Hi,

I recently had a recon R380 g/box and LT230 t/box fitted to my 1997 Defender 110 300tdi. Since then I have travelled less than 500 miles. However, due to a rear drive flange failure (and my ignorance), I managed to seize the centre diff. So I am now running without a front prop.

A couple of weeks ago I lost drive and could not regain it until I had come to a standstill. This happened several times on the same journey. I have tried running it without either prop in turn so I am sure it is not a problem with diffs, CVs or half-shafts etc.

I have read the previous posts on similar topics but they mostly relate to complete loss of drive, not intermittent. The clutch, bearings and fork were all replaced at the same time as the gearbox. The clutch operation is smooth and quite with no slipping, juddering or banging. Also, when drive is lost, there is still movement within the g/box & t/box (a chattering, rattling sound so the clutch is still transferring motion to the box. So I don't think the clutch is the problem.

I have checked the selector mechanisms for both boxes and they are smooth with a positive engagement. In any case, when drive has been lost there has been no movement of the levers.

This has only happened in 1st and 2nd gears, either when taking up drive to pull away from stationary or when slowing down to approach a junction etc. There is usually a bang from g/box or t/box when drive is lost (and regained) but I have not identified exactly where it come from. I have tried to re-engage or change gears when the vehicle is in motion. This has either no effect or, on one occasion, the rear propshaft locks solid.

So yesterday, I removed the front floors and tunnel cover for a further examination. I turned everything over by hand and there was no unusual noises or roughness. I drained the g/box and the oil was clean with only a small amount of steel particles on the sump plug. So that appears to be in good condition.

BUT the t/box had flakes of metal on the plug and the remains of two teeth from the diff gears. When holding the two output shafts of the t/box there appears to be an acceptable amount of backlash (from what I have read in this forum) but if I rotate both output shafts in the same direction, at certain points there is double the amount of backlash. I assume this is where the missing tooth is??

I have removed the t/box sump and inspected the input, intermediate and rear output gears and the are all in good condition. The dog gears are not damaged and the hi-lo ring works fine.



Apologies for the long post but I wanted to put in as much detail as possible.

Can anyone tell me if this damage to the diff would cause intermittent loss of drive? If not what would cause the problem?

Thank you for reading.

Warning, not going to mince my words.
Running without a prop is something you do to get home, driving lightly.
You seize the centre diff [ you think ] but then do nothing to sort it and keep on driving!
Bits from diff now circulating in the transfer box messing more things up.
Drive being lost now and then as diff unseizes itself as it breaks up and then jams up again is most likely.
Another transfer box I recon.

tottot said:

Warning, not going to mince my words.
Running without a prop is something you do to get home, driving lightly.
You seize the centre diff [ you think ] but then do nothing to sort it and keep on driving!
Bits from diff now circulating in the transfer box messing more things up.
Drive being lost now and then as diff unseizes itself as it breaks up and then jams up again is most likely.
Another transfer box I recon.

Click to expand...

Thanks Tottot,

I do accept the blame for mincing the centre diff in the first place. I assumed that because the power to the rear propshaft didn't go through the diff that it would not cause any further damage .

I kind of thought that it would need a new t/box but was also hoping I could get away with new diff internals. Apparently not

a few teeth missing there.... definitely need to remove the box before it minces everything else.

windy81 said:

a few teeth missing there.... definitely need to remove the box before it minces everything else.

Click to expand...

Agree, it's not moving until it's sorted.

I hope you can salvage some of the internals and save a load of dosh. Or buy new from Ashcrofts, easy option !

windy81 said:

I hope you can salvage some of the internals and save a load of dosh. Or buy new from Ashcrofts, easy option !

Click to expand...

I'm looking at Ashcrofts now. I don't have the time, tools or (more importantly) the skills to strip a box down and rebuild it . May even go for a ratio upgrade so my ears don't bleed on the motorway

Just to be clear the centre diff turning at all times one is driving whether it is locked or not.
A rebuilt box is probably the best option. Extra options are a stronger pin in the diff [I would go for that ] or if you want to push the boat out an ATB [ automatic torque biasing ] centre unit.

tottot said:

Just to be clear the centre diff turning at all times one is driving whether it is locked or not.
A rebuilt box is probably the best option. Extra options are a stronger pin in the diff [I would go for that ] or if you want to push the boat out an ATB [ automatic torque biasing ] centre unit.

Click to expand...

Stronger pins are an definite but the ATB is pushing my budget a little too far. There are lots of other jobs to be done on the Landy (bodywork, paint, interior etc) and a ATB would be an indulgence. But thanks for the advice though.

Old Landy's are an on going fix it job but that is what is good about them. They can be repaired without totally breaking the bank. Up coming on my 1990 90 is replace drivers door and renew intercooler.

Just a quick update.

I've just driven 60 miles today (rural, urban and motorway) with the new transfer box and it was spot on. No sign of the previous problem at all. Mind you, it was an intermittent fault so I'll be happier still after 600 miles

Cheers.

Hope that is all good then.