Rear diff issues

First a summary of what happened
I have a freelander 1 TD4 from 2006

I have for years heard noises from the rear, thinking the diff might give up at some point.

1 month ago I got 2 new tyres on the rear axle, and everything was good. A few days ago, I started hearing what I thought was a wheel bearing rumble, and it quickly got worse.
Also at low speed making tight turns I sometimes hear loud stuttering clunking noises from the rear.
After a 45km drive, I smelled something hot, so I measured the rear diff with a laser to be 130 degrees celcius on the outside! (I unfortunately didn't think of measuring the VCU temp.)
So I stopped driving it.

I have done the 120cm bar with 5kg drop test to check the VCU, and it took around 60-70 seconds to get from 1:30 to 3, so it doesn't seem too bad and I can also spin it by hand with some big pliers.

I don't know if it's the unmatched wheel sizes that could have caused it, but I will for sure replace the front tyres as well now.
However I think the rear diff is dead based on the sounds and temps it has experienced.


Then some questions
I'm just thinking if there is anything else I should be aware of or test/check?

And if anyone knows somewhere in EU (Not in the UK) where they sell remanufactured rear diffs?
As I live in Denmark and all sellers i find is in UK, but it's too expensive with customs/ import taxes from the UK.

And before buying another rear diff, does all freelander 1's use the same rear diff?
- When looking visually on my diff it says "51441 174" on the side of the housing, but when searching for used ones online I also find some that has these numbers on the side "47098 174" and when looking up my freelander on my VIN number I find these two numbers "TVK000180" and "LR006009" so I'm really in doubt which rear diff to get to be sure. My gut tells me to buy one with the same number on the side as my current. But maybe someone knows if they're in fact identical, or if there are different ratio diff's?

And finally, based on my VCU drop test, doesn't it seem fine? I know people are saying around 45 seconds, but I guess it depends on exactly where you start the drop from, as it goes very slow at the top.

The timing on the 1WUT does sound rather long, it is definitely in the region of "think its time to change".

If you've been driving on mismatched tyres, its just as well the VCU wasn't totally goosed as it would have trashed your IRD as well as diff.

However, you don't really know what damage has been done. I'd be changing the IRD oil to see what the current stuff comes out looking like. If its got signs of metalic dust in the oil (by colour), then the unit is only just hanging on. If that's the case, you can only really use it in 2WD (with props removed) even after you get your tyres matching, because I think its inevitable that it will trash the IRD sooner or a bit later.

I wouldn't drive it in 4WD until you have all matching tyres for sure - and check all 4 pressures.

I believe that diffs are the same in all F1s. Looking at the LRDirect website they say that LR006009 is superceded by TVK000180. This generally means that LR altered the unit in some way (eg they may have used a different manufacturer for gears or bearings), but its function was unaltered and either can be used.

Oh my... Just measured the diameter of my front and rear wheels, and the rear are 3cm bigger in diameter!!
A really bad combination of new vs old tyres and not the same brand, even though specs are the same.

I have driven 1 month / around 1200km with this!

For now I will:
- Change to identically sized tyres

- Inspect IRD oil, and put new in it
---- If really bad, maybe go 2WD and remove the propshaft
---- If OK, I might continue 4WD

- Change diff oil (suck out as much as possible and top it up)

- Monitor diff and VCU temps after long drives and generally listen if noises are cleared
---- If still noisy/hot, I will replace VCU and diff

Earlier freelanders had a different front to rear ratio, that my have been achieved by using different rear diffs. If so I would be fitting the later diff.

J_D said:

Earlier freelanders had a different front to rear ratio, that my have been achieved by using different rear diffs. If so I would be fitting the later diff.

Click to expand...

I don't think there has been discussion on here about different diff ratios. I'm pretty sure they are all the same.

The discussion has been about different ratios in IRDs. I don't know if we have any definitive information on this or whether it is old wives tales, but the 2000 model year had an IRD rear pinion ratio that ran the front and back prop shafts at a bit closer to 1 to 1. All IRDs gear the back axle down (or is it up?) 'very slightly' to give a front wheel drive 'feel' (with the VCU stopping any trouble occurring from it). From MY00, that changed to 'very very slightly'. This is my understanding.

Im considering replacing the VCU as well, but im not sure how bad is bad enough, did another test to be sure and there are 70 seconds between these two frames in my test.

120cm 5kg