List:
I welcome any feedback, agreements, disagreements, etc.
Dave
"David R. Conrad" wrote:
> Hi Charlie:
>
> Having spent just over two months (more than a month to receive parts) since I
> decided that it was "time to adjust my clutch", and just now having returned
> the car to drivable condition, your request is well timed, because all I've
> learned is still fresh in my mind. I'll document it also, for my own memory
> and for whatever use it my be to others...
>
> The facts and other information (which I've derived myself) are as follows:
>
> Master cylinder:
>
> 5/8" bore, 1-3/8th" maximum stroke (My calculations of the linkage are that
> normal pedal movement - to the floor board - would cause it to move only 0.95
> inch, so that there is no way the master cylinder could be "bottomed out").
>
> Slave cylinder:
>
> 3/4" bore Because of bore area difference, moves 69.5% of movement of master.
>
> Linkage wear and "slop":
>
> This factor works in a way to diminish the actual "throw" of the slave
> cylinder. In my case, it prevented me from achieving the recommended
> "clearance" between the actuating fork and the slave push rod, and at the same
> time provide for sufficient movement of the fork to allow complete
> disengagement for shifting. The only way I could achieve that was to
>eliminate
> the clearance, to a negative value, meaning there was a constant load on the
> release bearing - an unsatisfactory condition. My slave cylinder throw
> measured 9/16ths inch at this time.
>
> Ways to eliminate "slop":
>
> 1) Replace or repair parts.
>
> Replace master cylinder (or master cylinder push rod) with new, to eliminate
> the "hole" elongation. Weld and redrill hole in pedal arm to correct same
> condition there. Obtain a new "pin". Mine showed a lot of wear.
>
> 2) Provide for increase to master cylinder "throw":
>
> To compensate for the "slop", the master cylinder can be made to extend
> further. I was fortunate to have a clutch cylinder from a different car,
>which
> had an adjustable push rod. (see attachment) I modified this so that it would
> replace the push rod for my stock cylinder, and adjusted it to be "longer" by
> the amount of "slop" which I had measured.
>
> In the case of the linkage geometry which exists for my car, that amount of
> "slop" was 0.184 times the amount of "free play" observed at the pedal. In my
> case, that was 3/4 inch, mechanical, and another half inch before hydraulic
> resistance was "felt". That gave about a quarter of an inch. I "doubled
>that"
> for good measure, and extended the push rod by a half inch.
>
> The effect of this, when observed at the slave cylinder, was a throw of 3/4 of
> an inch.
>
> I adjusted the slave cylinder push rod to provide for 1/8th of an inch
> clearance, then test drove the car. I was amazed at the improvement in the
> shifting improvement! My clutch had obviously gotten "too tight", and I had
> just become used to it. For example, in downshifting to 2nd, I had to be very
> careful, to avoid "grinding". I had assumed that this was because of the
> syncho "going bad". Now, I can downshift very easily, at any time or under
>any
> conditions I've tried.
>
> The one bad effect of what I did, is that my clutch pedal now "sits" about 3/4
> inch above the brake pedal, and I have to get used to that. On the other
>hand,
> if I detach the spring, that difference about "goes away". I'll have to think
> about "anything bad" about doing that.
>
> Warning, these are simply my results and observations, YMMV ;-).
>
> Dave
> '68 1600
> Kailua-Kona
>
> Charlie wrote:
>
> > Hi David,
> > please send along any more info that you may have on the clutch cylinder.
> > thanks
> > Charlie Ellis
> > Littleton Mass.
|