Disco 2 Droning vibration starts at about 60mph

Disco 2 TD5 - runs great with new road tyres. Once it gets to about 55mph it starts to drone and a definite vibration starts under the seats. Steering has zero vibration.

Am I right in thinking it's likely to be a propshaft UJ? Is there one in particular or will it be obvious when I crawl underneath and start flexing them?

First thing to check is the condition of the "rubber doughnut" flexible coupler on the diff end of the rear prop shaft.

Thanks - will check it in the morning - are they hard to replace?

Also what is the best one to buy - they range on eBay from £10 to £50 - is a GKN one OK?

GKN is OK. when you do replace it, make sure that you fit it the right way round.
Yeah, I know, a round coupler with six holes what could possibly go wrong?
On the side, by each hole you'll see a little arrow shape, Those arrows must point towards the flange you're bolting it to. The centre bush is a right bitch to remove, so if this is the first time you've replaced the doughnut and the centre bush looks generally sound, I wouldn't bother to change it this time round.



Very small amounts of play in the U/J's can be taken up by greasing them fully, the same goes for the sliding joints in both prop shafts. The sliding joints have little bolts blanking the grease points which must be removed and a grease nipple fitted to grease them. Replace the blank plugs if you wish after doing it. I didn't bother, I left the nipples in place with no adverse effects.

Excellent - looks easy enough and I'll see what state the spigot is in - hopefully it's ok

Thanks loads!

Thanks for your help on this.
Removed the old one which was a GKN and it was quite perished - not sure if it was perished enough to cause the problem but worth changing and I'll be doing some motorway driving on Wednesday to test.
I could only get a Bearmach coupling and it didn't have any marks on it whatsoever and I couldn't see any noticeable difference from side to side - but after installing and tightening up with the torque wrench, I was a little concerned that I could see the metal inserts pulling through the rubber.

Also the centre bearing was a little loose on the spigot and despite my best efforts it wasn't budging - so I left it as is - I may pull the propshaft off again if I feel that it hasn't fixed the problem and either find a puller/extractor or an engineering shop.

@SteveClv

looking at that piccie and the diagram above, Are you sure you got the do-nut in the right orientation.

It looks to me like you have it on the wrong bolt holes.

Cheers

I did think that - but the handbrake was applied so the propshaft was locked and the differential flange of course cannot move - so there was only one way for the coupling to fit. But it didn't quite match the diagram.

Actually I just realised that it is wrong (bum) - if you think about it, the normal movement of the propshaft is clockwise (looking from behind) to drive the wheels forward and so the thicker part of the doughnut is being pulled and the thinner part is pulled when reversing - so yes, I'm going to have to move it.
I hate doing a job twice!!

SteveClv said:

I hate doing a job twice!!

Click to expand...

Look on the bright side, at least you know how to do it.............Watch your head.....

Cheers

LOL - lesson learned!

All fixed - as you say, I know how to do it now

has it solved the vibration

Yes, did a 500 mile round trip at 70mph and it cured that vibration! Not that she is silky smooth but quite happy at 70. Also returned 34mpg so very happy with that although I was a bit of a numpty and put 10 litres of Unleaded in before I realised what I was doing - topped up with diesel, ran it down to half full and topped up again and seems to be ok