Peter writes:
>Upon beginning a trip, shifting gears is silky smooth. For instance,
>moving into reverse is accomplished with no problem. After 1/2 hour or
>so on the road, shifting becomes quite hard. Shifting into reverse
>causes serious clashing. In fact, the clutch does not seem to be
>completely disengaging after warmup. The slave cyl. connector is on the
>lowest of the three holes in the clutch shaft arm. If I try to move it
>up to the middle hole, to get more throw, the throwout bearing will
>always be turning. What the %#&*! is going on in there?????
I have had similar problems in the past with my clutch, and the problem
always seemed to be rooted in the hydraulics. (a particularly troublesome
hydraulic system) First of all, the slave cylinder pushrod SHOULD be
connected to the drop-arm at the MIDDLE hole. However, some might
experiment with the upper and lower holes in an attempt at solving
(masking) problems caused elsewhere in the system. In my case, during one
period of time I was rebuilding clutch hydraulics every three weeks,
believe it or not, and during that period, and especially when the
hydraulics were ready to be rebuilt AGAIN, I would notice that it would
work better cold. Once things heated up a little, it became much more
difficult to disengage the clutch.
Another possibility is the pilot bushing. Our Toyota had trouble once with
this... can't remember if it got worse with heat or not, but I can imagine
that it could in your case. If the pilot bushing doesn't fit properly
around the end of the input shaft, it could create friction here and try to
spin the input shaft even when the clutch is disengaged. This can make
shifting difficult, and particularly shows up when trying to shift to 1st
or reverse when stopped. Certainly, the pilot bushing is in an environment
that gets quite hot, and this would aggravate the problem. The more I
think about it, the more I lean towards the pilot bushing. Feel like
changing your clutch? You may as well, 'cuz if I'm right, you'll be
pulling the gearbox to change the pilot bushing! If this is the route you
take, make sure you set everything straight inside the bellhousing... new
release bearing and sleeve, new pins in the ends of the fork, new taper
pin, new cross shaft bushings, etc. I suggest employing the additional
bolt-through-the fork trick to prevent your having to repeat this whole
procedure later when the taper pin breaks.
You also need to eliminate any play in the linkage... most notably, the
play that originates at the pedal's connection to the master cylinder
pushrod. The holes in the pushrod yoke get elongated quite a bit over a
short time, so if it's never been replaced this is the source of a LOT of
lost motion. If everything else is set up correctly, everything will work
as designed with the slave pushrod in the center hole on the drop-arm.
Also, measure the movement of the drop-arm... it should move rearward a
full 5/8 of an inch to provide the correct travel. If it doesn't, then the
problem is probably hydraulic.
Here's how I would attack it:
1) rebuild the master and slave cylinders and note the effect on the
operation of the system.
2) If this doesn't do anything, prepare to pull the gearbox and go through
everything in the clutch release mechanism thoroughly.
Hope this helps!
Pete Chadwell
1973 TR6 CF10732
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