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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / March 2006How do you drive a manual car?
I pretty much learned on my own after just knowing it works. And I street race very well. However, I found myself more and more troubled in slow city driving. Here is what I did in traffic jams. 1 always shift at 1500-2000 2 when staring at slope, use half clutch. But I heard from Pros that 1500-2000 is not healthy, and I should do it at 3000-3500, which is exactly how my automatic car shifts. When I drove BMW, I always felt speed reduce when down shifting at 3000 -- you know the feel of low gear to reduce the speed, just like what we should do to break in snow driving. I hate to down shift at 3000. It feels like I press breaks suddenly. Is there a perfect guide to how to use manual? > I pretty much learned on my own after just knowing it works. And I street > race very well. However, I found myself more and more troubled in slow city [quoted text clipped - 13 lines] > > Is there a perfect guide to how to use manual? Not really, because each car is different. One could drive a torquey car like an older VW exactly as you describe with few problems. A Porsche 944 will vibrate like mad if you ever let the revs drop below 2000 under load. it really depends on what car you're driving. That said, I don't like to let the revs drop much below 1500 under load unless I'm driving a big torquey V-8 that can handle it. No sense stressing the bearings like that... nate  Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel Cars have changed since people worried about lugging an engine. When the first oil embargo hit, in the mid 70s, one of the European (I believe it may have been VW) mfgs ran a long life test on a test track for many miles. They drove on car normally, lugged (short shifted) another. They tore down both, found no significant difference in wear on crank or bearings. Higher shifting rpm gives better performance, lower shift points give better fuel economy. With modern steels, bearing materials and lubricants, one no longer gets significantly more wear from lugging (short shifting- low shift rpms). FI has contributed to this, too. With a carbureted car, if you shifted at too low an rpm, the low air velocity in the manifold would cause fuel to deposit on walls of manifold, screwing up mixture and causing bucking and severe vibration. One can really lug down a port injected car these days and still accerate smoothly, though slowly. Yeah, old fogies like me were taught, never lug an engine. For the cars we were driving in those days, it was good advice. Today it is only good advice for the race track, not applicable to street driving in days of $2.50 per gallon gasoline. > FI has contributed to this, too. With a carbureted car, if you shifted > at too low an rpm, the low air velocity in the manifold would cause fuel > to deposit on walls of manifold, screwing up mixture and causing bucking > and severe vibration. OTOH, there was this old Willys Jeep step-in truck a lot of us drove, and no one could drive it without bucking and severe vibration. One day the boss said to give it NO gas, just let up the clutch. Danged if that didn't work beautifully. SignatureAll relevant people are pertinent. All rude people are impertinent. Therefore, no rude people are relevant. -- Solomon W. Golomb >>FI has contributed to this, too. With a carbureted car, if you shifted >>at too low an rpm, the low air velocity in the manifold would cause fuel [quoted text clipped - 5 lines] > day the boss said to give it NO gas, just let up the clutch. Danged > if that didn't work beautifully. sounds like a leaky rear main might have made the clutch chatter a little bit. You could also slip the clutch at high RPM a couple times to burn the oil off, but that has other consequences... nate Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel >>>FI has contributed to this, too. With a carbureted car, if you shifted >>>at too low an rpm, the low air velocity in the manifold would cause fuel [quoted text clipped - 9 lines] > little bit. You could also slip the clutch at high RPM a couple times > to burn the oil off, but that has other consequences... We *were* slipping the clutch at high RPM to try to get it to stop bucking and vibrating. That's what was making it buck and vibrate. This old 1940's vintage engine just had that kind of torque. SignatureAll relevant people are pertinent. All rude people are impertinent. Therefore, no rude people are relevant. -- Solomon W. Golomb >>FI has contributed to this, too. With a carbureted car, if you shifted >>at too low an rpm, the low air velocity in the manifold would cause fuel [quoted text clipped - 5 lines] > day the boss said to give it NO gas, just let up the clutch. Danged > if that didn't work beautifully. Yep, depends on carb and manifold design. Too much throttle at low rpm means MAP is high, creating poor evaporation. That is one reason for power enrichment in carbs. The bucking with too much throttle was very common in carbed engines. That is one problem port injection has largely overcome. Cars have changed since people worried about lugging an engine. When the first oil embargo hit, in the mid 70s, one of the European (I believe it may have been VW) mfgs ran a long life test on a test track for many miles. They drove on car normally, lugged (short shifted) another. They tore down both, found no significant difference in wear on crank or bearings. Higher shifting rpm gives better performance, lower shift points give better fuel economy. With modern steels, bearing materials and lubricants, one no longer gets significantly more wear from lugging (short shifting- low shift rpms). FI has contributed to this, too. With a carbureted car, if you shifted at too low an rpm, the low air velocity in the manifold would cause fuel to deposit on walls of manifold, screwing up mixture and causing bucking and severe vibration. One can really lug down a port injected car these days and still accerate smoothly, though slowly. Yeah, old fogies like me were taught, never lug an engine. For the cars we were driving in those days, it was good advice. Today it is only good advice for the race track, not applicable to street driving in days of $2.50 per gallon gasoline. If the car will accelerate at all in the higher gear, you did not shift too early. > I pretty much learned on my own after just knowing it works. And I street > race very well. However, I found myself more and more troubled in slow city [quoted text clipped - 6 lines] > But I heard from Pros that 1500-2000 is not healthy, and I should do it at > 3000-3500, which is exactly how my automatic car shifts. Which pro's gave that advice for all cars.... > When I drove BMW, I always felt speed reduce when down shifting at 3000 -- > you know the feel of low gear to reduce the speed, just like what we should > do to break in snow driving. I hate to down shift at 3000. It feels like I > press breaks suddenly. > > Is there a perfect guide to how to use manual? I doubt that there is a perfect guide that will fit all cars. As Nate indicated cars are different and you have to lear the characteristics of your car. Above all I would suggest reading the owners manual for the car in question. It will give suggested shift points to maximize milage and possibly more information. Of course you have to modify those shift points to fit a given situation. For example if you are starting out on a 12% uphill grade it would be prudent to run the rpm's up beyond 2,000 rpm. To be perfectly honest, the automatic transmission available for most cars does a very good job of matching shift points to load. In my experience, most drivers drivers do not make good use of the manual transmission in their car and over-rev and hold the engine in lower gears too long. It takes a bit of thought and training to make good use of a manual transmission, but that is becoming a lost art I'm afraid. Most of us would be much better off with an electronically controlled transmission that works in concert with an electronically managed motor. > > I pretty much learned on my own after just knowing it works. And I street > > race very well. However, I found myself more and more troubled in slow city [quoted text clipped - 8 lines] > > Which pro's gave that advice for all cars.... Other street racers. There is a famous story that how a Benz technician fixed the car. The benz was driven in China using the normal guide at 2000 rpm, then it got really slow and wasted a lot of gas. Then the Benz technician just drove it at 200km for 30 minutes. The problems are all gone. He said German cars don't like low RPM and must run at high to prevent carbon built up. > > When I drove BMW, I always felt speed reduce when down shifting at 3000 -- > > you know the feel of low gear to reduce the speed, just like what we should [quoted text clipped - 21 lines] > controlled transmission that works in concert with an electronically > managed motor. My idea is to drive an automatic car of the same model first to see at what RMP it up shift or down shift, then apply it to the manual. > My idea is to drive an automatic car of the same model first to see at what > RMP it up shift or down shift, then apply it to the manual. Not likely to be useful, as the gearing difference between a stick and an auto (even in the same year/model) are likely to be wildly different. (Never mind that most automatics are three speeds, sometimes with an overdrive, while it's rare to see fewer than four speeds anymore, and often 5 or 6 in a stick - That alone is going to blow the concept of trying to match shift-points between them right out of the water - How do you decide when you should shift to 4, 5, or 6 when the automatic you observed only has three gears to play with?) SignatureDon Bruder - dakidd@sonic.net - If your "From:" address isn't on my whitelist, or the subject of the message doesn't contain the exact text "PopperAndShadow" somewhere, any message sent to this address will go in the garbage without my ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info > > > I pretty much learned on my own after just knowing it works. And I > street [quoted text clipped - 13 lines] > > Other street racers. Now that is a reliable soure of technical information on how to effectively shift a manual transmisison. (sarcasm intended) > There is a famous story that how a Benz technician > fixed the car. The benz was driven in China using the normal guide at 2000 > rpm, then it got really slow and wasted a lot of gas. Then the Benz > technician just drove it at 200km for 30 minutes. The problems are all gone. > He said German cars don't like low RPM and must run at high to prevent > carbon built up. That's nonsense. Whose famous story is that and where is it documented. If German cars don't like low RPM then how do you account for the many MB sedans with automatic transmissions that shift below 3,000 rpm and hold rpm's to a liesurely < 2,000 rpm at 60mph. > > > When I drove BMW, I always felt speed reduce when down shifting at > 3000 -- [quoted text clipped - 27 lines] > My idea is to drive an automatic car of the same model first to see at what > RMP it up shift or down shift, then apply it to the manual. If you are going to try and commit to memory the many complex shift patterns possible in a modern electronically shifed automatic, why not just buy a car with an automatic transmission. Several car makers sell automatic transmissions with a manual override (Volvo, Porsche come to mind but there are others). With that feature you can play race car driver at will but still have the benefits of a properly shifted transmission when you tire of the effort. Heck, even D, 3,2 will work. > Other street racers. There is a famous story that how a Benz technician > fixed the car. The benz was driven in China using the normal guide at 2000 > rpm, then it got really slow and wasted a lot of gas. Then the Benz > technician just drove it at 200km for 30 minutes. The problems are all gone. > He said German cars don't like low RPM and must run at high to prevent > carbon built up. I don't believe this. Carbon built up is more a matter of the gasoline itself. I used to drive german cars - esp. Mercedes Benz - for many years, with stick shift and automatic transmission. With an automatic 2 litre 4 cyl the engine will already run with >=1200rpm while driving, with a 4 litre 8cyl >=1000rpm. > My idea is to drive an automatic car of the same model first to see at what > RMP it up shift or down shift, then apply it to the manual. With manual you may even use lower rpms. The automatic usually won't run in very low rpms, because the engine wouldn't be able to accelerate within modest response time. Thomas > Other street racers. There is a famous story that how a Benz technician > fixed the car. The benz was driven in China using the normal guide at 2000 > rpm, then it got really slow and wasted a lot of gas. Then the Benz > technician just drove it at 200km for 30 minutes. The problems are all gone. > He said German cars don't like low RPM and must run at high to prevent > carbon built up. Carbon buildup is much more a problem of throttle opening rather than rpm. One can use full throttle and still shift at low rpm. For the last several years I have do that to save gas, and have had no problems with carbon buildup. Driving easy and keeping rpm down are NOT the same thing (at least with stick shift cars). When one shifts early one can still put ones foot in it hard. |
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