uprated chain.

http://www.accessnorton.com/new-hydraulic-timing-chain-tensioner-t17009.html?hilit=cork%20tensioner






Last edited by kommando; 02/09/14 6:16 am.
Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #527232
02/09/14 2:50 pm
02/09/14 2:50 pm
Joined: Sep 2009
Posts: 632
SEATTLE WA
S
SEATTLE GS Offline OP
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SEATTLE GS  Offline OP
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Joined: Sep 2009
Posts: 632
SEATTLE WA
thanks...that is a very clever tensioner..why has no one (including Norton) thought of it before?

How much and where is the address to buy it?

Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #527234
02/09/14 2:58 pm
02/09/14 2:58 pm
Joined: Dec 2004
Posts: 9,551
Scotland
kommando Online content
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kommando  Online Content
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Joined: Dec 2004
Posts: 9,551
Scotland
The Cork one is no longer made, I have the parts to make 2 and a milling machine and lathe to do the work. For the Hydraulic tensioner go to access norton link and look for Dave Comeau. If I had not already got the parts I would be going for the heavy duty chain only with a new rubber coated standard tension plate pre grooved to eliminate the 1000 mile re-tension needed. As soon as the rubber pad wears enough so the rollers run on the rubber the initial rapid wear of the sideplates into the pad ceases.

Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #527502
02/11/14 11:15 am
02/11/14 11:15 am
Joined: Feb 2005
Posts: 625
Winter Springs, FL
Tom Sanders Offline
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Tom Sanders  Offline
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Posts: 625
Winter Springs, FL
I've installed a total of three of the spring-loaded wedge shaped cam chain tensioners in my life with Commandos. The first one on my pretty much stock '72 Combat seemed to have survived the environment in my timing case just fine.

The 2 I've installed on my fire-breathing '74 880 Commando are a different story. Both ended up as chunks in the bottom of the timing case. No damage to anything else. I've gone back to using the old style tensioner.

If I was going to upgrade the tensioner I'd use the Comstock piece. He builds good stuff.


LONG LIVE LOCKTITE

74 Roadster 880cc
1962 Norton 650SS
75 Ducati 860GT
1968 Commando Fastback SN 126157
1975 Honda CB400f AHRMA racer #842
email addy: sargehopp@gmail.com
Re: opinions of the Commando cam tensioner? [Re: Tom Sanders] #527508
02/11/14 11:54 am
02/11/14 11:54 am
Joined: Sep 2007
Posts: 1,127
Ottawa, Canada
gREgg-K Offline

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gREgg-K  Offline

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Ottawa, Canada
Originally Posted By: Tom Sanders
I've installed a total of three of the spring-loaded wedge shaped cam chain tensioners in my life with Commandos. <SNIP>
The 2 I've installed on my fire-breathing '74 880 Commando are a different story. Both ended up as chunks in the bottom of the timing case. <SNIP>


No doubt at all about the quality of Jim's stuff, Tom. But your experience with AMR's wedge-style tensioner begs the question: why did the fist one work so well, but the next two failed?

.. Gregg


Spyder Integrated Technologies
Lucas, BTH, & Miller Magneto & Dynamo Restoration
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Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #527509
02/11/14 12:01 pm
02/11/14 12:01 pm
Joined: Apr 2006
Posts: 1,406
New Zealand
J
johnm Offline
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Posts: 1,406
New Zealand
I used to the Cork tensioner on my Dommie race bike for about 6 seasons.

I cannot remember details now but I remember I had to do backing plate grinding and turning on the sprocket to get enough clearance in the 1956 Domminator cases.

After 6 years some lateral wear appeared in the holes in the backing plate and roll pin. Right now the bike is on the other side of the world from me and it was a while ago that I looked so I forget all the details. But there is a lot of torque applied to the unit and Im not so sure it is a real fit and forget option.

So kommandos options 1 and 3 look better to me. If you go with option one I would adjust it with a cut away timing cover so you can get the tension correct.

Re: opinions of the Commando cam tensioner? [Re: johnm] #527619
02/11/14 9:19 pm
02/11/14 9:19 pm
Joined: Sep 2007
Posts: 1,127
Ottawa, Canada
gREgg-K Offline

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Ottawa, Canada
I'd always thought the Cork tensioner was a hydraulic unit. After a close look at the Cloyes 9-5047, I realize now that it is a spring loaded plunger with an anti-retreat ratchet mechanism to hold its plunger in its most outward position. Seems to me a hydraulic tensioner would be a lot better if the chain were to wear unevenly.

.. Gregg


Spyder Integrated Technologies
Lucas, BTH, & Miller Magneto & Dynamo Restoration
SMITHS Chronometric Restoration
magneto@spyder-it.com
Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #527642
02/12/14 2:23 am
02/12/14 2:23 am
Joined: Apr 2006
Posts: 1,406
New Zealand
J
johnm Offline
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New Zealand

"I realize now that it is a spring loaded plunger with an anti-retreat ratchet mechanism to hold its plunger in its most outward position. "

This is correct.

Re: opinions of the Commando cam tensioner? [Re: gREgg-K] #527662
02/12/14 8:29 am
02/12/14 8:29 am
Joined: Nov 2003
Posts: 743
Orlando fla/ shady valley Tn
B
bill50cal Offline
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Orlando fla/ shady valley Tn
part of the trouble with the RMA tensioner IMHO is in it will not allow for very much run out in the sprockets. once it tension's to the part in rotation with the most slack and you rotate to the least slack there can be a huge amount of pressure on the chain, sprockets,cam bushes and the tensioner. IMHO it is a POS and can cause more harm than it is worth. also in toms case there was NO consideration as to ANY warranty help.

Originally Posted By: gREgg-K


But your experience with AMR's wedge-style tensioner begs the question: why did the fist one work so well, but the next two failed?

.. Gregg


windy
72 combat
switchbackcreek.com
Re: opinions of the Commando cam tensioner? [Re: bill50cal] #527667
02/12/14 9:11 am
02/12/14 9:11 am
Joined: Sep 2007
Posts: 1,127
Ottawa, Canada
gREgg-K Offline

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Ottawa, Canada
Originally Posted By: bill50cal
part of the trouble with the RMA tensioner IMHO is in it will not allow for very much run out in the sprockets. once it tension's to the part in rotation with the most slack and you rotate to the least slack there can be a huge amount of pressure on the chain, sprockets,cam bushes and the tensioner. IMHO it is a POS and can cause more harm than it is worth. also in toms case there was NO consideration as to ANY warranty help.



Exactly what I was getting at ... seems to me the RMA misses the whole point of what the tensioner should be doing: controlling the stack without overloading the chain at the inevitable tight spots.

One could achieve the same thing as the RMA by over-tightening the chain with a standard tensioner!

This all points to the sensibility of fitting a high quality chain that is more resistant to wear.

.. Gregg


Spyder Integrated Technologies
Lucas, BTH, & Miller Magneto & Dynamo Restoration
SMITHS Chronometric Restoration
magneto@spyder-it.com
Re: opinions of the Commando cam tensioner? [Re: gREgg-K] #527680
02/12/14 10:23 am
02/12/14 10:23 am
Joined: Nov 2003
Posts: 743
Orlando fla/ shady valley Tn
B
bill50cal Offline
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Orlando fla/ shady valley Tn
But with the RMA is, as it wears it will continualy keep it over tensioned. where IF you do this with the stock setup it will wear it self loose than stay loose. the chain is only one part but the real issue is the sprockets are not Concentric and some worse than others.

Originally Posted By: gREgg-K



One could achieve the same thing as the RMA by over-tightening the chain with a standard tensioner!

This all points to the sensibility of fitting a high quality chain that is more resistant to wear.

.. Gregg


windy
72 combat
switchbackcreek.com
Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #529411
02/21/14 1:00 am
02/21/14 1:00 am
Joined: Sep 2009
Posts: 632
SEATTLE WA
S
SEATTLE GS Offline OP
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Posts: 632
SEATTLE WA
I took 3 pairs of sprockets, idler plus cam and had them checked out for any Concentric problem and they all checked out. I thought that poor manufacturing was the problem but not so!

Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #529462
02/21/14 11:45 am
02/21/14 11:45 am
Joined: Nov 2003
Posts: 743
Orlando fla/ shady valley Tn
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bill50cal Offline
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Orlando fla/ shady valley Tn
I have not looked into it that deep but there is some reason for the chain to have tight and loose spots in rotation. the most logical would be something is not Concentric.even with your findings I would still not use the RMA unit.I have 2 motors to build and will do more research on them.


windy
72 combat
switchbackcreek.com
Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #535913
04/01/14 12:20 am
04/01/14 12:20 am
Joined: Sep 2009
Posts: 632
SEATTLE WA
S
SEATTLE GS Offline OP
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Posts: 632
SEATTLE WA
I agree that that would be the most logical and first place to look, which I did. That checked out at the local machine shop so I ruled it out. The only other thing it could be is the cam being pushed around in the cam bushing by the valvve springs. But that seems like a lot ov movement for such little clearance. Still a mystery. I would like to solve it with a plunger that follows the slack and tight moments.

Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #535963
04/01/14 11:21 am
04/01/14 11:21 am
Joined: Jan 2006
Posts: 7,088
Laredo (South) Texas, USA
GrandPaul Offline
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Laredo (South) Texas, USA
Don't the ordinary valvetrain forces feeding back through to the cam sprocket cause the tight/loose operation?


GrandPaul (does not use emoticons)
Author of the book "Old Bikes"
Too many bikes to list, mostly Triumph & Norton, some BSA & European
"The Iron in your blood should be Vintage"
Re: opinions of the Commando cam tensioner? [Re: SEATTLE GS] #535977
04/01/14 11:56 am
04/01/14 11:56 am
Joined: Dec 2004
Posts: 9,551
Scotland
kommando Online content
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kommando  Online Content
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Posts: 9,551
Scotland
Quote:
Don't the ordinary valvetrain forces feeding back through to the cam sprocket cause the tight/loose operation?


They will move slack from the top to the bottom and back again but the total slack will be unchanged. Any overall change in the slack is due to something else other than valve train pressure.


Moderated by  Dave Comeau 


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