I could be being over sensitive, but have noticed recently that when slowing to 50mph and then driving at that speed, I start to feel an increase in vibration coming from the drive train. Also noticeable if getting up to 50 and pootling along in top gear @ 1800rpm.

Just old age, just my old age , or the start of something? recon box fitted 80k ago, tranny oil changed twice since then. Thinking might be something to do with the torque converter ? .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Did you fit new wheels/tires?

Mine does this around 50 through 60 then stops at 70. Started happening after I put on the 22s and new tires I put on. I'm thinking its more to do with the tires. 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

Check those dreaded rear brakes for overheating/binding, as a starter for 10  There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

If it happens around 50 and speeding up or slowing down a little stops it, then i would start by getting the wheel balance checked. Even if the tyres aren't new, balance weights can fall off or pot holes can knock them out of balance a bit.

There is no vibration or wobble on the steering... Will check rear brakes, though. Not changed wheels or dyes for ages! Away for a few days so may be a few days before I can report back. .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Mine is similar as there is no wobble or vibration in the steering wheel. It is like a hum/resonance under the floor board/in the pedal that I can feel around 60 MPH and goes away once I hit 70 or drop below 55 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

I had this exact same issue and it was the TC, once it was replaced all noises gone. It's the lock up cloth that is disintegrating in the TC, between 50-70mph the lockup clutch starts to engage to lock the engine and gearbox together mechanically. When the clutch can't be engaged fully it makes like a vibration/drumming/cattle grid sound. For me it sounded like it was coming from the rear of the vehicle.

Hope this helps

Matt

What's the TC? I only seem to notice mine though after I put in the 22s. Maybe I didn't pay attention with the stock 18s.

How expensive was the fix? 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

TC = torque converter

The L322 especially the 3L TD6 was never designed or intended to have anything bigger than 19" wheels the 4.4 V8 petrol was the only model at the time to have 20" wheels. Butting bigger wheels on will adversely effect the gear ratios.

Matt

Someone explain the science? If correct tyres are used the rolling circumference is the same. How does this affect the gear ratios? I have been running on factory fitted 18" wheels for the last two years, prior to that 20" with correct tyres. I do think it may be the TC though  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

There is loads of cases and info about this issue on the site and on the Internet in general. This is a site I found for a quick search talking about the vibrations caused by larger wheels.

http://forums.lr4x4.com/index.php?showtopic=15803

In answer to your previous question my TC replacement and a gearbox refurbishment was about £1400 for my 4.4 petrol

Matt

^^ oh man....Not looking forward to that kind of pricey repair. Will it (TC) eventually fail if I keep the 22s on? I plan to go back to the 18s for winter. 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

Once the TC lockup clutch has started to fail you can't really stop it, the only thing u can do is replace the unit when the vibrations get bad.

Matt

So the TC is only "engaged" at the the 50-70 MPH range?

I guess the good thing is I don't do much highway driving to/from work. There is only one stretch of road about 2 miles long where I get above 50 and generally take it to above 70 so the noise stops. On the rare occasions I'm on the highway I am above 70 anyway. 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

the lock up clutch only starts to apply at around 50mph and above.

if you do a search on this site you will find lots of threads on the topic as its a very common issue

Matt