Kyle-
it depends on the type you have. The smooth Porsche-style are easy to
see, but hard to get to- you can see wear on the surface of the ring, if
you pull it out of the transmission. You can also measure it to see how
much it's compressed. And you can flip these over to get some use out
of the back of them, too.
The toothed Borg-Warner are different. The teeth should be in dcent
shape, but it's the cone inside that wears out. I've not worked with
the Nissan incarnation of these, but other manufacturers have a spec for
how close the "brass" synchro can get to the steel gear surface. As the
synchro wears, its inside diameter increases, and it moves furhter up
the cone-shaped ramp on the gear. When it reaches the top of the cone,
it loses its 'grip' on the cone, and you lose the synchronization
action. I'd guess, from that, that the B-W would be more consistent
throughout their life, but fail faster, than the Porsche style...
And yep, there is a different shaft (and case-end) style for the two
types.
Toby
Kyle Hagemann wrote:
>
> >How can I tell if the synchros in my 4 speed are in good shape while
> the
> >trans is out of the car? Visually everything seems fine, no missing
> teeth,
> >no discoloration from heating, no scoring or signs of wear anywhere
> inside.
> >The end play clearances on the countershaft are fine and the shift
> lever
> >seems to engage all the gears with no problem. Should I just button
> it up?
>
> Hi Dan.
>
> >From my limited manual trans experience, I think it's pretty hard to
> tell.... carefully compare the synchro for second (usually the
> hurtinest) and fourth. The rounded synchro teeth wear out, but not
> so you'd notice...
>
> FWIW
> Kyle... gonna be right there soon, rebuild time for me :-(
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