"alfred" <tomboy83=@yahoo.com> wrote in
news:ADaSj.59119$QC.16468@newsfe20.lga:

>
>>>>
>>>> You are causing 20 times the amount of wear in your transmission
>>>> each time you drive like this. At this rate, you will be looking
>>>> at a complete rebuild in about two years.
>
>> Shifting manually will do no harm at all; the tranny is designed for
>> this.
>>
>> According to the Owner's Manual:
>> "To shift from Second to First, press the release button on the
>> bottom of the shift lever. This position locks the transmission in
>> first gear. By upshifting and downshifting through 1, 2, D3, and D,
>> you can operate this transmission much like a manual transmission
>> without a clutch pedal."
>>
>>
>> Have fun. Just make sure you shift below the redline.
>>
>>
>>
>
> Okay so now I have conflicting information. Both seem to know about
> Honda's but since Tegger's information is like the manual I would tend
> to believe this. Also wouldn't shifting the auto manually be like
> using the sequential sport shifter in the acura's for instance? Either
> way theres no clutch.
>
>



Tegger has done lots of thinking about this. The product of that
thinking is below.

In a Honda automatic transmission, shifted automatically, the
transmission computer (TCM or PCM)decides when it will trigger the
shifts. It makes its decisions based on many factors, chief among them
being: road speed, engine speed, engine coolant temperature and throttle
position. The PCM effects automatic gear changes by powering/depowering
the various transmission solenoids (and there are many of them)
necessary to engage/disengage particular gear ratios.

Operating the shift lever manually means that you -- and not the
computer -- command the solenoids to operate. Placing the lever in "2"
for instance, causes the shift solenoids to assume the identical same
positions they would had the PCM forced the shift to "2" itself. Either
way the transmission responds in an identical manner using identical
parts, and will engage the new gear with identical vigor.

In other words, the same parts are operated to change gear whether the
PCM gives the signal via its logic or you give the signal using the
position of the gear lever. Honda did not install two separate sets of
transmission control mechanisms.

I can see just two possible problems with shifting an automatic
manually. These problems are: overspeed of the engine, and "lugging".

In a manual transmission there is nothing to save you from catastrophic
engine failure should you, say, shift into second and let out the clutch
at 85mph. Even though the engine's ECM will have cut off fuel near
redline, the solid mechanical connection between engine and road wheels
will pull the engine into mechanical failure territory and a rod will
poke itself through the block.

Likewise, if you choose to shift your manual 5th at 10mph, the engine
will labor mightly to keep the car moving, pounding the crankshaft and
rod bearings oval in the process.

In an automatic the PCM constantly monitors engine and road speed, even
when you shift manually. I would *think* the PCM would block the manual
gear-change signal from reaching the solenoids if the resulting engine
speed would exceed redline, but I have never tried this, not having a
disposable car to test on.

With an automatic, if you put the lever into a lower gear and repeatedly
forget you've done so, you'll be running the engine at a far higher RPM
than the PCM would run it at, leading to greatly increased engine wear.

Remember that moving the lever to "2" locks the transmission in that
gear. It is therefore possible to overheat and damage the transmission
and its fluid due to lugging at low road speeds in too high a gear,
provided you lug the powertrain for long enough.

It is interesting that the Owner's Manual mentions the engine speed
limiter (present on both models), but has a caution ONLY for the manual
transmission model. The manual transmission caution warns that the
engine speed limiter only works on upshifts, it does not work on
downshifts; you are warned to make sure you will not exceed the engine's
redline when downshifting. Plus there are tables indicating maximum
speeds in gears. The automatic transmission section gives no such
warning and has no speed tables. This implies that the PCM will protect
you from major stupidity.

Elmo's warning has truth to it: When you take upon yourself the
responsibility of choosing your own gear ratios, you also take upon
yourself the responsibility of knowing something of the machinery of
your car, and the damage you may cause by manipulating that machinery
incorrectly. Maltreatment of the equipment is called "abuse". Honda will
not honor warranty claims resulting from abuse.


--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/