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Triumph Crank Damper Pulley Survey


JohnD
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I retired a while ago, and since then I've gone back to college, where I'm now studying for a degree in Motorsport Engineering.     I need a research project and chose to investigate the crank damper pulleys that Triumph fitted to all the six-cylinder engines it made.   The crank damper was needed to suppress 'torsional', twisting vibration in the long crankshafts, and has a rubber layer between the inner hub and outer ring.   They were suspect even in the day, when they were new.     Kas Kastner described in his Handbooks his technique to ensure that the outer hadn't shifted, which would make the timing marks on them completely false.      Worse, a faulty damper could lead to crankshaft failure!

Today, none of those dampers are  less than forty years old, and many show the rubber to have deteriorated.  How many still work as timing indicators, let alone to suppress crank vibration?   

My study has two parts:   In the workshop, I'm building an engine rig with sensors on the pulley and flywheel to detect vibration, and I'm asking Triumpheroes about their experiences with the dampers.   Please help me by completeing the short survey questionanire I've put up on Survey Monkey?

Go to https://www.surveymonkey.co.uk/r/GPTCDSG    There are only five questions and it will take you less than two minutes!

Thank you!

John

PS I'm posting this on several websites, to catch as many people as I can but no need to complete it more than once!

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John,

Keen to help but, never heard of this. (Not unexpected :lol:) Canley's diagram for GT6 mk1/2 show crankshaft pulley and damper, part 133244, but for mk3 there is just a crankshaft pulley, part 154380. So the question is do I have a damper? Never had a problem and don't want to skew the survey!

https://www.canleyclassics.com/triumph-gt6-mki/ii-mki-crankshaft-and-camshaft

https://www.canleyclassics.com/triumph-gt6-mkiii-crankshaft-flywheel-connecting-rod-piston

Doug

 

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As far as I know, all Triumph sixes had them, but I'll be glad to be corrrected.    They all had effectively the same crankshaft, long enough to be vulnerable to torsion vibration.  No fours had a damper as that crank was too short for it to matter.    There are several different types of damper - the rubber, viscous one is the cheapest!

Looking at the 154380 item, the pulley diameter is as wide as the disc with the timing marks on it, while the earlier one is narrower.    I presume the later version was to drive the aleternator faster.  You may have to remove the whole pulley and look at the back to see the rubber ring.

John

 

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John,

When I rebuilt my Vit engine years ago, I decided to get the crank balanced along with the clutch etc. I took one look at my crank pulley and decided to replace the pulley, as the rubber bonding between the damper and pulley was badly cracked and perished. At that time - circa late eighties- the only pulley available new was the later type with the larger pulley ,to suit later GT6 with alternator - which wasn't a problem as I had converted to an alternator anyway.

Gav

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14 hours ago, JohnD said:

As far as I know, all Triumph sixes had them, but I'll be glad to be corrrected.    They all had effectively the same crankshaft, long enough to be vulnerable to torsion vibration.  No fours had a damper as that crank was too short for it to matter.    There are several different types of damper - the rubber, viscous one is the cheapest!

Looking at the 154380 item, the pulley diameter is as wide as the disc with the timing marks on it, while the earlier one is narrower.    I presume the later version was to drive the aleternator faster.  You may have to remove the whole pulley and look at the back to see the rubber ring.

John

 

Intriguing, I had no Idea the 6`s had damper, The Vittese we had in the 80`s, an 1966 2L model, had timing issues, occasional Misfire, But as my wife could by that time no longer drive a Manual car, It was traded for an Auto gearbox vehicle (Ford Granada Estate), which would double as tow car for the Caravan. Any way at the time I swapped out the Distributor, and did all sorts of electrical mod`s including "Electronic" ignition etc. which seemed to help but was not entirely successful. So after 30 plus years I have the possible answer to my issue!. The Haynes Manual, Which I still have, published 1982, and signed by John Haynes, (I used to do Factory Inspections in the print works at Sparkford back then), Makes the only reference on Page 51, Section 47, step 15, "Then fit the crankshaft nose pulley wheel spacer and Damper".

You learn something new every day.

P.s. It is unlikely that the width had anything to do with alternator speed, that would have required an increase in dia, or a smaller Dia on the alternator, or both. More likely to accommodate a more substantial belt.

 

Pete

 

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Hi John.

Not  problem, as they say. best of luck with your project. Sadly 30+ year on and now doing a Full re-build of a 13/60 convertible as my "retirement" project, I have no "Damper", so cannot help. But a whole stack of "other" work. This being the current "State of Play" Actually slightly more work done since that Photo.

Pete

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3 hours ago, PeteH said:

Hi John.

Not  problem, as they say. best of luck with your project. Sadly 30+ year on and now doing a Full re-build of a 13/60 convertible as my "retirement" project, I have no "Damper", so cannot help. But a whole stack of "other" work. This being the current "State of Play" Actually slightly more work done since that Photo.

Pete

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Hello Pete

                   Its nice to see another tidy? workshop like mine He He

Roger

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2 hours ago, PeteH said:

If I "tidy" it any more I wont find anything!. :D What`s the lathe?. Mine is a 1945 Drumond?. Rescued from a Diary being Demolished.

 

Pete

Hello Pete

                  Its a Woodhouse Mitchell Junior 7 mid 50,s I think? I have the build and test sheet and manual somewhere(7" swing! over bed with removable bed gap((19" swing))  owned for about 38 years!) I have a Myford ML7 as well?

It has earn t its keep over the years!

Roger

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Nice!. I had to buy a 4 jaw chuck off Flea bay, but it does what I want, mostly cleaning up bits for the Herald. When I get that finished I want to move it off the bench to it`s own place with a proper Stand. and give it a good clean and fettling. But it works OK, not bad for something that was heading for the "Skip".

I worked on a 27ft bed Mitchell, as Apprentice, Millwright, in the late 50`s. Making and refurbishing parts for various Factory Equipment. Before I went off to the Merchant Navy, for 20+years. Leaving to become a "Boiler" Surveyor. Which was part of what I was doing in the Dairy when I came across the Drumond, They where taken over by Myford BTW, and some of the Drumond Features found their way onto the later Myfords.

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3 hours ago, Anglefire said:

What's the red car in the picture Roger? It looks a bit like one of old disabled cars - only they were always hospital blue!

Hello Mark

                   My mate would be upset you saying that!

It is a Bond Minicar 198cc villiers engine(same as disabled cars) Type C I think?

Roger

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2 hours ago, JohnD said:

aHEM!

Tiny bit drifted?    Please start a Bond Minicar thread if you're that interersted!

John

John Apologies, I simply asked a question.

Besides, the thread drifted about 7 or 8 posts in.

I admin other forums and the best way in my experience is to report the post and the admin will split the thread if they think it appropriate.

 

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What parts fail well on the triumph one like on your vitesse there are two parts apulley and a outer ring with the timing marks on the two are bondened together with a rubber compound,  this over years breaks its adhesion and the outer rim can move around the base pulley 

There is a recess inside the mating faces that stops it coming off but the damper ring can move 

Investigations normally start by questionong why the timing has inexplicably changed from its last setting or problems with pinking or lost power with what you think are correctly set timings

Its not easy to check without making a piston stop so you arrest the piston and measure the halfway point between clockwise and anticlock turn of the engine as the overlap of rotation at tdc is considerable and the piston at tdc doesnt travel

If you stick a probe down a plug hole you will find quite a degree of rotation of the crank, but no real decernable change in piston height

when at tdc

  if you can accuratley drop the piston a known fixed amount  in both directions  and mark the timing ring then tdc is halfway between the marks,  just dont drop anything inside the cylinder !,,

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2 hours ago, Pete Lewis said:

Investigations normally start by questionong why the timing has inexplicably changed from its last setting or problems with pinking or lost power with what you think are correctly set timings

Wise words, Pete.  When engine building, I always use a piston stop to establish TDC, and then time the camshaft.     The pulley goes on later, and I can check that the timing marks on that are correct, but I've never found one that isn't.    But then I've not built a massive number of engines,  Sounds  as if you have come across this.  Any details please?

Jhn

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