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MG TD TF 1500 - Harmonic Balancer for the XPAG

Hi All,

as I a plan a rebuilt of an xpag for my TD (TD2/19435), I searched the archives and googled the www but did not find any threads upon a harmonic balancer for this engine.
Reading a lot of details upon crankshaft balancers, it seems to be quite normal for an engine as the xpag to run into problems with the durability of the crankshaft without one fitted.
By my understanding up to now, the balancer itself does not seem to be critical. The question by now is: has someone tried it already with a custom one or is there a OEM part of an other engine that is designed somewhat suitable an can be modified for the XPAG without the fabrication of new pulleys for the generator and the water pump?

Seasons greetings to all of you!

Ralph
R.S. Ralph Siebenhaar

Since no one else answered, I recall this was batted around on the board a few years ago. I think the conclusion was that the XPAG would benefit, but so far nobody has come up with anything that will work. I think someone even checked in to having some made, but the cost was too high. Since most of the cranks break at the first main/rod area, you would suspect basic harmonic vibration, or possibly vibration induced from the off and on load on the cam lobes? George
George Butz

The problem is harmonic vibration of the crankshaft, and the part in question is not a "balancer" but a "damper".
The damper is tuned to cancel the harmonic(s), and as such is specific to the entire crank assembly.
So, if you want one, it needs to be tailored at least to the standard assembly, assuming no great changes of mass distribution.
Fitting some part designed for another engine might work to a degree, or it could make things worse.
Viscous dampers may have a bit more latitude for being "not quite right". They are available to order from some manufacturers, at a price - which is a good deal less than a new engine.

FRM
FR Millmore

When building an XPAG it is a good idea to have the engine balanced. When this is done,the crankshaft pulley is also ballanced with the assembly.
D. Sander

The problem with the XPAG crankshaft developing cracks is not one of vibration, per se- it is one of resonance, which occurs in the range which we operate (with a standard ratio differential) about 55 miles per hour.
Dallas Congleton

Add in my lack of knowledge on the topic, but I thought that is why the 4 main engine came out. The three main engines had more resonance issues.
Bruce Cunha

Hey guys, there's this wonderful thing called Google; trouble is, just like BBS posts, some articles are good but most are not.

Here's a very good one:
http://www.bhjdynamics.com/downloads/pdf/tech/BHJDynamics_Damper_Info.pdf

FRM
FR Millmore

Great article. George
George Butz

This thread was discussed between 22/12/2011 and 24/12/2011

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