I'll bet it's due to worn synchro rings. When the trans is cold and the
gear lube is more viscous the synchro clutches work better (thick lube
more friction). When the trans warms up the lube thins out and the
synchros don't work as well. Heavyer gear oil might work short term, but
only real solution is a trans overhaul.
Transmission Background:
Hard to describe without a trans to illustrate, but here's how synchros
work. Synchro rings are conical (tapered) rings attached to the gears,
the gear selector is attached to a splined cylinder (dog clutch) that
slides along (and spins with) the driven shaft when gear changes are
made. As the dog clutch (tapered on the inside) contacts the tapered
sychro ring, the gear speed is increased to match the dog and the two
smoothly engage. Note the gears are always meshed with each other, it's
the dog clutch that you shift (not the gears) and the dog and synchro
teeth (auxillary gear teeth) that you engage. Yeah, basic stuff but some
times it helps.
Todd Osborn
68 2.0L D-A-T-S-F-U-N, San Jose, CA
snyler wrote:
>
> >does any body know why my car changes gears pretty good when cold, a bit
> >notchy though, but when hot its getting very difficult to select the
> >gears, could it be the clutch sp310 1500
> >
>
> Sounds like the way my 1600 behaved before I replaced the clutch master
> cylinder. Beginning of a trip it shifted fine, by the time I got home, I
> had to coax it into Reverse. Perhaps it is your hydraulics, is the fluid
> in the clutch master murky or black? Master, slave, or both may need
> rebuilding or replacing.
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