The other day we were going somewhere in Laureen's 740 Ti. She was driving. I noticed at a light that she was keeping the car in gear and had her foot on the clutch the whole time. I told her not to do that as I was always told you should take it out of gear and not keep the clutch pedal in. Laureen asked me why you shouldn't do that and it was then I realized I didn't really know the answer to that question. I just always accepted that one shouldn't do what she was doing and never questioned it. I guess I'm still a bit fuzzy on how the clutch works and what happens when you push the clutch pedal in, etc. I think I have a general idea of how it all works but I'm not sure I've got it all straight in my head.

So was I right to tell her that it's not good to keep it in gear and simply keep the clutch pedal pushed when standing still for any length of time ? If I am right then what exactly happens when you do that ?

Thanks,

Roger

Some people say that it wears springs out sooner, some people say it wears out the release bearing sooner. I've done it my whole life and have had no adverse effects. So its a preference.

It's simple physics, I'd say. With your foot on the clutch you've got the release bearing turning and with significant pressure on it. With your foot off the clutch you don't. I'm sure over the life of the vehicle you'll be replacing release bearings more often but that's pure speculation...

I never sit with my foot on the clutch...

With the clutch depressed you place thrust loads on both the release bearing and the crankshaft thrust bearings, although these bearings are well lubricated and designed to withstand these loads for prolonged periods of time.

I usually try not to leave the clutch depressed for any length of time, I have replaced enough release bearings over time and would rather have them last longer than the clutch, but realistically release bearing failure is usually attributed to riding the clutch.

While physics should sell the day, I also don't sit with my car in gear, foot on clutch on the off chance someone hits me and I lurch forward or my foot slips in wet/snowy weather and I do the same (idle day dreaming also counts).

So save the bearing and prevent accidents. Oh and full marks for being brave enough to critique your significant others driving.

Great answers to your question, I learned something today. I have to admit I have mostly sat with the clutch in, although my wife (who is short) I believe lets it out as it's a strain to hold it in for long. Having said that our 740 is at 471K on the original clutch.

To add to Craig's comments my wife and I now usually let the clutch out at lights using the time delay to re-engage as a buffer for avoiding red light bandits. My wife feels it has saved her getting T-boned on at least 2 occasions.

Clutches don't last long enough for me for it to matter lol.

I do all the worst things...I ride the clutch on slight up hills at idle, burn the clutch between gears, do clutch drops, slip it to get the revs up with the crappy M46 ratios, shift without fully disengaging the clutch, use the clutch to slow the car down or get it sideways...yeah.


Interestingly, my record is murdering a stock clutch with 11psi of boost in 25K miles, along with one M46. Since then I've reformed my ways a good deal and actually do catch myself driving like a sane person taking the car out of gear and using the parking brake (non violently...it is a 240 afterall) on hills to gently ease up the hill without wearing out the clutch or brakes excessively. I also scaled back my beatings after wearing a huge groove into my stepped flywheel and cracking it all the way across inside the outer ring.

On my DD, brake linings last forever however.

You know what, I've been taught the complete opposite my entire life. You do NOT let it sit in neutral while at an idle at lights.

It wears out the input shaft bearings in the transmissions.

Now I don't know if this is true or not. But I have 2 different friends (1 civic, 1 mustang) who drive like this. Both of thier transmissions are very noisey. My friend with the civic traded in on a Lexus IS300 and I told him what I had always been taught so he changed his driving habits, and so far no noise, but its only been 2 years and 60K km on the lexus, where he had had the civic for 4 years and over 100K km. The mustang guy obviously has a mullet and doesn't care because the mustang is the best car ever built.

We just finished up clutches at school, and they said that a throw out bearing should outlast a clutch. So I have nothing to say otherwise.

So I'll continue keeping my clutch in.

Jordan

Trying to figure out why having in "N" would wear out input shaft bearings??? Input shaft turning as is the counter shaft and all other gears, the only thing not turning would be the main shaft. All gears and bearings should be receiving lots of oil .... what am I missing???

I'll talk to the teacher about it tomorrow. We covered it in clutches.

I could have the wrong bearing. It has something to do with no load going through so it bernellies the bearing race over time.

Jordan

This would be the equivalent of saying that driving wears out the input shaft bearings. Sure your throw-out bearing should outlast your clutch, but if you ride it all day long and sit with it engaged (i.e. in gear) then it will die quickly. Think about what it does. It's not doing anything while the clutch is released and to think that the internals of a transmission can't handle the input shaft slowly rotating in an oil bath is silly.

I would hazard a guess that your buddies transmissions are noisey due to the thrashings they are given - not due to idling while in neutral (where the transmission is experiencing about as much stress as it would if you turned it by hand).

Talked to him,

Either way you're up shits creek. Things wear either way. I talked to the engine/tranny teacher also. He said same thing. But he said the bearings in the transmission will wear more on a 4cyl with a light flywheel, more than a smooth pulsing 8 or more engine. Thrust bearings in the engine will also wear of course, with the clutch in.

Then my main teacher brought out a "Manitoba stupid law handbook" and one of them was about once a car has entered a public road, then you have to keep the car in a gear and the only time its allowed out is during shifting. Another one was you aren't allowed to shift in an intersection .

About throw out bearings. Any car that had a self adjusting cable clutch, has the throw-out bearing riding on the pressure plate at all times applying light pressure. Hydraulic clutches also apply slight pressure to the pressure plate. So in other words, they are constantly turning. (approximately 90% of hydraulic clutches apply some pressure)
--This info pulled from--Automotive Technology: A systems Approach: First Canadian Edition ---
Jordan

I suppose opinions are like...well, you know what... Everyone has one. I'm going to keep my foot off the clutch pedal regardless of what obscure laws may be on the books. I'm going top do it in the interest of not wearing out my throw-out bearing (and pilot bearing) any faster than I need to and not putting excessive pressure on any thrust bearings on my crankshaft. I'll take my chances with the internals of the transmission wearing out and the geriatric cop who knows ancient laws...