Jim,
Yep, I'm way behind times on constant-mesh versus the old sliding-gear type
of transmission. However, to prevent gears from grinding or clashing during
engagement, a constant-mesh manual transmission still uses synchromesh,
haven't we all shifted a transmission that grinds gears due to worn
synchromesh?
I still think the synchros are what keep gears from grinding when the input
shaft is turning and it is attempted to move the gear lever into a slot
while the car is at rest. If not, what does keep the gears from grinding in
that case (no pun intended)?
Gary
'73
----- Original Message -----
From: "Jim Swarthout" <jswarth1@tampabay.rr.com>
To: "'Richard Good'" <goodparts@desupernet.net>; "'Sally or Dick Taylor'"
<tr6taylor@webtv.net>
Cc: "'Gary Fluke'" <res0s0t7@verizon.net>; "'TR6 list'"
<6pack@autox.team.net>
Sent: Wednesday, March 19, 2003 3:07 PM
Subject: RE: Shifting
> Richard,
>
> Thanks...
>
> I was just about to go take some pictures, and give a little gearbox
> seminar... :-)
>
> Best regards,
>
> Jim Swarthout
>
>
> -----Original Message-----
> Cc: Gary Fluke; Jim Swarthout; TR6 list
> Subject: Re: Shifting
>
> The TR6 trans is constant mesh. The only gear that moves in and out of
> mesh
> is reverse. The gear on the input shaft meshes with a gear on the
> countershaft driving the countershaft. Other gears on the countershaft
> mesh
> with and drive first, second and third gears which reside on bushings on
> the mainshaft. All of them turn all of the time but since they are
> different sizes, they turn at different speeds. When shifting through
> the
> four gears you are not moving gears but synchro hubs which engage the
> chosen gear to the main shaft to drive the mainshaft (output shaft) at
> the
> speed of the chosen gear. In fouth gear the mainshaft is engaged
> directly
> to the input shaft (1 to 1 ratio).
>
> Richard Good
>
> Sally or Dick Taylor wrote:
>
> > Gary---Thanks for the briefing on the "non-constant mesh" feature of
> > (for one) the TR6 transmission. Other than replacing an end bearing,
> > seals, and shifter O-rings, there is a lot I don't know about
> > transmissions. However, I was surprised at Swarthout's description of
> > what he felt was happening here.
> >
> > Eventually I'll have to find out how this all happens myself, as the
> > miles rolled past three hundred thou., and major work here is
> imminent.
> > First, I have to see if the recently rebuilt differential is going to
> > stay together, without protest! Also, thanks here to Berry and Bob
> for
> > sharing some of their experience in this matter.
> >
> > Dick
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