I have a really strange issue with my 04 disco I was driving and I started to hear this strange noise a vibration but just sounded strange then all of a sudden I started to get a vibration that I swore was my tire coming apart. I pulled over right away and checked and nothing ran my hand over all tires no bubbles etc.
It is NOT coming from the front end no steering wobble etc. the rootflex was replaced last year...I have a heavy duty front shaft that can be lubricated but when you put in gear there is no noise nothing.
I pulled back onto the road and it was fine no noise no nothing until I got to about 50 then I felt a vibration going through the car...felt like either under me or from the back go faster it got worse I slow down it is still there but not hardly go slow Nothing I am totally stupmed any ideas? it is Not coming from the front I have felt when ball joints etc go bad the steering wheel shakes etc this the steering wheel is rock steady no noise from the engine that is not normal thanks in advance

 

Could be a drive shaft issue, if a balancing weight came off but that is generally RPM related.
Could also be a bad rear tire, check all your lug nuts as well

 

whats really strange is I can go down a dirt road at 40 as smooth as silk 30mps smooth as silk above 45 start to feel it slightly 50 to 55 max go above that and it gets very bad So strange feels lke it is coming through the center console but it is hard to gell but from the back for sure but to be smooth as silk on a damn dirt road at 40 not a vibration but 50 and it starts rotoflex is less than a year old so weird

 

Vibrations felt at certain speeds only, because of self resonance of a moving mass, which depends on frequency of oscillation (rpm). Who is the manufacturer of the rotoflex? Some people have reported here that cheap ones fail quickly. I replaced mine recently, no problems so far. GKN (made in Germany, embossed on the rubber) is the recommended manufacturer.

 

Check engine/Trans/TC mounts

 

Check missing nuts holding the heat shields above mufflers...