Freelander 1 Drive ratio

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Hippo

Lord Hippo
Posts
51,599
Some of you may know I’ve been monitoring my vcu temp with some interesting results. This got me thinking… This ere 0.8% drive difference between front and rear on a Freelander 1, how does we know it’s 0.8%? Did we source this figure from a LR publication or somewhere else?
 
I believe it was passed down as oral tradition by generations of sioux shamans.

Joking aside wasn't their a technical bulletin about it released?
 
I found this on RAVE:
"The rear wheels are 0.8% under driven, so in most conditions the vehicle is effectively front wheel drive, with the rear wheels turning the rear propeller shaft slightly faster than the IRD drives the front propeller shaft. Since the speed differential is low, the increase in viscosity of the silicon jelly is marginal and there is little resistance to relative rotation of the slotted discs."
 
I thought it was tradition too. Also that someone measured it many years ago. Didn’t spot it in rave. Thanks both.

Well yer probably wondering why I is asking… I have measured my ratio. Reason being I’ve been looking into VCU running temps v tyres v speed v time etc. This got me wondering about the drive ratio we’ve talked about for many years. While checking me timings for the one wheel up test I thought I’d have a go. My method was:

  • Chock one front wheel.
  • Release handbrake and put in neutral.
  • Left opposite front wheel and the rear on the same side and support on axle stands.
  • Slowly but firmly turn the front wheel forwards to take up the slack in the transmission (ird and rear diff) and watch for the rear wheel to turn. Remove pressure slowly so as not to put any slack in the transmission by the rear wheel continuing when the front wheel stops.
  • Put masking tape on both prop shafts to see if they’re still inline and the vcu int slipping.
  • Put masking tape on the bottom of both lifted wheels, on the side wall, directly below drive shaft centre.
  • Now turn the front wheel while trying to keep the speed constant so as not to jar the vcu and cause it to slip too much (it shouldn’t). Turn the wheel 20 full revolutions and stop by slowing down slowly so you don’t put any slack in the transmission by the rear wheel running on further when the front wheel stops.
  • Now check the 2 props are in alignment and if not correct with 2 screw drivers through the UJ’s. If they were out, then turn the front wheel 90 degrees backwards, then turn forwards slowly 90 degrees to take out the slack, whilst removing slowing down slowly so yer dun’t put anymore slack back.
  • Now look at the rear wheel to see where the tape mark is. 20 revolutions is enough to see if the rear wheel turns faster or slower than the front wheels.
  • Now repeat the 20 revolutions cycle until the rear wheel is offset from the front wheel by a factor you can easily measure.
To be honest the vcu was only out by nearly the width of standard masking tape, during the whole test I did. So it won’t be out by much after 20 revolutions. Or I would expect this to be the case at least.

I then continued the above test in stages of 20 revolutions of the front wheel, until the rear wheel was out by half a full turn. Near the end I drop the number of revs before checking each time. You can see when your close. Then I did me maths to see what the difference was. That’s the puzzling bit. I don’t get 0.8% and can’t see why. I’d doubled my figures to change them from half a full turn out to one full turn out, and doubled the revolutions too. So I now know how many turns of the front wheel, will result in the number of turns of the rear wheel. Also I know what my Freelander % ratio is.

If x = front wheel and y = rear wheel then

x = y – 1 or x = y + 1 (for the maths peeps)

Now yer probably wondering why I int told yer me result of the number of turns, and if I found the front wheel to turn greater or fewer turns, when compared to the rear wheel, during the test. That’s because I’d like someone else to offer to do the same test. Then we can compare results. I know this may seem a bit mad, but you int seen nothing yet.

EDIT: Please PM me the results so we can discuss them before posting online. We may need a 3rd person to perform the test too. The only way to know for sure if someone has done the test is for them to provide results first without knowing our results beforehand.

The problem could be mine is a v6 and the ratio is different. Or mine has something non standard fitted causing the ratio to be different. Or the figure of 0.8% is incorrect. My Freelander is a 2001 v6. It would be good if someone with a v6 or td4 followed the above test to help me with this experiment. Earlier Freelanders were said to have different ratio’s in the IRD or rear diff or something… So it would be nice to compare some of your results too, if some of you would like to also follow the above test.
 
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Bump.

Would anyone like to count their wheel turns for me?

EDIT: Please PM me the results so we can discuss them before posting online. We may need a 3rd person to perform the test too. The only way to know for sure if someone has done the test is for them to provide results first without knowing our results beforehand.
 
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I can't as my IRD is'nt connected to anything at the moment!! Is soon as I've got my new engine up and running I'll do some wheel counting!!
Mine is a 2001 V6.
The diff ratio will give confusing results though with only 1 wheel raised
 
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Your figures will be affected by the differential gearing since your testing with one side of the vehicle is on the ground. If all 4 wheels were up and there was no movement of the diffs with an IRD reduction of 0.8% you would have 1250 turns on the front wheels to 1249 turns on the rear.

Not sure if anyone knows the later IRD ratio but it would take more turns until there was 1 revolution different.
 
I can't as my IRD is'nt connected to anything at the moment!! Is soon as I've got my new engine up and running I'll do some wheel counting!!
Mine is a 2001 V6.
The diff ratio will give confusing results though with only 1 wheel raised
Yes that could be an issue. Thanks for your offer to perform the test.

Seems ahard way to do it surely easier to just see what teeth are on the relevant gears in the IRD ?
Easier to count teeth on gears but getting hold of a selection of ird’s to crack open int that easy, unless I want to buy them.

Your figures will be affected by the differential gearing since your testing with one side of the vehicle is on the ground. If all 4 wheels were up and there was no movement of the diffs with an IRD reduction of 0.8% you would have 1250 turns on the front wheels to 1249 turns on the rear.

Not sure if anyone knows the later IRD ratio but it would take more turns until there was 1 revolution different.
That concept had crossed my mind. Hence trying to get peeps to perform the test in the same way, for comparison.

I’m thinking that measuring one side of the transmission whilst the other is stationary on the floor, will provide us with a value of number of turns on the front, giving Turns+1 or Turns-1 on the rear. But as I’m using the smaller gears in the rear diff during my counting as opposed to the larger gear used when driving forward… is my plan foiled?

My counting would at least give a comparison which would be comparable between Freelander 1’s? Do we simply double the values we get to take into account 1 wheel is stationary? My value for my test is a lot lower than those you mentioned above.
 
The rear diff will give a reduction ratio of X in relation to the prop with both wheels turning at the same speed. If one wheel is stationary then value of X will be multiplied be 2 if I remember correctly?
However that's only part of this calculation as turning 1 front wheel will be turning the prop and VCU at twice the speed compared to turning both wheels at the same time which makes the calculation complex but it gets worse as the prop output of the IRD is geared differently to the front wheel reduction.
I'll se if I can do some number crunching!!
 
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I thought what ever the ird did drive wise (like double the turns) then the rear diff would undo this as the ird would be power in on the drive shaft and power out on the prop. The rear diff would be power in on prop and drive shaft out. But we would still have an offset if the reduction was done in the ird, which it might not be. It's complex but must be do-able somehow.
 
The rear is under geared on a strait road but sadly few roads are strait which means the pore VCU is always being dragged about in the real world!!
 
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