Thread: D1 drivetrain clunk

Hi All - in a bit of a dilemma and unsure what to do next.
My 98 V8 auto disco 1 has developed a loud driveline clunk when changing from forwards to reverse while the car is stationary.

Background on the car -
bought it 6 months ago, drives smooth with no road noise.
smooth changes in the gearbox
no issue with transfer case or high/low selector

A month ago I changed out the front diff for a truetrac (changed the diff carrier bearings and pinion seal) - no vast change to the vehicles behaviour other than the steering would straighten up when coming out of corners (expected with this diff) and have driven ~1500kms on it.

On the weekend I changed out the rear diff for a detroit locker (once again changed the carrier bearings). put the car back together and checked the diff for correct operation according to the manual - all worked fine.
Went for a slow drive around the block and other than the mild clicking from the detroit there was no change to the car.

Drove the car 5kms that day, then 5kms the next day to a mates house.
When reversing out his driveway there was a clunk that sounded like driveline slop when selecting reverse.
selected drive and there was a lesser clunk, but still there.
tried shifting between drive and reverse while the car was stationary, it felt like the front axle was trying to escape from the car!
i wasnt sure why the front was making noises as i had just changed the rear diff.....

had a look under the car while my mate changed it from drive to reverse, the front diff definitely had a loud driveline bang - so I thought it was the culprit.
Drove the car home and it behaved well on the road, no abnormal noises.

So once home got underneath the car - I assumed the rear diff was the culprit as it was the last thing I changed but was unsure why the front diff was making the noise.
I had the car in neutral and tried twisting the driveshafts by hand, the front moved more than the rear - approx 30 degrees compared to 10 degrees.
No major slop in the rear wheels or diff.
I jacked up the front wheels individually and jiggled them forward and back, and there was slop, but nothing I thought worrying.
Have just pulled out the front diff to inspect - no noticeable faults or slop.

Now twisting the driveshafts (with the front diff disconnected and rear connected with wheels on the ground), there is quite a bit of slop in the front driveshaft (~45 degrees) compared to rear (ie through the transfer case) - I tried locking the centre diff, and there is still slop.
I found that even with the centre diff locked I was getting ~20 degrees of 'differential' action before both driveshafts moved the same direction in a locked manner.
I felt this slop could be the cause – Im hypothesising when selecting drive/reverse the gearbox starts to spin the transfer gears creating momentum, when it runs out of slop it jolts and the minute amount of slop in the front diff makes a loud bang..????..

Another test - Jacking up the rear wheels with the centre diff lock engaged in high range and the gearbox in neutral - it needs a medium force to turn the rear wheels forwards but a STRONG for to turn the rear wheels backwards??!!?? I was unsure why this could be?

I have read issues about the output shafts on the transfer case – this is my next check, but will have to wait till tomorrow.


Anyone have any ideas, or recommendations…..i don’t want to have to change my diffs back to the original centres to isolate the slop

Steve
(sorry for the long post)

yeah mine clunks too