It became difficult to go into the first gear when the car is stationary and engine is on (I have to double- or triple-clutch at times). It is not constant, but quite repeatable.
When that happens I can hear some clicking behind me (in the diff?).

I read that it could be due to the clutch master/slave cylinder fluid issues (clutch not disengaging completely) are there any suggestions?
The gearbox always seemed to be stiff to me (never driven other S2Ks), but now the first requires a lot of force to go into.

 

Is the clutch fully disengaging?

Maybe air got into the system?

Bleed it first.
See if that works.

Also, what kind of clutch is in it?

 

Sometimes the slightest movement of a car can affect gear selection. Obviously reverse and first gear. Release the brakes and see if that helps.

 

Maybe, try changing the fluid may helps.

 

This is classic symptoms of clutch not fully disengaging.

The primary reasons for that are:

Air in fluid. Do a proper gravity bleed. Rule #1 for bleeding, never let primary cylinder reservoir run dry.

Clutch out of adjustment. Adjust clutch rod for zero play (sufficient play built into primary cylinder). See excellent diyguy youtube video.

Crappy ebay or exedy so called oem disk is failing. These disks all fail the same way, dropping a spring. First symptom is often clutch starts getting more difficult to disengage. Eventually spring fully drops, jamming clutch and making car all but undrivable. If clutch isn't a Honda part, a clutch replacement may be in your future.

Dirty or rusted splines, or a worn clutch release guide. Either of these would require dropping trans, at which point you'd be foolish not to just do a full clutch job, as the labor, even if its diy, is so significant.

Sometimes you can alleviate much of such clutch disengagement issues by doing a less common clutch adjustment. The pedal height os adjustable. Adjusting so its higher off the floor than stock will provide more total pedal throw, which will produce more clutch fork travel, which may be just enough to allow clutch to fully disengage.

That should be a last resort though. Done only to stave off doing a clutch job until funds and downtime align with reality.

But it'd be worth measuring clutch pedal height to make sure it hasn't been set too low, which would cause your symptoms. The service manual details how to measure pedal height and what the spec is, as well as how to adjust it.

Adjusting it is super easy, if you can contort yourself under the dash and reach up into the abyss to get to it. You just use an open end wench to loosen a locknut, then turn by hand the sensor that also acts as the upper pedal stop. You also need to unplug sensor so wires don't twist up whioe you loosen sensor.

 

Hope its not a loose flywheel bolt. I had same symptoms and there were 3 loose. Red lock tyte now theyll never come off/ become loose unless i impact them

 

They aren't thread locked from the factory. They just need to be properly torqued to 92LB-FT.

It would be very strange for one to come loose if they were properly torqued. THREE of yours came loose....

Were yours properly torqued, or just impacted on?

 

My guess: either not cross-torqued properly or stretched bolts or both.

 

I would go with not cross torqued properly. Lesson learned

 

About your avatar. A friend had a red Komfort, back in the 1990s. He brought it back from Germany. Two things... FAST and low to the ground. Like being in a go-kart. That engine revved like an S2000 on steroids.

Sold it after a year.