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Tachometer Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 12 Feb 2004 08:28:17
In Reply to: Lots of Questions about driving a 5 Spd 900S, SS, Thu, 12 Feb 2004 07:37:49 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The tachometer is a useful tool in driving a standard.
The first thing to know is that the engine doesn't have much power below 1500 rpm. It takes at least 2000 rpm to get reasonable power, and you're starting to get decent power at 3000 rpm. Much above 4000 rpm is just noise, not power.
If you're accelerating, and want to keep on accelerating, you want to keep the revs up - shift at higher RPM (3500, 4000)- when you drop into the next higher gear, the engine will still be turning at 2000-2500 rpm, where there is power. If you want engine power and flexibility, you need to be above 2500 rpm.
If you're just cruising along and don't need a lot of power, a higher gear means that the engine is turing slower, and using less fuel. So if you're just crusing along at 45 on a side road and don't need to accelerate, drop into whatever gear will give you 2000-2500 rpm. Much below 2000 rpm and you'll be 'lugging' the engine. However, if you need more power from the engine, like going up a hill, you'll want higher rpm - 3000 rpm or so. Typically that's around 3rd gear.
After a while, you'll get to know the sound of the engine, and can use the tach less. But the basics are there - if you want power, use the gear that gets you in the 'sweet' spot of 2500-4000 rpm. If you're just cruising and don't need power, use the highest gear (4, 5) to reduce RPM. Just don't go below 2000 or so.
Planning also helps. If you see a hill coming up, you may want to shift down.
As to pampering the clutch - there are a few things to do. When you engage the clutch, you don't want to 'slip' it more than necessary for a smooth takeoff. The clutch connects the engine to the tranny. If the tranny and engine speeds are very different, you're going to rub off more of the friction material on the clutch. If you downshift, it's good to actually bring the engine revs up a bit to match the speed the engine would be going once everything is engaged.
When shifting, don't just 'dump' the clutch - remove your foot fast. You'll know that because the shift will be jerky. At the other end, don't take the pressure off the clutch really slowly, because that means the clutch surfaces are spinning at different speeds for a long time. That's like sanding the surface, wearing it down. That's why driving a clutch is a skill to be learned, and well worth mastering.
It's hard to describe how to shift over the Internet.
In general, 1st gear is for starting from a stop. I try and stay in 2nd for slow speed driving. But again, it's all about revs. You don't want to be driving at 4000 rpm in 1st gear unless you're in the process of accelerating hard.
I assume that the enging rev up at start means that you're being too careful on the clutch. Namely, you aren't taking pressure off the clutch fast enough. The engine is going at speed, and the transmission isn't. The clutch is just two plates of friction material connected to the engine and tranny. If you take the pressure off the clutch slowly while applying gas, the engine speed will increase, but very little power is getting to the tranny. Most of the energy is spent with the clutch plates polishing each other. Ideally, you apply power gently while you take pressure off the clutch - engine speed increases smoothly while the car speeds up. Take it off too fast, and the car will jerk or even stall the engine. That's why it's a skill.
What's the sign of a bad clutch? It slips. You take your foot off the clutch, but engine speed doesn't match the tranny speed - the engine over-revs, then comes down. A really bad clutch slips a lot - going up a hill, you hit the gas, the engine speed jumps up, but the car doesn't accelerate. It's like grabbing a greased rope and pulling.
When must you stop driving the car? When the clutch is slipping so badly you can't drive up a hill, or it's slipping so badly you can smell it. I've had cars like that - it would be funny if it wasn't a sign of needing to do some work. A bad clutch isn't subtle - it's like watching a cow on ice - lots of slipping, not much forward motion.
I suggest you find someone that knows how to drive a standard, and drive around with them. Practice clutch engagements to get the feel. And the time is now, with a clutch on the way out. Learning to drive a standard can be a strain on a clutch, and it's best to get it out of the way on one that's due for replacement.
posted by 192.249....
, Thu, 12 Feb 2004 08:28:17 <-- Viewing This Message
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