Re: As US mileage limits increase, trannys will get better.

Post #350,860 by pwhysall 11/18/11 7:48:37 AM Reply	Re: As US mileage limits increase, trannys will get better. DCTs are still less efficient than manual transmissions, as the numbers i posted (the "powershift" is a DCT transmission) show. Not by much; the yawning gulf between auto and manual has gone. As you point out, DCTs don't have torque converters (learn something new every day, etc), and I'd bet a pint that that's the reason. However, DCTs are complex, and I wouldn't want one on a car if I were picking up the maintenance and repair bills. But this is dancing around the edge of the MPG problem. Y'all need to get over yourselves and start driving cars with diesel engines.
Post #350,862 by Another Scott 11/18/11 8:11:00 AM Reply	Some of us do. ;-) Another advantage of DCTs over manuals is that they're easier to control by the car CPU. Presumably one of the things the car manufacturers are thinking about is "economy" modes where the throttle and gears are automatically selected to maximize efficiency. One can do that with a manual too, e.g. old Corvettes that shifted themselves into ultra-overdrive to get 20 mpg (or whatever), but people expect manuals to be manual and don't like it. I think the US fleet is too big for most cars here to be diesels. I don't think there's a way to change the fuel mix to get enough diesel for another 150M cars. Could be wrong, though. Refineries can adjust the cracking mix to some extent, and the cracking depends on the qualities of the starting crude, but you can't (easily) go from, say, 20 gal gasoline per barrel with 15 gal of diesel to 30 gal of diesel and 5 gal gasoline. http://www.theoildrum.com/node/6089 Efficiency all around is the way to go. Cheers, Scott.
Post #350,863 by pwhysall 11/18/11 8:23:11 AM Reply	Re: Some of us do. ;-) DCTs have some driving advantages over manuals - see Lincoln's paean to his girly clutch-operating leg above - but the figures are clear: manual gearboxes yield better efficiency. Whilst I don't expect the actual figures I quoted above to be reflected in real-world driving, I wouldn't be at all surprised to see that the difference between manual and DCT is indeed present. Another factor which a DCT cannot consider, no matter how cunning its ECU, is that a manual gearbox's computer is equipped with forward-facing oculation devices, aka the Mk1 Eyeball. A DCT transmission will make shifts that a human driver wouldn't, thus reducing fuel efficiency a little.
Post #350,865 by pwhysall 11/18/11 8:28:22 AM Reply	Re: Some of us do. ;-) Simply put: if you need (in the most extreme sense of that word) to transition more of the US vehicle fleet to diesel, you'll figure it out. Whether that's brutal enforcement of HOV lanes, cranking up efficiency regulations to the point where's it's diesel or a hybrid, or something I haven't thought of, is all moot. Personally, I think we're headed for fuel cells, once we figure out how to produce, handle and distribute hydrogen. Massive-scale solar-powered electrolysis is surely going to be on the agenda at some point.
Post #350,866 by Another Scott 11/18/11 10:27:38 AM Reply	On the numbers... I think we agree that it's very hard for a conventional automatic not to have a several MPG loss compared to a conventional manual. That's one reason why I didn't consider an automatic for my Jetta TDI - the MPG hit was too large (4+ MPG). For the DSG vs manual, I think in real life it'll often be a wash. E.g. some numbers for BMWs - http://www.7machine.com/bmw/31274.html Apparently the EPA says the hit is 1-2 mpg compared to a manual - http://articles.chic...1_dct-clutch-gear but it likely depends on the engine displacement (smaller engines can use "dry clutch" versions that weigh less, are less complex, etc., etc.). I'll certainly consider a DCT (if I have a choice) when I next shop for cars. By that time, manuals might not be available anyway here (they're pretty rare as it is). I don't think the complexity argument is a big deal. Not having to replace a clutch at 100k miles for $1000+ is a big selling point, I think. Cheers, Scott.
Post #350,867 by pwhysall 11/18/11 10:39:48 AM Reply	Re: On the numbers... No, instead you get to replace TWO clutches :-) I don't know of many people who have replaced clutches that "just wear out". The people I know who replace clutches seem to be the same people every time, and when you're on your third vehicle in a row where you've replaced the clutch, then I reckon the problem is the nut on the steering wheel, not the clutch itself. If ya know what ah'm sayin'. Most (manual) cars that go beyond 100K miles do so on their original clutch. Perhaps British drivers are just more sympathetic in their driving style. Perhaps clutches fitted to vehicles in the UK market are beefier. I dunno. One of the things that worries me most on the 528i is that it has a DMF, and those babies are expensive if they go wrong, both in terms of parts and labour. I suspect that if the DMF fails, i'll be weighing the car in for scrap or breaking it for parts, as the cost of fixing it will be not far off the resale value of the whole car.
Post #350,879 by static 11/18/11 6:28:30 PM Reply	Clutch replacements and drivers. Clutch replacements are done frequently enough most mechanics know how long it will take them to get inside the thing and do it, but most cars last for years without one. My sister's car came with a new clutch and the car wasn't that old (20 years?): that strongly suggests a previous driver did the damage. That is also suggested by my own experience: got a new clutch for my 924, but that was mainly because the pilot bearing was dying and if you're going to spend the time to get into the bell housing, you may as well replace the clutch plate as well. Turns out it was a bit dodgy, but then it is a sports car and I've little doubt at least two previous owners saw that aspect first and foremost. And since I've now seen what a clutch mechanism looks like (and how much it weighs!) I am somewhat astonished they've figured out how to put two clutch plates in one, driving a concentric axle for the gearbox. A DCT, in other words. Wade. Static Scribblings http://staticsan.blogspot.com/
Post #350,889 by Another Scott 11/18/11 8:20:45 PM Reply	I'm assuming the machine can shift better than me. Yes, it's a good point that it has 2 clutches. :-) However, if it can shift in 8 ms, then there's almost no stress on the clutch linings (compared to normal US drivers who work hard to minimize jerking even as they burn up their linings) so they should last the life of the car if it's designed properly. But it sounds like the US tuning is different from yours - http://www.nytimes.c...ml?pagewanted=all Oh well. I wasn't aware of dual-mass flywheels. I guess you need to keep on the look out for vibrations at 900 and 1800 rpm. Fingers crossed. Enjoy your new buggy! Cheers, Scott. (Whose SIL just got a new Prius.)
Post #350,892 by folkert 11/18/11 8:22:29 PM Reply	I use the clutch for startup from being stopped only. After that its a clutchless affair, even most downshifts.
Post #350,894 by Another Scott 11/18/11 8:36:56 PM Reply	Bike? Car? Both? I haven't tried that myself. Some claim it's hard on the synchronizers not to use the clutch; others says there's no problem. I dunno. Presumably if you're good enough to match the RPMs without the clutch then you're good enough to put little wear on it anyway. I dunno if I'll try it in my TDI - the turbo kicking in would make it challenging.... Thanks. Cheers, Scott.
Post #350,897 by drook 11/18/11 10:25:08 PM Reply	Upshifting, yes; down, no That's on the bike, anyway. In the car, the throw on the shift lever is long enough that it's not worth it to try. -- Drew
Post #350,901 by folkert 11/19/11 1:36:37 AM Reply	You are... Full of crap. I can hit my Lancer near every time up and down with out grinding the syncs except from 2nd to 1st... Heck, if I do it right I can even get my car to go into gear without grinding from a start without using the clutch. My Bikes, easy to do with the throttle and the toe shifter.
Post #350,903 by drook 11/19/11 1:59:35 AM Reply	I"m happy for you You like clutchless shifting, and you're good at it. I don't mind using the clutch, and of all the manuals I've owned I've never had to replace a clutch. Looks like we're each happy with our own driving. -- Drew
Post #350,905 by pwhysall 11/19/11 2:21:17 AM Reply	People who change gear without using the clutch are... (a) in a tiny, tiny minority (b) inevitably still going to make some alarming grunching noises when they don't quite hit the spot; no-one's perfect
Post #350,906 by Steve Lowe 11/19/11 3:05:53 AM Reply	(c) they're driving a semi
Post #350,907 by crazy 11/19/11 6:03:10 AM Reply	Or mildly retarded Really, that's the word. My brother's best friend (neighbor 3 doors down) since he was a little kid ended up with a volkswagon beetle (in 1979). The guy is mildly retarded, which makes for great "best friend" material. Nicest guy in the world, but dumb enough to annoy constantly unless you partition out that area of your brain while talking to him. Grind it until you find it was his standard method of shifting.
Post #350,914 by folkert 11/19/11 8:25:10 AM Reply	... c) People that use the clutch inevitably still going to make some alarming grunching noises when they don't quite hit the spot; no-one's perfect
Post #350,960 by pwhysall 11/21/11 3:40:16 AM Reply	Re: ... Shrug. If I miss a gear, I dip the clutch again, no harm done other than feeling a bit daft. If you miss a gear, it's metal-to-metal contact in the gearbox. Still, if it works for you, that's cool.
Post #350,976 by folkert 11/21/11 11:05:57 AM Reply	Re: ... I haven't ground a gear not using the clutch either... it I miss a shift, it doesn't sound like you think. It sound just like when you miss a gear. There is metal to metal contact when you miss a gear as well. Especially with these modern manual transmissions. You guys are just daft.
Post #350,902 by folkert 11/19/11 1:41:43 AM Reply	Well, obviously... I've done it on all of my manual cars since I was 16. My Dad's 1973 Pinto, my 1976 Pinto, the Nissan Sentra, Monte Carlo with a saginaw tranny, the Ford 3 on the tree, the chevy truck 454 with a Muncie, My honda Accord, My Mits Lancer. Of course the bikes I've had and have. All without grinding the syncros. Heck, even when I drove a delivery truck for a while, never used the clutch after a start... up or down, except to 1st. Its not hard, it just takes finesse and timing properly... the shifter just falls into place when you do it right. I guess I just do it right.
Post #350,910 by boxley 11/19/11 7:39:59 AM Reply	yes, years ago I even offered crc to teach his kid to do it some brit whiner started complaining that he wouldnt lend me his car if I visited Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free American and do not reflect the opinions of any person or company that I have had professional relations with in the past 55 years. meep
Post #350,959 by pwhysall 11/21/11 3:39:00 AM Reply	Re: On the numbers... 500 mile round trip at the weekend; 55.4 MPG. I expect this to rise as the car runs in.
Post #350,963 by Another Scott 11/21/11 8:36:40 AM Reply	Nice.
Post #350,965 by boxley 11/21/11 9:09:35 AM Reply	remember that is about 38mpg US still good tho Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free American and do not reflect the opinions of any person or company that I have had professional relations with in the past 55 years. meep
Post #350,971 by malraux 11/21/11 9:49:26 AM Reply	How is 55.4 MPG == 38 MPG...? Regards, -scott Welcome to Rivendell, Mr. Anderson.
Post #350,972 by drook 11/21/11 9:57:12 AM Reply	Miles are shorter in the U.K. Hell, they can cross their whole country in a day without trying hard. -- Drew
Post #351,028 by static 11/21/11 6:59:33 PM Reply	No, UK gallons are larger. Static Scribblings http://staticsan.blogspot.com/
Post #350,979 by crazy 11/21/11 11:27:50 AM Reply	It's not - it's 46.13 US according to this... http://www.mpgtokpl.com/mpgustompguk.htm
Post #351,015 by boxley 11/21/11 5:24:41 PM Reply	they get an extra litre per gallon of gas Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free American and do not reflect the opinions of any person or company that I have had professional relations with in the past 55 years. meep
Post #351,040 by pwhysall 11/22/11 2:39:31 AM Reply	Re: they get an extra litre per gallon of gas What? No-one told me! Is there a coupon I have to redeem? Wait a minute. Is this an extra American litre? It'll be fucking tiny, if it is! Or imported from China.
Post #351,041 by drook 11/22/11 5:02:50 AM Reply	It's tiny because it's imported from China -- Drew
Post #350,977 by folkert 11/21/11 11:07:46 AM Reply	MPG == MILES PER GALLON... not KILOMETERS PER LITER. Man, just add gas to the flame.
Post #350,988 by pwhysall 11/21/11 12:44:26 PM Reply	Re: MPG == MILES PER GALLON... 23.9 KM/L Yes, I have a spreadsheet with this stuff in. </sad>
Post #350,986 by pwhysall 11/21/11 12:42:36 PM 11/21/11 12:45:57 PM Reply	Re: On the numbers... 250 mile to the Big Smoke. 63.7 MPG. Getting 3.3 MPG away from a manufacturer's quoted figure is, quite frankly, unsettling. ETA: That's 56 miles to one of your imposter gallons. Edited by pwhysall Nov. 21, 2011, 12:45:57 PM EST Expand All History

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