Hi folks,
We recently got a RAV4 XT3.
We were told it was 4x4 only when the car sensed it needed all 4 wheels.
Having driven it on icy roads a few days back the ABS came on and the car skidded a couple of times, on what were roads that weren't very icy.
We weren't that bothered by the 4x4 issue anyway, hence we didn't investigate it at the time, but can any confirm confirm whether (1) this model does have 4x4 ability and (2) when it is enabled?
TIA
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It sounds like you're expecting the 4x4 system to help with cornering and braking, or am I misunderstanding your post?
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Is it new or second hand ?
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I could be expecting too much :-)
I guess it was not so much an issue of grip, but skidding while braking.
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How far is it skidding and what speeds ?
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Just a few metres, and at < 10mph.
It behaved pretty much as my Focus would have done, but I was expecting a little more grip.
But before I get away from the point too much, I was trying to understand when the 4x4 system kicks in, so I understand the RAV4 better.
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From what I have seen of RAV4's its only the 1.8 which is 2WD, all the others are AWD.
These are very much a lifestyle 4x4, so dont expect too much from it. Grip when braking is down very much to the tyres, whether or not its 4x4 wont make much difference, in fact braking is likely to be inferior to a saloon car due to the higher centre of gravity of the RAV4.
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as far as I know the bigger engined models are all permanent AWD (I could be wrong though!).
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What tyres have you got on there?
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IIRC RAV4 is reactive 4x4 via viscous coupling - rear ones are powered only when front wheels slip.
Same as CR-V or Fiat Panda etc.
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rear ones are powered only when front wheels slip.
Under acceleration, it should be stressed. I think it needs to be spelled out that 4x4 of any kind doesn't help with braking!
Although, I'm wondering whether some 4x4 systems could help preserve traction under engine braking?
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Except as per a previous comment/post
ANY 4WD still brakes just like ANY 2WD
ie on ALL four wheels
So the ONLY benefit of 4Wd ig getting moving/ keeping moving
re stopping.....NO benefit
handeling/ steering...Hmmmm
I suspect no advantage over a FWD, except the power is better distributed for those who lack a light right foot
per my experience leastwise
cheers
M
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A proper old fashioned 4x4 permanent drive like Discovery/Defender is far better than the auto 4WD via a slip coupling. There is an even "damping" effect from both driven axles meaning that in snow at sensible speeds engine braking is very effective and balanced front to rear.
Also with a proper 4x4 you don't get the wheels whizzing away on an extra slippery bit which on front wheel drive causes momentary loss of steering.
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Except as per a previous comment/post ANY 4WD still brakes just like ANY 2WD ie on ALL four wheels
Actually, that's not always true.
My Toyota has a clever mode for descending very steep or slippery hills at 2-4 mph. It mostly uses engine braking, but when the car starts to break free it then activates the amount of hydraulic pressure each individual brake requires to slow each wheel in order that the car keeps in a straight line - I'm told that it doesn't do it using the ABS (ie. its much more sensitive, working on the hydraulic pressure).
But I haven't had to use it yet!
Edited by Marlot on 06/01/2010 at 16:10
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handeling/ steering...Hmmmm I suspect no advantage over a FWD except the power is better distributed for those who lack a light right foot
I think also 4wd gives much more benign handling on slippery roads. Whereas a 2wd might be at risk of snapping-out front or back on ice, the 4wd tends to run wide but with the same yaw angle. Keeping power on tends to drag you back on line, while in 2wd it often makes things worse...
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A few winters ago I got given a Jeep Grand Cherokee with beefy winter tyres as a rental car. There was heavy snow and I enjoyed whizzing along at apparently unfeasible speeds. At one point I had to brake heavily at a junction and if there'd been anything to hit, I would have hit it. I've no idea whether any of the wheels actually locked up but the car sailed on regardless before slewing sideways into what I presume was the kerb hidden under the snow. Since then I've been very circumspect both of 4x4s on slippery roads and of the tendency of their drivers to underestimate the laws of physics.
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Bagpuss, what you described happened right in front of my eyes this afternoon; I took my 2 daughters out to the park for a bit of sledging and on the way back was waiting to cross at a major intersection - saw a (new'ish) Landcruiser bombing along towards us (probably doing only 20mph but even that was 10mph too much for the conditions) and wanting to turn right at the junction "behind" us. I said to my girls "He's not going to make the turn at that speed" - literally just as I finished saying that he slammed sideways (nearside) into the curb on the corner.
Thankfully no injuries or (visible) damage to the car. Only a bruised ego for the driver probably but it could have been much worse had there been more traffic/pedestrians.
I think a lighter car would have just about made the corner at that speed but no way was the Landcruiser going to do it. I owned a Landcruiser for almost 5 years and one of it's main handicaps in these situations is it's weight/bulk.
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IIRC RAV4 is reactive 4x4 via viscous coupling - rear ones are powered only when front wheels slip. Same as CR-V or Fiat Panda etc.
I think you'll find the RAV4 has is permanent 4WD via a viscous centre diff and standard front and rear diffs. Its the CRV that has the part-time slip-sensitive 4WD. People often get the RAV4 and CRV mixed up.
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As far as i'm aware the 4x4 system on the older models is only activated by pushing the big round cone shaped button to the left of the steering wheel.
Then, the 4x4 system is only active up to 18mph.
Which imo is fine, as normally you only need 4x4 at slow speeds, like climbing a hill (snowy hill), stuck in mud etc...
They do this (temp 4x4) partly to give better fuel consumption and co2 emissions compared to using a full time 4x4.
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