new manual driver: does this destroy my tranny?
 

I've recently just learned how to drive manual. To save gas and engine wear; recently I've been coasting on the highway at high speeds.


Ie, I'd accelerate to 135kmph (85mph) in 6th gear then clutch in, go to neutral and coast down to 90 kmph (55mph). I would then blip the throttle, and shift back into 6th and repeat.

Someone told me this increases wear on the tranny; but I'm not sure if this guy knows what he's talking about.

Can someone shed some light? Thx.

This will not increase wear on the transmission. You can google and search about how exactly a manual transmission car works and you'll understand why the tranny wear statement is incorrect.

Tranny clutch plate wear could be increased with this type of driving if you don't evenly match revs each time, just like more stop and go driving is going to wear faster as well. In the end, this type of driving won't hugely affect the longevity of the clutch likely.

Coasting in neutral uses gas to keep the engine at idle. Coasting in gear uses no fuel. The wheels are effectively turning the crank so the ecu cuts fuel. This is the most efficient way to decellerate. It's called engine braking. Downshift to put yourself into a lower gear at a higher rpm to increase the effect. Blip the throttle between gears to match revs.

I believe doing what you are doing would reduce fuel economy somewhat. I'd think that keeping yourself at speed with light throttle is better than constantly accelerating to pick up speed and then idling while you slow down.

There's no need to try to baby the transmission.

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Are you only popping it into neutral when you're going downhill? Because if you're putting it into neutral on straights then I don't think you would be saving any gas. The best way to save gas on straights is to drive at a consistent speed. Setting cruise to 100-110 kph for straight stretches, accelerating in anticipation of going up-hill and popping it into neutral when going down hill will probably save you the most money.

Accelerating to 135 and coasting down to 90 will probably only get you tickets, wasted gas and a sore leg.

this will not harm your tranny

but it will harm your MPG as you are essentially letting the engine idle, and that consumes gas

if you just lift the gas pedal then the car will coast and consume zero gas until your rpms drop below 1200 or so.

plus it's always better to be in gear than in netural in case you need to get back on the gas

Also coasting in neutral is illegal in many places. If you need to accelerate quickly to avoid an accident you will not be prepared to do so.

I quite literally get a feeling of helplessness or being a target whenever I'm coasting not in gear. My only instant defense is braking and that is not always what you need yo protect yourself.

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i would avoid engine braking (down shifting to a lower gear to slow down). this just puts more stress on your engine.

use your brakes instead. that's what they're there for. brakes pads are a lot cheaper than engines.

as suggested earlier, the safest and most economical way to drive is to be consistent with your gas (avoid sudden accelerations).

I'd like to see some info to support this. Not saying you're wrong. I've just never heard that engine braking harms the engine.

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Regarding engine braking: my friend doesn't revmatch for engine braking. He just downshifts and feathers the clutch. This is bad imm assuming?

Back to driving style:
Well here's the dilemma

Coasting in gear allows friction in the engine to slow down the car; thus making the length of the coast a lot shorter... (IE you will drop from 85mph down to 90mph a lot quicker). Consumes less gas

Coasting out of gear reduces friction annd allows you to keep your speed for longer, and let's you go farther (due to the wheels not having to turn the engine). This consumes more gas (aparently?)

- so which one is better....?

Please dont say stuff that's not true. Engine braking does no harm to your engine at all.

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coast in gear, it's safer for you and everyone around you.

6th gear high speed running is actually super fuel efficient.

last weekend i put close to 400 highway kilometers in um.. ahem, spirited driving, and my MPG was still significantly better than city driving.

if done improperly it will, severe shock to all components if you clutch dump into 2nd while doing 100kph or something.


ever see a car's RPM needle go past the tachometer faceplate? ask me how i know. :bonk:

i wouldn't say it 'harms' the engine. it probably puts as much wear as revving to X RPMs. i suppose if you don't rev match it properly, then you put stress on your drivetrain.

i just don't see the point in engine braking when your brakes do a way better job at it. brake pads are also relatively cheap to replace. :iono: