Re: [A/S] I just looked at a 1997 F350 Crew Cab

[Jim Dunmyer <jdunmyer@xxxxxxxxxxx>]

George,
 There is a right and a wrong way to use engine braking:

Normally, you should leave the clutch engaged while slowing down, so the
engine gives you an assist. You should NOT downshift, and you should
disengage the clutch only when you're down to a very slow speed,
probably 20 MPH or less. You should not press in the clutch pedal and
use the brakes for all slowing down, as this creates a lot of extra wear
on the brakes.

You should not simply push in the clutch, downshift, then release the
clutch to get more engine braking. This does several Bad Things: puts
excessive and unnecessary wear on the synchronizers (listen closely as
you push on the shift lever and you can hear the gears in the tranny
speed up before engaging). It puts a lot of wear on the clutch as it
forces the engine up to speed before becoming fully engaged.

If you NEED to downshift for additional engine braking, as when
descending a steep hill, you can disengage the clutch, downshift, then
blip the throttle just before releasing the clutch pedal. This will get
the engine up to speed so the clutch actually does no work as it
engages.

Best of all, learn to double-clutch when downshifting. This alleviates
all work of the synchronizers and the clutch, but should still only be
done when you NEED the additional engine braking, not for normal stops.
Even a well-executed double clutch downshift adds wear to the 'back
side' of the transmission gears and the rear axle gears. Brakes are much
cheaper than gears.

Here's how you perform a double-clutch downshift:

Get the rig down to a safe speed for a downshift, you cannot shift into
a lower gear at a higher speed than you'd drive in while accellerating.
Push in the clutch and pop the shift lever into neutral. Release the
clutch and blip the throttle. (This is the tricky part: you must get the
engine speed up to nearly exactly what it would be if you were already
in this gear with the clutch engaged; the faster you're going for that
gear, the more you blip the throttle.) Then, depress the clutch, shift
into the lower gear, and release the clutch.

Done properly, a double-clutch downshift should be VERY smooth, and the
only 'extra' wear incurred is on the clutch linkage, nothing else is
affected. You can easily downshift a transmission with bad sychronizers
(or NO synchronizers at all) without grinding a tooth. When driving a
stick shift, nearly all my downshifts involve double-clutching, even
when just going from 5th to 2nd when I turn a corner in my VW. It just
makes for a smoother operation. You can use this technique to shift an
older tranny with unsychronized first gears into first while rolling.

I once taught a young girl to double-clutch her Pinto with totally shot
second gear synchronizers. Although she really didn't want to learn, the
alternative was expensive tranny work that she couldn't afford. After
just a bit of practice, she would corner and downshift like a pro truck
driver, never ground the gears at all.

You can often upshift even a non-synchro tranny without double-clutching
if you're careful. It should never be necessary to double-clutch while
upshifting a synchronized transmission.

                                           <<Jim>>