Crankshaft damper

[paul 300358]

Phil
I don't suppose that you can lighten them by much or you would probably reduce the dampening effect? Can you weigh yours before you fit it, it would be interesting to have a comparison.

Paul

[philthehill]

Paul
With a tuned engine the harmonic unbalance/vibration is usually moved into a higher rev band and will or may require a lighter weight damper. The weight of the damper required for a tuned engine is determined by extensive testing and most commercially offered dampers are lightened to a generalised weight.
I will weigh the TAM2011 damper in the morning and post the weight on here.
I will also post the weight of the CAM4902 damper.

Anatomy of the Classic Mini arrived this morning - cannot read the book till Christmas but saved the part book link above to my favourites so having in the mean time a good read of that.

Phil

[philthehill]

Damper weights

TAM2011...………………………...1305 grams.

CAM4902...…………………………1452.5 grams with timing disk removed. I will weigh the timing disk once removed from TAM2011.

A difference of 147.5 grams.

[Declan_Burns]

Phil,
The MG T series XPAG engine cranks are notorious for breaking and throwing con rods as there is a non radiused step on the crank and a resonant frequency at approx. 4200rpm. Billet cranks are available at 2000+ pounds. Vizard mentions that fitting a crankshaft damper pushes the frequency out of the useable rev range. I know it is not that simple but I often thought of fitting one of those dampers machined to take XPAG crank and the 17mm wide fan belt which is standard on the XPAG engine. The XPAG engine is 1250cc and similar to the A series in many ways. That would lighten the damper considerably which could be either beneficial (or quite the opposite ?) and no easy way of knowing what the damper is actually doing without specialized measuring equipment.
What do you think as there is no crankshaft damper available for the XPAG engine?
Regards
Declan

[philthehill]

Declan
Having now looked at photos and read reports relating to the crank shaft of the MG T Series XPAG engine and with its very small and therefore small mass crankshaft pulley I consider that there is a lot to be gained by fitting a crankshaft damper. There is very little spare metal in the 'A' Series damper though to machine for a larger cross section fan belt.
May be better if the other two pulleys were changed to suit the damper pulley.
Phil

[Declan_Burns]

Phil,
You could very well be right there and I will certainly kook into it. It would increase the speed of the water pump which would be beneficial anyway but it would also increase the speed of the dynamo which in turn drives the rev counter via a gearbox. Building little gearboxes is my speciality anyway.
Thanks for your input-that will give me food for thought.
I will mention it on the MG forum and see what the think.

Regards
Declan

[philthehill]

Declan
BMC Special Tuning produced a larger dynamo pulley to reduce the dynamo revs so that it would not throw the commutator windings off when the engine reached high revs.
I have a NOS BMC Special Tuning dynamo pulley somewhere - when I find it I will measure the overall diameter and post the diameter on here.

[Declan_Burns]

Phil,
Just in from the garage and the damper @ 120mm will collide with the engine mount which is directly below the pulley. A damper for the XPAG engine would have to be close in size to the original pulley 3.75" / 95.25mm.
Ah well it was worth a try-thanks anyway!
Regards
Declan

[philthehill]

Declan

Looking at the cross metal under the crankshaft pulley could the cross metal be modified to increase the clearance between it and the crankshaft pulley?

http://www.mg-parts.co.uk/image/cache/c ... 00x500.jpg

Phil

[Declan_Burns]

Phil,
No so easily and very difficult to see what would have to be done with the rad in place. There is actually less than 1/2" clearance between the engine front bracket and the pulley. Your link to Peter Edney shows a deeper bracket which could be from a test bay. One of my mates has his engine out at the moment and I will ask him to take a close look at what can be done. It's a pity he is so far from here so I can't just pop around.
Regards
Declan

[don58van]

Hi Declan

It might be worth your while contacting James Baxter at Tiptop Engineering UK. This company is a crank damper specialist. They use new technology for damping -- not rubber. I gather that their components would be very expensive though

I was in contact with James about a NOS crank damper (not A-series) I have. He advises that rubber dampers have a limited life (like tyres) of about 10 years. That would mean that all the used and NOS dampers from A-series engines are beyond their use-by date.

Don

[Declan_Burns]

Don,
Thanks for the tip!
I sent him an email this morning.

Regards
Declan

[paul 300358]

Morning Phil,
The next time that I have the front of the car off, I will remove the pulley, photograph and weigh it. I will let you know.

Paul

[philthehill]

Paul
Thanks.

Removing the damper fits nicely into the next part of this damper thread.

Whilst it is easy to fit the damper by sliding over the front nose of the crankshaft removing the damper is not so easy.
Some dampers have two threaded holes through the damper hub so a slide hammer can be used to pull it off.
With the TAM2011 damper there are no threaded holes.
My intention is to remove the timing disk from the rear of the pulley and drill and tap through the three timing plate rivet holes and use a harmonic damper puller to pull the damper off the crankshaft.
Using a 2 or 3 legged puller on the outside of the damper risks damaging the damper. The pull must be exerted on the inner hub of the damper.
I will post some photos of the intended task on here.
Phil

[Declan_Burns]

Phil,
Is there enough clearance behind the damper to get one of these in? It will pull anything off
Regards
Declan

[philthehill]

Declan
There most likely is enough room but there is a good chance that the rear fan belt pulley flange gets damaged.
Pulling on the central hub alleviates the possibility of any damage.
Phil

[philthehill]

I have today removed the timing disc from the TAM2011 damper. Using the three timing disc rivet holes I have drilled and tapped them to 5/16" UNF. They can now be utilised for removing the damper from the crankshaft nose using a Harmonic Damper three bolt puller.

[philthehill]

Damper pulley TAM2011 modified to accept 3 bolt Harmonic Damper puller to facilitate removal.

Damper puller.JPG (1.45 MiB) Viewed 3235 times

[Declan_Burns]

Phil,
Looks good but does it really need to be an interference fit? I don't think so. On my 1275 engine it just pulls off. I may have honed it with a flap wheel at the time.
Regards
Declan

[philthehill]

Declan
I have never been able to just pull the pulley off the crankshaft nose by hand unless either the pulley or crankshaft (or both) are worn.
Whilst it does not have to be a tight interference fit it should be a good to tight fit on the crankshaft.
I would expect to have to use a leather faced mallet to lightly encourage the pulley onto the crankshaft nose.
If the pulley is not a good tight fit there is the possibility that the pulley could work/move and wear both pulley and crankshaft.
Corrosion occurring between the pulley and crankshaft nose will not ease the pulleys removal especially if the pulley has not been removed for some time.
My 948cc Sprite engine which was fitted with a plain three piece pully took some effort to remove the pulley. If it had been fitted with a damped pulley with either two or three bolts holes I could have used the puller and it would have been off in a jiffy. Corrosion between the original factory fitted pulley and crankshaft in that case was the problem.
For use in cleaning machined surfaces a 'Scotch Brite' pad is ideal as it cleans but does not take metal from the surface. I also use them for cleaning the beds and bright parts of my lathe.
Having also found 'A' Series engines with loose pulleys and worn crankshaft noses; it is an expensive repair to salvage the crankshaft and that is if you can salvage.
Phil