I'm assuming this is a question about the clutch of any car, not sure if the M5 is different. When I back down my driveway, i usually keep the clutch pedal pressed all the way down after being in reverse for a second to get the car rolling down the hill. I bump the shifter to Neutral, keep the clutch pedal pressed the whole time, then when I'm ready, 1st gear and on my way.
The question is does this hurt the clutch or reduce its life? I'm not letting out at all when backing down my drive way (about 25 feet). Would it be better to move to neutral and let off the clutch?
Also, at a red light, is the clutch being "hurt" by keeping it engaged while waiting to move?
I'm assuming this is a question about the clutch of any car, not sure if the M5 is different.
It's not. You are not hurting the clutch at all ... except you are shortening the life (usually no problem) of the clutch spring ... same at a stop.
BUT, you are shortening the life of the throwout bearing ... it has a life, sometimes less than the clutch. I would NEVER hold the clutch pedal down unless I was ready to move the car.
Also, and minor, but since the engine maintains a constant idle speed, you would slightly increase your need for gas ... since there is more drag on the engine with the clutch depressed.
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Interesting question, I've always wondered the same things, you know how people are always saying, hey don't wear out my clutch!
I'm no expert, but I don't think there's any harm in what you are talking about, my guess is that it does "technically" wear the clutch out faster, but it's not abuse or anything to be worried about.
Don't you hate that though, sometimes when you are at a stop light, you depress the clutch thinking the light is about to change, then it never does! That happens to me from time to time around here with some of these long traffic lights in Atlanta.
Garrett
__________________ 2003 M5 Titanium Silver/Black - A Few Mods 2005 330i Alpine White/Tan - Wife's Daily 2006 M5 Silverstone/Silverstone - Family Sedan
It's not. You are not hurting the clutch at all ... except you are shortening the life (usually no problem) of the clutch spring ... same at a stop.
BUT, you are shortening the life of the throwout bearing ... it has a life, sometimes less than the clutch. I would NEVER hold the clutch pedal down unless I was ready to move the car.
Also, and minor, but since the engine maintains a constant idle speed, you would slightly increase your need for gas ... since there is more drag on the engine with the clutch depressed.
So you're saying if at a red light, best to have car in neutral/clutch out? Thanks.
Interesting question, I've always wondered the same things, you know how people are always saying, hey don't wear out my clutch!
I'm no expert, but I don't think there's any harm in what you are talking about, my guess is that it does "technically" wear the clutch out faster, but it's not abuse or anything to be worried about.
Don't you hate that though, sometimes when you are at a stop light, you depress the clutch thinking the light is about to change, then it never does! That happens to me from time to time around here with some of these long traffic lights in Atlanta.
Garrett
The lights aren't so bad in Greenville, but I know what you're talking about. Another thought: I've always been told while driving, like on the freeway with not many shifts, people have a tendenancy to rest their left foot on the clutch pedal, partly depressing it. I would think that if you're resting your foot on the clutch pedal, and it it pressed only 1/4 of an inch or so, this really isn't "engaging" any clutch mechanisms, although I could be wrong. The reason I bring this up, I drove my Dad's 1979 Fiat Spider every now and then when i was a teenager, when the clutch went I was accused of resting my foot on the pedal while I drove. I would think there is a small amount of play where the first inch or so of pushing in the clutch doesn't really do anything. Any truth to this?
Last edited by billrM5; 11th August 2006 at 20:23.
There is a small distance between the clutch fingers and the throw out bearing. If your not causing the TOB to ride against the fingers then there is now problem. If it is then the bearing gets hot and the oil inside it gets worn then bearing life is shortened.
One other thing that no one has brought up is that when you push the clutch in it pushes the whole clutch/flywheel forward causing the thrust bearings in the engine to rub more then normal. When a engine is first fired up I would try to limit it so the oil can work its way in better. But then also we have Alloy blocks which shrink when cold and expand when hot. So there should be room for the oil thats flying around in the sump is working its way there.
I'd suggest let the pedal out so it also spins the trans main shaft helping warm it up quicker.
$.02
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So you're saying if at a red light, best to have car in neutral/clutch out? Thanks.
Yes, but I find myself often depressing the clutch early and holding it in gear with the clutch depressed longer than I would wish ...
BUT, clutch bearing wear is an issue ... and, sometimes they go dry (use up all of their internal grease).
The clutch pedal free play is different (a little) on every car. The BMW has a system that automatically adjusts it to optimum (in BMWs opinion), but I suspect it is very small ... SO I WOULD NEVER SUGGEST YOU REST YOUR FOOT ON THE CLUTCH ... That is why there is a left foot rest plate on the floor ... to encourage drivers NOT to leave their foot on the pedal. Remember, resting your foot on the pedal probably uses up the free play (it is not very resistant to pressure) and the throw out bearing just touches the clutch ... wearing both the clutch bearing and the clutch fingers faster ... and, heating both items up more ... and, worse yet, if you start to disengauge the clutch just a little, it will begin to slip eventually ... guaranteed. The fingers on a clutch are not very thick and I have seem clutches where the fingers were worn completely through and the clutch (otherwise in fairly good condition) would not disengauge.
Last edited by jclyman; 11th August 2006 at 21:07.
One other thing that no one has brought up is that when you push the clutch in it pushes the whole clutch/flywheel forward causing the thrust bearings in the engine to rub more then normal. When a engine is first fired up I would try to limit it so the oil can work its way in better. But then also we have Alloy blocks which shrink when cold and expand when hot. So there should be room for the oil thats flying around in the sump is working its way there.
I'd suggest let the pedal out so it also spins the trans main shaft helping warm it up quicker.
$.02
I don't totally agree with your statement. When you depress the clutch pedal it releases the pressure on the clutch disk through the action of the clutch fingers (which are connected to the pressure plate which actually presses the clutch to the flywheel surface). The clutch inner housing and flywheel go nowhere ... except aroung and around. The disk actually moves slightly toward the rear of the car. BUT, and you are correct here, the thrust bearing you refer to is in the center rear side of the flywheel and if the clutch is depressed, the shaft is stopped, and the flywheel is turning (at the speed of the engine, always) ... and the thrust bearing gets more, much more wear ... The thrust bearing is probably a $ 5 part ($ 15 max.) ... it is actually a bronze bushing ... with a lot of labor involved to get to it.
Last edited by jclyman; 11th August 2006 at 21:25.
The thrust bearing I was refering to was the crankshaft thrust.
When the pedal is depressed it pushes the whole assembly forward making the crank rub the rear of the crank thrust bearing
Idling in neutral with the clutch out is not particularly good for certain transmission internals, due to marginal oiling issues. Idling with the clutch pushed in is not particularly good for thrust main & throwout bearings. Towing a car with a manual transmission with the rear wheels turning results in similar issues.
The moral of the story is to flatbed your car home and park it.
Seriously, I'd forget about popping your car into neutral at stop lights. I almost never do that and I've got 250K mi out of a single clutch & throwout bearing. I have been running high mile cars with manual transmissions for 20 years and I've never failed a thrust or throwout bearing with my behaviors. If a bearing is going to fail prematurely from lack of lubricant or some bearing defect, it won't matter much how the car was "driven". In my experience, thrust main bearings fail from idiots using impact tools to install or remove a clutch or flywheel.
Any truth to this?
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