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-   -   Do you lug your engine? (https://www.team-bhp.com/forum/technical-stuff/53754-do-you-lug-your-engine-12.html)

I never do that. In bumper to bumper traffic, I just use first gear (or second) and let go the clutch without pressing the gas pedal - the car will continue moving at a constant speed and engine will not shudder or stall. BTW, i tried this with a Swift and engine just died when there was a slight slope upwards.

Its painful to see some people killing their engines in second gear at dead slow speeds, sometimes the metallic (tappet?) noise so unbearable even from new generation engines, but their drivers with the 'Uncle driving style' do not mind that at all.

Random thought : Wouldn't engine lugging have an effect on the clutch too? While offroading, and whenever possible, it's common practice to choose a lower gear to preserve the clutch under stressful situations (towing, steep inclines etc.).

IMO : lugging is one of bigger causes for faster clutch wear.

It will, especially with "half clutch" driving which puts undue pressure on the clutch and pressure plates.

I quite agre. With due respects some members have tried to define rpm ranges. This is not valid, since what will be acceptable dawdling about town, will be totally inadequate when on the highway. Also, in some cars having the AC or or off may make a difference of two gears esp. on the highway.

Modern FI engines are more forgiving since they try and compensate and do not easily come up knocking, unlike the old carb engines.

I think it is the gear box which would be under stress and not the clutch.

I never lug my engines, be it car or bike. I always move freely through all the gears, and never hesitate to downshift depending on traffic / road conditions.

I feel the most damage is caused when you floor your accelerator to gain speed and the engine is not able to respond in and adequate manner due to the car being in higher gear.
If the same scenario was repeated but instead of flooring the accelerator you very very gently press the accelerator and let slowly the car build up sufficient speed then the damage would be much less. So I feel that if you slightly lug your car then its ok given the condition that when you accelerate you do it in a very gentle manner. A person can feel by experience what should be the gentle acceleration to avoid engine making any different noises.
Yes the clutch is going to be damaged because it will always be carrying a higher torque when it is being lugged.When you switch to a lower gear say from 3rd to 2nd the torque requirement coming from the wheels onto the clutch gets reduced. Engine damage is another consequence ofcourse.

If you are going up a slope in 3rd gear at 20 kmph, I don't see how you can avoid full throttle.
This is incorrect. When you are lugging you are probably at 1K RPM in 3rd or 4th gear whereas peak torque would be somewhere near 2.5-4.5K RPM depending on the vehicle. So definitely you are nowhere near peak torque when you are lugging.

Why not?

Depends on the momentum of approach to slope. In my Viva, even if the momentum is not that great, i have to use roughly 40% depression of accelaration even when i am in 4th gear at 20kmph for the car to surge ahead.:thumbs up

Sorry, the scenario I mentioned was mostly for my petrol Swift. In a pete'd Viva you are probably not lugging the car even at 4th gear
and 20 kmph.

My bad. True, i never experienced the word "Lug" in my car:)

A good sign of lugging will be if the engine labours. My Accent with gentle pressure of the throttle will pick cleanly from under 800rpm in 5th but I will probably have to go down to second if I want a clean pick-up in a hurry. I remember having to shift down a gear in my Esteem (carb) in order to overtake. In the summers I had to go down two gears!

It all boils down to how sensitive and gentle you are.

Driveline shunt is a shuddering or jerking that is felt due to the small amounts of play through the transmission system - each union joint has a tiny amount of play - the clutch spline drive, each gear mesh, including the differential, each cv joint and finally the wheel hubs. If they were all tight, there would be no drive line shunt at all, but in practice every one has a tolerance.
Even if none of them are badly worn, that's a lot of gears/joints etc in the system, and these can add up to give a noticeable lurch when powering on / lifting off.

Of course, if one or more joints is worn out, then it's even more noticeable.

Engine lugging shouldn't harm the clutch facings per se. In case driveline shunting occurs, it can break the little shock absorbing springs in the clutch plate, or wear out the splined shaft connecting the engine/gearbox to the clutch.

Choosing a lower gear while towing/going up inclines doesn't just preserve the clutch - it reduces wear and tear of the engine and transmission system as a whole.

Thanks for the clarification.