thklam

How does the 'self adjusting hydraulic clutches' work???

B-Nez

The one in my Nissan has a valve in the clutch master cylinder to allow fluid to pass once the piston is all the way forward. Basically, as the clutch wears down, the pressure plate surface gets nominally closer to the disc lining and the flywheel, which also "moves" the engagement of the release bearing with the plate "fingers". Without the self-adjustment, your pedal engagement would also move. The master cylinder is able to take in or bleed off fluid as needed to keep the line pressure constant - thereby keeping your engagement zone constant.

I know, not a hugely technical response, but I'm a bit rusty on the details. Of course, someone correct me if I've gone astray...

wakeech

woooow, that sounds cool...
the only manual thing i've ever driven (and "learned" to drive manual on) was a 30 year old, propane powered, torqueless, dog box, 4000lb fork lift that had dodgy brakes and hydraulics...

anyways, the clutch engagement was like an inch from the top, so it was completely unnatural to me to only push the clutch a tiny bit of the way in to disengage the gear (and i only drove the thing like once per week)...
this self adjustment thing sounds great for a long-term use vehicle.

Wing

So..... how do you know when your clutch pedal is starting to wear, does it still slip?

Superfan

Never seen a clutch pedal slip but my foot has slipped off the clutch pedal. As for the disc, when it wears down the disc will slip. Trust me, you'll know when it's time to replace the clutch :D

Wing

Geez, I meant to type disc..... not sure where pedal came from , the pedal does slip..... when it rains

shahpor

Seeing that the majority of cars here in the UK are manual, this technology is pretty common over here.

B-Nez is correct in that a valve in the master cylinder controls the fluid going into the slave cylinder, which is usually on the gearbox housing.

My current car has this system in place and it makes for a much smoother clutch action.

Shahpor

B-Nez

What's really annoying about my 240 is that it also has a clutch dampener. What a freakin PITA!! The line goes from the master cylinder to a brass "splitter" block. Another fat rubber line comes out of the block, goes forward about a foot or so, then is folded back on itself a few inches, and ends in a bleed screw. A third line goes from the block to the master cylinder. This supposedly makes the clutch engagement much smoother, and reduces wear to the master cylinder. Don't know about that, but it a HUGE hassle to bleed the system. I contemplated bypassing the whole mess - I mean my RX-7 didn't have any of that, and the clutch worked super.

thklam

so
is that mean the clutch will be lighter with the help of hydraulic
or is mean you can change your gear smoother?

B-Nez

Generally speaking, the clutch CAN feel lighter with hydraulics, because a larger piston in the master cylinder will provide more leverage against the clutch release fork than with a cable. So, it depends on the size of the piston. It is much easier to maintain and service than a cable clutch, however (in my opinion, anyway).