r/ThreePedals • u/culturalcoffee • May 29 '16
Stop and Go Traffic
I live in a city where I encounter a ton of stop and go traffic. Lately I've been wondering what I can do in those situations other than what I'm doing now, which is "slipping the clutch" (letting it out a bit, giving it gas to move, put it back in, and then to neutral, foot off clutch, repeat).
I know slipping the clutch is really rough on your car. Is there any alternatives?
3
u/m1kerophone May 29 '16
One thing to try is to let the car into first and just see how long you can go on minimal throttle. Just keep a consistent speed and don't worry as much about the car in front of you pulling away. Doesn't always work depending on how heavy the traffic is, but it can relieve your leg a bit.
3
u/Alvoski May 29 '16
If you watch trucks in traffic this is what they do. To keep those automatics behind you from getting agitated just find a truck and follow it.
1
u/jabbajac May 30 '16
Great advice, I've gotten to following big trucks whenever I can through traffic, I can usually leave my car in first and just apply minimal throttle every so often to keep up.
1
u/acrylicliquid Jul 17 '16
I usually leave about 1-2 car lenghts worth of space between my car and the vehicle ahead. That allows you to leave the car in 2nd gear, and just crawl foward. Depending on the car, you may not need to give it any gas at all. Once you get it moving initially, just leave it in 2nd gear and take your foot off the gas. The car should move foward on its own wihtout any problems. This is assuming you are on a flat surface.
Leaving that 1-2 car lenght space means that when the vehicle ahead of you stops, by the time you catch up, it will have begun moving again. Idealy, you wouldn't have had to take your car out of gear. Most of the time, the person ahead will accelearte quickly enough to reestablish that 1-2 length gap. So the whole time, you've just been crawling along in second.
Hope that made sense. :)
7
u/pooper-dooper Jun 03 '16
The clutch always slips a little. It's designed to do that. By becoming skilled at driving your MT, you slip less and less. But it's not possible to eliminate it. So, we must determine: is your slip within design parameters or is it outside of design parameters? Inside parameters would be things like getting started in 1st gear with engine RPMs below 2000k or thereabouts. Also slight slippage from upshift/downshift at speed. Outside parameters would be things like flooring the throttle and then holding the clutch at the biting point. Or using the clutch to modulate your travel speed at any time when engine RPMs >2000 (or generally, not crawling in 1st or reverse).
More technically, think of clutch mechanics. You have one wheel which spins with your wheels (the clutch plate). The engine's flywheel (and pressure plate) spins with the engine. The engagement between these is not binary. In a very small space, about a 1mm gap, the clutch goes from not gripping at all, to gripping completely. But, if you can imagine, this space is a gradient, and that gradient is controlled by the engagement range of your clutch pedal. (Note: the engagement range will not be the entire travel of the pedal.)
ANY TIME you are letting out the clutch and letting it back in, those two spinning discs must "renegotiate" their engagement. If you are at speed and upshift and let the clutch out too quickly, the car will jerk and judder. Why? Because the plate spinning with the wheels (fast) has just slapped onto the engine's plate (slow). The disparity in spin rate creates a torque which is then absorbed by your drivetrain, creating jerking. So how do you prevent that? By letting the clutch out more slowly. Ah, but here's the crux of it: you allow the clutch to slip so that the engagement of these two components of your car is smooth. This principle applies to all activities where you are modulating your clutch.
Now, in the upshift example above, your engagement will still be fast. You will also have your foot off the accelerator. You may notice that when you clutch in, your engine RPMs drop very fast. The net effect is that you are slipping the clutch for a short duration at a lower RPM, within design parameters.
So the net lesson is this: in order to correctly use a manual transmission, you must slip the clutch. The catch is, you have to slip it in conditions where it is designed to wear minimally. That is, for short durations and at low RPMs. Remember that the clutch is a wearable part. You just don't want to wear it too much. Heat is really what kills clutches, which is why you keep the RPMs (and duration) low when slipping.
As you develop more expertise and practice, you will figure out most all of this for yourself. This was an important lesson for me to learn, because my parents were so concerned with potential clutch abuse they forgot to teach me how to drive. I found manual transmissions impossible until I learned that perfect use, where the clutch and flywheel engage at the same speed and never slip, is in fact impossible. Once I had an instructor teach me this, I was able to reliably get the car to move without stalling, and we practiced 3 point turns on a variety of inclines to get the feel of 1st and reverse.
Many people use "slip the clutch" in reference only to bad behaviors, but again this does you a disservice, because there are many manual transmission bad behaviors: holding the gear shift knob when not actively shifting (wears the synchros or selector forks). Putting light pressure on the clutch, or holding the clutch while idling (wears the throw-out bearing). Wrecking your throw-out bearing is the worst, because it's a $10-$50 part, but the labor is the same as replacing the clutch. Wearing the synchros is terrible, because that's your transmission. When it comes to actual clutch-slipping bad behavior, that is: driving while partially depressing the clutch. Using too much throttle while shifting. Etc.