Newbie question. I know in automatic damage can be done to a tranny if put into neutral while the car is in motion. Is this the same for manual transmissions? The reason I ask is where I live I have roads that have steep grades and I can pretty much coast down these roads at close to 50 to 60 mph. However, I don't want to throw the tranny into neutral if it can damage it.

I was led to believe that manual transmissions don't have the same issues as the automatics. Auto relies on the transmssion pump while the manual does not have one. Is this correct?

 

It will not hurt the gearbox but why your suggesting you want to do it is dangerous and wrong. Why on earth would you want to coast at such a high speed ? Certainly it will not save any appreciable gas. I'd leave it in a gear that allows you to do the speed you want via a combination/balance of engine braking and gravity.

Coasting down a steep grade in an MT at 60MPH at idle is plain creepy. If I were your passenger I think I would jump out the window first chance I got!

 

Do you know how a manual works?

Once you press the clutch in the transmission is disengaged from the engine... no damage can possibly be done.

Why not just hold the clutch in, instead of shifting into neutral??? lol

 

Do you? Even worse since that will wear the throw-out bearing unnecessarily. You want to minimize "clutch in" time since the throw-out bearing is a "dry" bearing meaning it gets no circulated lube through it. It is usually "speced" for the light duty it sees.

 

Why on earth would you want to coast at such a high speed ? Coasting down a steep grade in an MT at 60MPH at idle is plain creepy. If I were your passenger I think I would jump out the window first chance I got! -Adobeman


Well I failed to mention that the speed limit is 55mph on many of these roads or rather highways. I somewhat see your reasoning for traveling at such high speeds when not in gear but I don't take chances where I can endager myself or others.

It was a question that I was sure would warrent additional questions so I tried to provide additional info. My root question was about the gearbox so thank you for your response to my question.

 

In gear on a decline you will get better mpg and CONTROL in your vehicle since the injectors are shut off during decelaration and you are in gear in case something was to ever happen and you needed to make an evasive manuver. In nuetral and coasting the car is at idle and using fuel, not to mention you are in a controlled yet uncontrolled situation if something was to occur and you need to react quick enough. On a decline you should be in a lower gear as to not over rev the motor but to keep good engine braking as to not accel the vehicle.

 

Welcome to the forum.
No damage occurs to the tranny if put into neutral while the car is in motion.
However, it is UNSAFE to coast with the car out of gear, per the posts above. With a long decline, or any grade approaching "steep," shifting to neutral will cause a car to accelerate down the hill. Just downshift a gear (or two, to 5th or 4th) and let the engine braking maintain the downhill speed-- it's safer than neutral and you maintain more control over acceleration and braking.

 

Sorry, but the TOB is not designed for "light" duty... coasting in gear is NOT going to wear it out... lol

 

What Adobeman is refering to correctly is when you press the clutch in the throwout bearing is in action or motion. Meaning it is spining with the throwout arm side being stationary and the pressure plate side spining. This causes wear on the throwout bearing, if you put the gearbox in neutral and release the clutch then the throwout bearing is not spining. In addition when the clucth pedal is pushed in, the clutch is somtimes clattering around between the pressure plate and flywheel againg causing some small wear.

Most throwout bearing in transmissions are difficult to get to, so replacement is typically only possible when you remove the bell housing. It only makes sense to push in the clutch all the way shifts or for a few seconds when you are getting ready to move from a stationary position (ie - a stop sign or a traffic light about to change). The only throwout bearing I've ever had to replace in clutch replacements are for those folks who would use the clutch pedal for alot for neutral instead of shifting into neutral on the gearbox.