As above... how would you know if your prop shaft was nakered ? what would be the warning signs/ problems.... and how would you be able to test it.?

If you get the car on a ramp like the ones at an MOT station or at WIM, where you can jack up the
back axle independantly (& safely), engage the car in gear and slowly release the clutch whilst someone takes a gander.

It would vibrate like the world is ending IMO.

yes it would vibrate
they are carefully balanced so any discrepencies would be very noticable in driveability, and probably not visible to look at

Gearbox mount may cause same symptons, is it speed related or revs related?

Reason i ask is that ive got a bad vibration from 70mph and above

last week went to WIM and Tony found out i had 2 bad and flat spotted alloys so brought 2 new ones ......but although this stopped the steering wheel shakeing ive still got this really bad and annoying vibration through the car ...you can feel it through the floor pan Both passenger and driver seat.....even through the foot rest ......just cant see or got a clue as to what it is or what it might be........will change slide pins in front callipers ( just for peace of mind ) but cant really see it being that...

Any one have a clue ??

yeah i get a shudder sometimes when i put my foot down over a certain speed(worse when people are in the back). i thought it was the prop. but was told it was probably cos mine is so low.

my freinds car had a shaking problem at higher speeds and it turned out one of the front tyres had a blister on the tyre wall, it was on the inner side so not visable untill the wheel was off the car.

so best to get things checked first before you start spending your hard earned cash

Its speed related mate get to 70-80mph and its kinda a really annoying vibration.you cant hear it just feel it.......when you look in the rear view mirror its fine cant notice the mirror vibrating..but you can feel it in the seat and foot rest and floor pan.......

If it's only happening over a certain speed range it could simply be a case of your wheels not being balanced. I had a vibration between 60-70mph one of the front wheels were out of balance. Has one of your wheels thrown a weight? Did WIM balance your wheels for you, do you know?

I've got the same in my 300 sportx.

In a previous life (before Lexus) I had lots of propshaft problems - and as the theory is the same - here's a brief overview.

If the vibration occurs at slow speeds and feels like a flat-spotted tyre, then it's a sagging rear gearbox mount that's at fault.

If it starts at higher speeds normally 50+ then it could be the centre support bearing failing.

If it's neither of those then it could be wear in the CV joints. They have to be tight and notchy so that they transfer the power at the right time (in the rotation cycle).

Looking at the rear gearbox support bearing of the Lex, it's well designed and dosn't look like it'll sag. I've tried spacers to lift it but they made no difference.

The centre bearing is supported by a flexible rubber doughnut - if this hardnes (and eventually cracks) then you'll get the vibes you are experiencing. But, it's hard to check this without removing the prop.

Assuming that it's as well designed as the gearbox support then we can eliminate this and go straight to the CV joints.

If you remove the prop and they are loose (or the prop has lost one of it's balancing weights) then you'll need to send it to a place like The Propshaft Clinic (Doncaster way I seem to remember - have a look on the web) and they'll either replace them or tighten them - and rebalance everything - inc delivery budget for about £100 - £120...

Good luck

Jack

Cheers for that info Jack appreciate it.....will have a look into it ...

Seeing as it's 70-80mph I'd check wheel balance first because it's normally that speed where problems show up. Hopefully it's nothing serious.