Prado All wheel Drive Hows it Work ??
Submitted: Tuesday, Aug 21, 2007 at 11:48
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Member - Stephen M (NSW)
Hi all, not sure on how the all wheel drive set up works on a prado ?? I jumped on it this morning just trying some thing out and noticed that the rear
wheels spun (wet road) then gripped and took off. Now I don't normally drive like this but was wondering isn't it that it is an all wheel drive that this shouldn't happen and should have transferred the power to part front to stop this from happening. I know by locking the transfer lever to 4HL is locking 50/50 front and rear, are they like a Subaru or totally different set up.How do they determine wheel spin and transfer to the wheel that isn't spinning or have I got it all totally wrong ?? Is it done through the transfer case even though I have not locked it in 4HL. I was told that I can lock it into 4HL on wet and greasy roads but then have been told no, Ill end up causing windup in the transfer etc not that I would bother putting into 4HL on normal wet roads only snow,sand mud etc. Whats peoples thoughts on how all this all wheel drive stuff works on the prados. Regards Steve M
Reply By: Member - Tom V (WA) - Tuesday, Aug 21, 2007 at 12:52
Tuesday, Aug 21, 2007 at 12:52
Steve
have a look @ the DVD attached to the current 4WD Monthly, there is an article in there on traction control with 3 prado's.
probably not 100% what u are looking for, but will answer some of yr question.
cheers Tom
AnswerID:
258276
Reply By: traveller2 - Tuesday, Aug 21, 2007 at 15:21
Tuesday, Aug 21, 2007 at 15:21
With a constant 4wd like a Prado you only have to get one wheel to break traction to cease forward motion.
In HL you have to get one wheel on each axle to break traction to cease forward motion.
What you felt/saw was probably the traction control or lsd taking over.
AnswerID:
258294
Follow Up By: Member - Stephen M (NSW) - Tuesday, Aug 21, 2007 at 16:39
Tuesday, Aug 21, 2007 at 16:39
Hi Traveller2, I thought that if say the rear right hand wheel (my case this morning) started to spin it would either flick across to say passengers been LSD (although its probably r/s anyway 150k being a toyota lsd) if it continued to spin then it would then transfer partly/full ?? to the front to gain traction, I thought thats what all wheel drive meant, then if needed you would lock (HL) so you get a constant 50/50 front and rear. So what Im saying in short is I thought it flicked from front to back in standard 4H no lock ?? Excuse my ignorance just trying to understand how it works. Regards Steve M
FollowupID:
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Follow Up By: disco1942 - Tuesday, Aug 21, 2007 at 18:03
Tuesday, Aug 21, 2007 at 18:03
Stephen
Is your traction control gone as
well? Or is it a bit slow to actuate? You probably only got wheel spin until the traction control came into play.
PeterD
FollowupID:
519605
Follow Up By: Member - Stephen M (NSW) - Tuesday, Aug 21, 2007 at 19:07
Tuesday, Aug 21, 2007 at 19:07
Hi there Peter,
mine is series one so no traction control in
mine, mind you I have seen it in action when we did high country on one of the other prados and worked
well in a TX 3 litre diesel. I have heard there around 3k for a new one if it goes bang apparantly controls abs as
well. Scary thought . Regards Steve M
FollowupID:
519615
Reply By: Member - Tim - Stratford (VIC) - Tuesday, Aug 21, 2007 at 17:43
Tuesday, Aug 21, 2007 at 17:43
Stephen,
As said above - it is my understanding too, that if you lose traction on one wheel then the drive goes to the spinning wheel - then no traction or motion (in 4H unlocked centre diff).
In 4H with centre diff locked (as in 'old tech' 4WDs) with a front and rear wheel without traction- this will halt your progress.
As an example if you get out of shape 4WDing with a front and opposing rear wheel stuck in the air then without cross axle lockers there is no progress.
AnswerID:
258310
Follow Up By: Member - Stephen M (NSW) - Tuesday, Aug 21, 2007 at 19:16
Tuesday, Aug 21, 2007 at 19:16
Hi there Tim yes I know exactly what you mean have been in that situation with the old hilux but was thinking even without being in 4HL in the prado it would transfer some drive to the front like the subarus but they are obviously a different set up. Putting in 4HL would give me a positive 50/50 but as you said get opposing
wheels in the air and your going nowhere unless you have either front or rear diff locks or both. Regards Steve M
FollowupID:
519616
Reply By: lc_120man - Tuesday, Aug 21, 2007 at 18:34
Tuesday, Aug 21, 2007 at 18:34
On Prado when 4wd ransfer level is not engaged the drive is distributed at around 70(rear)/30(front)
http://www.lcool.org/technical/diffs/diffs.html
AnswerID:
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Follow Up By: Member - Stephen M (NSW) - Tuesday, Aug 21, 2007 at 20:44
Tuesday, Aug 21, 2007 at 20:44
Thanks Lc, good read. I presume the 95 series is exactly the same. Thankyou Regards Steve M
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519638
Reply By: Ken - Tuesday, Aug 21, 2007 at 20:10
Tuesday, Aug 21, 2007 at 20:10
Steve, your Prado is not an all wheel drive but a real full time 4WD. It has a transfer case and most importantly a centre differential. When the centre diff is unlocked you will not have transmission wind up but if you loose traction on either the front or rear axle the power will all go to that axle. It is not hard to spin the
wheels at either end in some conditions and as you found you will go nowhere.
If you lock the centre diff the torque is delivered equally to the front and back axles and provided there is equal grip on the
wheels at one or both ends you will move. If there is not equal grip and one front and one rear wheel spins you won't move.
The term 4WD is actually a misnomer ans it really means it is capable of driving all four
wheels. Without axle diff locks there is always the opportunity for it there to be less the 4
wheels driven.
Regards,
Ken
AnswerID:
258355
Reply By: Markymark - Tuesday, Aug 21, 2007 at 21:20
Tuesday, Aug 21, 2007 at 21:20
Driving around unlocked the power will go to the wheel with the least resistance or traction. If the rear LSD was any good, drive would be transferred across to the other opposing rear wheel but as standard Toyota LSD's aren't very good new, yours at 150k is probably RS as you said. BEcause the rest is a simple mechanical set-up and you have a normal open centre diff, no drive would be sent to the front
wheels at all if a rear one started spinning. Some old Rangies had a centre viscous diff that did send power from the faster spinning driveshaft to the slower spinning driveshaft, see link
here
Cheers,
Mark.
AnswerID:
258377
Follow Up By: Member - Stephen M (NSW) - Tuesday, Aug 21, 2007 at 21:32
Tuesday, Aug 21, 2007 at 21:32
Thanks Mark just had a read learn new things everday. Regards Steve M
FollowupID:
519664
Reply By: Shawsie (Bris) - Wednesday, Aug 22, 2007 at 14:46
Wednesday, Aug 22, 2007 at 14:46
Hi Steve, my gxl is getting close to 170k and i don't have any problems so far with any of my running gear. When low range lock is engaged
lookout! as it will go anywhere ;o) only last week i took it up a very steep loose
hill and with a bit of coaxing got to the top. The centre diff lock IMHO make a big difference. Go the Mighty Prado :o)
AnswerID:
258443