Another annoying bump

OK, here we go again.
This has been going on for a while now, and I buggered if I can track it down.
When I am turning into a tight right hand junction and drop into second gear then proceed into the turn I get this damn annoying bump bump bump bump in quick succession, I can feel it under my seat as if somethings knocking against the chassis where the seats mounted. I've been under the car 3 or 4 times and just can't see anything remotely close enough to be touching the chassis. I've waggled the exhaust violently and no bumping there, I recently changed the front diff mount which was knacker ed hoping that would cure it along with the changing gear bumps, and whilst it cured that, this other bumping persists. I checked the rear 2 diff mounts, and they seem OK.

Also, what is the function of the vertical donut rubbers on the rear diff mounts? they don't seem to do anything.
Any thoughts chaps?

I had something similar on my 1.8 when I first got it and traced the fault to the exhaust downpipe bracket not being attached to the sump, 2 bolts screwed in and all was well, not sure if the TD4 has a different exhaust mounting system though

im thinking drive shaft cv joint, as there isnt much else it would be , although noises can be transmitted and difficult to trace,
may be worth checking engine mountings too

Thanks chaps.
I'm pretty sure it's not the exhaust or the cv's, it's definately something hitting the chassis, just really difficult making it do it without actually driving. Engine mounts are a possibility I suppose, I'll look into them, though it does seem to be mid or rearward rather than foreward. Might even change the rear diff mounts just to be on the safe side.

Another sugeston would be the wishbone bushes or ball joints. Better to get the unit as a whole with the bushes otherwise your be there all day drilling rivets and pressing bushes.
I changed one of mine a few weeks back as the noise started getting on my tits, felt n heard like a heavy thump against the chassis.

Not saying that's its the wishbone on ur car but uve got the exact symptoms I had.

Andrew, I've got a similar 2nd gear knock, which to me seems like a selector linkage fault, which I shall check out after I've removed the props to repair the VCU. Hopefully I'll do it in time to report back on here

Hi, had the exact same thing on my 1.8, changed the drop links, these attach to the anti roll bar, and problem sorted. They did not look or feel worn and I had to insist my Honest mechanic change them on the off chance (£55 all in). Worth doing the antiroll bar bushes at same time as they are also cheap and very easy.

As you turn into the corner you get a donk, donk, donk, donk, noise particularly if the road is off camber, and sounds like somethings gonna fall off sooner or later, it will get worse! Generally quiet in a straight line. Two Mots never picked it up and it was on the 2nd visit to the garage I told the guy to do the drop links after a suggestion on here.

Oh, forgot to say, on the antiroll bar there should be 2 round sort of plastic washers about 10mm wide and 3 mm thick, these sit immediately to the side of the clamps that hold the bushes in place. They stop the bar moving from side to side and clonking on the suspension apparently. My moneys still on drop links but you can easily see these washers with the bonnet up to rule them out.

Hmm, thanks for the help chaps, but I'm not convinced, the bumping just doesn't seem to be that sort of suspension noise, sounds like something far more solid, I can feel it as well as hear it, almost like someone hitting the floor pan with a lump hammer, and I'm sure it's not from the front.
I will have a look at it though, just to be on the safe side.

rear box? fuel tank? both on the offside rear...??? you'll be amazed how a sound can travel thru the body....

i will second the quote about sound travelling through a car body ,
a few years back while i was driving along i thought i could detect a thumping noise from under the car, it turned out to be a loose ladder rack clamp on the roof,

good luck

rear subframe mounting is known fault from memory

Agreed, but I've checked and re-checked the exhaust system mate.
My latest theory is possibly the bearing mounts on the vcu. It's a big chunk of spinning weight and is on rubber mounts, which on inspection seem quite soft and movable, so I'm thinking of fixing up a web cam under the car to try and get a video under proper working conditions. Have to get a web cam first though as mine's part of the laptop.
Watch this space.

OK, I've sussed it.
It's the VCU support bearings.
I layed down beside the landy and slid a leg under and against the prop shaft next to the rear VCU bearing and pushed a few times. I got the exact same bumping noise, as I assume the bearing is hitting against the inside of the bearing bracket. The rubber mounting around the bearing housing must be shagged.
Ahh well, guess that's another trip to my parts supplier and another weekend rolling about under the freeby. The joys of owning a landy eh?

Make sure you get good quality or OE bearings or you will be changing them again in a few months.

Will do Nick, thanks.