About crankshaft dampers

[johnny250]

My damper has been heavily 'modified' and the rubber didn't look too good when fitted, 5 years+ of revving to 5500 at each gearchange.......I wouldn't worry too much...... or should I?

 

[Peter Cobbold]

My damper has been heavily 'modified' and the rubber didn't look too good when fitted, 5 years+ of revving to 5500 at each gearchange.......I wouldn't worry too much...... or should I?

 

The outer steel ring that has been machined provided the mass that counteracts the torsional vibrations. So its lighter now, and less effective. Problem is, no-one knows how much less effective. But for road use you'll only be at 5500rpm very briefly, its not like circuit racing. And even the racers dont seem to get snapped cranks

So I would not be too concerned. Eventually the rubber rings are going to fail and we'll get reports of dampers flying loose around the engine bay. Its a known hazard when using a timing light....but not (yet) on 6s.

Peter

[jellison]

Kastner was doing stuff back in the 60's just changing parts very regularly.

 

Alan is meaning current tstae of the art 6 pot TR race engines - these can revs to 7500 and 7k all race.

 

You need and ATi Damper for this level of prep / performance. Like Alan says, use a stand damper on an otheriwse full race fully balanced engine and you could easily snap a crank (easy on a std road cast one and even a trick modern Steel one (£3.5 - 4k!!!)).

 

Anthing over moderately fast road your be crazy not to run an ATi. (IMHO).

[Mark69]

 

Can any body tell me which one of the above is correct for a 69 tr6.

Thanks Mark.

[graeme]

20140919_160048.jpg

Can any body tell me which one of the above is correct for a 69 tr6.

Thanks Mark.

 

Mark,

 

My '69 TR6 has the one on the right. However, I wouldn't use the one in your pic as the chip will likely cause the belt to come off.

 

Cheers

 

Graeme

[Mark69]

Thanks Graeme

The one one on the right came of my car, I bought a replacement the one on the left, obviously different but suppliers are adamant its the correct one for the car.

I looked in the brown bible and the diagrams show the one on the left!!.

I'm confused as to which is the correct one.

Mark.

[johnny250]

Eventually the rubber rings are going to fail and we'll get reports of dampers flying loose around the engine bay. Its a known hazard when using a timing light....but not (yet) on 6s.

Peter

 

 

As my ignition timing relies on the pulley/damper I expect I will notice when it starts to fail........I would however be interested in a new or rebuilt replacement.

 

john

[Peter Cobbold]

Cant recall exactly, but it sticks in me mind that a 4 was better than a 7

looking ont interweb for the article, but as yet,no luck

 

but it was in a Car article in late 70,s i think

 

M

Less friction from four?

Peter

[jellison]

ATi's on my 4 and 6.

[Peter Cobbold]

ATI's engineer on their website:

http://www.atiracing.com/products/dampers/101/index.htm

""......I have collected considerable data that allows me to determine “how much damper” a certain engine needs. When given the crank weight, peak normal operating RPM, horsepower, rotating system materials, rules about the damper specifications (if racing), and the application of the engine (road racing, oval or drag), I can make a very good prediction of the amount of inertia weight and the type of device your engine will need.""

 

PerhapsTR owners who are concerned get together and ask him to recommend a solution for the 6 in standard form for road use. They do an off-the-shelf for the TR4 cylinder but not the 6, and several of those parameters will be larger on the 6: crank weight for instance.

[john.r.davies]

My original concern in raising this thread was that:

A/ 'ordinary' owners (inc. me) know little about this important factor for longevity of their engines.

B/ the longevity of the OE rubber dampers was unknown in the day - see KK's habit of putting a drill hole in the damper so that it could later be tested for twist - so how and if they function at all today is unknown.

C/ what to do replace the OEs with something else?

 

Pursuing these Qs, I came across a long article about dampers, from BHJ Dynamics in the US. It is readable! http://www.bhjdynamics.com/index.php?main_page=page&id=4&zenid=5d9u2e2lq33qabts8h7uhlch64

 

And that mentions "Pendulum Dampers" aka Sarrazin dampers, invented successfully for aero engines.

Rubber dampers cannot be easily made, outside a properly equipped factory.

Viscous, fluid dampers ditto.

But a pendulum damper is 'just' a solid disc with holes drilled in it, loosely containing rollers, with a light cover plate. THAT could be made by a garage shade mechanic! All that would be needed is to be able to work out the dimensions!

 

Anyone know about that?

John

[Peter Cobbold]

John,

Your plan sounds like the 'Rattler' damper.

http://vibrationfree.co.uk/introducing-sterling-rattler/

"" We have Sterling Rattlers available for the following engines:

Aston Martin, Jaguar, Subaru, Ford Cosworth, Mini, MGB, Healey, Rover V8, TR6 and many more ""

 

I reckon this is a highly specialised fieled of engineering that few auto engineers fully understand, certianly not to the point of being able to design a damper. Fortunately this Oxforshire company appears to be highly skilled in all sorts of vibration anlysis.

And they have presumably analysed a TR6's crank torsional vibrations. Quite what stat of tune that engine was in we dont know, but is that important ? - I have no idea... but they will know.

 

Peter

Edited March 16, 2015 by Peter Cobbold

[Motorsport Mickey]

ATI damper fitted in 1998 to 6-pot (good on 4-pot, but not vital)

End of problem.

PM if interested.

Has anybody tried approaching Jon and seen what he recommends ? experienced 6 cylinder builder and racer I'd have thought he would be worth canvassing ?

 

Mick Richards