Date:         Thu, 23 Sep 1999 18:16:30 -0700
Reply-To:     AL_KNOLL@HP-ROSEVILLE-OM2.OM.HP.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Al Knoll <AL_KNOLL@HP-ROSEVILLE-OM2.OM.HP.COM>
Subject:      Re: Auto Trans, Shift Points etc.
In-Reply-To:  <19990924004459.196AB8E@palrel1.hp.com>

Item Subject: cc:Mail Text

     Virtually all non-electrically activated "automatic" transmissions use
     a fluidics computer based on valving and pressure and throttle
     position to determine when to change clutches (gears).

     Adjusting the level at which the fluidics valves activate (they have
     springs in 'em to dictate at what pressure they change state) allows
     you to select your shift point based on rpm by changing the springs.

     Adjusting the way the throttle input (a measure of throttle position)
     denies the pressure signal allows you to dictate how throttle position
     affects shift point.

     The ratios are fixed of course unless you change the actual drive
     gearing inside the transmission.

     What you can adjust is when they change using the model above.

     The fluidics computer is that really weird looking things with all the
     passages thats left over when you throw the rest of the transmission
     in the dustbin.

     Usta call 'em valve bodies.

     Al (usta have a BW-65 with 7500 rpm shift points in a non-street
     gofastgadget)

     Jim Hall of Chaparral fame coined the term "Clutch, what for?"  when
     developing the automatic for the famous Chaparral racers.  Those
     trannies could handle 1200 HP.

     Tis rumored ATF coloration is irreversably temperature sensitive to
     allow monitoring of overheat conditions.

     But, that was long ago and far away at Rattlesnake Raceway.

     Al