Downshifting to brake

[Greg Spark <sparkg@wave.co.nz>]

I've been following this thread for a while and am surprised that most
posters seem to drive at max all the time using racetrack techniques
that I feel are unnecessary for normal road driving. I suppose its
nice to fantasise that you're Fangio!

This post from James says it all from my point of view - common sense
at last.

--------------------original message------------------------------
> From: Marriott@grolen.com
> Date: 7 Feb 1997 23:28:06 EDT
> Subject: Downshifting to brake
> 
> Greetings other members of this exclusive (read "big $$$$$$$) club,
> 
> Several things to note about comp. braking and downshifting:
> 
> 1. Every time you use a mechanism, you're wearing it. When you shift
> (whether up or down) you use:  the shift lever and all the linkages; the
> hydraulics (MC and slave) or cable; the clutch pedal; the clutch boost spring;
> the ToB arm; the Tob; the pressure-plate fingers, hinges, and springs; the
> clutch disk, flywheel, and PP; the clutch disk springs. For braking:
> pedal/return spring/MC/light switch/CC cutout, caliper, pads, rotor. I can
> change my front brakes (rotors and pads) for $135 in 20 minutes. A clutch for
> my 4kq is ??? and takes a few days, as I understand. On a related note, I ride
> with some people who will hold the clutch in, while braking to a stop, and
> downshift through every gear. Huh?
> 
> 2. Going down I-40 from Flagstaff to the Colorado River while towing a
> trailer is one thing, getting off a limited-access highway is another. Pushing
> the brake pedal once, and loading all the suspension components once, causes
> more wear to the drivetrain than three or four downshifts? How about the fuel
> to rev the engine for each shift?
> 
> 3. Shifting without using the clutch _will_ wear the synchros and/or
> blocker rings, as applicable. Some people will say, "I've been doing
> that for years with no ill effects." Well, the transmission isn't
> designed to come out of gear while it's loaded _at all_. If engine or output
> RPM change after you've gotten past the S/BR, but before you've engaged, you
> will grind the gear. Everyone's BTDT. Gears are hard, and won't really wear
> without abrasive, but they _will_ chip. The clutch is on there for a reason.
> 
> 4. As far as "being in the right gear to get out of the way," I don't do
> that either. It's five miles from my house to the highway, at 35 mph. I
> don't drive in second gear in case a runaway truck is chasing me. Nor to
> I go 60 in third, or 75 in fourth, on the highway.
> 
> 5. I have more control over the friction brakes than the engine brake,
> as my Girlings work the same every time. With three open diffs, who
> knows what's going to happen. BTW, A4 folks, does the EDL work whilefor comp
> braking? Interesting concept . . .
> 
> 6. Heel-toeing and downshifting on the track is an invalid comparison to
> street driving. It's by definition more aggressive. Just because my car
> has great suspension and brakes and acceleration (yeah, right! ;-)
> doesn't mean I flog it continuously. There is a time and place for
> everything; just because I know how, doesn't mean I have to do it every
> time.
> 
> 7. My clutch pedal is never depressed for more than about one second at a
> time.
> 
> 8. I do match RPM while performing a non-double-clutch downshift.
> 
> Just my 0.03 Dm of mechanical design experience (at current exch, of
> course :-)
> 
> James
> James Marriott, BSME (603)483-8587 Auburn, NH
> '64 Falcon Sprint Convertible, B&B 260 V-8 and CR 4-spd.
>     GOES great. Stopping?!? 217k
> '86 4000S wife's commuter (heated seats), 32 mpg, 100k ++ ?
> '87 4000CSQ H-stock und daily driver, Hakkas & :-) , 140k


-- 
Greg Spark            '96 A4 1.8Tq
sparkg@wave.co.nz     MTM 187hp
Hamilton, New Zealand