Freelander Diff Ratios

[101RRS]

Hi does anyone know the front diff ratios of Freelanders. The Haynes manual has the rear diff ratios but not the IRD ratios - unfortunately the fronts and rears are different.

I have a 2001 IRD that I want to put in a 98 model but do not know the ratios of either model.

On a normal diff, if you turn the input shaft and one of the wheels is locked - does the other wheel turn at the correct rate according to the diff ratio or at double the speed.

Thanks

Gazz

[camel_landy]

AFAIK the ratios are the same.

Mark

[101RRS]

Thanks Mark - thats what I thought - except for the slight change from 99 to 00 to fix the Viscous Coupling/IRD failure problem.

However the book lists the rear diffs having ratios of 4.2:1 for petrol, 3.647:1 for the L series Diesel, and 3.182:1 for TD4 manual. Hence my logic said that front diffs should be similar to the rears. If the IRDs are all the same ratio and the vaious models have different rear diff ratios, then in theory the VCs would have to work real hard on some models to prevent transmission windup and fail after an extended period.

I am at the point of putting a 01 model IRD into my 98 car and the dreaded thought that the IRD ratio might be all wrong crept into my head.

Thanks for the info. - Hope you are having a great trip.

Garry

[camel_landy]

Hmmm.... OK. I wasn't aware of any difference in the drive train between them.

I don't have any of my Freebee stuff with me but if you wanted to get a decent answer, pop a note onto the Freelanderclub Yahoo E-Group (http://groups.yahoo.com).

Mark.

[101RRS]

Did it - Thanks Mark

[101RRS]

Couldn't get any info on the Freelander's front diff ratios and when I removed my IRD today, I found some interesting stuff in counting input shaft rotations vs output shaft rotations. It would seem that when I stipulated a post 2000 version IRD from the wrecker to replace my buggered one, it would seem he mixed up L series diesel with TD4 diesel and I have one out of a TD4.

I would have expected the rear output shaft of the IRD to turn at the same speed as the input to the IRD but this is not the case. The rear output shaft of the IRD actually turns at about 2.333 times faster than the input from the gear box - so the actual diff ratios in the IRD and the rear diff are substantially different but generally balance out at the wheels. While the rear diff ratio is in a L series is 3.637:1, because of the increased speed of the tail shaft, the effective ratio is only about 1.565:1.

My investigation showed up the problem with the diff ratios in the 98/99 cars.

In the L series, at 1000 revs output from the gearbox (about 600 engine RPM), the front wheels are rotating at about 683 RPM (1.464:1) but the rear wheels are trying to rotate at 640 RM (1.565:1) so the viscous coupling is working constantly to take this difference out and after a time ends up failing which in turn causes the IRD and/or the rear diff to fail.

The TD4 doesn't have the problem of the 98/99 models - under the same 1000 RPM from the gearbox - the front wheels turn at 740 RPM (1.351:1) and the rears at 733 RPM and this difference is most likely because of my crude method of measuring (rotate the input shaft 10 times and count how many times the output shaft turns). The TD4 has a rear diff ratio of 3.182:1 which is an effective ratio of about 1.351:1 when the higher gearing of the tail shaft is taken into account.

As I now have a IRD out of a TD4, the rear diff ratio is all wrong. I have to do some work on the rear diff so if I want to retain the reliability of the TD4 drive train it might be simplist to replace it too - the end result will be slightly worse lower end performance but better cruising and a poorer Gazz.

Guess I will be front drive only for a while yet - at least until I can save up to buy a rear diff.

Gazzz

[camel_landy]

Originally posted by garrycol+--><div class='quotetop'>QUOTE(garrycol)</div><div class='quotemain'>Couldn't get any info on the Freelander's front diff ratios and when I removed my IRD today, I found some interesting stuff in counting input shaft rotations vs output shaft rotations. It would seem that when I stipulated a post 2000 version IRD from the wrecker to replace my buggered one, it would seem he mixed up L series diesel with TD4 diesel and I have one out of a TD4.
[/b]

Post 2000 is TD4.


Originally posted by garrycol+--><div class='quotetop'>QUOTE(garrycol)</div><div class='quotemain'>I would have expected the rear output shaft of the IRD to turn at the same speed as the input to the IRD but this is not the case. The rear output shaft of the IRD actually turns at about 2.333 times faster than the input from the gear box - so the actual diff ratios in the IRD and the rear diff are substantially different but generally balance out at the wheels. While the rear diff ratio is in a L series is 3.637:1, because of the increased speed of the tail shaft, the effective ratio is only about 1.565:1.

My investigation showed up the problem with the diff ratios in the 98/99 cars.

In the L series, at 1000 revs output from the gearbox (about 600 engine RPM), the front wheels are rotating at about 683 RPM (1.464:1) but the rear wheels are trying to rotate at 640 RM (1.565:1) so the viscous coupling is working constantly to take this difference out and after a time ends up failing which in turn causes the IRD and/or the rear diff to fail.
[/b]

Sounds about right....


<!--QuoteBegin-garrycol@
The TD4 doesn't have the problem of the 98/99 models - under the same 1000 RPM from the gearbox - the front wheels turn at 740 RPM (1.351:1) and the rears at 733 RPM and this difference is most likely because of my crude method of measuring (rotate the input shaft 10 times and count how many times the output shaft turns). The TD4 has a rear diff ratio of 3.182:1 which is an effective ratio of about 1.351:1 when the higher gearing of the tail shaft is taken into account.[/quote]

OK... The problems come from the difference between front & rear wheels rather than anything relative to engine speed. I don't s'pose you've tried counting the revolutions of the front wheels vs the revolutions on the output shaft (effectively pretending that the drive is on the centre prop shaft)?

<!--QuoteBegin-garrycol
As I now have a IRD out of a TD4, the rear diff ratio is all wrong. I have to do some work on the rear diff so if I want to retain the reliability of the TD4 drive train it might be simplist to replace it too - the end result will be slightly worse lower end performance but better cruising and a poorer Gazz.

Guess I will be front drive only for a while yet - at least until I can save up to buy a rear diff.

Gazzz[/quote]

I'd hope you don't have to do that. There's guys in the UK that are running the later IRD in the older trucks and AFAIK they haven't touched the rear diff. They've covered plenty of miles without problems and have better tyre wear.

Mark.

[101RRS]

Camel Landy said
<div class='quotetop'>QUOTE</div><div class='quotemain'>OK... The problems come from the difference between front & rear wheels rather than anything relative to engine speed. I don't s'pose you've tried counting the revolutions of the front wheels vs the revolutions on the output shaft (effectively pretending that the drive is on the centre prop shaft)?


I'd hope you don't have to do that. There's guys in the UK that are running the later IRD in the older trucks and AFAIK they haven't touched the rear diff. They've covered plenty of miles without problems and have better tyre wear.[/b][/quote]


Have effectively done what you suggested ie pretend the drive is on the center prop shaft - answers are the same as the input shaft to the IRD and the rear drive output shaft are directly connected - geared together. Wheras the drive to the front wheels goes through the front differential.

I also have heard that the later IRD should go straight in and be compatible with the rear diff - but the logic doesn't hold - if the initial problem was caused by the difference in diff ratios - putting in a TD4 ird with a different diff ratio should make the problem worse. I am sure you are right about your experiences - then that begs the question was the initial problem the IRD - what if it was in fact the first lot of VCs that just failed and caused the IRDs to fail. What if the later VCs are better able to handle the different diff ratios - I am sure your friends who are running later IRDs are only doing so because the original IRD failed along with the VC and as such they put in new VCs.

Thanks for the tips Mark - I really appreciate your assistance.

Oh - Harveyg77 from the Yahoo Freelander Club sends his love 8O

Catchya later

Gazzz

[camel_landy]

Originally posted by garrycol

Have effectively done what you suggested ie pretend the drive is on the center prop shaft - answers are the same as the input shaft to the IRD and the rear drive output shaft are directly connected - geared together. Wheras the drive to the front wheels goes through the front differential.


Bugger.... style_emoticons/<#EMO_DIR#>/sad.gif



Originally posted by garrycol

Oh - Harveyg77 from the Yahoo Freelander Club sends his love 8O


LOL... Great guy. He used to be in the navy too... :wink:

Mark.

[101RRS]

In the Navy, (thinking Village People) LOL

Mystery solved - you were right Mark - the Freelander rear Diffs are all 3.214:1. Alan at British 4WD e-mailed me the specs from the real handbook. I cannot thank British 4wd and Alan enough.

The Haynes book mis-lists the ratios - what they list as the rear diff ratios are in fact the effective ratios for the front.

When looked in this light the problem is really obvious - 1800 4.2:1, L series 3.647:1 TD4 - 3.182:1. No wonder the 1800 ad L series were wrecking VCs and IRDs.

So - the lesson is check the VCs regularly, know the symptoms (seems to happen about every 100,000km depending on road services), if the VC is dodgy, replace (expensive), if not then replace the IRD and VC - if not buying a new IRD - get one from a good used TD4.

Gazz

[camel_landy]

Phew.... I was starting to get worried there!

Mark

[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?

[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?

[101RRS]

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/65337-freelander-constant4x4.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

[101RRS]

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

[camel_landy]

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

[profis]

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?

[Scouse]

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 :(.

[camel_landy]

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

[profis]

I have removed VCU and cardan. And driving front wheels.
When I am pushing acceleration clutch I feel little vibration on the foot? Could it cause bad IRD?