Funny noise in 4wd

[philfree]

Hi
I have a 2000 gu dx 4.2td ute ive only recently got the car. It drives fine in 2wd i took it to the beach about 3 weeks ago and when driving through the very soft sand sounds like from the rear you will hear a sorta bang sounds similar to a rock being smashed i think when this happnes the whole rear of the car gets unseattled and it surges forward. But being in the soft sand under the tide line i want going to stop to check. i went again last weekend forgot about the noise went for about 2 hours in low range up some tracks was fine then came back though soft sand did it again like last time. ive now had sunrasias fitted and they have for a more woren tyre on one side at the back then the other i tried 4wd on gravel and it makes the noise a fair bit but only surges the car forwards.
Can any one help me im getting worried it might fail on me when i need it to get me out of trouble.
Thank you

[Bigrig]

Sounds like one for Paul, Tony and crew - hang tight mate, someone will be able to offer some suggestions.

[AB]

Hopefully someone can help you out mate. If it's happening in low would it be possible to have someone walk behind you try and identify the clunking area maybe?

[Killametre]

Never had a patrol tranfer case apart but if they use a morse chain in there (and I think they do) it can exhibit that sort of symptom if it is stretched and jumps a tooth, I have seen this in ford/mazda utes and ford explorers that have done a bit od 4WD on hard surfaces or with missmatched tyres. happens worse on turns when driveline winds up

[philfree]

Thanks that fits into what im hearing but still very open into others opinions Also it does it in high and low range.

[boots]

phil you have written worn tyre on one side than the other. how much of a difference is it ?

[philfree]

well i should add that it started when they where all pretty similar i then had the wheels changed and one back is like 30 % other back maybe 60% and it's got worse don't know if the problems getting worse of the wheels have changed things it's also got a different brand on the front and their abour 70 - 80%

[boots]

checked your tailshafts - uni joints and slip joints . how many km's on it ? service history with oil changes ? and a ute - spring leaf or coil ?

[philfree]

its done 290000 i checked unis recently and good look underneath all looked good it dosent have log books but been serviced all the time its leaf rear coil front

[Dozer]

i may have the reason for the sound for you bud. A while back i drove my "old" GQ up to double island for the day, that afternoon we went home through high tide and the first bit of soft sand i hit in H 4wd the truck had this wierd winding up sensation and the followed by a bang that scared the crap outa me. Pulled over and had a look around to find that one of the kids had been screwing with my fron left hub and it was half engaged. I locked the hub up and went for a bit more until the next bit of soft sand and then bang again with that wierd winding up kinda sensation again. Pulled over and she was half out again.

I too thought it was from the rear but ended up being my hub. Strange thing is i got home pulled it appart and no damage was to be found! i cleaned everything back up, re greased and threw it back together only to never have it happen again. Might be worth a look as it sounds exactly like what you have mentioned.

It also didnt do it in Lw4d only in high for some reason.