To fit a crank damper or not?

Side valve, 803, 948, 1098., 1275 and Vizard mods

To fit a crank damper or not?

Postby HotRodMatt » Fri Oct 18, 2019 9:14 pm

Hi all,
I'm thinking of fitting a 12G940 head onto my 1098, along with an HS4, alloy inlet, and LCB. I have read online that fitting a crank damper off a Mini is recommended (but of course cannot find it for the life of me now!), but is it really needed?
In RWD, only the 1275 had one so I'm not sure.
Any advice gratefully received!
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Re: To fit a crank damper or not?

Postby philthehill » Mon Oct 21, 2019 8:03 am

To answer your question is a damper needed? Yes - if you are modifying your 1098cc engine. it is one of the best modifications you can do. It will make your engine smoother and reduce any crankshaft vibrations that occur - in other words it will help the engine to last longer. The 1098cc engine in standard form is not the smoothest and is prone to vibration.
If buying S/H beware of cracking of the rubber damping material. If badly cracked the damper can fly apart. It is better to buy new in this instance.
There are several types of factory crankshaft damper available which are suitable for the Minor 'A' Series engine but do not purchase the Cooper 'S' two piece damper unless you intend to balance the crankshaft assy.
You may have to remove the timing sensor ring from the rear of the damper to fit but that is only a question of drilling out the rivets. It will not need rebalancing afterwards. If you drill and tap the holes you can use a puller to remove the damper at a later date. Do not use a two or three leg puller to remove as you can damage the damper.
The starter dog can be used with the damper.
All of my 'A' Series engines have been fitted with crankshaft dampers.
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Re: To fit a crank damper or not?

Postby HotRodMatt » Mon Oct 21, 2019 8:37 am

philthehill wrote:To answer your question is a damper needed? Yes - if you are modifying your 1098cc engine. it is one of the best modifications you can do. It will make your engine smoother and reduce any crankshaft vibrations that occur - in other words it will help the engine to last longer. The 1098cc engine in standard form is not the smoothest and is prone to vibration.
If buying S/H beware of cracking of the rubber damping material. If badly cracked the damper can fly apart. It is better to buy new in this instance.
There are several types of factory crankshaft damper available which are suitable for the Minor 'A' Series engine but do not purchase the Cooper 'S' two piece damper unless you intend to balance the crankshaft assy.
You may have to remove the timing sensor ring from the rear of the damper to fit but that is only a question of drilling out the rivets. It will not need rebalancing afterwards. If you drill and tap the holes you can use a puller to remove the damper at a later date. Do not use a two or three leg puller to remove as you can damage the damper.
The starter dog can be used with the damper.
All of my 'A' Series engines have been fitted with crankshaft dampers.
Thanks very much for your reply. I've read they are more for high revving engines and even though I know not to take the 1098 above 6k I've now bought one to fit anyway.
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Re: To fit a crank damper or not?

Postby philthehill » Thu Oct 24, 2019 6:31 pm

Most high revving engines will have been balanced throughout and the damper will be adjusted in weight to suit the dynamic.
My own 1380cc ''A' Series is fully balanced and I use the Cooper 'S' two piece damper. The engine used to easily rev to 10,000rpm when the original build cam was fitted without any problem and was smooth throughout the rev range. The engine is now electronically limited to 7,500rpm.
The 998cc engine previously installed in my Minor had the one piece damper fitted and it greatly improved the smooth running of the engine.
Whilst you will keep the revs below 6,000rpm the damper will benefit your 1098cc engine greatly and make for smoother running at all revs. So money well spent.
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Re: To fit a crank damper or not?

Postby MM » Fri Nov 01, 2019 3:19 pm

Streuth! Do you have any videos of the engine running at such high rpm? :shock:
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Re: To fit a crank damper or not?

Postby philthehill » Tue Nov 05, 2019 8:09 am

Unfortunately I do not have any videos of the engine running at 10000rpm.
The engine is full race and fully balanced. I appear to be having difficulty posting pictures on here but pictures of the car and the engine can be found on the Morris Minor Owners club web site. The car has appeared on several speed hill climb videos and once appeared on a TV classic car programme when competing at the Brighton Speed Trials.
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Re: To fit a crank damper or not?

Postby dp » Thu Nov 07, 2019 5:41 pm

I don't want to thread hijack but what were the reasons for limiting to 7500rpm? Was it engine life or other parts of the drivetrain not coping?

I love the idea of a 10,000rpm a series
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Re: To fit a crank damper or not?

Postby philthehill » Fri Nov 08, 2019 9:26 am

There main thing that made me decide to limit the engine to 7500 rpm was that the Quaife SC/CR Clubman gearbox main shaft runs in a plain bearing but it is guaranteed to run without damage continuously at 7500rpm. Bearing in mind how expensive it would be to repair the Quaife gearbox I installed the electronic rev limiter.
When doing a timed run it is easy to get distracted and easily run the engine over 7500rpm. The rev limiter is my insurance policy.
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