Balance shaft diagnosis

[VPRob]

Hi Guys,
My V6 VP has developed a quite strong vibration under load, most noticeable in the 60 - 85 km/hr speed range. My mech thought it might be the torque converter but an engine and transmission guy has driven the car (without me in it) and says it is the balance shaft. Can I just disconnect the balance shaft or do I need to remove it? What's the effect of doing that? What's involved in disconnecting or removing it?
I know I can do a fair bit of reading about the balance shaft on this forum but I'm asking anyway first. Thanks in advance for any replies.
Cheers

 

[losh1971]

Yes you can just disconnect it. It is sump off, and timing cover off and remove the drive gear near the timing chain.

I'm a bit suss on the diagnosis though.

 

[Immortality]

I'm not sure the balance shaft will cause the vibration. Bad engine mounts, worn out harmonic balancer, misfire, drive shaft, wheels/tires.

Easiest way to disable is to remove the timing cover and just remove the drive gear on the front of the balance shaft and just leave everything else in place.

 

[VPRob]

Thanks Losh and Immortality.
Engine mounts are new, tyres were balanced just before the mech drove the car (to eliminate them as a cause), drive shaft has just had new centre bearing and CV join fitted and spins true on the hoist.
I thought the centre bearing was going to be the cause of the vibration and that the CV join being dry and worn was maybe the cause of the last centre bearing only lasting 2 years. Shaft has been balanced some years ago and alignment was maintained by the mech who did the work this time around.
Vibration seems to be getting worse quite quickly

 

[Immortality]

I doubt the balance shaft would do that, it's there to counter certain engine harmonics.

 

[MikeC]

Can you judge if the vibration is wheel speed or engine speed?

 

[VPRob]

Can you judge if the vibration is wheel speed or engine speed?

That's a good and logical question Mike. My impression is that it is speed (or wheel) related rather than engine speed.
If that's the case it presumably rules out the balance shaft?
Next drive I'll shift between 3rd and 4th and see if that makes a difference to the vibration. If no difference it can't really be in the motor is what I am thinking.

 

[Immortality]

That is always my first test if I get a weird vibration, shift it down a gear and see what it does.

 

[losh1971]

I think if it was the balance shaft, you would have had a lot earlier signs of it being a problem before it got to the stage it is.
They get pretty noisy, especially on start up once the mileage is getting up.
The bearings can seize a bit and get blue but still the early signs of that you will know.

 

[losh1971]

The annoying part with BS is you really need to take the sump off and it's almost worth slipping the engine out, by the time you unbolt the engine mounts raise the engine and also lower the K frame so the sump can be slid out.