LR NUT

4x4

10 posts in this topic

Does anyone know what the power percentage split is from the freelander 1 I know it is bias to the front wheels but what percentage is allocated to the rear wheels?? Similarly the Freelander 2 has intelligiant fwd how does this work and is it stilll permanent fwd like the freelander 1

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In lieu of a grown up coming along who really knows what they're talking about...

RE Percentage - FL1 uses a viscous coupling to send power the rear wheels when traction is lost at the front. I've never quite understood the numbers of front/rear split in conjunction with TCS, as they seem entirely academic and are so variable so I won't attempt to :unsure:

FL2 uses a multiplate clutch (haldex coupling) to do the same thing, which is electronically controlled depending on the level of slip detected at the front wheels. IIR the blurb correctly only 20 degrees of front wheel slip (18th of a turn)is required to trigger the haldex unit.

I would describe both FL1 and 2 as front wheel drive with an automatic, on-demand 4wd system with no driver input required. Neither is permanent per se, but its none the worse off for it.

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It varies, on the road the power is pretty much 100% to the front until a wheel slips, as the gearing front-to-back is such that the front pulls the back along. If the front wheels were in the air then the split would be 100% to the rear.

FL2 with its haldex clutch I think means the split is 100% to the front and the rear is only engaged when the front loses traction or the ETC system thinks it might need it.

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i beleive it is a 60% front 40% back spilt. As fridge says the front pulls the back along because the rear prop is geared down via the IRD thus the viscous allows the rear wheels to travel faster than the prop powering them. So if you lift a rear wheel it becomes a 50/50 split although the rear turn slower than the front but you have no traction because you can't lock the rear diff which is where the traction control comes in. On the other hand if you lift a front wheel the viscous locks up giving you a 50/50 split but the rear wheels will be turning slower than the front.

well thats how i read it :huh:

mike

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The norm is about 90% to the front, until slippage is detected.

Cheers guys but alot of different answers????

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Cheers guys but alot of different answers????

Another one, on FL1 up to late 2000, the rear is driven at 80% of the front. On 2000 on the rear is driven at 99% of the front. The ratio in the IRD box was altered to stop the VCU's seizing so frequently and thus blowing the IRD box

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It's in the RAVE manual:

Viscous Coupling

The VCU (Viscous Coupling Unit) is a major component of the driveline. It effectively

controls the difference in speed between the front and rear prop shafts and

influences the amount of torque distributed to the front and rear differentials. In

theoretical terms the rear wheels are 0.8% “under driven” in comparison to the front

wheels, however, this figure will change continuously as the vehicle’s speed and

dynamics alter.

The VCU is a sealed unit filled with a silicon fluid material. It comprises an input shaft

and plates, and an output shaft and plates. The plates fitted to both input and output

shafts contain holes through which the silicon fluid is able to pass. The silicon fluid

material offers a resistance to shear. Its effective resistance to shear increases as

the differential in speed, between the input (i.e. front prop shaft) and output (i.e. rear

prop shaft), increases. This characteristic results in the appropriate division of drive

torque between the front and the rear differentials to maximise traction in all

conditions.

In practice, whenever the front or rear wheels start to spin, the difference in speed

between the two prop shaft sections increases. The VCU reacts in these

circumstances, as described. It consequently makes it more difficult for the prop

shafts to revolve at different speeds and thus delivers a greater proportion of the

drive torque to the “non-spinning” differential. The VCU is sealed for life component

and does not require any routine maintenance or servicing, over and above visual

inspection to its external casing.

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From the legal point of view, both FL1 and FL2 are "permanent integral (4x4) traction" vehicles. I think this is because, unlike with other vehicles, the driver cannot select 2WD.

For this reason here in Romania can't have the compulsory periodic technical check (I think you call it MOT in UK) in any authorized service unit, but only in those able to check permanent 4WD cars.

Speaking about 4WD, we had (again) a heavy snow - more than 60cm in just 2-3 days - and I tested (again) the FL2 on snow. It managed the snow great, although next winter I'll buy winter tyres (the car came with factory-fitted Goodyear M&S tyres, which tend to slip laterally, while the front/rear traction is rather OK). The Haldex stuff was used several times, you can feel the "clutch smell" when driving in reverse.

Overall, it's a nice sensation to "float" between cars which are stuck in snow, and to be able to help other people :-)

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