Trying to balance the front and rear halves of the prop to each other would be pointless because of the VCU.

However am I correct in thinking that the flange on the IRD output isn't completely symmetrical? I saw something in a video about IRD blanking plates.

If the IRD flange isn't symmetrical then it would be REALLY important to fit the prop front half in the correct orientation to the flange otherwise it would be out of balance.

I'm with Hippo here - turn the prop front 90 degrees relative to the IRD flange and see what happens. I think it will make a difference. If it gets worse, turn another 90 degrees and test again. Only 4 possible positions and you have tested one of them!

Prop front to VCU? Less important as the rotating plates in the VCU have a lower mass and therefore a lower rotational inertia. In my opinion. YMMV.

davidsmith1307 said:

Trying to balance the front and rear halves of the prop to each other would be pointless because of the VCU.

However am I correct in thinking that the flange on the IRD output isn't completely symmetrical? I saw something in a video about IRD blanking plates.

If the IRD flange isn't symmetrical then it would be REALLY important to fit the prop front half in the correct orientation to the flange otherwise it would be out of balance.

I'm with Hippo here - turn the prop front 90 degrees relative to the IRD flange and see what happens. I think it will make a difference. If it gets worse, turn another 90 degrees and test again. Only 4 possible positions and you have tested one of them!

Prop front to VCU? Less important as the rotating plates in the VCU have a lower mass and therefore a lower rotational inertia. In my opinion. YMMV.

Click to expand...

ird flange is symmetrical in any case that end of prop is a cv

nickcc said:

I believe the front prop joint only comes with the front prop. It's not like the usual cv joint as it has 3 fixed rollers. When I stripped mine down the grease had turned to liquid, perhaps re packing with cv joint grease may cure the vibration.

Click to expand...

its either worn or not ,though grease will stop wear ,but it wont renew a worn joint

davidsmith1307 said:

RAVE says to make sure that the prop is marked on the IRD and rear diff before removal so it goes back in the same place. The prop sections are balanced and they will vibrate if put back in a different orientation.

I think.

Click to expand...

no it doesnt matter were shafts are fitted in relation to ird or rear diff flanges,

The pinion case connection has 5 bolts to the ird but that if fixed and doesn't move. The front prop to pinion connection is a cv joint which is fixed inside by 3 rollers (can't remember their name). The outer case of this bolts to the pinion spinning bit with 6 bolts which is evenly balanced you would think.

As I said above this is only a very slight wobble. Hence things have to be spinning very fast for it to show up. After having a steering geometry + 4 wheel alignment at the main dealers the chap said mine has a slight vibration at 80mph. This was some years ago but still sticks in my mind as I know their preferred test routes which are max 60mph. That's similar to the OP's problem. Vibration at high speed only. Turning or disconnect/reconnect the props is guess work but it seems to have worked for some.

Could this fault be down to wheel balance being slightly out? Has a wheel been kerbed or mud etc built up on the inner edge of the wheel where the brake dust collects? I've never had a wheel out of balance but I have had mud build up when oft road.

The OP's vibration problem has now been resolved. Result in this fred:

http://www.landyzone.co.uk/lz/f9/update-vibrating-through-seat-274717.html