Thud when on/off throttle

[M&S]

I've asked on another forum but thought I'd get some ideas from here...

TD5 Discovery, no CDL, pretty standard otherwise.

When I come off the throttle or go on it from off (so totally on or totally off, "feeding it" on or off is ok) theres a thud that I can feel in my seat base and it makes the vehicle a bit jerky.

Now, I have just fitted a rebuilt propshaft today and a lot of the knocks and clunks have gone (it was seized solid at the transfer box end) or calmed down, but this one still remains.

There is 10 degrees of backlash in the front diff, no more than there was a year ago.

There is 3mm front to back movement in the lower front shock bushes. Doubt this could cause the problem though - will change them anyway.

Rear diff, prop and donut are fine (diff only a year old).

It has been suggested that it could be bushes, anyone had this experience and could tell me which one to start with? I can't see or feel any play in any of them, and don't want to/can't afford to change a full set for the sake of it. Will work towards changing them over this summer, but if I could start with the right one that would be great

Cheers, Martin

[Yostumpy]

Try checking ALL the bolts are tight on the locating arms. I had about 50% loose, this cured it for me.

[FridgeFreezer]

Transfer box input gear splines can do this, new input gear is £50.

[RPR]

Before you get to internals, make sure you give your gearbox and engine mounts a through inspection. They go with some frequency and play in either might give you engine torque "thud".

[M&S]

Thanks for the tips, appreciated. Hadn't looked at the engine and gearbox mounts. I have checked the bolts but will check them all again, I might spot something I have missed when I'm back under there.

RPR - your "engine torque thud" describes it perfectly!

FF - Will check everything else first and then consider removing the transfer box. Wouldn't mind fitting a CDL when it is out, and replacing the idle shaft seal that's weeping. Cheers.

[Phantom]

Knacker 'A' frame ball joints knock / thud when on & off throttle, worth a pry-bar

Lee

[Phil Hancock]

Err, no A frame and ball joint on a TD5 is there?

[landroversforever]

Disco 2 has Watts linkage and arms like the front

[steve b]

..then the bushs in the radius arms must be a suspect?

Steveb

[M&S]

Thanks all, I was going to ask what was meant by the A-frame

I'm going to start with changing the front shock lower bushes because I can see that they are worn (and the MOT due next month), and then take off the radius arms and physically check the bushes in those. Work my way through a bit at a time, should make it more affordable - especially if I cure the problem early on

Cheers, Martin

[M&S]

Juyst to say, turns out it was the front diff in the end. Just took a while to properly show itself

All changed now, drives as smooth as ever!