Synchro rings work to match rpm. In your case, the 2nd gear synchro
is not doing well. On the first going to second shift, you are using the
synchro, but since the shaft is already slowing down because of
drag, the matching is much easier. This is why you tend not to
grind any gearbox on an upshift. On a downshift, where the
shaft now has to be sped up, the synchro really has to work.
Hence the typical half second delay, whine, and then engagement.
In your case, double clutching would help, but you've got to
bring the shaft (engine) rpm up past the rpm it will be in when you
downshift. Otherwise the synchro is still being forced to rev the
shaft up, instead of slowing it down.
>>> "Gary Hutton" <hutton@evansville.net> 08/01 11:34 AM >>>
Hi all,
My 76 single-rail transmission has started to grind when I downshift
from third and I suspect that this is the synchronizer going out, but
wanted to consult the list. It upshifts without any problem which I
don't understand - don't the synchronizers come into play on the
upshift? I've tried double-clutching to circumvent the grind, but
either I'm not doing it correctly or it doesn't work in this situation.
My only solution so far is to really drop the speed before downshifting.
If I continue to drive it with the occasional grind, am I chewing up my
second gear also? Any suggestions and/or comments are appreciated.
That grinding sound takes a whole lot of pleasure out of my driving!
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