4WD on Bitumen Surface

Submitted: Wednesday, Mar 12, 2014 at 15:25
ThreadID: 106671 Views:3378 Replies:11 FollowUps:16
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Occasionally I need to tow a heavy caravan up a steep bitumen access road approx 120m long.

I can mange in first gear high range but when the bitumen is wet the rear wheels slip and also I would like to go slower to avoid trees.

Should I use low range without locking the front hubs or will this risk overloading the rear drive shaft and diff?

Or should I lock the front hubs and hope the front and rear drive components don't get damaged?

Thanks,
Al


Currently towing with LC76
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Reply By: Robin Miller - Wednesday, Mar 12, 2014 at 15:44

Wednesday, Mar 12, 2014 at 15:44
Lock the hubs and use low range in the wet.

Windup is a consideration but lesser of 2 evils.

One trick is to ensure the wheels with tyres are the same diameter by adjusting air pressures.

Also don't have tyres up to high , lower pressures give better traction on bitumen at low speeds same as dirt, but only lower if you still slip.
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Follow Up By: Robin Miller - Wednesday, Mar 12, 2014 at 15:53

Wednesday, Mar 12, 2014 at 15:53
Forgot to say that you should use minimum steering lock.

On my own Patrol I adjust tyres so that there is equal squash front and rear and can drive on dry bitumen a bit without lockup.
Occasionally I put it into 4wd when road is slippy to avoid wheel spin and getting hit by the local ute driver getting sideways leaving the lights.

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Reply By: CSeaJay - Wednesday, Mar 12, 2014 at 16:22

Wednesday, Mar 12, 2014 at 16:22
Al

I reckon if the bitumen is wet and slippery enough that you have wheelspin,
then it is slippery enough not to worry too much about windup problems either
Cheers,
CJ
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Reply By: pepper2 - Wednesday, Mar 12, 2014 at 16:25

Wednesday, Mar 12, 2014 at 16:25
Is the driveway straight or curved,the more curved the more windup will occur,if straight it should be fine with all wheels engaged,i have driven patrols in low range with front hubs unlocked without a problem several times.
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Follow Up By: Alsub - Wednesday, Mar 12, 2014 at 16:30

Wednesday, Mar 12, 2014 at 16:30
There is one small curve at the start of the climb and one near the top to get through a gate. Unfortunately the bitumen is not always wet.

Thanks for the replies, it appears that there may be more risk by driving on low range 2WD than low range 4WD.


Al

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Follow Up By: pop2jocem - Wednesday, Mar 12, 2014 at 18:30

Wednesday, Mar 12, 2014 at 18:30
Assuming you don't have an auto diff lock in the rear, just the standard Toyota offering that stops working about 10 k's after the first service, my option has always been to leave the FWH's unlocked and select low range.
I'm assuming you don't use much accelerator when manourvering your van so very unlikely to do any damage. I have done this many times over the years with various Cruisers and never had a problem. The reason Mr Toyota engages 4WD with low range is that he has no idea of when someone may floor it and dump the clutch.
Unfortunately if the driveway is that slippery that the rear wheels cannot give you enough traction then you have very little option other than engaging your front hubs as well.
Fortunately if the driveway is that slippery there will be enough give so that the likely hood of doing any damage is remote.



Cheers
Pop
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Reply By: scandal - Wednesday, Mar 12, 2014 at 18:20

Wednesday, Mar 12, 2014 at 18:20
I always use low range with the hubs UNLOCKED for maneuvering trailers/vans, much less strain on pretty much everything.
I would not have a problem using this method in your situation in on dry driveway, I very much doubt you will do any driveline damage, damage is much more likely to occur with shock loading, such as spinning wheels suddenly gripping while you still have boot into it.
If traction becomes an issue, lock the hubs, if it's spinning with the hubs unlocked than I doubt "windup" will be an issue, but once you are in place and ready for maneuvering, unsure the hubs are unlocked,

Shane
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Reply By: Kanga1 - Wednesday, Mar 12, 2014 at 18:25

Wednesday, Mar 12, 2014 at 18:25
Hi Al, for years I used low range with the free wheeling hubs in 'UNLOCK' on boat ramps because the boat was heavy and the ramp steep. Lower speed going down the ramp for better control and accuracy, and no slipping the clutch going back up with the boat on. If anything lower your rear tyre pressures to ensure you have 100% traction on the climb up the hill with the van on. Cheers, Kanga.
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Reply By: The Bantam - Wednesday, Mar 12, 2014 at 22:48

Wednesday, Mar 12, 2014 at 22:48
Another vote for using low range 4wd with the front hubs unlocked for manovering trailers....it slows everthing down and makes things much easier.

as for the wheel spin.

Slowing things down will reduce the incidence of wheel spin and improve control.

If however you have continued problems with wheel spin....there is obvioulsy enough slip that transmission wind up will not be an issue.

As for defating tyres......not at all a reliable way of preventing transmission wind up.

Delfating tyres may however improve your traction....how much ...well that is a good question that can not be answered unitll we know what tyre pressures you are running.

Another thing that may reduce your wheel spin.....is putting something in the back of the vehicle...50 to 100 KG can make all the difference.


cheers
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Reply By: kiwicol - Thursday, Mar 13, 2014 at 00:03

Thursday, Mar 13, 2014 at 00:03
Hi Al
Lock the hubs in and select L4x4 for the speeds you are doing , wind up will never be an issue, for any 4x4
Get into it and don't be scared of what you have heard.

Col
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Follow Up By: Member - Bruce C (NSW) - Thursday, Mar 13, 2014 at 20:49

Thursday, Mar 13, 2014 at 20:49
Dead right Col, I second that. They are made for it.

Bruce.
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restless and lost on a track that I know. HL.

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Follow Up By: Alsub - Saturday, Mar 15, 2014 at 20:22

Saturday, Mar 15, 2014 at 20:22
Kiwi, maybe in your Morris 1100 you will not get windup, but actually speed has nothing to do with it.

I was concerned that I might damage the rear diff by overloading it, but the damage that could occur due to windup is probably greater.

So slow I go, in low range with front hubs UNLOCKED.

Rgds,
Al
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Follow Up By: kiwicol - Monday, Mar 17, 2014 at 10:49

Monday, Mar 17, 2014 at 10:49
Alsub, if you are loosing traction from the rear, locking the hubs in is going to give better traction and wind up will never happen, as there still will be a small amount of slip.You are really underestimating your vehicle if you think you could damage a diff doing a simple procedure as posted.
I make my comments from over 35 years of experience of owning operating and working on 4x4 vehicles from trucks, heavy machinery to the average 4by. I have yet to see a vehicle do any damage using a locked system and doing what you ask.
You will still get the same problem in low range hubs unlocked, ie lack of traction.

Col.
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Follow Up By: Alloy c/t - Monday, Mar 17, 2014 at 16:17

Monday, Mar 17, 2014 at 16:17
Alsub , 120 metres and your worried about windup ?? 120 klm yeah windup could start to be a concern , but no way in a lousy 120 mtrs , lock the hubs , put her in low range and drive up WET OR DRY.
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Reply By: Crusier 91 - Thursday, Mar 13, 2014 at 15:33

Thursday, Mar 13, 2014 at 15:33
On the 80 series we do the "centre diff lock mod" which allows you to engage low range without engaging diff lock. It is used for the purpose for reversing trailers up curved bitumen hills in low range.

So instead of auto centre diff lock when engaging low range it allows you to engage and disengage it manually by the button. It a great mod for what the OP needs.
AnswerID: 528249

Follow Up By: Crusier 91 - Thursday, Mar 13, 2014 at 15:35

Thursday, Mar 13, 2014 at 15:35
I forgot to mention, the procedure for this mod is located at www.offroad80s.com.

Full step by step instructions including pictures.
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Follow Up By: Crusier 91 - Thursday, Mar 13, 2014 at 15:43

Thursday, Mar 13, 2014 at 15:43
Its also been cover here on a 100 series http://www.exploroz.com/Forum/Topic/97970/Driving_on_Bitumen_in_Low_Range_central_diff_lock_engaged.aspx
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Follow Up By: Crusier 91 - Thursday, Mar 13, 2014 at 15:47

Thursday, Mar 13, 2014 at 15:47
Here's a link to the write up
http://www.offroad80s.com/how-to-get-full-control-over-centre-diff-lock-in-low-range-t1091.html
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Follow Up By: Alsub - Saturday, Mar 15, 2014 at 13:03

Saturday, Mar 15, 2014 at 13:03
Interesting, but I don't think I have a centre diff....

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Reply By: Member - Bruce C (NSW) - Thursday, Mar 13, 2014 at 20:47

Thursday, Mar 13, 2014 at 20:47
That diff windup would NOT be a problem over the 120 metres distance.

I would therefore use the front wheels locked in when wet or if traction is a problem, no problems there I reckon. Low range wheels unlocked is also OK.

If however you were driving down the highway on bitumen for 10K or so I would say don't do it, take it out of 4wheel drive, but 120 metres. Not a problem.

The small amount of diff windup can easily be unwound once you have the caravan up where you want it and unhitched. All you have to do is reverse slowly till you can slip the gear lever out of 4 wheel drive, then get out and unlock the hubs. Not a problem.

These vehicles were made for that small amount of bitumen work. I can't see what all the fuss is about. You can get far more damage to the drivetrain on a dirt track sometimes.

Much better to be safe than sorry, if that heavy beast gets away with you there will be hell to pay.

Cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Reply By: Alsub - Saturday, Mar 15, 2014 at 13:07

Saturday, Mar 15, 2014 at 13:07
The bitumen was completely dry couple of days ago so I tried using low range with the front hubs UNLOCKED.

Just sneaked up at 1200rpm. Appeared to be no problem so I think this is the way to go.
I might use locked hubs but only if the bitumen is wet.

Rgds,
Al
AnswerID: 528390

Follow Up By: Member - Ross Gabb - Saturday, Mar 15, 2014 at 20:55

Saturday, Mar 15, 2014 at 20:55
They are called 4wds for a reason the front diff is designed to be locked when in 4wd you don't see 2wd low range vehicles do you.
You will do no damage. I have had 3 big vans and 3 big 4wds never had a problem.
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Follow Up By: Member - Bruce C (NSW) - Monday, Mar 17, 2014 at 12:36

Monday, Mar 17, 2014 at 12:36
That's the ticket Alsub.

You took a bit of convincing but I suppose that is on account of all the doomsayers on here.

LCs are built for it mate, that is why they are so popular. They are no toy, they are the real deal. Built tough for the tough jobs. Why do you think the mines use them, and pretty much, only them.

Happy travels and cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Follow Up By: get outmore - Monday, Mar 17, 2014 at 16:38

Monday, Mar 17, 2014 at 16:38
while this is true you will also find in underground mines where the cruisers remain permantly in 4wd around the LV workshop there is a pile of gearboxes, a pile of front diffs and a pile of clacking cv joints

make no mistake having your vehicle in 4wd when it can be avoided or longer than need be WILL shorten the lives of those componants
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Follow Up By: Alsub - Monday, Mar 17, 2014 at 17:17

Monday, Mar 17, 2014 at 17:17
Exactly why I have decided best to use low range two wheel drive on hard dry surfaces.

I mainly wanted to find out if this was likely to put too much load on a single diff and axle.

Rgds,
Al
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Reply By: Shaker - Saturday, Mar 15, 2014 at 23:45

Saturday, Mar 15, 2014 at 23:45
It's the main thing that disappoints with my Prado, no low range unlocked!

AnswerID: 528428

Follow Up By: Alloy c/t - Monday, Mar 17, 2014 at 16:21

Monday, Mar 17, 2014 at 16:21
That just means you should have bought an FJ Cruiser with Crawl control ….
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