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Greetings,

I am seeking advice on when I should be driving in 5th and 6th gears, which I understand are both over-drive. I live in a semi suburban area (mix of 60, 70 and 80 Kph speed zones). I have been told that driving in too high a gear (5th or 6th) can/will labour the engine.

Thanks,

Madonna

5th gear in a 6 speed is 1:1
4th gear in a 5 speed is 1:1

If the vehicle in Madonna's profile is correct, then 6th gear is 1:1

usually it's just a matter of feeling when the engine labours.

If you put your foot down and it feels really sluggish, it's probably labouring.

Alternatively, most cars have the recommended change speeds listed in the booklet, so just have a read.

Use whatever gear you need to get the revs you want.
Keep the revs in the 2500-4500RPM range and won't have too many issues in normal driving.
If going up a hill then use around 3000+RPM depending on steepness of the hill to avoid labouring the engine.

For normal puttering about in the NC, I only use 6th at >95km/hr on the flat and go back to 5th if there are any longish hills. I only use 5th at >80km/hr for flat cruising and go back to 4th or 3rd as required to keep the revs up.

Basically, use the tacho to see the revs and select gears to make the revs right.

I seem to be using one gear higher than most of you. Driving local streets at 60kph I'll be in 5th, if I get much over that (65 - 70) I'll shift up to 6th. I tend to keep the tach <3k when cruising. My car is turboed though, so extra torque and horsepower might be helping the engine from labouring ... or I could be doing it wrong?

It shouldn't matter how many gears a car has got. You make a gear change at a certain rpm point that always further accelleration after the gear change.

Comparing 5 and 6 speeds is like comparing apples and oranges. They are different in many way. All the ratios are different. And normally when a car has extra gears, the ratios are closer together. It's not 1 = 1, 2 = 2 etc with 6th being an extra. It is more like 1 = 1 and 5 = 6, and there is an extra gear in the middle for improved accelleration.

So @ 3,000 rpm, you might change at 20/40/60/80 for a 5 speed, and 20/35/50/65/80 for a 6 speed for a very rough example.

JBts view is about where I am. I rarely use 6 th ( overdrive on NB P2) ) except on freeways / toll ways and never around suburbia with 80klm limits. People driving for economy are advised to shift up to a higher gear. One of the points about having too higher gear is that for quicker acceleration you have to shift down. A mate of mine often just skips gears completely i.e. 1 to 3 or 2 to 4- not something I don't do that but limits are so low today that modern cars can handle this very well.

ManiacLachy wrote:I seem to be using one gear higher than most of you. Driving local streets at 60kph I'll be in 5th, if I get much over that (65 - 70) I'll shift up to 6th. I tend to keep the tach <3k when cruising. My car is turboed though, so extra torque and horsepower might be helping the engine from labouring ... or I could be doing it wrong?

This is how I operate. The motor in my NB seems happy in any gear at 2000rpm on even throttle openings.
On the open road 100kays is a smidgen over 3000rpm in 6th.
Around town on a decent flat stretch I'll slip it into 5th and it doesn't labour on an even throttle.

Bear in mind that an NC is pulling 2700rpm in 6th and 3200rpm in 5th at 100km/hr.

A 1.5 ND is pulling a mere 2500rpm in 6th and just under 3300rpm in 5th at 100km/hr. The 1.5 needs to be dropped back to 5th at 100km/hr to accelerate quickly or to climb a hill. The 2.0 will do it better with 30% more torque.

Still comes down to selecting the right gear to get the revs you need.

Thanks to All! Much appreciate the advice and knowledge shares.

Madonna