Transmission damper

I have a diesel XJ with a manual transmission and a 231 transfer case. I'm looking to replace the 231 with a 242 with a SYE etc to give me full time 4wd.
My 231 has a counter weight on the back of the case called a 'transfer case damper' by Jeep.
242 cases do not come with this counter weight, Does anybody know why the weight is there presumably it is to damp the possible snatch of the clutch but what would happen if it wasn't there? Anybody got any experience of it
They are also fitted to TJs as standard.
TIA
Pete

It's there to dampen the harmonic vibration from the engine. 4 cylinder engines, especially diesels have a problem with a kind of vibration called rocking couple harmonic. A good example of harmonic is spare change buzzing in the console...or the mirrors going blurry at just the right road speed.

Thanks for the reply, you are right, however there are two dampers!!, one on the prop yoke which is the same as the damper on the crankshaft of the 4.0L which removes driveline vibes, the other is a lump of steel about 4x3 that is bolted to the back of the TC and sits off to one side. That's the one that I want to know what it is for unless that is the one your talking about!!

You can take it off, but be aware that if you do...something could end up stress cracking from the vibes...it's yer call...obviously if you take it off and you get yer eyes crossed from the vibes, you need to put it back on.

Jeepinpete said:

Thanks for the reply, you are right, however there are two dampers!!, one on the prop yoke which is the same as the damper on the crankshaft of the 4.0L which removes driveline vibes, the other is a lump of steel about 4x3 that is bolted to the back of the TC and sits off to one side. That's the one that I want to know what it is for unless that is the one your talking about!!

Click to expand...

The crank damper and the one on the driveline are there for rotational vibrations. The motor/tranny/transfercase assembly, rocking on the three-point motor mounting system has it's own natural frequency. Obviously, the engineers recognized a destructive or problematic vibration in that system which needed to be controlled.

It seems it is unusual to have both so close together, on the prop and on the transfer case, so I will remove the one on the case and see how it goes.
Thanks everyone
Pete