Thread: Freelander Diff Ratios

HI
I have 99 LAND ROVER FREEALANDER 2,0l Di DIESEL. I had problem with rear differential. At first it spreaded hard noise and pumped out all oil and the differential broke out. I have replaced it but after 2 month the problem has repeated. Differential pumped out the oil and crashed again. SO I replaced the differential and drive about 10 km and the noise in differential repeated again and it was very hot.


Maybe someone know what rear diff ratio should be for mine car?

Because the last diff which I replaced was 3,21 ratio, maybe this was aproblem?

Just out of interest, what was the theory behind driving the front and rear wheels at different speeds? What were the designers hoping to achieve by doing so?

Originally Posted by profis

HI
I have 99 LAND ROVER FREEALANDER 2,0l Di DIESEL. I had problem with rear differential. At first it spreaded hard noise and pumped out all oil and the differential broke out. I have replaced it but after 2 month the problem has repeated. Differential pumped out the oil and crashed again. SO I replaced the differential and drive about 10 km and the noise in differential repeated again and it was very hot.


Maybe someone know what rear diff ratio should be for mine car?

Because the last diff which I replaced was 3,21 ratio, maybe this was aproblem?

The rear differential is 3.214:1. So you replaced it with the correct ratio - but then that is the only ratio.

To your problem - clearly there is something making this happen. When the center viscous coupling fails it normally takes out the IRD and sometimes the diff. So the only thing I can think of is that your VC has failed and is causing you problems. See this thread about VC related issues http://www.aulro.com/afvb/freelander...nstant4x4.html

There are a whole lot of issues here so go through it carefully - noting how to test bthe VCU. Other than this I have no idea why your diff should keep on failing.

Garry

Originally Posted by B92 8NW

Just out of interest, what was the theory behind driving the front and rear wheels at different speeds? What were the designers hoping to achieve by doing so?

Actually it is quite common - most awd cars (and partcularly those with a VC) have different ratios - the most common is subarus - even part time 4wd subarus have different front and rear ratios.

In the Freelander - two reasons - the first is that it gives the car a front wheel drive feel which from a marketing point of view is apparently important.

The second relates to the VC. The front wheels need to slip before it engages so there is a lag. The VC locks when it detects a difference in the rotational speed on the input shaft compared to the rotational speed of the output shaft and vice versa. To minimise the lag a small difference in diff ratios is built in so that the input and output shafts of the VC are turning slightly differently - so the VC is detecting this and starts to lock - however the diffence is not enough to make it lock but just bind a bit. This provides about 10% torque to the rear wheels all the time, the VC slips enough to stop transmission windup and as it is already bound up a bit when full 4wd is needed drive to the rear wheels is almost instantaneaous.

On pre 2000 freelanders this diff ratio was too much and the VC worked too hard and failed (locks up). Is no longer an issue for post 2000 freelanders and those earlier ones that had their IRD replaced with a new one.

Garry

Originally Posted by profis

HI
I have 99 LAND ROVER FREEALANDER 2,0l Di DIESEL. I had problem with rear differential. At first it spreaded hard noise and pumped out all oil and the differential broke out. I have replaced it but after 2 month the problem has repeated. Differential pumped out the oil and crashed again. SO I replaced the differential and drive about 10 km and the noise in differential repeated again and it was very hot.


Maybe someone know what rear diff ratio should be for mine car?

Because the last diff which I replaced was 3,21 ratio, maybe this was aproblem?

Hi Profis,

I've not heard of that one before!!! Sounds like you might have to do a bit of trouble shooting first to try & isolate where the problem is coming from.

Firstly, check the operation of the VCU. Do the good old jacking up of the rear wheel, stick the wheel brace onto one of the nuts on the raised wheel and see if it turns (you'll probably have to stand on it).

If it works properly, remove the prop and go for a drive...

This way we can see if the problems with the diff are the symptoms of something else.

If the diff shows the same problems there is a problem somewhere in the rear... You've isolated the problem, you then just need to track it down.

If the diff is fine, you may well have a problem somewhere in the IRD.

Check it out & report back...

HTH

M

Originally Posted by camel_landy

Hi Profis,


If the diff is fine, you may well have a problem somewhere in the IRD.

Check it out & report back...

HTH

M

It seems that VCU is ok.
Maybe someone know how to check does my IRD is fine?

Profis,
Check your tyres & make sure they are all the same size.

One of our customers had an axle set replaced by a reputable tyre shop who assured him that the minor difference in size wouldn't matter.

The rear diff lasted less than 1km .

Originally Posted by profis

It seems that VCU is ok.
Maybe someone know how to check does my IRD is fine?

Have you removed the prop and driven without it fitted yet?

M