4wd theory: maximizing traction....
Submitted: Saturday, Sep 22, 2007 at 23:15
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Bware (Tweed Valley)
Not taking into account traction control and various modern traction aids, I'm curious what others' techniques would be in a hypothetical situation.
Firstly, let's establish the premise that a 4wd's purpose is to give greater traction. Not too much traction though, otherwise there may be damage to the driving parts of the vehicle.
So, it seems the accepted practice is to drop the tyre pressures for general off road tracks to give greater traction. My question is - How do you tackle a steep, windy track that may have sections that have no 'slippage' (causing wind-up in transmission/drive-line). You folk with diff-locks must have to consider this question regularly.
Reply By: Rock Ape - Sunday, Sep 23, 2007 at 05:46
Sunday, Sep 23, 2007 at 05:46
Yep, you do get wind up but due to the fact you are not on a solid surface, ie: cement/ bitumin one wheel will slip and wind up is gone. Even rock is normally uneven and will allow slip when weight transfers off one wheel.
The utes I have driven at work for years now are locked in low range 4wd and do short stints on bitumin, they are always turning on 1 in 6 declines due to being used underground, and yes you can feel the wind up on the bitumin but not on dirt or rock which is normally wet.
As for broken diffs, yes we break the odd front diff, more so because of the flogging they get than wind up, even the cvs last around 12 months.
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Follow Up By: Bware (Tweed Valley) - Sunday, Sep 23, 2007 at 13:41
Sunday, Sep 23, 2007 at 13:41
That's very interesting info; thanks for the reply.
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Reply By: Member - Davoe (Nullagine) - Sunday, Sep 23, 2007 at 07:30
Sunday, Sep 23, 2007 at 07:30
Was in a situation lime that a while back on a large granitite
hill. I was taking the track to the top to some masts and alot of it was
granite but wound around a few boulders.
was a while back but i think i wondered much as you before doing it in 2wd. i think i figured if it gavenough grip to cause wind up then it would have enough to use 2wd
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Follow Up By: Bware (Tweed Valley) - Sunday, Sep 23, 2007 at 13:44
Sunday, Sep 23, 2007 at 13:44
Yeah, that makes sense. It does depend on knowing the whole track is going to be a hard surface though.
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Reply By: Mick - Sunday, Sep 23, 2007 at 09:43
Sunday, Sep 23, 2007 at 09:43
If there's no slippage you don't lock the centre diff (or don't put it in constant 4wd in layman's terms). If there's slippage as on anything other than a sealed surface lock it up.
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Follow Up By: Bware (Tweed Valley) - Sunday, Sep 23, 2007 at 13:49
Sunday, Sep 23, 2007 at 13:49
No centre diff on my poverty-pack LOL
If the track is steep you need to commit to 4wd or 2wd before attempting it. You don't want to be touching the clutch to change once you're going up.
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Follow Up By: Muddy doe (SA) - Sunday, Sep 23, 2007 at 18:57
Sunday, Sep 23, 2007 at 18:57
Many constant 4wd vehicles such as my Prado will only use low range with the centre diff locked. Thus Bware's question is quite valid. On a steep climb/descent on a solid surface (like a solid rock surface) I want to be in Low range to maintain better speed control but cannot engage LR without the centre diffbeing engaged.
Muddy
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Follow Up By: disco1942 - Sunday, Sep 23, 2007 at 19:27
Sunday, Sep 23, 2007 at 19:27
Muddy - sounds like you need a Disco and not a Prado. You can run them in low range without locking the centre diff.
PeterD
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Follow Up By: Member - Olcoolone (S.A) - Sunday, Sep 23, 2007 at 21:00
Sunday, Sep 23, 2007 at 21:00
Wait until Muddy gets his NEW 200 series Landcruiser!!!!
Regards Richard
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Follow Up By: Muddies Doe(Trippn) - Sunday, Sep 23, 2007 at 21:18
Sunday, Sep 23, 2007 at 21:18
Mr Doe
That would be OUR Prado.....mmmmmmmmm?
Richard
Not likely, these days he has other things on his mind!
Cya
:)
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Reply By: obee - Sunday, Sep 23, 2007 at 17:33
Sunday, Sep 23, 2007 at 17:33
I once did about twenty k's in 4wd on the bitumen before I realized my mistake. Weakest point is the tyres which will slip and wear a little. I would'nt worry about a bit of rock crawling if you need the traction.
Owen
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Follow Up By: Bware (Tweed Valley) - Tuesday, Sep 25, 2007 at 12:08
Tuesday, Sep 25, 2007 at 12:08
Thanks for that Obee
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Reply By: Member - Phil G (SA) - Sunday, Sep 23, 2007 at 23:43
Sunday, Sep 23, 2007 at 23:43
Main issue is where you get the very sharp turns - like switchbacks.
Better to take these as 3-point turns (or even 5-point turns), as the wind-up goes away when you reverse.
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Follow Up By: Bware (Tweed Valley) - Tuesday, Sep 25, 2007 at 12:09
Tuesday, Sep 25, 2007 at 12:09
Great point, thanks Phil
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