Can a damaged rear diff cause vibration?

I have an annoying vibration and steering wobble on my 90 TD5 when exceeding over 50kmph and it remains at any speed above this. I have eliminated the steering system as its now pretty much all new...steering rods, drag link, panhard rod bushes, steering drop arm, etc. I've rebuilt front left hub and ball joint completely as the bearings were shot on the swivel housing (haven't done the right as I think it is ok). I've had the wheels rebalanced perhaps three times across two sets.

Anyway, my mate has had a look underneath and there is A LOT of play on the rear diff. Basically, with the car parked up he is able to rotate the drive shaft perhaps 20 degrees each way with just his hand. Surely that is not normal? He says the diff is damaged and is causing excessive vibration. What are your thoughts? He will be starting a full nut and bolt rebuild on it soon after he finished my 110 300tdi but I would really like to keep driving the 90 whilst I'm waiting. It has certainly become worse after doing some very muddy offroading.

As a side note, I am going to view a D3 on saturday as I hate being without a land rover that I can use.

My thoughts...your bloody lucky you've got a 110 a 90 and can afford someone to rebuild them and buy a D3 as well...lol...

Can't see why an imbalance on the rear would affect your steering.
However, I would start with looking at the prop shafts and UJ's first, as in is there any playand have they been split apart and reassembled with the tell-tales out of line?

Both propshafts have been replaced around 3 months ago for new ones.

Shippers said:

My thoughts...your bloody lucky you've got a 110 a 90 and can afford someone to rebuild them and buy a D3 as well...lol...

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I always wanted a defender and when I could finally think (afford) about buying one they went out of production. As I live in Slovakia labour is much cheaper to have them rebuilt and the guy who is doing them is a mate so he's given me mates rates. In fact buying and rebuilding 2 old ones will cost me less than a new one would have. The original plan was to sell the 90 once the 110 was finished but I really like it.

20 degrees is not bad,my 90 has a lot more than that and still runs smooth,check diff input shaft for side to side,up and down movement.
For steering wobble check that swivel preload has been correctly set.

tottot said:

20 degrees is not bad,my 90 has a lot more than that and still runs smooth,check diff input shaft for side to side,up and down movement.
For steering wobble check that swivel preload has been correctly set.

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I will check both, thanks! What is the correct swivel preload please? Is it 4kg... I was looking at a video when doing mine.

I'd say that +/- 20 degrees isn't anything out of the ordinary

That is about right with the big swivel seals in place,half without. I have done so many over the years I just do it by feel thees days.Cheers.

I have ordered parts to replace the swivel on the other side as well. I may as well do it just in case.

Could an unbalanced prop be the cause? Could I remove the rear prop and run on the front wheels and visa versa to see if it makes a difference and narrow down the problem area? Would new bushes, joints etc on the steering system make the shake more noticeable?

can you put it on axel stands and run it with all wheels of ground also as above take off one prop shaft at a time and see what happens was the front prop shaft set out of phase was proplem the same befor fitting new props? is steering box free play set correctly have you got the smaller tyres to see if it is still there when fitted when running on axel stands fif lock engaged with spacers to stop drums flying off at speedtry running with wheels on and then with wheels off if you have drums on back put 2 nut back on with washers to stop drums flying off at speed the rear prop should be fitted in phase the two arrows should be together the front prop should be set out of phase by one or two splines as said befor check on doogel etc to find out which is correct acordidg to a diagram I saw it front prop shaft should be off set by 2 splines other members bay be abel to confirm if this is corect

The steering was fine to begin with when I got the vehicle last year. Then it began to vibrate a little, then more so after I had fitted larger tyres (265/85/16). I've since replaced a lot of components and it hasn't helped much...in fact the vibration is more pronounced. Thinking about it, the vibration has probably become worse since replacing both prop shafts for brand new ones.

What is weird though is that at almost any speed below approx 50kmph the car is as sweet as a nut. However, when going really slow (i.e. slowing down to park) I can sometimes here a knocking coming from near the rear diff.

Good shout on the axle stands...I will give that a go during next week as I'm away from home at the moment

Are the yolks lined up properly on the props ?

landowner said:

Are the yolks lined up properly on the props ?

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I'm not sure...how can I check?

There is a diagram somewhere showing how they should be (google), but if they were new or recon they should be ok, could be engine or gearbox mounts, mine are cheapo ones and they do transmit some vibration rather than quality ones which don't.