knight@rlgvax.UUCP (Steve Knight) (04/06/84)
Sorry that it took a bit longer than I intended to post this, but this
*is* the promised summary of responses to my request for hints and
techniques on handling a manual transmission. I received 18 replies,
and didn't see a single followup posted--would that readers of other
newsgroups were as helpful and courteous as the readers of net.auto!
This will be, I hope, a genuine summary of the response; i.e., I've
tried to distill the relevant points from the body of responses I
received. I've also tried to arrange things by topic, but there's
definite overlap between areas, so please bear with my editorial
inconsistencies. There were, of course, some differing opinions, so
I've tried to draw some sort of reasonable conclusion when faced with
conflicting advice. In any event, I will keep the entire set ( >700
lines, ~33K bytes) of responses around for about another two weeks,
in case anyone wants to mail me for the complete transcripts.
Lastly, since I'm not knowledgeable enough to judge the relative merit
of these suggestions, I can't make any claims that everything mentioned
here is accurate or desirable; I'm merely passing on what I've been
told. So please don't try to drag me into any follow-up discussion of
what's here, okay?
1. GENERAL DRIVING. PRACTICE until everything's second nature; you
shouldn't have to think through the individual steps involved in
shifting. Try to make things smooth as a courtesy to passengers.
Also learn to shift by sound and feel; don't rely strictly on the
tachometer/speedometer to "tell" you when to shift. Try putting a
half full glass of water on the passenger side of the floor, and
cross town in heavy traffic while keeping the floor dry. This will
not only help with smoothness, but also teach you to look ahead and
anticipate things. (This suggestion was my personal favorite.)
Avoid excessive lurching--make gradual throttle movements in the
lower gears. Practice by accelerating to your upshift RPMs while
in first gear, and then use *only the gas* to slow down to the lug
RPMs. Keep accelerating and decelerating smoothly up and down the
range without using the clutch.
2. THE CLUTCH IN GENERAL. Keep your foot OFF the clutch unless you're
going to shift (the single most widely-accepted piece of advice).
This includes not driving at "half-clutch" to get extra power from a
cold engine, and *not* using the clutch to hold still on an upgrade--
the brake's for holding in place, so use that. If it's particularly
steep, you can use the handbrake and release it as the clutch grabs
into first gear.
Additionally, at longer stops (such as red lights), shift into
neutral and release the clutch. Holding it in doesn't wear the
clutch itself, but it's not good for the release bearings.
3. SHIFTING. Floor the clutch when shifting; this makes things easier
on the synchronizers. Let the clutch up as quickly and smoothly as
possible, and also try to minimize clutch slippage when taking off
from a standing start (although some slippage is unavoidable in this
case). Don't increase your RPMs *before* letting out the clutch,
but start to let it out a split-second before giving it gas. (This
takes some practice.)
When shifting between gears, don't make it too fast--it's better
to rest a few milliseconds between. Try to get out of first gear
quickly, since it's "large and causes a lot of resistance." Do not
skip gears when upshifting--it's tough on the synchronizers. One
person mentioned a BMW study that claimed the most efficient driving
style was to accelerate "briskly" through the gears until you reach
the desired speed.
4. WHEN TO SHIFT. There's no specific reason to doubt the RPM upshift
figures presented in the owner's manual; they're probably reasonably
accurate for good mileage. On the other hand, there's not much
sense to treating them as an exact standard, since the optimum
shift points are bound to change as the car gets out of tune.
To find the optimum shift point for acceleration, you can approximate
your torque curve by shifting to second at about 10 mph, then
accelerating quickly; the acceleration will be slow at first, then
pick up strongly, and then slow down again after a peak. Your
optimum acceleration shift point is just over the peak.
In general, the lower the RPMs at which you can successfully shift,
the better the mileage. Viewed against this guideline, the owner's
manual recommendations may be a little high. You can try shifting
at lower RPMs until either there's a pronounced lack of power or
the engine lugs (growls and bucks) after the upshift.
Especially in four-cylinder cars, maximum acceleration demands
shifting at higher RPMs; the 4000-4500 range was mentioned. This
does not apply when shifting from first to second, though; you still
want to shift around the mileage point then. Although the occasional
foray into high RPMs doesn't hurt anything, you generally don't want
to stay in the high RPM range more than a second or two.
A few people also pointed out that the local landscape can be a help;
i.e., you can afford to upshift at lower RPMs when going downhill.
You do, however, lose some control and may have to brake to stay
within the law.
Lastly, one person mentioned that Civics like to keep the RPMs under
4000 for better longevity, and that most imports advise keeping the
RPMs over 2500 to allow for proper battery charging, burning off oil
contaminants, clean exhaust, and other benefits.
5. WHICH GEAR. The general rule for gear selection is: higher gears for
mileage and saving on engine wear, lower gears for acceleration and
more control (while going downhill, etc.). More specifically, for
BEST mileage, keep it in the gear that gives you the lowest RPMs
without lugging; for ready acceleration, keep it in the gear that
gives you RPMs around the recommended shift point.
Even more specific: when you're driving around town in that "mid-
point" between third and fourth, where you can conceivably go either
way (about 40 mph on my Civic), there's no problem with upshifting
to fourth, provided you remain prepared (hand on stick) to downshift
when necessary.
6. DOWNSHIFTING. The question of whether or not to downshift in order to
slow down ("power braking") was the single most "controversial" subject,
some advising it, others saying never do it. The best conclusion I can
make is that power braking is not GENERALLY advisable, since the gas
spent and engine/clutch wear don't justify the savings to the brakes.
As a few people pointed out, the brakes are *there* for braking, and
it's cheaper to replace them than to replace a clutch. On the other
hand, power braking is not as subject to skidding, so it's apt to be
useful when the roads are slick.
Apart from the power braking question, downshifting is useful when
you need more power (for passing, or beating a light) and for handling
curves, and even downright necessary when you suddenly find yourself
lugging while climbing a hill.
You shouldn't downshift if the RPMs in the new gear will be more than
120% of your normal upshift RPMs. It's helpful if you can match the
engine speed and the transmission speed before releasing the clutch,
but don't spend a lot of time in neutral trying for perfection. This
can be accomplished by giving the gas a small tap, but since this
isn't always possible when braking (e.g., for a curve), you can try to
"heel and toe" it by having the ball of your foot on the brake and
using the heel/side of your foot to tap the gas pedal. On curves, you
generally want to downshift to the gear you want to be in JUST BEFORE
you enter the curve, and then accelerate through the turn.
7. DOUBLE-CLUTCHING. Another controversial technique, one person said
never double-clutch while downshifting, others suggested it if the
synchronizers were worn (or just to save wear on them), and also
explicitly for downshifts into second gear.
The procedure is to shift into neutral (depress clutch, shift,
release), spend a bit of time there matching your engine and road
speeds, then shift into the desired gear. The trick is, of course,
the second step, which would seem to rely on a good bit of
experience. One person suggested that for downshifting, you only
need let your foot off the gas, and upshifting just needs a shot
on the pedal to get the RPMs up in the right range.
8. PUSH-STARTING: Turn on the ignition, and shift to first or second
gear. Depress the clutch. Get the car moving by having someone
push it until it's going maybe 5-10 mph. Warn whoever's pushing to
stand clear and release the clutch. If it starts, you'll probably
want to depress the clutch and ensure that the engine's running
smoothly before starting again.
With that all said and done, I would like to acknowledge those who were
good enough to share their experience. Many thanks to:
wivax!tackett cbosgd!ksh wxlvax!paulson
cca!howard mts!chak ihuxv!cuda
lzmi!ziegler psuvax!IKS@PSUVM.BITNET
tekchips!terryl tekecs!ronb ganehd!mp
sjuvax!bbanerje ihu1g!fish houti!psv
dual!jeff ihu1j!gek dartvax!andyb
tekcae!philw
--
"If you lived here, you'd be home by now."
Steve Knight
{seismo,allegra,some other sites}!rlgvax!knight