550 Clutch Pedal Adjustment
This page is a chapter in the book 550 - 575 Book.
On delivery of my 550, I noticed the new OS Giken clutch was engaging in the top half of the clutch pedal travel. I didn't think this was at all odd, because being a triple disc setup, it's normal for it to have a much shorter travel between disengaged and engaged.
But, my preference for any clutch's engagement point is much lower. In fact I prefer to feel the clutch start to bite in the first inch of pedal travel from the bottom, and I like to have plenty of free play on top, to ensure the release bearing is fully off the clutch "fingers".
After driving the car a bit, I thought I noticed the clutch was engaging even higher, which I just attributed to bedding in, however I couldn't feel any free play on top, which concerned me a bit, as I thought it might not be fully engaged, and a not-fully-engaged clutch will soon turn to toast. Too, I was a bit worried about all that pedal travel at the bottom, and possibly overextending the release bearing's piston and blowing seals.
So I decided to adjust the clutch pedal.....
Slipped under the dash, and sure enough, I couldn't measure any real free play with my hand working the clutch pedal, so after studying it a bit, I decided to screw the actuator rod (#1 in the diagram below) further into the clevis, effectively making the rod shorter, which, I thought, would probably pull the slave piston away from the fingers.
Once I had it readjusted, I tested it, and sure enough, the clutch started to bite a lot lower in the pedal, but then I noticed I didn't have nearly as much pedal travel either, and there still wasn't any free play on top. What's up with this?
So as a last resort, I decided to have a look at the 550 service manual and was enlightened to find that this clutch has a "no free play" hydraulic release bearing setup. According to the service manual ".....clutch thrust bearing is constant contact type." In layman's terms, I'm assuming this means the bearing is riding on the fingers all the time?
As a confirmation of this, looking at the clutch pedal adjustment table in the service manual, it plainly shows "Zero" for the free play. Wow.....
So although I "thought" I changed the engagement point on the pedal, apparently all I did was adjust the pedal position closer to the floor? I didn't change the engage or disengage points at all?
As this is the first time I've fooled with a "no free play" release bearing, I could sure use some affirmation from a guru that I haven't screwed something up here......
Would adjusting the 2 pedal stop screws (4 & 6) bring back the total pedal travel?
I would prefer to keep the engagement point closer to the floor, as it's more comfortable for my leg muscles, but not if it means I'm damaging this clutch.
As it is now, the car shifts fine, it's not difficult to get it into or out of any gear, so I assume the clutch is fully disengaging OK. When the pedal comes off the floor, the clutch starts to bite after about 1.5" to 2" of pedal travel, then by 3" of pedal travel, it's fully engaged. Still no free play on top, which is unnerving for someone like me.....
Here's the text from the service manual and the diagram of the pedal:
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