I am unsure as what you mean by “plate” adjustment. I have never seen an “adjustable” plate before. You can adjust the clutch pedal, and that can/will affect how far in you must depress the clutch before it engages. If that is what you mean, I will concur that a pedal that is adjusted in too much may always cause the bearing to ride into the plate and that in turn make clutch always “semi” engaged and a bad thing.
As far as I am aware, it isn’t even adjustable on many new cars … and thats a good thing.
This is one of those ‘angels on the head of a pin’ arguments.
Even if they are knowledgeable, those ‘Car Talk’ guys are annoying, wacky-morning-DJ morons.
Leaving the clutch pressed in does put wear on you throw-out bearing & pressure plate, BUT even if you do this both of these parts will probably still outlast your whole car.
Not using you manual transmission for braking does not significantly shorten brake life. If this were true the brakes in an automatic would always wear out sooner and they don’t.
Safety wise, assuming you don’t panic, it would be a little quicker to get out of the way if you left it in gear.
But none of these arguments are compelling enough to discount the idea that, basically, it’s doesn’t matter one way or the other.
[nitpick again]
I disagree with you there. A release bearing will probably last somewhere in the many years range, as will a PP but they shouldn’t outlast a car. The bearings slowly but surely loose their lubricant out of the seals and do dry out and will fail.
The PP will develop hot spots and if not replaced at the same time as the friction material will wear the new clutch much, much faster.
I could probably figure out the theoritical bearing life of a release bearing tommorow at work (part of my job) but I really don’t want to. An educated guess of regular driving of say 2 hours a day (give or take) I wouldn’t think that 6-9 years would be possible. I would hope your car would last longer than that.
[/nitpick]
Most newer cars use self-adjusting clutches and these don’t always work. Some are hydraulic, and the fuid in the resivoir is basically the adjustment medium. I have heard of self adjusting cable systems, but I haven’t actually seen one, so I can’t describe it. Several of my cars, trucks, and motorcycles, though, have had non-adjustable mechanisms and required occasional adjustment to the cable or rod. It has always been part of my routine maintainence program to check clutch engagement play. Also, bent clutch pedals are a common occurrence. I’ve even had to replace pedals that bent too many times and would not retain the original shape. If the pedal bends enough, the clutch does not fully disengage when the pedal is fully depressed, resulting in friction plate wear and heating of the pressure plate.
I have a small argument on the side of leaving the clutch in while stopped, but it’s certainly very minor: When you release the clutch, even if the shifter is in neutral, you’re still causing the pressure plate to go from a disengaged state to an engaged state. One side of this coupling is not spinning, and must be made to catch up, so there’s a little bit of wear. I’m not sure how much mass there is to get moving in between the pressure plate and the gearbox, but it’s definitely miniscule compared to the mass that has to get moving when you’re in gear (i.e. the whole car).
That said, I prefer to stick it in neutral and give my clutch leg a break.
Here’s a question: if you were to sit in neutral with the engine idling and press and release the clutch continuously for years, which would give out first? The bearing or the pressure plate? I’d put money on the bearing dying first.
Just sitting there and pumping the clutch and not moving? Hmmm. I’d probably say the bearing too just since plates are built so tough. Bearings are built really tough too though and as I mentioned are more likely to fail due to a lubrication or contamination problem as opposed to just “fatigue”. You generally don’t see a spring/diaphram faliure unless there’s another problem but you never know…
Isn’t it a good thing to have the brakes engaged when you get hit, if you are stationary? I guess it depends on where you want to distribute the damage. With the brakes on, the car absorbs more damage and you absorb less, with the brakes off, the car and your body undergo more acceleration, but the car itself will be deformed less.
Disclaimer: This statement does not apply universally.
A stronger case for leaving the car in gear is so the driver can GO when the light turns and not hold up traffic behind him/her.
While I don’t necessarily advocate jumping off a green (especially in Phoenix, where we seem to have more red light runners than other cities), I HATE it when I’m behind another car at a light and can see the driver putting the car in gear after the light turns, particularly if they don’t hit the gear on the first attempt (notorious among VW drivers, since reverse is next to first (at least on some models), rather than down and right).
