Updated August 2016
Ere's the results of testing my Freelanders VCU using the One Wheel Up Test.
A quick refresher of what we're trying to achieve ere:
Q. What vehicles do the test results apply to?
A. Freelander 1. Other vehicles fitted with VCU's can perform the same test, but their results will differ due to rear diff gearing and their vehicles VCU design characteristics.
Q. Why are we doing this test?
A. To collate results from different VCU's in order to see if theres a common result trend.
Q. What would we like to get out of the results?
A. Hopefully a common trend which members could compare their test results too, in order to spot premature failure of VCU's before they fek up their Freelanders transmission (possible failure of IRD and/or rear diff).
Q. What does the test do?
A. It applies a known steady pressure (force) to the VCU (via the rear diff) while we time how long it takes for the bar to turn 45 degrees to the horizontal. This will give us a value in seconds we can use to compare different VCU's, whilst performing the same test.
Q. How do you do the test?
A. Chock front wheels. Release handbrake. Doesn't matter if it's a manual or automatic gearbox, or what position the gearbox is in. Jack up one rear wheel. Remove plastic centre wheel cap. Fit a 1.2m bar (made up of ratchet and wood) with a 32mm socket on the drive shaft nut. Raise bar and add a known weight (8kg is preferred). Allow the bar to start turning before the 45 degrees start point, in order to take out the slack in the transmission. Time the bar while it turns 45 degrees to the horizontal. Use masking tape markers to help you with the 45 degrees and horizontal stop/start positions.
Q. What's your bar made of?
A. 32mm socket, small metal extension bar, ratchet to attach the length of wood to the drive shaft nut and length of wood with a nail in the end. Use several tie wraps to secure the wood to the ratchet. Measure a distance of 1.2m from the pivot point (extension bar) to the end of the wood. Cut the wood at the 1.2m point and put a nail in the end to use as a hook. Apply known weights to the end of the wooden bar (I used tie wraps hooked over the nail).
Q. Why have you repeated the test with different weights?
A. This gives an overall view of the performance of the VCU with different weights applied. It also allows us to compare other peeps results if they've used a different weight. 8kg is still the preferred weight to use as this applies pressure to the vcu in the linear result region. 1kg = 1 litre of water. if
Q. Can I do the same test too?
A. Yes. If we all carry out the same test and pool our results we will gain a better feeling of the average time to perform the test, as a comparison against others.
Q. Can you perform a similar test on a VCU on a bench?
A. Yes. I have done this already and will put up the results soon after editing the video. I will edit this post and add the results at a later date. I will also add another post to this thread to confirm when this has been done.
Q. If my One Wheel Up Test time is high and I want to remove my VCU for peace of mind (until I get a replacement, or I may just leave it off for a while), how would I do this myself?
A. Follow the link below. It's easier to remove the VCU and both prop shafts at the same time when doing it at home. If you do this you will need to advise your insurance company as it's considered a modification. The link provides the method of removal, changing the support bearings and refitting.
https://www.landyzone.co.uk/land-rover/freelander-1-vcu-bearing-replacement-how-to-guide.156068/
Q. What should I do if my test result is higher than yours?
A. Ideally someone performing the test would do the same test a few times to make sure they get a similar result each time. If the result is high then I would do the following:
- chock the front wheels and release the handbrake
- lift both rear wheels off the ground
- turn the rear wheel you were using for the One Wheel Up Test to check it turns freely.
Don't be surprised when turning the rear wheel when you see the wheel on the other side turning in the opposite direction. This is because the rear prop to rear diff connection isn't turning. This is correct, as you're turning the opposite wheel via the rear diff internal gears. When the rear diff is being used in normal on road operation the rear prop to rear diff connection is turning, which allows both rear wheels to turn in the same direction. The internal rear diff gears then allow both rear wheels to travel at differing speeds to allow for cornering.
Q. Referring to the last question, I would prefer to lift both wheels on the same side, if I need to check the handbrake has released, to check the wheel being tested turns freely, as I feel safer.
A. Yes you can do this if it makes you feel safer. This will only test the handbrake is released on the lifted rear wheel. This is all you need to know for the test. The method would be:
- chock both front and rear wheels which will remain on the ground, on the same side of the Freelander
- release the handbrake and put the auto gearbox in neutral (neutral for manuals too)
- lift both wheels on the other side and turn the rear wheel. The front wheel will then turn in the same direction (assuming the props/vcu are fitted and the rear diff/ird are working correctly). It takes a little bit more effort than turning both rears, but easily possible by hand.
Test results:
My VCU's temperature measured 23 degrees before and after the testing. VCU temperature is an important factor which will produce different results, for the same VCU. My Freelander hadn't been driven over night to allow the VCU to cool to an ambient temperature. At the time of testing my VCU was 11.5 years old. It's an original Land Rover VCU supplied when my Freelander was manufactured in 2001. It's stamped GKN. Current mileage at the time of testing was 32,000 miles. My Freelander is a 2001 Freelander 1 v6.
Weight in kg / Time in seconds
3.0 kg . . . . . . . 80.0 seconds
4.1 kg . . . . . . . 49.5 seconds
5.0 kg . . . . . . . 35.5 seconds
6.2 kg . . . . . . . 25.0 seconds
7.1 kg . . . . . . . 20.0 seconds
8.0 kg . . . . . . . 16.0 seconds
8.9 kg . . . . . . . 14.0 seconds
10.0 kg . . . . . . 12.0 seconds
11.0 kg . . . . . . 10.0 seconds
12.4 kg . . . . . . 8.0 seconds
13.8 kg . . . . . . 7.0 seconds
Ere's a video I made during testing:
One Wheel Up Test Results - Viscous Coupling Unit VCU Torque Test - Freelander 1
Ere's a graph of my results. Blue X is my measured results. Green line shows an estimated curve for my VCU.
The graph shows a curve (non linear) and straight line (linear) sections. OWUT results should be done in the linear section for more precise, reliable results. You will get more reliable results with 8kg on a 1.2meter bar, when compared to 5kg at 1.2meter bar.
OneWheelUpTestResultGraph 3paXgcc
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Bench test figures in this post are approx to about the nearest second. Figures are the same when my vcu was brand new and after a few thousand miles. I will put a full list up when i get round to editing the video.
The test is all about force applied
force in Nm applied = length of bar x 9.8 x weight on bar
owut with 5kg on a 1.2m bar is 35.5 seconds
bench test on vcu with 5kg on a 0.38m bar is approx 41 seconds
owut with 8kg on a 1.2m bar is 16 seconds
bench test on vcu with 8kg on a 0.38m bar is approx 20 seconds
