Topica Loopframe_Guzzi Archive
 

Subject: RE: Understanding a 4-Speed Trans

Author: Keith Ruff

Date: Oct 24, 2002, 7:29 PM

Post ID: 1711268231

And he said the word: "constant mesh"

After reading and re-reading and re-reading the manual for about an hour
and a half, and studying the figures and drawings, it finally all came
together. Constant mesh and the "sliding dog gears" is what finally put
it in place. I thought something needed to be moving in there, i.e.,
gears sliding back and forth to choose which gear is selected. Instead
it is the sliding dog gears that are engaging a gear within the contant
mesh. Ahhhh, now I get it. Still don't know why I would get a drop in
idle though. Something must be getting caught up or perhaps there is
not enough push on the clutch spring to release the clutch plates?
According to Andy, everything looked great inside, and the hub is now
clean and lubed. He said it shifts like butter, but still get a drop in
idle when pulling in the clutch. Wonder if it's another Guzzi dealer
screw up with that new rear case cover and Eldo style throwout bearing.

Keith


Eric Lamberts wrote:
 On Thu, 24 Oct 2002, Keith Ruff wrote:

 Was thumbing through my 70's vintage Chilton manual and came across the
trans. I was wondering how the trans actually operates, how it selects
the different gears. Pic shows an "assembled 4 speed transmission"
drawing. The "layshaft" which goes to the driveshaft, has 4 gears on it

and 2 arm looking things, one on each side of the 2 inside gears with
one gear outside of each arm. Then there is the "mainshaft" which also
has 4 gears on it that appears to mate directly with the 4 gears on the
layshaft. Next there is the shaft that goes to the clutch, the one that

the actuator arm pushes on in the center of the rear case (aka plunger)
that I just replaced the O-ring on - it came out with the throwout
bearing magnetically attached. The final shaft is attached to the gear
selector. What I don't understand is what happens to select the gear?
I see that the clutch handle pushes the plunger which then will
disengage the clutch, and the book says that the gear selector rotates
the other shaft which then selects a different gear, but I don't follow
that part. What is also confusing is that the 4 gears on the layshaft
and mainshaft are in perfect alignment, indicating that all gears are
turning at the same time, so how are the different gears selected.
Highly confused here.

The gears are in constant mesh, but in neutral at least one of each pair
that are engaged are not hooked to the shaft. The shifter forks slide
the gears back and forth on the shaft--there are dogs on the sides of
the
gears that engage with the shaft to lock it in place to transmit power.

Check out:

www.dansmc.com/gearbox.htm

Kind of interesting, because loopers use neither of the 3 types of mc
gearboxes listed
Eric Lamberts ew-@unr.edu Reno NV



Keith Ruff
71 Police Ambassador - NJ

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