Unusual intermittant vibration

This problem is on my 1990 td[now with 200tdi, been in 2 years]and happens only at speeds over 40 and only for in the moment of no load between accelarating and deaccelarating and to a lesser amount the other way.It is a resenaunce type vibration and for a short time can be quit strong.Have checked the usual suspects, ujays, trans box outputs,diff inputs,have swapped props for others i have also run with props off in turn,no change Landy has done 140 000 mls gearbox/clutch renewed 4 years ago the rest of the transmition is original. Any one else had this? and if so what the heck is it?

swap wheels front to back

engine & gearbox mounts

could be steering damper or worn swivel pins

Have changed engine mounts but not gearbox,will try that. Steering damper and swivels are good. Have swaped wheels[got two sets on and off road]no difference.As you may have guessed been trying to sort this one for some time,so when I get a mo new gearbox mounts it is,I will let you know the outcome.

The vehicle has not been raised has it? maybe if it had and a doggy gearbox mount or if the new engine had lifted the gearbox it could ave put the drive shaft phasing out.
My father use to have a 98 range rover that would get a shudder at times on motorway. it would not happen all the time but every now and then it would be bad enough you had to slow for it to go away
it ended up being a steering idler worn out.

Could be wear in the transfer box bearings it it has high mileage

you can sometimes get something similar with worn intermediate brgs if you drop t/box sump and feel for end float in gear you can remove it by tigthening 30mm nut on rear of t/box with large bar enough to remove float but not too much to load brgs

jamesmartin said:

you can sometimes get something similar with worn intermediate brgs if you drop t/box sump and feel for end float in gear you can remove it by tigthening 30mm nut on rear of t/box with large bar enough to remove float but not too much to load brgs

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I think you could be on to somthing James I renewed the o rings on the intermediate not so long ago and just put the nut back in the position it was,I will try what you say.Thanks

you cant just put nut back without knowing how it works the gear runs on 2 x taper brg seperated with collapsible spacer so can be tight but brgs loose ,as said remove sump feel end float as you tighten and remove then rock gear and feel you dont load it to much and make it stiff

Ok will do it as you say,thanks John

jamesmartin said:

you cant just put nut back without knowing how it works the gear runs on 2 x taper brg seperated with collapsible spacer so can be tight but brgs loose ,as said remove sump feel end float as you tighten and remove then rock gear and feel you dont load it to much and make it stiff

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Did it just as you said took up a small amount of slack,gears still easy to turn by hand,re peened nut in new position,no play in input or output gears.Did not solve problem vibration still there.will try new mounts ,one looks iffy.

well at least youve prolonged t/box life.how does vibe feel thru transmission or vehicle

Have finaly found the cause of the vibration and to some extent it was of my own doing.Just before last xmas for a few tokens got a hold of 2 s/h rear shafts in good nick,and replaced my manky shaft with one of them,but the next day fell ill with the swine flu and was out of action for next three months,forgetting I had changed the shaft when I started driving again.However I did swap to the second shaft but it was the same and I was stumped,then the other day I spotted the problem, out of alinment ujays/journals and would you belive it the first shaft had also been incorrectly put togeter together.Aha well live and learn,thanks to all responded.