300TDI Clunk only with diff lock engaged and driving.

[Lugslandrovers]

Hi
1998 Disco 300tdi auto box
Just been to Abingdon 4x4 and came away with a clunk.
Only happens when i have diflock low range engaged and driving off. not there all the time seems to happen going up and down lumps.
Drove it home normal with no clunks.
Some one said it was probably the CV joint but that would surely be there all the time.
Any Ideas please.
Also ABS sensor wont go out after i have reversed out of the drive. OK if i restart and drive forward.
Thanks

[crazymac]

The ones to check are the a frame ball joint, steering joints etc, but I would have thought that they would be MORE obvious in high?

[thermidorthelobster]

Len, you're in the same town as me.

My Discos have ALWAYS clunked in low box.  Are you sure it's anything unusual?

Re your reversing problem, check your ABS sensors, maybe one has got caught by a bit of dirt and is getting knocked when you're in reverse.

[Lugslandrovers]

Thanks Guys
But the sound is more like a snapping twang and only in low diff lock when moving. not changing gear as it happens when manual 1,2,3 gears selected.
Not the usual clunk that all suffer from when changing gear etc.

ABS sensor can i take it out and clean it with out upsetting the programming?.

thermidorthelobster
Fancy a pint some evening.
Email me.

[L90OOK]

Thanks Guys
thermidorthelobster
Fancy a pint some evening.

thermidorthelobster is T-total  :lol:

He does have a nice new NANOCOM though  

As for you clunk... :? I would take it back to Abingdon 4x4 & ask them to sort...at least call them & log the fault with them.

[Lugslandrovers]

Thanks
But Abingdon 4x4 was actually an off road event .Not a garage. It happened whilst i was getting muddy doing what all land rovers are supposed to do.

[Jimbo]

But the sound is more like a snapping twang

Shot in the dark here - you sure it's not a coil spring relocating ?, I can't explain why it only happens in low-diff lock, but coils do make that sort of noise you describe.

[Lugslandrovers]

Hi
Could be the springs but they have not been lifted although i think they and the shocks are about had it.  Job for me in the next two weeks.
Just took it for a short drive in low diff lock and guess what the noise is not now there. Suppose i will have to leave it until i am doing the 2"lift and have a good look with a crow bar.

[TDi90]

As for you clunk... :? I would take it back to Abingdon 4x4 & ask them to sort...at least call them & log the fault with them.

yes i think you should go and ask the big bomb hole why it is clunking  8)

haha silly billy  :roll:  :lol:

[boss]

first thing that springs to mind is "transmission wind up".(stopp me if im wrong) the idea of fitting a centre diff is so the car can tirn around corners as the front and rear wheels spin at different rates while turning(because the circumfrance of the front wheels is greater than the rear while turning).
the obvious problem with this is that while offroad the centre diff will distributr power between the axels differentley which isnt what you need(bare with me im not trying to teach you something you alredy know) so the centre difflock is imployed which negates the original application off the centre diff, so if you were to turn a corner with the diff lock in the forces applyed on your running gear are enormous, usually what happens things will twist a little then work its self out while spinning in mud ect.worst case scenario this could snap half shafts, cvs, propshafts, ujs, kill your gear box or your centre diff. it doesnt usually happen in discos more in the series models but i would say thats what happend. did you turn on tarmac atall?

[crazymac]

first thing that springs to mind is "transmission wind up".(stopp me if im wrong) the idea of fitting a centre diff is so the car can tirn around corners as the front and rear wheels spin at different rates while turning(because the circumfrance of the front wheels is greater than the rear while turning).
the obvious problem with this is that while offroad the centre diff will distributr power between the axels differentley which isnt what you need(bare with me im not trying to teach you something you alredy know) so the centre difflock is imployed which negates the original application off the centre diff, so if you were to turn a corner with the diff lock in the forces applyed on your running gear are enormous, usually what happens things will twist a little then work its self out while spinning in mud ect.worst case scenario this could snap half shafts, cvs, propshafts, ujs, kill your gear box or your centre diff. it doesnt usually happen in discos more in the series models but i would say thats what happend. did you turn on tarmac atall?

Slightly right! when going around a bend the wheels turn at different speeds side to side, not front to rear! so therefore the centre diff allows this to happen and not "wind up" the transmission.

When off road you lock the centre diff so that the power is distributed evenly, so if one wheel has traction then that will help get you out. equally if you have wound up the transmission then it can unwind by spinning in the mud (or generally loose surface)

Where people make mistakes is they automatically engage diff lock just cos they are off road! Thats not good as you could be on solid ground. Diff lock should only be engaged when you are "likely" to loose traction.

If the clunking or twanging is not present when you run straight in diff lock, it would suggest that it is not transmission wind up unless off course it has solved itself already, when you had this happening what sort of terrain were you driving over? if the axle was articulating it is entirely plausable that the bottom securing plate has come loose (rusted!!) and so when given the opportunity the spring will waggle about.

try jacking the body as high as you can ( a highlift jack would help here) so the axle dangles and you may see?

otherwise as you say, sort out the lift and have a look then!!

[Lugslandrovers]

Thanks
No this happened just i as i started through the off road course although it was quite a hard surface in places. But you do have me thinking. Maybe it got wound up on the hard surfaces. I pulled out before the end of the course onto taramac and it did it then. I stopped changed to high diff/normal and was ok no knocks or twangs. Just tried it this afternoon twenty yds on tarmac forward and reverse up the kerbs and no noise.

[SteveGoodz]

Slightly right! when going around a bend the wheels turn at different speeds side to side, not front to rear! so therefore the centre diff allows this to happen and not "wind up" the transmission.

When cornering all four wheels are rotating at different speeds. If the front to rear speed was the same then the centre diff wouldn't be needed. The axle diffs enable side to side speed differences.

[boss]

Slightly right! when going around a bend the wheels turn at different speeds side to side, not front to rear! so therefore the centre diff allows this to happen and not "wind up" the transmission.

When cornering all four wheels are rotating at different speeds. If the front to rear speed was the same then the centre diff wouldn't be needed. The axle diffs enable side to side speed differences.

exactly!

[crazymac]

Slightly right! when going around a bend the wheels turn at different speeds side to side, not front to rear! so therefore the centre diff allows this to happen and not "wind up" the transmission.

When cornering all four wheels are rotating at different speeds. If the front to rear speed was the same then the centre diff wouldn't be needed. The axle diffs enable side to side speed differences.

exactly!

I won't argue cos I don't know enough  I was always told the difference was side to side, but I suppose there is some sense in front to rear as well??