Question about cars and clutches

February 19, 2004 7:51 PM

What, exactly, is "riding the clutch"? [more inside]

I take it to mean using the clutch halfway out, unnecessarily, when you should use the brakes. Or, generally, holding down the clutch pedal too long after the proper release point. However, I have found that "riding the clutch" is used as an unfocused criticism of manual-shift driving technique, which makes me wonder if there is an agreed upon meaning , or a family of usage, or what.

posted by crunchburger to travel & transportation (16 comments total)

I've always heard: placing one's foot upon the clutch pedal when not intending to use it, regardless of the applied force.
posted by daver at 8:23 PM on February 19, 2004

Some people have a habit of lightly resting their foot on the clutch just about all the time. Very bad things happen when this occurs. The clutch slips intermittently, heats and wears away. I think the term has also become sort of generic for any undue slippage of the clutch, such as undue feathering on take off from a stop, or holding the car on a hill by slipping the clutch.
posted by caddis at 8:24 PM on February 19, 2004

I have always understood the term to mean partly letting out the clutch pedal to stop a car rolling backwards on a hill instead of using the brakes, but have also heard it applied to those who rest their left foot on the clutch pedal while driving, particularly when they do so with enough force to partially disengage the clutch, making it slip, therefore overheat, wear out and ultimately fail (sometimes spectacularly).
posted by dg at 9:13 PM on February 19, 2004

I usually push the clutch in when I am coasting, to save a little bit of gas. Is this bad for my clutch? I don't throw the bitch into low gear when I need to get back to speed, I adjust gears for my relative speed and I don't hear any noises.
posted by Keyser Soze at 10:23 PM on February 19, 2004

Indeed, it is when you lightly rest your left foot on your clutch. As everyone else has mentioned, it kills the clutch and will kill it.
Keyser: I don't think that should matter. By pushing in the clutch all the way, you're pretty much just disengaging the engine and keeping your engine in neutral, much like if you just had the shifter in neutral and no foot on the clutch and coasting. Try comparing the two sometime and you shouldn't notice a lick of difference (or at least I never do).
posted by jmd82 at 10:24 PM on February 19, 2004

Keyser - If your car lets you, just drop into neutral without using the clutch, and then go back to where you were when you need power. (Learn to do that without the clutch too, you should be able to for third and above quite handily with practice.) The fewer times you press the clutch down, the longer it will last. If you're at a stop light, put it in neutral instead of sitting there with your clutch to the floor. At least this is what my mechanic tells me.

It's also saved my bacon a few times. Rather than sitting in first, I've been in neutral with the clutch out. All of a sudden a situation occures in which I'm forced to throw it into reverse in a hurry, and because I'm already in neutral it's easy to do so.
posted by woil at 11:06 PM on February 19, 2004

woil- I'm confused what exactly you mean about shifting. I know I can shift into neutral with the clutch popped out, but you make it sound like I can go back into 3rd gear without popping in the cluth? Can I can shift back into 3rd from neutral without using the clutch, or am I did I more than likely miss the point.
posted by jmd82 at 11:19 PM on February 19, 2004

Can I can shift back into 3rd from neutral without using the clutch

You sure can. When the engine revs are at a certain point, you can slip it into the higher gears (third and higher) quite easily, it just takes some practice.
posted by biscotti at 11:36 PM on February 19, 2004

Keyser: Sitting still with the engine running and clutch depressed is not terrible, but still not advised. It puts excess wear on your throwout bearing, and, overtime, will lead to a noisy clutch, and, eventually, failure. But were talking over tens of thousands of miles here... not exactly something to stress too much over. I try not to do it, though.

jmd82: Yes, it is possible to shift *into* gears without using the clutch, but it takes a bit of practice, and is pretty harsh on your transmission until you get it right. It's easiest to learn when you're accelerating. Get in fourth gear, and accelerate to above where you normally shift to fifth. Then, without touching the clutch, push the shifter out of fourth, over to fifth, and *gently* keep forward pressure on it. When the speed of the engine and crankshaft match, the shifter *should* slide forward into 5th.

It takes practice, but is cool, once you can do it.
posted by jammer at 11:55 PM on February 19, 2004

I'm not sure how well I understand these mechanisms, really, but here's what I was taught. The clutch, in a car, is a pad which presses on either the crankshaft or something attached to it (the engine side of the transmission) and slows it down so that its gear will be able to engage with a different gear on the drivetrain side of the transmission. Riding the clutch means pressing the gas and clutch at the same time (in an excessive amount), thereby speeding up the crankshaft and trying to slow it down simultaneously.

Now, I was also taught that riding the clutch on a motor cycle is okay, because the transmissions are built differently. Instead of a pad that slows down a flywheeel, a motorcycle transmission is basically two metal plates that meet one another inside a bath of oil. Pulling on the clutch simply moves them apart, where they can spin freely in oil all you want.

So basically, it's fine to ride the clutch on a motorcycle, but not a car. Can anyone confirm or deny that?
posted by scarabic at 10:45 AM on February 20, 2004

I can confirm that. Motorcyclists call it "engine braking" and do it frequently. Well, it's a little different - you back off the gas and ride the clutch a little, but then eventually you back off the clutch again almost all the way and let engine compression slow you down. That's why a lot of times you will here a bike revving up as they are slowing to a stop. I tend to stop my bike with an even mix of engine braking, front brake, and back brake. Or, when I'm going down a steep hill (I live in San Francisco, so this is pretty often), I use no brakes, no throttle, and just let engine braking keep me at the right speed.
posted by badstone at 10:55 AM on February 20, 2004

Engine braking can be done in a car, too -- simply downshift and let the compression of the engine slow the car. With modern braking systems, it's not really necessary in most circumstances.

I know jack about bikes, so I can't address thouse points.
posted by jammer at 1:38 PM on February 20, 2004

With modern braking systems, [engine braking]'s not really necessary in most circumstances.

Nah, I do this all the time. It's highly convenient when driving down steep, curvy hills - downshift into third, and you get a nice, moderate speed with no need to even think about the brakes. It's much smoother than having to ride the brakes down the hill in fourth or fifth.
posted by vorfeed at 2:31 PM on February 20, 2004

I've heard from many mechanics and "car specialists" that engine breaking is very hard on your engine and in the end, adds much more wear and tear than normal brake-braking. Anyone here know more about it?
posted by jmd82 at 3:44 PM on February 20, 2004

Yeah, my moms 70 mustang got its engine blown when my dad was engine braking. He was used to driving semi trucks, though.
posted by Keyser Soze at 7:26 PM on February 20, 2004

Scarabic - In a car the clutch is a disc with a pad (like a brake pad material) on both sides, and in the center is a hole with "fingers". There is also a Pressure Plate, and this bolts to the flywheel (which is bolted to the crankshaft). The clutch disc is sandwiched between the pressure plate and flywheel. The tranny has an input shaft with splines that fit into the fingers on the clutch disc.
  When the clutch pedal is out the disc is sandwiched. When the pedal is in (on either hydralic or cable system) a "control arm" is pivoted to press in on fingers on the pressure plate. When those fingers are pressed the disc is no longer sandwiched in.
  When you ride the clutch you are anywhere in between those two absolute states (clutch out/in). Riding the clutch means the clutch is slipping, but to what degree depends on if you are leaving your foot resting on the pedal or "feathering" a muscle car to get the most low end horsepower without spinning the tires. Basically slipping clutch means more friction means wearing down the disc's pad and heating up both the pressure plate and flywheel surfaces. Too much heat leads to cracking. Wearing down the pad leads to the metal rivots which hold the pad on the disc to wearing grooves in either or both pressure plate and flywheel. Similar results to over heating your brakes.
  When you have your clutch changed the shop/person should be changing your disc, pressure plate, and throw out bearing (it is on the control arm and presses in the pressure plate fingers). They should also remove the flywheel and have it resurfaced.
  How stuff works has some good animated images of how this all works.

Engine breaking if done properly is not going to wearout the clutch or hurt the engine.
posted by sailormouth at 7:36 PM on February 20, 2004