Thread: Transmission Talk

My LT230's never gave any trouble (except leaking) from behind my engine. I swapped the original 1985 1.22 version for another 1985 1.003 version about 5 years back.

Doesn't most of the play come from the centre diff?

Hey Dougal I have a serious lack of knowledge in this depart however the centre diff is part of/ bolted to the t/c right???

If I had excessive play and decided to have the t/c overhauled, would this include overhaul of the centre diff or is that regarded as separate job?

I'm not sure if I can describe this properly but here goes:

Apart from the obvious movement in the two prop shafts as I described earlier, there is a clunking sound and (also shunting felt through the vehicle), presumably somewhere in the transmission, when traveling in either forward or reverse both clutch in/out. This is most prominent when moving slowly. e.g. when free rolling backwards down a gentle grade.

From the drivers seat it feels like the props are trying to rotate at different speeds i.e. one is rotating slower than the other causing the faster one to 'catch' up to the other 'clunk clunk'.

Applying the brakes seams to settle it a bit.

Is this an obvious symptom of slack in the centre diff?

Cheers,

How much is done in a transfercase overhaul will depend on who is doing it and what they consider necessary. I have never had to open up and work on my centre diff, but it is located in the forward snout of the LT230.

Clunks in landrover drivelines can be really hard to track, main because there is a litte bit everywhere. Front diff, front CV's, rear diff, both propshafts, centre diff, LT230 input gear splines, gearbox output shaft splines. It can even be suspension related (rear ball joint).

Originally Posted by 110Landy86

......

Apart from the obvious movement in the two prop shafts as I described earlier, there is a clunking sound and (also shunting felt through the vehicle), presumably somewhere in the transmission, when traveling in either forward or reverse both clutch in/out. This is most prominent when moving slowly. e.g. when free rolling backwards down a gentle grade.

From the drivers seat it feels like the props are trying to rotate at different speeds i.e. one is rotating slower than the other causing the faster one to 'catch' up to the other 'clunk clunk'.

Applying the brakes seams to settle it a bit.

Is this an obvious symptom of slack in the centre diff?

Cheers,

Actually, it is more likely to be a symptom of a dragging handbrake, usually because a little bit of oil is leaking onto it! The major source of slack is likely to be the thrust washers in the centre diff, although there are a lot of other places that could contribute, but unless the handbrake is dragging or driving techniques is very bad, it is usually not apparent. It only becomes apparent when the slack is suddenly reversed, which rarely happens unless the handbrake is dragging. In this case, it is reversed whenever the clutch is disengaged.

John

To remove the centre diff just remove the front tail shaft and then remove the front cover snout off the transfer case and pull put the c/diff.

Just remember, if you're going to do donuts in a land rover do it CCW, otherwise all the oil moves away from the centre diff and it explodes (literally) and blasts the snout cover off.

Originally Posted by 110Landy86

Ppl, did all LT85 gearboxes in the 110s have the same final drive ratio or did they vary from year to year.

What is the average design life of the LT230 t/c behind a 4bd1.

Reason I ask is that the t/c has never been touched and with noticeable amount of 'slack' somewhere in the transmission I'm thinking rebuilding it may be priority over other components.

I can turn by hand either the front or back prop shaft about 3/4 of a rev before meeting resistance.

Thanks.

Large slack is normal for Land Rover transfer cases - the gearing (side gear to pinion gear) in the centre diff doubles the motion when you turn one driveshaft while the other is stationary (with normal driving both front and rear shafts rotate together and no such affect occurs from center diff).

Generally two areas cause play in the LT230 and both relate to the Centre Diff:
The first being centre diff wear of the spider gear bushes and normally only occurs if the vehicle has been allowed to spin excessivley without the centre difflock in. The spinning action forces the oil away from the spider gear bronze/cooper cup bushes and leads to accelerated wear. If you use your diff lock going up hill and in mud then this should not be a significant factor.

The second is the dog clutch that bypasses/overrides the centre diff operation with the diff lock engauged. This is a loose fit collar with eight (?) dogs on it that has an inherntly large amount of movement when in anyway.

Now what to do about it - It costs about $350 in parts to overhaul an LT230 with no significant wear other than bearings and shims - do it yourself. When to do it is the question, and for me when it starts to become noisy and the whining is driving me mad! Due to the second reason above it is hard to remove all the slop from these transfercases.

One quick test is to measure the amount of turn (slop) in the front shaft (one front wheel lifted off the ground) unlocked. With the diff lock in do this again, if the second is less than the first the centre diff needs work. This can be done with the T/case in the car but its a pig to put the centre shaft back in!! Shim the centre diff as per the manual when puting it back and the car will feel tighter. Regards.

Originally Posted by 110Landy86

Ppl, did all LT85 gearboxes in the 110s have the same final drive ratio or did they vary from year to year.

What is the average design life of the LT230 t/c behind a 4bd1.

Reason I ask is that the t/c has never been touched and with noticeable amount of 'slack' somewhere in the transmission I'm thinking rebuilding it may be priority over other components.

I can turn by hand either the front or back prop shaft about 3/4 of a rev before meeting resistance.

Thanks.

Thanks guys this is all so helpful!!!

How much whine is too much is subjective but to give you an idea, I struggle to hear the Isuzu when it's sitting on anything lower than 2000 rpm (minimum) It has been getting worse overtime but its gradual and ive learnt to live with it...to a certain extent. After all the vehicle is 25 yo!!!

Nevertheless, I will explore each avenue and hopefully get to the bottom of it once and for all.

Cheers Joe