clutch

[dopey454]

Hi Guys hoping someone can guide me. I live a long way from the dealer.
My car is AMT with a clutch actuator which kept throwing up OBD faults so I replaced it with a new actuator. . Car drove ok on test drive of 800 yards or so but then the clutch started slipping a bit so for the last 200 yards I drove very slow but when I went to stop it it continued wanting to drive as if the clutch was not releasing.
Took the actuator off and I cannot move the clutch fork by hand pressure using a socket extension to press against it. Car is a 1.5 diesel so not big. Should I be able to move it ? I am reasonably strong. It feels seized to me. Would the clutch seize in the drive position ? If so would I be abler to move the clutch fork somehow ?

[HustleRussell]

AMT?

Pressure plate springs are pretty strong, doubt you could get them to deflect fully with your whole body weight.

[dopey454]

Thanks for the reply - Amt = automated manual transmission. I will check see if a relay or fuse stopped the clutch actuator disengaging the clutch

[The Wookie]

Is the actuator external to the bellhousing and pushing against a fork, or is it hydraulically actuating a throw out bearing?

Either way it sounds like something may be sticking, or may have been stuck and then failed with the force of the new actuator. It may even be what killed the old actuator

Alternatively perhaps there’s some weird bleeding issue with either the actuator itself or the hydraulics that it’s actuating, depending on how it works

[dopey454]

Hi Wookey -The clutch actuator is external to the Bell housing. An electric motor turns a worm drive which triggers a rapid movement of a piston ( the rapid movement is caused by the release of a strong spring which presses the piston against the clutch fork). I have bench tested the actuator after removing it from the car and it works ok.
I suspect the ECU clutch bite position is out of sync with the new actuator so the ECU has somehow stopped electrical contact to the actuator . The reason I say that is when I have been underneath the car and when my wife flicks the gearlever to drive no movement takes place in the actuator. I now suspect that is why the car continued in drive when I tried stopping (footbrake at stoppng speed should release the clutch) as the car had reverted to a limp mode drive.
My basic question is what force is normally needed to move the clutch fork ? With two hands pushing a socket extension as hard as I can I cannot move it. I read in a technical paper that the force needed for my size of clutch is between 200 and 300 Newtons which I translate to 20 to 30 Kilo pressure(if I am right) . I would have expected to be able to push 30 kilo so I am baffled. What could cause it to bind ?

Edited by dopey454 on Tuesday 24th October 11:14

Edited by dopey454 on Tuesday 24th October 11:37

Edited by dopey454 on Tuesday 24th October 12:36

[Martin350]

What make and model car is it?

A typical car clutch needs around 500 - 750 kg force to push the diaphragm spring in, so even with some leverage from the clutch fork I don't think you'll be able to push that in by hand.

[CrutyRammers]

As above, you'll not press in a clutch spring by hand. Better to watch underneath while someone else engages/disengages it.
You say it's slipping, but then are worried that it's seized? Those two things don't really go together.

[dopey454]

Thanks guys - it is becoming clearer in my mind now. The Ecu must have recognised the clutch slip then switched off the clutch actuator leaving the car in drive as if the clutch was seized on. You are saying I should not worry about not being able to move the clutch fork manually ? I was hesitant to refit the actuator and clear the OBD fault in case the pressure damaged the new actuator. As I am cautious maybe I will rig up a lever system to move the fork and if it moves carry on refitting the actuator. Car is Smart Forfour CDI I read somewhere that they can relearn the clutch bite position after disconnecting the battery for 30 mins then starting the car so it goes into learn mode

[The Wookie]

Surprising that it would fail into the clutch being engaged, I'd have thought it safer to attempt to wallop it open as far as possible and select neutral if it detected a fault

As said, you're unlikely to be able to disengage the clutch by hand but it doesn't mean that it isn't jammed

[GreenV8S]

dopey454 said:

As I am cautious maybe I will rig up a lever system to move the fork and if it moves carry on refitting the actuator.

That's going to involve very high forces and the potential to injure yourself or damage something. Refitting the mechanism designed to operate it seems like a far more cautious approach to me.

[CrutyRammers]

GreenV8S said:

That's going to involve very high forces and the potential to injure yourself or damage something. Refitting the mechanism designed to operate it seems like a far more cautious approach to me.

I'd agree. You're as like to move the whole car or strain something. We're talking about half a ton of force here.

[dopey454]

Thanks guys I have taken your advice.
Had another go today. Car up on axles stands. Had bench tested the new actuator and it works ok. Fitted it with 2 vernier markings . Cleared OBD fault code p0702 and then disconnected the battery for 30 mins or so. Apparently so I read the car goes into clutch bite learn mode after reconnecting battery and restarting. Started the car all ok. A (means drive)in speedo with wheels turning on axle stand. Kept alternating from A to N to see if the car would learn. Feeling chuffed at this point then bummer pressed brake pedal car kept trying to drive then drive stopped car did not stall . Left it in the state of A in speedo but no drive to the wheels. Will have to trailer it to MBStar garage 55 miles away.

[The Wookie]

I wouldn’t have done that on axle stands unless the procedure says to, it could easily be confusing the control system. I’d disconnect the battery and have a go again with it on the ground

[dopey454]

The Wookie said:

I wouldn’t have done that on axle stands unless the procedure says to, it could easily be confusing the control system. I’d disconnect the battery and have a go again with it on the ground

Had a go with it on the ground same result as on the axle stands. Got A or R in speedo tried reversing out of the garage then a Kangaroo lurch as if the clutch released too rapidly then lost drive. Going to have to trailer it to a garage 55 miles away with Smart Car software to teach it the clutch bite position.