the inner life of engines
8 Sep 2004 04:37 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
kaigouThe other post reminded me that I'd promised Asuka (France-Asuka, not GMU-Asuka) to explain a bit more about engines and how they work, for use in Two Knights. Here's hoping that a bit of information will suddenly inspire her to produce the rest of the story and reveal herself as a Not-Entirely-Slow-Girl. Just a Partially-Slow-Girl.
Let's start with an older engine (less intricacy) and assume you're sitting behind the wheel, key in the ignition, and you're starting the car. The other reason for the 'older car' explaination is that a) it's the kind I know, and b) a lot of stuff now is controlled by computer. This is what's happening, in a rather simplistic way and to the best of my ability to remember. I could be wrong on specifics (anyone feel free to correct me if so; I'm doing this from memory), but I'm relatively confident on the general elements.
1. The battery holds a charge, and when you put the key in the ignition and turn it, you're completing a circuit. The key's presence allows energy to move from the battery to the starter.
2. The starter is a round electrical motor that usually sits on the underside of the car. The battery charge hits the starter, which turns the engine over. (Turning the key again once the car has started makes the starter do its work a second time, which means it's trying to turn an already-turning engine.)
3. The distributor is a small rotor that usually looks like a soda-cup sized black plastic object. The cap nestles down over the distributor, with wires running from the cap to the engine. The electricity goes through the distrbutor, which sends it to the sparkplug wires in sequence. As the distributor turns, it's kind of like a mill-wheel - each bucket on the wheel (cap) picks up a charge and sends it through the wire, then there's a break, then the next bucket, and so on.
4. From there the charge travels to the sparkplugs, which are where the spark actually zaps the fuel/air mix and powers the engine and keeps it turning once the starter's done its job (at which point it's bypassed).
In the engine, there are three things required to make the engine go: gasoline (or any flammable liquid, really), oxygen, and a spark. When gas and air mix, it aerates the gasoline, making it especially flammable. The spark hits it, the gasoline has a tiny controlled explosion inside the engine, and the release of that energy pushes the pistons/rods.
Think of the gasoline/air mixture going POW and pushing the rods which then push everything else - if you visualize an old-time steam train, with the rods along the wheels...y'know how those swing forward, and around again, and forward, with a bit of a jerky motion at first? If you imagine a little POW as the rod starts to push forward (and pushes the wheel around), that's sort of what the sparkplug-gas-air explosion is doing.
Now, a few tips! How to impress your mechanic, confuse your enemies, and scare the bejabbers out of your friends.
If you come out in the morning and your car won't start, the battery is probably dead. Duh. However, if you've driven it for more than fifteen minutes, stop for morning coffee, and come out to find the car is dead, it's not likely it's the battery (unless you've got a really bad battery).
Put the key in the ignition & try to start.
-- If the car goes click-click-click, this is the starter attempting to lodge a charge from the battery. The battery is dead; starter's fine.
-- If the car doesn't make a single sound, but the lights can be turned on, the radio works, etc, then your starter has died. Sometimes this is gradual - the car gets harder and harder to start.
Sometimes it's sudden - when the starter went on my Golf, it was one minute fine, next minute...nothing. Bleah.
If the starter is dead, and the engine is warm...don't bother to jump start the car. As long as the starter is warm, the car's wiring is such that it's not going to accept a charge from the starter because it's thinking "we're already past that point, we don't need no starter now!" You will have to wait until the engine has cooled down. I learned this the hard way, when some blasted NJ gas station scum insisted I turn off my engine before filling the tank. Ended up stranded at the Vince Lombardi service station for two hours, at 3 a.m. on a rainy Tuesday, waiting for the engine to cool down. Grrrr. Once the engine is cool, then you can try to jump-start it.
Not all cars will allow you to jump-start with a dead starter. Some of the newer ones - like my Golf, damn it - have computer sensors that essentially prevent anything from the starter if it's below a certain threshold. When you're jump starting with a dead starter, you're kind of tricking the starter into giving up the last little bit of juice-building power it's got.
Next, carbuerators vs. fuel injection...it's pretty much the same concept. A carb, at its heart, is a small jet. The gasoline comes from the gas tank down the fuel line, and through the jet, where it's sprayed out in a fine mix. The 'butterflies' around the base of the jet, which look like little half-circle wings, flutter back and forth, allowing air in at a certain rate to mix with the sprayed gasoline. There's your air/gas mixture which is then run past the spark plugs.
This mix is crucial in all cars, whether it's carbs or fuel injection. If you're running 'lean' - too much air, not enough gasoline, the car will knock, possibly backfire, and generally make a lot of noise. It'll still be spunky, and may be better off a full stop, but it'll be noisy. If the engine's running 'rich' then this means it's getting too much gas, and not enough air. It'll be sluggish, and hard to start, and won't have nearly as much pick-up. (If it's just cold, then this will go away once things warm up; if it's consistently sluggish, the air intakes on a fuel injector might be whacked, or the butterflies may need cleaning if it's a car with carbs.) The technical term is the 'air-to-fuel ratio,' or just 'ratio' for short. When I say, "I need to balance the carbs," (which you do semi-regularly, depending on the car, how much you value performance, and the make/type of the carbs) what you're really doing is 'balancing' the ratio between the jets and the butterflies.
Minor tangent so I don't overload, but still provide another option for a scene: balancing the carbs consists of opening the hood, placing a small device over the opening of the carbs (often it looks like an upturned trumpet). This measures the air-flow going in; because of the size of the jets (and you dismantle and clean them in solvent before balancing, if you're really picky or it's been a while), you already know the jet-half of the ratio. Then, you start the car. Never, EVER lean over the carbs - a sudden backfire will send a flame up, and take off your bangs, if not burning your face. Some mechanics use a mirror held over the carb to read the gauge; I just kinda kept my distance and tried to read the dial at an angle. Now, the car's started and is in neutral. Someone's in the car, calling out the rpms at idle. Adjust a very tiny screw on the side, which opens/closes the jets, or another screw to adjust the angles of the butterflies. These will both change the engine's idle. When you're happy, then have the person rev the engine, let it idle, rev it again, idle, about four or five times, to see if the ratio gets thrown off.
There are ways to balance the carbs at all gears, but balancing the idle is the most important thing. It's actually easier to rev the engine from the engine compartment, but if you have someone helping you who has no clue, this is a way to have them involved without requiring too much knowledge of cars on their part. Have them listen to the engine, and point out changes in the sound as you adjust. The engine's sound is the most basic piece of knowledge one can have about a car, and is the source of perhaps 80% of all troubleshooting you'll ever do. The sounds a car makes will help you narrow down when and where and how to look for more information to pinpoint the actual issue.
Fuel injection is pretty much the same thing, but using an updated technology which is damn hard to work on if you're not like Mister Professional Mechanic. I've only dealt with fuel injection once or twice, and it was a bitch and a half. Carbs are a much simpler way to do it, plus there's more room to play with them, if you're a gearhead.
Okay, this part's for Asuka, and anyone else still with me. If I were working on an old car, and I had someone around that didn't know cars, here are some of the chores I'd assign them that they could do, that wouldn't mess up too much, and would be easily explained.
1. Clean the spark plugs.
Look at any car engine, and you're going to see four (or more, depending on cylinders) thick reddish rubber wires leading to the main engine. The wire will have a black cap that fits around a nipple on the engine. Pull that cap off, and there's your spark plug. Now, to visualize: hold up your hand and crook your finger over just a little. That's what the end of the sparkplug looks like. Between the sparkplug base (the base of your index finger) and the tip (the end of your finger) is where the spark occurs. This distance is very important; it helps determine how big that spark will be. Too big and kaboom, too little and nothing. There are nice little gadgets for checking the plug depth - I used to carry one around on my keychain. Most gearheads do.
Gunk and age and whatnot can build up on the sparkplugs, making them spark less; it can also sometimes (in really bad engines) lead to the two parts connecting. If the spark plugs aren't that corroded, then I would hand all four to the newbie, and set them in a well-ventilated corner with some solvent, a pair of strong rubber gloves, eye protection (sunglasses work fine if it's sunny), and a small wire brush. Scrub at the spark plugs, dip in solvent to rinse, scrub lightly, dip, etc. Spark plugs end up shiny, and can be dried off and stuck back in the engine.
2. Clean the interior of the wheel rims.
This was actually my first task ever, working on a car. My dad has a picture of me at fourteen or fifteen, holding the wire brush, perched on one tire while pausing from scrubbing the other. The expression is pretty much: "Can I go now? My arms are tired." Again, wire brush, solvent, eye protection, and set the person out on the driveway to get off all that brake dust and whatnot that will gunk the insides of the rims after thirty years of driving. When done, rinse with water, let dry, treat with rust protector, and then paint with silver rustoelum if you really want to be anal. (Which my dad was, and still is.)
3. Remove paint and old rust-proofing from the chassis.
This is the fun part, and anyone can do it. Hell, my sister even did some, and that's saying something. Eyeprotection is mandatory - one of the metal-working face protectors, like you see steelworkers using. Use the spark-cap (identical to what we used in high school chemistry) to light a blow torch. Hold the blow-torch to the metal until the paint shrivels or the rust-proofing looks wet, then scrape it off with a metal knife - looks a bit like a paint spackler. When you've heated and scraped everything you can, then you go at the chassis (car body) with a wire brush. A lot of elbow grease is necessary, but not a lot of skill. (It's also one of the most satisfying jobs, because a newbie can see the results.)
4. Organizing things.
We had about fifty old coffee cans in the garage, and each one - though none was labeled - were for a certain use or part of the engine or a size of bolt, screw, or whatnot. List the uses (label the cans if necessary) and then start using your newbie like a gofer. "These are three-quarter-inch." So they get hustled to the three-quarter can. "These are parts for the starter." They go in the starter can. Etc. Everyone has their own system; mine was highly organized. My dad's system was more like "Uh..." *eyeballing it* "That look like a Porsche part or an Austin-Healey part, to you? Oh, put it over there." Hunh.
5. Ripping apart the interior of the car.
Fun, and if you're not planning on saving that carpet, very easy! A screwdriver (for prying stuff off), and a bit of strength and some grunting, and there you go. Nothing like deconstruction to put the fun in fun.
And finally, an inside joke for people who love British cars. The first Austin-Healey I ever got (Sprite, '66, named True) had a slipping clutch and bad transmission. In order to replace the transmission on an Austin-Healey, you have to remove the entire engine. It's one of the more aggravating engine designs I've seen. Anyway, this means taking everything out between the nose and the dashboard, so it's out of the way for the lovely task of lifting the transmission out (which goes in and out much like your foot into a shoe). While removing and dismantling everything, I got to the dashboard. Behind the dashboard is the wiring harness, which controls the wires that run from there to everything in the car - obviously, or else how would the gauges for speed, oil, rpms, etc, work, right?
Well, the wiring harness in the Austin-Healey looked like a rat had crawled in there and turned it into a nest. I mean, tangled all over the place. Colors everywhere, with no consistency, and knotted and screwed-up...I pointed at it, and told my father, "Someone's been working on this car and they didn't go a very good job!"
Dad looks over, shrugs, and says, "No, that's original. That what all British wiring harnesses look like."
(And it's true. They're notorious for their bad electrical systems.)
Ah, I think that's enough for the day.![[livejournal.com profile]](https://www.dreamwidth.org/img/external/lj-userinfo.gif)
askerian, your brain broken yet?
About the transmission:
Okay. The engine is connected to the transmission by the clutch:
engine--> clutch--> transmission --> drive shaft --> axle --> wheel.
The clutch sets the gear, and then the transmission translates this into rotation speed (of the axle).
See, the deal is that if your engine turns over once, in a one-to-one, the axle would (roughly, and being really simplistic here) turn over in proportion. That's not always the best application of torque or power. Think of a three-speed bike - a lower, larger gear for easier downhill slopes and a smaller gear that gets more torque per foot-push. The clutch is going X speed (rpms) and it's locked into small rotation (low gear) or big rotation (high gear) as it matches up with the transmission. The transmission then turns in proportion to that combination (gear ratio) and that's the rotation applied to the drive shaft and down the line.
On True, my first Austin-Healey, the clutch was slipping. Plus, the speedometer was connected not to the transmission but to the engine, and essentially used that whole ratio-equation to say, "if you are in second gear doing three thousand rpms, you should be going X miles per hour." But with a slipping clutch, the clutch's friction plate is worn to the point that when it hits the transmission's flywheel, it can't catch - which means the transmission and the clutch (and behind the clutch, the engine) aren't travelling at synchronized speeds. When the transmission isn't turning at the same pace as the clutch, you lose power. There's nothing driving the wheels, even though the engine is turning, because the clutch isn't turning the flywheel.
As for mentioning where the speedometer was connected, now you understand why I had my foot on the gas pedal - going downhill! - and was losing speed - at the same time my speedometer confidently stated I was doing fifty-five. Hell, I could've had a frickin' hurricane for a tailwind and that car wasn't going fifty-five. The clutch slipped more than it caught, which meant the engine was produced massive amounts of torque and power...and barely any was getting to the transmission, and hence to the drive shaft.
Ever heard the catchphrase 'limited slip differential'? Same area - on a basic level, it's a technology that's supposed to keep the clutch from slipping out of sync. Limiting the slip-caused difference between transmission and clutch. Etc.
Btw, in one of my stories when a character says his truck has a synchro-mesh transmission, this is *way* old news. Back in the day, you had to 'double-clutch' on almost all trucks. The first push on the clutch pedal disengaged the tranmission from the engine. Then, in neutral, you had to rev the engine to the right rpms for your gear, and then push on the clutch to re-engage the clutch & transmission.
Synchro-mesh was just a way to let the two parts slam up even when travelling at different speeds (due to the pause while they pull away when you're in neutral). So it was an innovation that meant when shifting you just put your foot on the clutch, shifted to the new gear, and there was no crunching sound. Yay.
[I doubt you'd ever hear a car dealer even mention synchro-mesh as a selling point, unless they're really trying to snow you. Alternately, if you ever go shopping for a car and want to be a smart-ass, ask the salesman if the car has synchro-mesh. If you can say it with a straight face and the guy has no clue, you might be amazed at some of the wild claims. It's sort of like asking if the car has a brake pedal, when you think about it. Pretty much all cars have 'em now - except some race cars, which still require double-clutching. ]
One last point: it's possible to drive a manual car without using the clutch. This simply requires knowledge of the car's specific gear ratios, when the clutch and transmission are at such-and-such a matchup that changing the clutch to a different speed won't make things grind. If you think of the transmission as a plate with a few holes in it, and the clutch as something that locks into those holes - like fingers held as a claw, digging into cookie dough - then you can visualize the reason for 'grinding' - those 'teeth' aren't finding their proper holes. But if you know the gear ratios, you look at the speed, the rpms, and say: I am in third gear. When the rpms drop to 2600, then I can shift down or up. Ta-dah.
Each car is different, but they used to print the gear ratios for cars in the owner's manuals (probably because a lot of people were still used to double-clutching). My Golf manual, however, doesn't have it, and this annoys me. Fortunately, I've yet to break a clutch cable or even snap a clutch - which is possible; my dad did it on his Volvo. The thing just shattered, so he couldn't even drive home. He made it almost 250K on a single clutch, which is actually pretty phenomenal, but when it went, it went.
Let's start with an older engine (less intricacy) and assume you're sitting behind the wheel, key in the ignition, and you're starting the car. The other reason for the 'older car' explaination is that a) it's the kind I know, and b) a lot of stuff now is controlled by computer. This is what's happening, in a rather simplistic way and to the best of my ability to remember. I could be wrong on specifics (anyone feel free to correct me if so; I'm doing this from memory), but I'm relatively confident on the general elements.
1. The battery holds a charge, and when you put the key in the ignition and turn it, you're completing a circuit. The key's presence allows energy to move from the battery to the starter.
2. The starter is a round electrical motor that usually sits on the underside of the car. The battery charge hits the starter, which turns the engine over. (Turning the key again once the car has started makes the starter do its work a second time, which means it's trying to turn an already-turning engine.)
3. The distributor is a small rotor that usually looks like a soda-cup sized black plastic object. The cap nestles down over the distributor, with wires running from the cap to the engine. The electricity goes through the distrbutor, which sends it to the sparkplug wires in sequence. As the distributor turns, it's kind of like a mill-wheel - each bucket on the wheel (cap) picks up a charge and sends it through the wire, then there's a break, then the next bucket, and so on.
4. From there the charge travels to the sparkplugs, which are where the spark actually zaps the fuel/air mix and powers the engine and keeps it turning once the starter's done its job (at which point it's bypassed).
In the engine, there are three things required to make the engine go: gasoline (or any flammable liquid, really), oxygen, and a spark. When gas and air mix, it aerates the gasoline, making it especially flammable. The spark hits it, the gasoline has a tiny controlled explosion inside the engine, and the release of that energy pushes the pistons/rods.
Think of the gasoline/air mixture going POW and pushing the rods which then push everything else - if you visualize an old-time steam train, with the rods along the wheels...y'know how those swing forward, and around again, and forward, with a bit of a jerky motion at first? If you imagine a little POW as the rod starts to push forward (and pushes the wheel around), that's sort of what the sparkplug-gas-air explosion is doing.
Now, a few tips! How to impress your mechanic, confuse your enemies, and scare the bejabbers out of your friends.
If you come out in the morning and your car won't start, the battery is probably dead. Duh. However, if you've driven it for more than fifteen minutes, stop for morning coffee, and come out to find the car is dead, it's not likely it's the battery (unless you've got a really bad battery).
Put the key in the ignition & try to start.
-- If the car goes click-click-click, this is the starter attempting to lodge a charge from the battery. The battery is dead; starter's fine.
-- If the car doesn't make a single sound, but the lights can be turned on, the radio works, etc, then your starter has died. Sometimes this is gradual - the car gets harder and harder to start.
Sometimes it's sudden - when the starter went on my Golf, it was one minute fine, next minute...nothing. Bleah.
If the starter is dead, and the engine is warm...don't bother to jump start the car. As long as the starter is warm, the car's wiring is such that it's not going to accept a charge from the starter because it's thinking "we're already past that point, we don't need no starter now!" You will have to wait until the engine has cooled down. I learned this the hard way, when some blasted NJ gas station scum insisted I turn off my engine before filling the tank. Ended up stranded at the Vince Lombardi service station for two hours, at 3 a.m. on a rainy Tuesday, waiting for the engine to cool down. Grrrr. Once the engine is cool, then you can try to jump-start it.
Not all cars will allow you to jump-start with a dead starter. Some of the newer ones - like my Golf, damn it - have computer sensors that essentially prevent anything from the starter if it's below a certain threshold. When you're jump starting with a dead starter, you're kind of tricking the starter into giving up the last little bit of juice-building power it's got.
Next, carbuerators vs. fuel injection...it's pretty much the same concept. A carb, at its heart, is a small jet. The gasoline comes from the gas tank down the fuel line, and through the jet, where it's sprayed out in a fine mix. The 'butterflies' around the base of the jet, which look like little half-circle wings, flutter back and forth, allowing air in at a certain rate to mix with the sprayed gasoline. There's your air/gas mixture which is then run past the spark plugs.
This mix is crucial in all cars, whether it's carbs or fuel injection. If you're running 'lean' - too much air, not enough gasoline, the car will knock, possibly backfire, and generally make a lot of noise. It'll still be spunky, and may be better off a full stop, but it'll be noisy. If the engine's running 'rich' then this means it's getting too much gas, and not enough air. It'll be sluggish, and hard to start, and won't have nearly as much pick-up. (If it's just cold, then this will go away once things warm up; if it's consistently sluggish, the air intakes on a fuel injector might be whacked, or the butterflies may need cleaning if it's a car with carbs.) The technical term is the 'air-to-fuel ratio,' or just 'ratio' for short. When I say, "I need to balance the carbs," (which you do semi-regularly, depending on the car, how much you value performance, and the make/type of the carbs) what you're really doing is 'balancing' the ratio between the jets and the butterflies.
Minor tangent so I don't overload, but still provide another option for a scene: balancing the carbs consists of opening the hood, placing a small device over the opening of the carbs (often it looks like an upturned trumpet). This measures the air-flow going in; because of the size of the jets (and you dismantle and clean them in solvent before balancing, if you're really picky or it's been a while), you already know the jet-half of the ratio. Then, you start the car. Never, EVER lean over the carbs - a sudden backfire will send a flame up, and take off your bangs, if not burning your face. Some mechanics use a mirror held over the carb to read the gauge; I just kinda kept my distance and tried to read the dial at an angle. Now, the car's started and is in neutral. Someone's in the car, calling out the rpms at idle. Adjust a very tiny screw on the side, which opens/closes the jets, or another screw to adjust the angles of the butterflies. These will both change the engine's idle. When you're happy, then have the person rev the engine, let it idle, rev it again, idle, about four or five times, to see if the ratio gets thrown off.
There are ways to balance the carbs at all gears, but balancing the idle is the most important thing. It's actually easier to rev the engine from the engine compartment, but if you have someone helping you who has no clue, this is a way to have them involved without requiring too much knowledge of cars on their part. Have them listen to the engine, and point out changes in the sound as you adjust. The engine's sound is the most basic piece of knowledge one can have about a car, and is the source of perhaps 80% of all troubleshooting you'll ever do. The sounds a car makes will help you narrow down when and where and how to look for more information to pinpoint the actual issue.
Fuel injection is pretty much the same thing, but using an updated technology which is damn hard to work on if you're not like Mister Professional Mechanic. I've only dealt with fuel injection once or twice, and it was a bitch and a half. Carbs are a much simpler way to do it, plus there's more room to play with them, if you're a gearhead.
Okay, this part's for Asuka, and anyone else still with me. If I were working on an old car, and I had someone around that didn't know cars, here are some of the chores I'd assign them that they could do, that wouldn't mess up too much, and would be easily explained.
1. Clean the spark plugs.
Look at any car engine, and you're going to see four (or more, depending on cylinders) thick reddish rubber wires leading to the main engine. The wire will have a black cap that fits around a nipple on the engine. Pull that cap off, and there's your spark plug. Now, to visualize: hold up your hand and crook your finger over just a little. That's what the end of the sparkplug looks like. Between the sparkplug base (the base of your index finger) and the tip (the end of your finger) is where the spark occurs. This distance is very important; it helps determine how big that spark will be. Too big and kaboom, too little and nothing. There are nice little gadgets for checking the plug depth - I used to carry one around on my keychain. Most gearheads do.
Gunk and age and whatnot can build up on the sparkplugs, making them spark less; it can also sometimes (in really bad engines) lead to the two parts connecting. If the spark plugs aren't that corroded, then I would hand all four to the newbie, and set them in a well-ventilated corner with some solvent, a pair of strong rubber gloves, eye protection (sunglasses work fine if it's sunny), and a small wire brush. Scrub at the spark plugs, dip in solvent to rinse, scrub lightly, dip, etc. Spark plugs end up shiny, and can be dried off and stuck back in the engine.
2. Clean the interior of the wheel rims.
This was actually my first task ever, working on a car. My dad has a picture of me at fourteen or fifteen, holding the wire brush, perched on one tire while pausing from scrubbing the other. The expression is pretty much: "Can I go now? My arms are tired." Again, wire brush, solvent, eye protection, and set the person out on the driveway to get off all that brake dust and whatnot that will gunk the insides of the rims after thirty years of driving. When done, rinse with water, let dry, treat with rust protector, and then paint with silver rustoelum if you really want to be anal. (Which my dad was, and still is.)
3. Remove paint and old rust-proofing from the chassis.
This is the fun part, and anyone can do it. Hell, my sister even did some, and that's saying something. Eyeprotection is mandatory - one of the metal-working face protectors, like you see steelworkers using. Use the spark-cap (identical to what we used in high school chemistry) to light a blow torch. Hold the blow-torch to the metal until the paint shrivels or the rust-proofing looks wet, then scrape it off with a metal knife - looks a bit like a paint spackler. When you've heated and scraped everything you can, then you go at the chassis (car body) with a wire brush. A lot of elbow grease is necessary, but not a lot of skill. (It's also one of the most satisfying jobs, because a newbie can see the results.)
4. Organizing things.
We had about fifty old coffee cans in the garage, and each one - though none was labeled - were for a certain use or part of the engine or a size of bolt, screw, or whatnot. List the uses (label the cans if necessary) and then start using your newbie like a gofer. "These are three-quarter-inch." So they get hustled to the three-quarter can. "These are parts for the starter." They go in the starter can. Etc. Everyone has their own system; mine was highly organized. My dad's system was more like "Uh..." *eyeballing it* "That look like a Porsche part or an Austin-Healey part, to you? Oh, put it over there." Hunh.
5. Ripping apart the interior of the car.
Fun, and if you're not planning on saving that carpet, very easy! A screwdriver (for prying stuff off), and a bit of strength and some grunting, and there you go. Nothing like deconstruction to put the fun in fun.
And finally, an inside joke for people who love British cars. The first Austin-Healey I ever got (Sprite, '66, named True) had a slipping clutch and bad transmission. In order to replace the transmission on an Austin-Healey, you have to remove the entire engine. It's one of the more aggravating engine designs I've seen. Anyway, this means taking everything out between the nose and the dashboard, so it's out of the way for the lovely task of lifting the transmission out (which goes in and out much like your foot into a shoe). While removing and dismantling everything, I got to the dashboard. Behind the dashboard is the wiring harness, which controls the wires that run from there to everything in the car - obviously, or else how would the gauges for speed, oil, rpms, etc, work, right?
Well, the wiring harness in the Austin-Healey looked like a rat had crawled in there and turned it into a nest. I mean, tangled all over the place. Colors everywhere, with no consistency, and knotted and screwed-up...I pointed at it, and told my father, "Someone's been working on this car and they didn't go a very good job!"
Dad looks over, shrugs, and says, "No, that's original. That what all British wiring harnesses look like."
(And it's true. They're notorious for their bad electrical systems.)
Ah, I think that's enough for the day.
askerian, your brain broken yet? About the transmission:
Okay. The engine is connected to the transmission by the clutch:
engine--> clutch--> transmission --> drive shaft --> axle --> wheel.
The clutch sets the gear, and then the transmission translates this into rotation speed (of the axle).
See, the deal is that if your engine turns over once, in a one-to-one, the axle would (roughly, and being really simplistic here) turn over in proportion. That's not always the best application of torque or power. Think of a three-speed bike - a lower, larger gear for easier downhill slopes and a smaller gear that gets more torque per foot-push. The clutch is going X speed (rpms) and it's locked into small rotation (low gear) or big rotation (high gear) as it matches up with the transmission. The transmission then turns in proportion to that combination (gear ratio) and that's the rotation applied to the drive shaft and down the line.
On True, my first Austin-Healey, the clutch was slipping. Plus, the speedometer was connected not to the transmission but to the engine, and essentially used that whole ratio-equation to say, "if you are in second gear doing three thousand rpms, you should be going X miles per hour." But with a slipping clutch, the clutch's friction plate is worn to the point that when it hits the transmission's flywheel, it can't catch - which means the transmission and the clutch (and behind the clutch, the engine) aren't travelling at synchronized speeds. When the transmission isn't turning at the same pace as the clutch, you lose power. There's nothing driving the wheels, even though the engine is turning, because the clutch isn't turning the flywheel.
As for mentioning where the speedometer was connected, now you understand why I had my foot on the gas pedal - going downhill! - and was losing speed - at the same time my speedometer confidently stated I was doing fifty-five. Hell, I could've had a frickin' hurricane for a tailwind and that car wasn't going fifty-five. The clutch slipped more than it caught, which meant the engine was produced massive amounts of torque and power...and barely any was getting to the transmission, and hence to the drive shaft.
Ever heard the catchphrase 'limited slip differential'? Same area - on a basic level, it's a technology that's supposed to keep the clutch from slipping out of sync. Limiting the slip-caused difference between transmission and clutch. Etc.
Btw, in one of my stories when a character says his truck has a synchro-mesh transmission, this is *way* old news. Back in the day, you had to 'double-clutch' on almost all trucks. The first push on the clutch pedal disengaged the tranmission from the engine. Then, in neutral, you had to rev the engine to the right rpms for your gear, and then push on the clutch to re-engage the clutch & transmission.
Synchro-mesh was just a way to let the two parts slam up even when travelling at different speeds (due to the pause while they pull away when you're in neutral). So it was an innovation that meant when shifting you just put your foot on the clutch, shifted to the new gear, and there was no crunching sound. Yay.
[I doubt you'd ever hear a car dealer even mention synchro-mesh as a selling point, unless they're really trying to snow you. Alternately, if you ever go shopping for a car and want to be a smart-ass, ask the salesman if the car has synchro-mesh. If you can say it with a straight face and the guy has no clue, you might be amazed at some of the wild claims. It's sort of like asking if the car has a brake pedal, when you think about it. Pretty much all cars have 'em now - except some race cars, which still require double-clutching. ]
One last point: it's possible to drive a manual car without using the clutch. This simply requires knowledge of the car's specific gear ratios, when the clutch and transmission are at such-and-such a matchup that changing the clutch to a different speed won't make things grind. If you think of the transmission as a plate with a few holes in it, and the clutch as something that locks into those holes - like fingers held as a claw, digging into cookie dough - then you can visualize the reason for 'grinding' - those 'teeth' aren't finding their proper holes. But if you know the gear ratios, you look at the speed, the rpms, and say: I am in third gear. When the rpms drop to 2600, then I can shift down or up. Ta-dah.
Each car is different, but they used to print the gear ratios for cars in the owner's manuals (probably because a lot of people were still used to double-clutching). My Golf manual, however, doesn't have it, and this annoys me. Fortunately, I've yet to break a clutch cable or even snap a clutch - which is possible; my dad did it on his Volvo. The thing just shattered, so he couldn't even drive home. He made it almost 250K on a single clutch, which is actually pretty phenomenal, but when it went, it went.
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no subject
Date: 8 Sep 2004 04:39 pm (UTC)[Bows down before the beautifiousness that is Sol]
Caroline
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Date: 8 Sep 2004 05:48 pm (UTC)btw, feeling better? y'know, mebbe you need chocolate...depriving yourself of the glory that is chocolate can't possibly be healthy, babe.
no subject
Date: 9 Sep 2004 03:13 am (UTC)But all these accomplishments don't take away from the fact that I am a chocoholic on the wagon. Sigh. It's one day at a time.
Caroline
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Date: 8 Sep 2004 05:10 pm (UTC)thank you ^________^ I'll try working on two knights after I finish the yuri fic. KR poked me first <_<;;;;;
no subject
Date: 8 Sep 2004 05:49 pm (UTC)no subject
Date: 8 Sep 2004 05:54 pm (UTC)no subject
Date: 8 Sep 2004 06:09 pm (UTC)A'course, it was also highly annoying. Driving north through Hackensack NJ at midnight on a Wednesday (to avoid traffic, I always drove at night), and stopping at every service station. Do you have some grease? I just need a handful, to pack around my ball bearings. No, I don't even need a lift - I would drive the car up so two wheels were on the curb, which gave me just enough clearance to wriggle underneath, and I always carried one hydraulic jack. (Yes, there's the sign of a MAJOR gearhead.) So, just grease, please? And every place told me, in thick new jawsey accents, "oh, that's a furrin car, you need special grease." I was like, bastards, just because I'm nineteen and not driving detroit steel does NOT mean you're right, nor does it mean I'm stupid enough to believe you. Grease is grease, gimme!
No one ever did, hence the major damage by the time I got to Maryland.
Oh, and if you turn the wheel sharply and the car goes 'chunk-chunk-chunk' around the curve but the sound goes away when the wheels straighten out, that's your CV joints. Bad, but not irredeemable.
Hah.
I'm not that smart. I'm just a former gearhead! >.<
no subject
Date: 8 Sep 2004 06:47 pm (UTC)no subject
Date: 8 Sep 2004 07:32 pm (UTC)engine--> clutch--> transmission --> drive shaft --> axle --> wheel.
The clutch sets the gear, and then the transmission translates this into rotation speed (of the axle).
See, the deal is that if your engine turns over once, in a one-to-one, the axle would (roughly, and being really simplistic here) turn over in proportion. That's not always the best application of torque or power. Think of a three-speed bike - a lower, larger gear for easier downhill slopes and a smaller gear that gets more torque per foot-push. The clutch is going X speed (rpms) and it's locked into small rotation (low gear) or big rotation (high gear) as it matches up with the transmission. The transmission then turns in proportion to that combination (gear ratio) and that's the rotation applied to the drive shaft and down the line.
On True, my first Austin-Healey, the clutch was slipping. Plus, the speedometer was connected not to the transmission but to the engine, and essentially used that whole ratio-equation to say, "if you are in second gear doing three thousand rpms, you should be going X miles per hour." But with a slipping clutch, the clutch's friction plate is worn to the point that when it hits the transmission's flywheel, it can't catch - which means the transmission and the clutch (and behind the clutch, the engine) aren't travelling at synchronized speeds. When the transmission isn't turning at the same pace as the clutch, you lose power. There's nothing driving the wheels, even though the engine is turning, because the clutch isn't turning the flywheel.
As for mentioning where the speedometer was connected, now you understand why I had my foot on the gas pedal - going downhill! - and was losing speed - at the same time my speedometer confidently stated I was doing fifty-five. Hell, I could've had a frickin' hurricane for a tailwind and that car wasn't going fifty-five. The clutch slipped more than it caught, which meant the engine was produced massive amounts of torque and power...and barely any was getting to the transmission, and hence to the drive shaft.
Ever heard the catchphrase 'limited slip differential'? Same area - on a basic level, it's a technology that's supposed to keep the clutch from slipping out of sync. Limiting the slip-caused difference between transmission and clutch. Etc.
no subject
Date: 8 Sep 2004 07:34 pm (UTC)Synchro-mesh was just a way to let the two parts slam up even when travelling at different speeds (due to the pause while they pull away when you're in neutral). So it was an innovation that meant when shifting you just put your foot on the clutch, shifted to the new gear, and there was no crunching sound. Yay.
[I doubt you'd ever hear a car dealer even mention synchro-mesh as a selling point, unless they're really trying to snow you. Alternately, if you ever go shopping for a car and want to be a smart-ass, ask the salesman if the car has synchro-mesh. If you can say it with a straight face and the guy has no clue, you might be amazed at some of the wild claims. It's sort of like asking if the car has a brake pedal, when you think about it. Pretty much all cars have 'em now - except some race cars, which still require double-clutching. ]
One last point: it's possible to drive a manual car without using the clutch. This simply requires knowledge of the car's specific gear ratios, when the clutch and transmission are at such-and-such a matchup that changing the clutch to a different speed won't make things grind. If you think of the transmission as a plate with a few holes in it, and the clutch as something that locks into those holes - like fingers held as a claw, digging into cookie dough - then you can visualize the reason for 'grinding' - those 'teeth' aren't finding their proper holes. But if you know the gear ratios, you look at the speed, the rpms, and say: I am in third gear. When the rpms drop to 2600, then I can shift down or up. Ta-dah.
Each car is different, but they used to print the gear ratios for cars in the owner's manuals (probably because a lot of people were still used to double-clutching). My Golf manual, however, doesn't have it, and this annoys me. Fortunately, I've yet to break a clutch cable or even snap a clutch - which is possible; my dad did it on his Volvo. The thing just shattered, so he couldn't even drive home. He made it almost 250K on a single clutch, which is actually pretty phenomenal, but when it went, it went!
no subject
Date: 8 Sep 2004 07:40 pm (UTC)no subject
Date: 8 Sep 2004 07:55 pm (UTC)All the textbook I needed, baby! Then again, I learned this all through a lot of listening, watching, and breaking stuff. And more than a few arguments with my father - some of them pretty intense. Like the time he caught me using the old oil around the top of the oil filter, before putting it in place. Dunno where I heard it - probably one of the race car drivers I knew, who were always a little touched about such things - but he hit the roof. Dirty oil, you're ruining the whole point of changing the oil! But the broken oil works better as lubricant (or whatever)! We never did resolve it. My mother had to break it up and send us to our separate corners.
But it was also a bit o' pride, to be balancing my carbs in the school parking lot. Yeah, I was sweaty, filthy, covered in grease, but the cute chicks would walk past and look at me like, "are you from another planet!?" and I'm thinking, "screw you - you'll be the girl on the side of the road with a flat, helpless, and I won't stop!"
It's the little things.
(A pity I didn't realize my aptitude/enjoyment of engineering earlier - or that my mathematical ability isn't nearly as bad as I'd always assumed. I really think I would've enjoyed engine design immensely.)
no subject
Date: 8 Sep 2004 08:53 pm (UTC)I've got some car repair work that's going to be needed *real soon now*. Maybe I won't come off quite as blonde and braindead as usual. Although I'll probably still be handing over the credit card and saying 'you guys do it'.
Have a good trip, by the way. We'll all want to see photographic proof of that ball of twine.
no subject
Date: 9 Sep 2004 06:09 am (UTC)My advice, FWIW. Have your mechanic pop the hood and point out *exactly* what will be repaired (even if you do plan to have them do it all, have them explain *anyway*). And while they're there, ask more questions - is that the distributor? what are these things? where does this go? how does that work? If the guy (or gal) gives you attitude for asking basic questions, then unless this mechanic otherwise walks on water, don't waste your time with that place again! Or if it's the dealership, ask for a manager and explain you just don't feel that comfy, and you want some basic engine questions answered. :-D
As for the trip - packing the cameras now. Got my eighty-year old Ansco for the roadside attractions, and now I just have to find Jiji. He was around here somewhere - he's going with me, and I'm gonna take as many pictures as I can with Jiji in the shot. Why not, eh? It's MY frickin' vacation!
heheheh