High speed pinking

Discuss mechanical problems here.

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philthehill
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Re: High speed pinking

Postby philthehill » Tue Aug 28, 2018 11:57 am

Below is a photo of a 1098cc 'A' Series with a 3 piece crankshaft pulley.
The pulley is made up of:-

1............Front pully plate

2......…...Rear pulley plate

3...……...Pulley centre.

They are riveted together to form the pulley.
1098cc enginer.jpg
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Below is the later one piece damper pulley. Fitting the damper pulley pays dividend as it helps to eliminate crankshaft vibrations which can lead to a longer crankshaft life and less vibrations through the transmission.
The Damper pulley became standard fitment on later 1098cc and 1275cc engines as well as the 998cc 'A' Plus engines.
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100_2019.JPG
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pgp001
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Re: High speed pinking

Postby pgp001 » Tue Aug 28, 2018 12:33 pm

Phil

Is it possible to "feel" any movement between the two parts of the damper pulley ?
I have bought a second hand Mini one ready to fit to my spare Minor engine, but it feels pretty solid to me, I dont suppose there will be much give in the rubber membrane though.

Phil

philthehill
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Re: High speed pinking

Postby philthehill » Tue Aug 28, 2018 5:38 pm

Phil
You will not feel any movement between the inner and outer parts of the damped pulley.
If buying S/H you do need to be careful of any cracks in the rubber between the inner and outer parts of the pulley when looking from the rear of the pulley.
If the cracks are serious the pulley can come apart at speed.
If considering a damper pulley with serious cracks my advice is to give it a miss and look for a better damped pulley.
As aside the Cooper S damper pulley is a two piece pulley similar to the damped pulley but much lighter and which is bolted to the crankshaft pulley boss. It is much lighter as the occurrence of the crankshaft vibration happens at difference revs so requiring a damped pulley of different weight/mass. The crankshaft damper either standard or Cooper S can be tuned (lightened)
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to suit the engine spec/revs.
Phil


Nickol
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Re: High speed pinking

Postby Nickol » Sun Sep 16, 2018 9:24 am

To tidy up the thread, we did replace the timing chain and sprockets after setting the pulley and distributer to TDC. We decided not to install a duplex. We found the orginal chain was at the extreme of floppyness.

The noise at 70/80 kmh is "nearly" gone. If it had not been so pronounced before. I would not have given it any consideration - compared to a modern, a Morris is quite noisy anyway. That is part of the charm. Whilst driving my own Morris T, I now notice this noise ( perhaps change of tone is a better description) as well so perhaps it is a characteristic just like the "burp"?
Gott schütze mich vorm Sturm und Wind und Autos, die aus England sind.
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philthehill
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Re: High speed pinking

Postby philthehill » Sun Sep 16, 2018 11:09 am

Well done.
Whilst I appreciate that is it was your decision not to install the duplex chain and sprockets I would consider it a retrograde step to replace the simplex chain and sprockets like for like.
The two rubber tensioning rings are very good when new but their effectiveness soon starts to wane after very few miles/km.
Latterly BL whilst fitting the simplex (without rubber tensioning rings) to the 'A' Series engine installed a tensioner to keep the return (slack) side of the chain under tension.
BMC fitted the cast iron duplex chain set up to those engines that had more loading on the valve train i.e. MG Midget and in the case of the Cooper 'A' Series engines steel duplex sprockets were used.
Phil


don58van
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Re: High speed pinking

Postby don58van » Sun Sep 16, 2018 11:29 am

Reading the last few posts, it occurred to me that maybe poly tension rings of the right hardness would be preferable to rubber ones. I base this on 1) Phil's comment that the rubber tension rings work reasonably well for a while, but all too soon they allow slack in the chain; 2) the common observation that rubber suspension bushes tend to fail far quicker than poly ones.

Of course, poly tension rings for the Minor do not currently exist (not to my knowledge anyway). I do know of a one or two very innovative Minor fans though ...

Yes, a duplex might be the best solution, but poly tension rings might be an improvement over rubber for those who want a quick, cheap and simple solution.

Just a thought.

Don

philthehill
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Re: High speed pinking

Postby philthehill » Sun Sep 16, 2018 1:51 pm

Don
That seems like a very good idea.
We will have to watch this space.
The most effective timing chain/sprocket mod you can have is to fit a duplex set up with tensioner so you have the best of both worlds.
Phil



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