Transmission Clunk while Acceleratiing

[kingscoop]

When accelerating hard, up a hill or with a trailer there is a banging / clunking noise coming from the transmission. The harder the acceleration / steeper the hill the louder it all gets and with a heavy trailer going up a steep hill it all starts to sound very worrying and I have to take my foot off the gas because I'm scared of busting something. Sometimes I'm able to drop a gear and it all quietens down a bit.
Accelerate gently and there is no clunking at all. The clunking happens at the rate of nearly twice per second and has disappeared by the time I've got to 40mph or so. The best description of the noise is that it sounds like you're driving over the expansion joints in a concrete road.
Looking at other posts recommendations include looking at UJ's but there seems to be no play in them at all - I would expect a clunk when decelerating as well as accelerating.
I know that the 4x4 shift motor is out of alignment so I always leave the car in auto, I never use the 4x4.
Any help would be gratefully received.

My Explorer is 1999 UK spec.

 

[ThisVman]

Transmission Clunk on 1999 UK Spec Ford Explorer

When accelerating hard, up a hill or with a trailer there is a banging / clunking noise coming from the transmission. The harder the acceleration / steeper the hill the louder it all gets and with a heavy trailer going up a steep hill it all starts to sound very worrying and I have to take my foot off the gas because I'm scared of busting something. Sometimes I'm able to drop a gear and it all quietens down a bit.
Accelerate gently and there is no clunking at all. The clunking happens at the rate of nearly twice per second and has disappeared by the time I've got to 40mph or so. The best description of the noise is that it sounds like you're driving over the expansion joints in a concrete road.
Looking at other posts recommendations include looking at UJ's but there seems to be no play in them at all - I would expect a clunk when decelerating as well as accelerating.
I know that the 4x4 shift motor is out of alignment so I always leave the car in auto, I never use the 4x4.
Any help would be gratefully received.

My Explorer is 1999 UK spec.

 

[ThisVman]

I have just returned from holiday in Dorset towing a caravan and appear to have your identical problem, mine seems to be like a limited slip diff clunk coming I think from the N/S/F, If and when I locate the problem I shall be in touch, in the meantime good luck.

 

[gijoecam]

Is it a 4x4? If so, it could just be the normal operation of the transfer case. To verify that, unplug the connector near the transfer case shift motor, and see if the problem persists. If it goes away, that's what's causing it.

FWIW, mine's done it since day-1. They all do it. Some are more noticable than others, but they all do it.

 

[ThisVman]

thanks for information on transmission clunk, Vince.