Toyota Prado 4WD- Use of 4wd on sealed roads.

Submitted: Thursday, Mar 29, 2012 at 14:57
ThreadID: 92870 Views:6094 Replies:9 FollowUps:9
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I've got a 1996 Prado 4WD. The model is constant 4WD but has a lock-up centre diff that engages when you shift the lever to "high range lock" or "low range.

The other day I drove the vehicle on a sealed road around some tight curves for about 4ks and noticed the drive line becoming stiff, particularly when I reversed to park the vehicle.

It was then I noticed that it was in "high range lock".

What was happening with the drive line? And could this cause damage after 4ks.

Any answers out there??

Regards...
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Reply By: Michael A (VIC) - Thursday, Mar 29, 2012 at 15:10

Thursday, Mar 29, 2012 at 15:10
Yes, it will cause damage. Jack one wheel off the ground on each axle and the wheel should unwind the windup.
AnswerID: 481739

Follow Up By: fisho64 - Friday, Mar 30, 2012 at 02:22

Friday, Mar 30, 2012 at 02:22
completely un-necessary if you can get it to unlock.
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Reply By: Whirlwinder - Thursday, Mar 29, 2012 at 16:19

Thursday, Mar 29, 2012 at 16:19
BNDN,

If there was no "BANG", then no damage has been done BUT you were bloody lucky!

Do NOT used car with centre diff locked on any sealed road, only on loose surfaces so the wheels can sort out the windup problem.

Buy a lottery ticket for yourself.
AnswerID: 481744

Reply By: Member -Dodger - Thursday, Mar 29, 2012 at 16:21

Thursday, Mar 29, 2012 at 16:21
Join a 4wd Club and learn about your 4wd and it's capabilities and it's bad points.
And yes you may have done some damage but at 4k you may be lucky.
It pays to always check any controls before driving as sometimes inquisitive fingers fiddle with things.


.


I used to have a handle on life, but it broke.

Cheers Dodg.

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AnswerID: 481745

Reply By: Ross M - Thursday, Mar 29, 2012 at 17:24

Thursday, Mar 29, 2012 at 17:24
It is good you noticed it before too far and I agree a Tattslotto ticket is in order.
The powers of observation and instinctive checking is necessary if you own a 4wd as they are different from a 2wd in a few ways.
If you didn't do too much turning and one of the front cv's didn't go bang then you are lucky.
PS if you win with the Tlotto we can all supply our addresses to collect a share.
Call your entry Lucky Prado

Ross M
AnswerID: 481756

Reply By: Member - Phil G (SA) - Thursday, Mar 29, 2012 at 17:55

Thursday, Mar 29, 2012 at 17:55
"What was happening to the driveline"

Its called "Wind-up". When you turn a corner, the front wheels travel further than the rears. If the centre diff is locked, then you create a heap of tension in the driveline. Thats why if feelss like it doesn't want to go forward.

When you are on a loose surface, this is not an issue because the tyres can slip, but on bitumen, it is a lot harder for tyres to slip.

If nothing went bang, then you are fine - people do the same every day!
AnswerID: 481759

Follow Up By: Shaker - Thursday, Mar 29, 2012 at 18:14

Thursday, Mar 29, 2012 at 18:14
I thought the outside wheels travel further than the inside wheels.
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Follow Up By: Member - Phil G (SA) - Thursday, Mar 29, 2012 at 20:13

Thursday, Mar 29, 2012 at 20:13
They do! But the outside front travels further than the outside rear and the inside front travels further than the inside rear. Side to side doesn't matter is the diffs are open. Its the difference between front and rear with the centre diff locked that causes wind-up.
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FollowupID: 757089

Reply By: Shaker - Thursday, Mar 29, 2012 at 18:18

Thursday, Mar 29, 2012 at 18:18
One of the things that annoys me with my 120 series, is being unable to select low range with no centre diff lock!

AnswerID: 481762

Follow Up By: Member - Tour Boy ( Bundy QLD) - Thursday, Mar 29, 2012 at 20:36

Thursday, Mar 29, 2012 at 20:36
You can with the 80, 100 and 105 series if you do the "7 pin mod" it will only lock the centre diff in high or low if you push the button. There are different ways of doing it. One is the 7 pin mod under the dash if you have ABS and if you don't you can simply undo a connection on the transfercase that activates it when low is selected.
Maybe the prado can have something similar done ask the guys on LCOOL. You can search the 7 pin mod there to get the idea of what I'm talking about with the cruisers.
Cheers,
Dave
2010 Isuzu FTS800 Expedition camper
2015 Fortuner
Had 72 cruisers in my time

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Follow Up By: Member - Phil G (SA) - Friday, Mar 30, 2012 at 10:30

Friday, Mar 30, 2012 at 10:30
Dave,
Its depends on which model Prado. Some of the 120series have mechanical engagement and some are electronic. Can't do anything about the mechanical engagement. But the way I understand it, with the electronic engagement you can already use low range and the centre diff only locks when you press the dash button.

cheers
phil
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FollowupID: 757148

Follow Up By: tim_c - Friday, Mar 30, 2012 at 12:11

Friday, Mar 30, 2012 at 12:11
Being 1996 Prado it will be the 90 series. It has a lever to select 4WD-lock and 4WD-Lo. I've never actually checked but I've heard it is still an electronic lock (rather than mechanical) although it is activated by shifting the lever.

There is no separate button to lock the centre-diff, so if you modified it to not automatically lock when Lo-range was selected, you'd have to install a separate button to lock the centre diff.

A friend of mine modified the family 80 series 'Cruiser and he found while it was helpful to be able to use lo-range to manoeuvre the caravan into positiion without tearing up the campsite (ie. centre diff unlocked), virtually every other situation which required lo-range also required the centre diff to be locked - eg. when ascending a hill steep enough to require lo-range, the front wheels would just slip unless the centre diff was locked. I think in the end he decided the mod hadn't been worth the effort.
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FollowupID: 757161

Follow Up By: Member - Phil G (SA) - Friday, Mar 30, 2012 at 21:03

Friday, Mar 30, 2012 at 21:03
Tim, there were 2 systems on the 90series as well. The VX/Grande had push button centre diff lock while the GXL and RV have what you describe.
Shaker's comment was for his 120series.
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FollowupID: 757213

Reply By: desray (WA - Thursday, Mar 29, 2012 at 23:16

Thursday, Mar 29, 2012 at 23:16
The Prado should have a light on on the dash when locked in 4WD, is it not working or you didnt see it?
AnswerID: 481814

Follow Up By: Member - Phil G (SA) - Friday, Mar 30, 2012 at 21:00

Friday, Mar 30, 2012 at 21:00
He only drove 4 kilometres with it locked.
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FollowupID: 757212

Reply By: lkgr - Thursday, Mar 29, 2012 at 23:56

Thursday, Mar 29, 2012 at 23:56
To stop Centre Diff Lock being engaged automatically when low range is selected - go to LCOOL.org have a read about CDF - do it that way or install a CDL switch.
AnswerID: 481820

Follow Up By: Member - Phil G (SA) - Friday, Mar 30, 2012 at 21:07

Friday, Mar 30, 2012 at 21:07
His 90series has a mechanical centre diff lock - engaged when you pull the lever - its different to the 80series.
Anyway, that wasn't the original poster's problem.
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FollowupID: 757214

Reply By: Crackles - Friday, Mar 30, 2012 at 23:01

Friday, Mar 30, 2012 at 23:01
Several of the replies are possibly over stating the likelyhood of damage caused when driving on a sealed road while 4x4 is engaged for just 4 km. The reality is while there was certainly axle wind-up & some difficulty in turning, damage to the transmission would rarely occur over such a short distance. A good example is over at Moab in the US where they drive on solid rock all day in low range. We've had vehicles at work left in 4 wheel drive for 100km+ on sealed roads with no ill effect.
While it's certainly something to avoid, in your case I wouldn't lose too much sleep over it.
Cheers Craig................
AnswerID: 481933

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