Thread: Transfer case

Originally Posted by whitey56

Answers to a couple of questions please.
Is the wear on the CDL thrusts dependent on the amount of locked 4wd driving or will it still happen with tarmac miles.
With no oil contamination during their life what K's would you expect out of the thrusts with mostly tarmac driving.
When the thrusts are worn to the stage that they need replacing {not buggered} is the play that noticeable on the output flange compared to a good CDL.

Thanks for any replies.

As Rick points out not using the CDL appropriately when 4WD'ing will lead to accelerated wear of the centre diff thrust washers. It's also worth noting that most D2's don't have an operational CDL, only the D2a's.
The centre diff thrust washers are wearing all the time regardless of terrain covered, the amount of wear is determined by km's traveled, and load on the vehicle/centre diff ie towing, acceleration or hard off road work.

Locking the centre diff doesn't remove its slop from the rear drive train.





In 'normal' operation the centre diff carrier assembly rotates and delivers drive via the spider gears and side gears to the front and rear drive shafts, just like any other diff. When the CDL is activated the two gears shown are coupled, effectively joining the diff carrier and the front drive shaft together. This stops the front drive side gear(in the centre diff) from rotating which stops the spider gears from rotating and effectively disables the centre differential action. Drive to the rear diff is now fed via the 'locked up' centre diff gears. Any 'slop' in this drive path ie. worn side washers is still there.

It doesn't take much to wear the bronze side washers and instill a bit of 'slop' to the drive train eg. my 2002 D2 has done 160k Km only, never towed or been off road or even used low range, it's been a 'shopping trolley' all its life and it has slop in the centre diff, not much, but it's there.

Comparing the slop between a 'good' TC and a worn TC is quite easy if you have CDL and a good one to compare it to . What I do is activate the CDL and see how much I can rotate one drive shaft with the other one held. About 45 degrees is normal and with a good centre diff the pre load should be obvious. Disconnecting a drive shaft(s) is important to ensure full rotation isn't restricted by an axle diff. Without a CDL it's a bit more difficult as you need to 'feel' the take up in the centre diff.

It's worth noting that drive train slop is cumulative ie. front diff, centre diff and rear diff all wear and contribute to overall slop. As Rick notes ............ "IMO the best fix for this is an Ashcroft ATB...

It also takes so much backlash out of the t/car it isn't funny".

A characteristic of an ATB/Torsion type diff centre is that it effectively 'winds up' the drive train slop to give the feel of a slop free drive train. Whilst this might give a more 'enjoyable' driving experience with the benefit of a more efficient centre diff the downside is that it can mask the effects of wear/out of mesh in the comparatively weak D2 Rover diffs leading to avoidable failure. IMO using the ATB/Torsion diff to disguise the symptoms of wear could be a double edged sword.

Deano