I have an > URGENT question. If you could spare me a minute I would be very grateful.> Our car is a 2000 model diesel freelander, and we love it.> I had to replace what I think is called the IRD or trans-axle. It is a > type of gearbox at the front end of the propshaft.> Please understand that I live outside the UK and my mechanic, who is very > conscientious, speaks no English. He refers to this replaced part as the > 'little gearbox'> My great worry is that my VCU is seized and that is why the 'little > gearbox' failed.> My mechanic says the part that I think is the VCU is only to absorb > vibration. Hence my fears are groundless.> Please can you explain to me (please treat me as an idiot) what the VCU > looks like in order that I can be sure I am pointing out the right part to > my mechanic. If it is the big round thing in the middle of the prop shaft > then I know where I am. I put marks on both sections of the casing and on > the inner rear part. I have then driven the car some distance (450km) on > windy and straight roads. The marks have remained in alignment, indicating > to me that both parts of the propshaft are always moving together. i.e. we > have a problem with the VCU. Was my test an appropriate test? Is my > diagnosis correct?> I am desperate to know as we are supposed to begin a big road trip (3500km > or so) in a couple of days and I do not want to do more damage to the > car!!> Many thanks for any help you can give.> Mike.
Freelander V.C.U. worries
- Thread starter ambermike
- Start date
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Hippo
Lord Hippo
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- 52,059
:welcome2:
The little gearbox is the IRD Intermediate Reduction Drive which reduces the ratio of the drive from the main gearbox by about 1.6 and splits the power to the front wheels, and the front prop shaft.
The VCU viscous coupling is seized if the markers are still in alignment. Yellow dots in the photo below shows where to put the markers on the prop shafts for this test. A seized VCU will put permanent excess stress in your transmission, causing the IRD to fail. Also the rear diff may fail too.
Either take off the rear prop, making it 2 wheel drive or get the VCU replaced now. If not you’ll continue to put additional stress on your transmission and something will fail again.
The VCU does have a damper next to it on some models. In the photo below, mine doesn't as it's the v6 model.
vcutest 8e4Dw2n
The little gearbox is the IRD Intermediate Reduction Drive which reduces the ratio of the drive from the main gearbox by about 1.6 and splits the power to the front wheels, and the front prop shaft.
The VCU viscous coupling is seized if the markers are still in alignment. Yellow dots in the photo below shows where to put the markers on the prop shafts for this test. A seized VCU will put permanent excess stress in your transmission, causing the IRD to fail. Also the rear diff may fail too.
Either take off the rear prop, making it 2 wheel drive or get the VCU replaced now. If not you’ll continue to put additional stress on your transmission and something will fail again.
The VCU does have a damper next to it on some models. In the photo below, mine doesn't as it's the v6 model.
vcutest 8e4Dw2n
Last edited:
Missing Link
New Member
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- 653
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- Colchester, Essex
The VCU is not to absorb vibration but to allow the two axles to rotate at different speeds when manouvering but still to transmit power when required. THe fact that the marks have not moved in relation to each other after such manouvres does indicate that the VCU has siezed. However you do not have to move very far to see this. One or two complete turns around a circle should be enough to verify this.
To protect the parts you have replaced the immediate thing is to remove the propshaft before driving any further distance.
To clarify the parts under the vehicle what you have coming out of the rear of the engine/gearbox is a short shaft. This is attached to the front propshaft by six bolts around a steel tube about 75mm long and 100mm in diameter. This is the Constant Velocity Joint. The output of this is welded to a tube approximatly 900mm long ending in cross bearing Universal Joint. This has a bolt in the middle which fits into a shaft which itself passes through a bearing frame bolted to the bottom of the car. There is a second bearing further back and the large round assembly in between these bearings is the VCU. Finally there is a second propshaft going from the back of the VCU to the rear axle with a Universal joint at either end.
The test is to put a mark at the back of the front propshaft and at the front of the rear propshaft and reverse round in a complete circle. If you then check the marks they should not be in alignment.
To protect the parts you have replaced the immediate thing is to remove the propshaft before driving any further distance.
To clarify the parts under the vehicle what you have coming out of the rear of the engine/gearbox is a short shaft. This is attached to the front propshaft by six bolts around a steel tube about 75mm long and 100mm in diameter. This is the Constant Velocity Joint. The output of this is welded to a tube approximatly 900mm long ending in cross bearing Universal Joint. This has a bolt in the middle which fits into a shaft which itself passes through a bearing frame bolted to the bottom of the car. There is a second bearing further back and the large round assembly in between these bearings is the VCU. Finally there is a second propshaft going from the back of the VCU to the rear axle with a Universal joint at either end.
The test is to put a mark at the back of the front propshaft and at the front of the rear propshaft and reverse round in a complete circle. If you then check the marks they should not be in alignment.
