Xref: cantaloupe.srv.cs.cmu.edu rec.autos:103164 rec.autos.tech:54190
Newsgroups: rec.autos,rec.autos.tech
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!howland.reston.ans.net!usc!sdd.hp.com!hpscit.sc.hp.com!news.dtc.hp.com!srgenprp!frankb
From: frankb@sad.hp.com (Frank Ball)
Subject: Re: RFI: Art of clutchless shifting
Sender: news@srgenprp.sr.hp.com (News Administrator)
Message-ID: <C5yD1D.GCH@srgenprp.sr.hp.com>
Date: Fri, 23 Apr 1993 20:03:12 GMT
References: <1r8u71$fhq@usenet.INS.CWRU.Edu>
Organization: HewlettPackardSantaRosaSystmsDiv,RohnertParkCA
X-Newsreader: TIN [version 1.1.4 PL6]
Lines: 41

& >I'm not familiar with the trannies used in Winston Cup, but in the trans-am
& >cars I've played with the  transmissions were the racing variety, with
& >dog clutches instead of sychros.  In a transmission with dog clutches, the
& >gears are always  engaged with each other and moving the dog clutches
& >engages the gears to the shafts.  Motorcycle transmissions are the same way.
& >Shifting without the clutch on a transmission with syncros can and will cause
& >transmission damage, the only question being how long it  takesto grenade
& >something (for the trans in my 87  Pulsar SE, it was  about 3-5k miles, but
& >it had a weak  tranny in the first place).
& 
& just out of curiosity, how is this "dog clutch" any different from a synchro
& transmission.  What you described SOUNDS the same to me.  In fact, what little
& i've studied on trannies, the instructor referred to the synchros as "dogs"
& and said they were synonymous.  The gears are always meshed in a synchronized
& gearbox, and you slip the synchro gears back and forth by shifting. Or at least,
& that is what i was taught.  Explain, por favour?

Motorcycle transmissions don't have synchros.  The engagment dogs are very
corse and sloppy.  There are maybe 6-10 teeth (dogs) on the side of the
gears that engage the next gear over as the forks slide the gears back
and forth.  To shift:  start to apply pressure at the same time the
clutch is pulled (the clutch is a hand lever) and shift quickly.  If 
you try a slow lazy shift it will grind, you just have to pop it into
the next gear before it has a chance to grind.  There isn't a neutral
between gears (obviously there is, but you can't select it with the
shifter) so double clutching is not a possibility.  "speed shifting"
(which is what I have always heard "clutchless shifting" called) works
pretty well for upshifts with some practice, but I usually use the
clutch-especially for the lower gears.

I think auto (as in automobile) trannys are similar, except that the
engagment dogs are very fine, with no slop.  And the addition of
syncho rings.  The gear teeth are always engaged in auto transmissions
that are synchronized, but may not be in non-synchro gears (reverse
and sometimes first).  

--
Frank Ball   1UR-M          frankb@sad.hp.com    (707) 794-4168 work,
Hewlett Packard             (707) 794-3844 fax,  (707) 538-3693 home
1212 Valley House Drive     IT175, XT350, Seca 750, '62 F-100, PL510
Rohnert Park CA 94928-4999  KC6WUG, LAW, AMA, Dod #7566, I'm the NRA.
