Thanks for the replies.
Magiver, what do you mean by ‘excessive slippage by the user’?
We seem to need a new clutch every few years, and I’m wondering why we go through them so fast.
riding the clutch more than necessary to move the car forward. Holding it on a hill with the clutch instead of using the brake.
'Cause it’s a rental. 
Actually, I wonder if they don’t rent out manuals for that very reason.
I could make a clutch last nearly forever, but everytime I allowed anyone else to drive my car, I felt like they had put a thousand miles or more on my clutch
Probably still is best to use the clutch to change gears, unless you are really good at rev matching, or you’ll blow your synchronizers early. They aren’t really made to take up the full torque of the engine to transmission
That said, it is good practice to rev match, even with the clutch, and if you are good enough, then when your master cylinder goes out, you can still get it home without a tow, as long as you have a friend willing to give you a shove at intersections.
Maybe yes, maybe no. You’re engaging the synchronizers regardless of clutch use. For daily driving that isn’t aggressive you should be able to slide it into gear with little or no resistance. Not something you do when racing because, as you say, the full torque of the engine is set against them.
And I’ve sorta done what you suggested. I severely injured my left ankle once and drove the car home using my right foot on the clutch for first gear and then shifting without the clutch.
Long time manual transmission driver here. I get many extra miles out of my brakes by engine braking via downshifting, and always double-clutch when downshifting to save the synchros. Never had to replace a clutch nor transmission, and this includes several vehicles over 250,000 miles.
And I’ll add my voice to the recommendation that when stopped, ALWAYS put your car in neutral and leave the clutch out to save its bearings until you’re ready to move again.
Another thing that’s helped me get many miles out of those components is to pull the gear into neutral w/o the clutch in stop-and-go traffic by unloading the drivetrain when closing the throttle quickly. For those of you who can put the car into gear w/o the clutch by rev-matching, more power to ya but I feel the risk isn’t worth it due the improved modern clutch design.
It doesn’t seem to take much to get great mileage out of a clutch/throwout bearing.
I drove my Mazda 323 for 225+k miles and neither was replaced.
On the one hand I didn’t ride my clutch. OTOH, I didn’t shift into neutral and take my foot off at stops. Just basic “take it easy” shifting and such.
“Excessive slippage by the user” means operating the car in a way that causes the clutch to slip more than necessary for the given task.
When launching from a dead stop, the ideal engagement as far as clutch life is concerned is low engine RPM and high torque. Low engine RPM means minimal speed differential across the slipping clutch during the engagement process; high torque means rapidly get the car up to a speed where you can fully release the clutch and end the slippage.
When upshifting, you should, in theory, be able to do so without any clutch slippage whatsoever by carefully managing the throttle. This requires taking your foot off of the accelerator a split-second before clutch-in, thus unloading the drivetrain so that there’s no torque being transmitted across the clutch while it disengages. Then the engine RPM falls while you are changing gears, and if you time it right, you can release the clutch again when engine RPM is perfectly matched with transmission input shaft RPM. If you’ve been driving a particular manual-trans car for a while, you get used to timing your shift and clutch activity so that you can reliably achieve this.
When downshifting, RPM matching is a bit more challenging, especially since one is often using the brake pedal at the same time. It requires tapping on the accelerator pedal to bump up the engine RPM so that it’s at the right speed when you let the clutch out in the lower gear. If you do this right, there should be no clutch slippage whatsoever.
When stopped on a hill, using the clutch for hillholding constitutes excessive slippage. Your brakes can do this job without any wear, so use them instead and practice transitioning from right-foot-on-brake to right-foot-on-accelerator so that you can launch the car with minimal rollback. If you struggle with this on steep hills, using the handbrake will give you a chance to get your right foot over to the accelerator and start your launch without rolling back down the hill at all.
Keeping the transmission in gear and the clutch pushed in while the car is stopped means the clutch is slipping. Theoretically there’s zero torque being transmitted, but it’s not perfectly zero: there is still contact between the friction material and the pressure plates, so there will be wear and heat generation. If you’re at a stop sign waiting for an opportunity to go, then you need to be ready - but if you’re at a stoplight that’s definitely going to be red for a minute or so, then select neutral and let the clutch out for the duration.
Some drivers (especially those new to a manual-transmission car) may absentmindedly let the clutch pedal come up off of the floor a little while preparing to launch (e.g. from a stop sign or from a light they know is about to turn green). This is similar to using the clutch for hillholding, except instead of the hill holding the car back, it’s the car’s own brakes. This is excessive slippage by the user.
Coasting down the highway with the transmission in gear and the clutch pedal down is worse. When cruising with the clutch engaged, the transmission input shaft is spinning at engine speed, typically somewhere around 2500 RPM. Push the clutch in, and the engine falls to ~750 RPM: now the clutch is slipping at 2500-750 = 1750 RPM. Contrast this with the situation when the car is stopped (see above paragraph), in which the clutch slip RPM is equal to the engine idle RPM, i.e. just 750 RPM. IOW, the higher slip rate means proportionately higher wear and heat production. This situation is even worse on motorcycles for which engine RPM at cruise is considerably higher), and particularly on BMW motorcycles which for years have utilized dry clutches. I once read a story of a guy on a BMW who was coasting down a long mountain pass in the Rockies at highway speed. Engine RPM under this circumstance would have been about 4000 RPM - except he had pulled the clutch lever in, letting the engine fall back to 1000 RPM. Now the clutch slip RPM was about 3000, and it stayed in this condition for a couple of minutes, generating heat. As I recall, the friction material became so overheated that it disintegrated when he re-engaged the clutch at the bottom of the hill. I don’t know the origin of this story, so it’s possible it was exaggerated or even entirely untrue - but you can see from the math that coasting down the road in gear with the clutch disengaged is worse than being stopped in gear with the clutch disengaged. If you feel the need to coast down the road for some reason (maybe your engine died?), then select neutral and let the clutch out.
Basically, for me the only rule I’ve really followed was try to keep the time of my left foot on the clutch to a minimum. I don’t bother with rev matching on downshifts or heel-and-toeing or anything like that. I do that when I’m bored, but it’s not a daily habit. On upshifts, I may instinctually just wait a sec for the engine RPMs to drop before throwing it into gear for a smoother shift, but it’s not a conscious decision. I’m always in neutral at stop lights. At hills (which, admittedly, not much of here), I don’t “balance” the car on the clutch and throttle. I’m either in neutral and foot on brake and throw it into gear when the light turns (on slight inclines) or use the handbrake and do a proper hill start for steeper inclines. Basically, just avoid riding the clutch as much as possible. I haven’t tried getting a clutch to 200K, but the last two have survived 140K with me (and I have no idea what happened to those cars afterward. For all I know, they may still be on the original clutch.)
I taught myself how to drive a stick when I picked up my first stick shift car from the dealer. I had done some reading up before, so by the time I got the car home I was driving fine (this was in a pretty flat area of upstate New York). Biggest problem was stalling the car at a red light or stop sign (forgetting to disengage the clutch until too late), which I got over in a few weeks. Most of the rules for maximizing clutch life are perfectly logical. That original clutch lasted the life of the car (blown head gasket at 160k miles) so I don’t think I caused significant damage.
Yeah, getting into first is really the main challenge when learning to drive a manual. I had the same issue when I was learning. Once you’re moving, it’s pretty easy. I still remember learning with an old 1970s diesel Mercedes W123 with a really, really, really heavy clutch by today’s standards. Every time I was stuck at a stop and had to start up in first, I was nervous as all shit about being able to get that thing in gear without stalling it. But once I got it into first, I was fine.
How about if one is on a downhill slope stopped at a traffic light in neutral with a foot on the brake. The light turns green, foot comes off the brake, the car gets a pretty good roll going and the clutch gets engaged and the transmission is put into second rather than starting out in first. Is this OK for the clutch?
Right turn going up a hill. Instead of breaking to make the right turn, downshift from third into second to slow the car to a safe speed to make the turn. (A cop was right behind me one time when I did this and he turned his light on to pull me over for not having break lights. When I pulled over, he saw my break lights and yelled out his window to “go ahead”.) Is this right turn maneuver OK for the clutch?
I think this is one scenario in which it is OK to start off in second because the car already has natural momentum. It has been brought to the proper wheel speed for 2nd gear, albeit without the engine playing a part in it.
Absolutely. Hell, if you get a good enough roll on a steep hill, you may even be able to start in 3.
I will actually start in 2nd in really slippery conditions (usually snow) to minimize slippage.
The physics of the clutch and the gearbox apply in isolation of the engine. The throttle is only there to help, if that makes any sense.
An automotive clutch is one of the simpler torque transfer devices between an engine and transmission, with only basically 2 primarily related wear/shock/moving points: The transmission input bearing and the clutch friction surfaces. Anything you do, including driving the vehicle normally(?) eventually wears out these parts. Jerky, sudden impactful moves are most damaging to the input bearing. The friction surface part is pretty obvious, and would come with attendant throwout bearing wear, done aggressively for long enough.
Having run a shop for about 40 years I can tell you the number one cause of excessive clutch wear is starting off in 2nd gear instead of first, usually followed up by not promptly getting the clutch adjusted once the free play was gone. Anytime I had a customer come in for a clutch adjustment in less than 60 days I would have a talk with them about what gear they were starting off in. I drove sticks most of my life and seldom needed to adjust my clutch in less than 10,000 miles, probably closer to 20,000 as I really never kept track I just know I didn’t have to adjust my clutch very often. I have never had one wear out.
From a stop, you mean. Any time the clutch “bites” it is taking wear. Obviously it’s supposed to handle a little friction, as in transfering from a stop to first gear or reverse, but you don’t want the clutch to “bite” at higher revs. More friction = more wear. But if the car is already rolling at the proper revs of second gear (in neutral), engaging the clutch (from neutral) isn’t going to wear it anymore than just shifting into second gear from first while applying throttle. Right? You’re talking about people starting the car in second gear.
BMWs motorcycles do use dry clutches, but they are designed to last the life of the bike. Clutch failure is incredibly rare on BMW message boards. Abusing it like described may be enough to do it, though. Motorcycle clutch behavior is different from car’s, because on a bike it is appropriate to do things like slip the clutch while simultaneously dragging the rear brake or shift without completely disengaging the clutch.
That is just engine braking, and doing it shouldn’t hurt the clutch at all. It is the downshift to start the engine braking that may cause clutch wear. Matching engine and transmission speed is best, and using the clutch to simultaneously raise the engine speed and decrease the transmission speed is bad. Once the clutch is fully engaged, the stress of engine braking on the clutch, transmission, and engine are no different than during acceleration, just with the opposite change in velocity.
Really??? I am surprised. Do that many people really start from second? I can’t think of a single person I’ve observed doing so. The only case for starting from second is when you don’t want to spin the wheels. While it’s not difficult, it does require a little more feel than starting from first, so I’m surprised there’s a significant amount of folks who do this regularly.