Hi guys,

When I put the dual transfer cases in my Pajero, I had 2 custom shafts made up, front & rear.

They both had to go back for a rebalance & the front one went back for a rebuild as it had 40thou runout.

The rear shaft has 11 thou runout at the transfer case end & the front one still has 12 thou run out.

I still have vibes when I run the car in 4wd highway mode, no vibes that worry me when I run in 2wd with front axle disconnected.

Heres my theory,

Most sources seem to indicate that 12 thou is 'within spec' for run out tolerance on driveshafts.

If so then why do I have vibes in 4wdh? My theorey is that whilst one shaft with 12 thou runout may not produce vibes, 2 shafts with 12 thou runout each however running at the same time, tip me over the tolerance level & hence I get vibes? What do you guys reckon?

The driveshaft guys say they cant get the tolerance any lower (cheap arses they are), so I am in discussion atm with Tom Wood over in the US to make me a custom front shaft.

I also believe that others who have done this mod, ie dual cases, have used the NP231 which doesnt have the highway 4wd mode, so shaft vibrations may not have reared their head since the NP231 doesnt run in 4wd on the highway. Does this sound reasonable/

cheers