We are advised to set off in 2nd on slippery roads, as this offers a lower torque and therefore less likely to slip.
On the other hand, anybody with a low ratio box would stick it in low ratio and choose first and have no trouble - despite having enough torque to shift the tarmac if you wished.
Confused??? I am.
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If you have a low-ratio box you also have 4-wheel drive.
And if you are in deep mud using low ratio means less clutch-smoking as it slips in 2nd.
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Blinking heck what is this about higher gears, and per the comment above commensurate clutch slipping. doh indeed.
a low gear and proper clutch modulation with the right foot morelike.
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I'm confused too, keeping in a higher gear does make sense whilst trundling along but not in every scenario, so long as one keeps their wits about them.
Lets be honest some drivers out there have no 'feel' for whats happening under their wheels in almost any circs, and without various traction assistance systems wouldn't get very far, we've all seen them.
In a higher gear an undetected wheelslip can quickly mean the wheels can be spinning at high speed compared to actual road speed, whereas a lower gear would limit attainable wheelspin and the usual increase in revs might be easier heard.
I don't think there's any hard and fast rules for gear selection in bad conditions, gentle throttle brake and steering control and learned feel are far more important together with reading the road, learned and refined better maybe in cars that don't do it for them a driver gets to know whats going on at the wheels.
Edited by gordonbennet on 30/12/2009 at 12:15
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Frictional force = u*m*g
Force applied via wheel torque = Torque on wheel * radius of wheel
Slippage occurs when torque on wheels exceeds frictional force available.
Torque on wheel = engine torque * gear ratio * final drive
First gear sends more torque to wheel compared to second gear. So chance of wheel slippage is less in 2nd gear.
Yes, 3rd or 4th gear sends even less torque on wheel BUT engine can't develop enough POWER in lower revs to pull the car - so using 3rd/4th to start from standstill will cause the car to stall.
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>>Force applied via wheel torque = Torque on wheel * radius of wheel
I think you might want to review that formula
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Very gentle throttle is a great starting point.
MD
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When driving a 4x4 with a transfer box which provides a set of low ratios, I would not set off on a slippery road in low ratio, I would use the normal set of ratios, though would probably set off in 1st.
The low ratios allow your 4x4 to travel at very low speeds over rough terrain without dipping or slipping the clutch. Even so, you might well pull away in low ratio 2nd and reserve low ratio 1st for maximum engine braking when descending steep, slippery inclines.
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