Clutch adjustment?

[TomGaval]

With the car off, I can engage all gears(6 speed). With the engine running I can't select any. No grinding though. I have a hydraulic master and slave cylinder set up. Any Ideas, suggestions. Tom

[allen]

Tom,

 

Have you checked the fluid level and repeatedly pumped the pedal? Get someone else to look and see if there is any movement at the slave cylinder - check also for leaks at the slave and along the pipework.

 

I'm not a 6 speed box expert but problem is most likely to be with the hydraulics, possibly a leak, more likely the slave cylinder, possibly the master cylinder.

 

If Fluid level OK and slave cylinder is actuating the release bearing fulcrum lever (there is sure to be someone who knows the correct measurement of the required movement) then problem may be with the clutch or release bearing or in the box itself. Has it made any funny noises recently?

 

Regards

 

allen

[TomGaval]

Thanks Allen, Just finished the build and finally got the wiring sorted, so this was the first start up. No strange noises. I had to fabricate a clevis from the slave cylinder to the clutch arm. Apparently Caterham never anticpated a hydraulic clutch for the six speed dry sump clutch fork. (At least that's what their engineer Charles Hayhurst told me. It appears that I am getting movement at the clucth arm. Any one know how much movement is required? Tom

[RodW]

Had a similar problem with a five speed box on my recent build. Could select gears vey reluctantly with engine off but running it wasn't interested. Had SVA and post build check booked and imminent at John Noble Motorsport. It turned out to be a warped centre plate, supplied by Caterham with engine -ie it all had to come out again! Hope this is not the problem with yours.

Regards

RodW

[Peter Carmichael]

It could just be that the clutch has seized in storage and transportation - not uncommon.

 

With the engine off, engage first gear. With the clutch pedal depressed, get someone to push the car and see if it moves. If it does then you have some clutch drag - force it a few times on the synchros and it might clear up. If it doesn't move then try engaging 6th gear (engine off) and then depress and hold the clutch pedal. Turn the starter motor and see if this frees the clutch.

 

If this doesn't work, jack up the rear of the car engage gear, depress and hold clutch. Start engine, rev up to 6000rpm and then get a helper to drop the car off the jack - only kidding eek.gif

[Tony Martyr]

Tom,

My clutch yoke as it passes out of the housing hole has a total movement of 7/8 inch.

In taking this measurement I noticed that at full depression the yoke damn near touches the front of the housing hole.

 

[TomGaval]

Thanks guys, I just started it up. At idle, when I try to put in gear with the clutch in, the revs start to drop off, no grinding or other noise. If I let the clutch out I get just the slightest movement. Again, does not feel like the gear is fully engaged. Will try the previous suggestions when I get home tonite, unless this info leads to other good suggestions Peter. Tom

[TomGaval]

Ok Peter, followed your instructions, in 1st gear with engine off. tried to rock car. No go. Put it in 6th, turned starter over, car lurched forward. Started car, tried to put in gear even with clutch in, car tried to move forward. Turned car off put in 6th gear, clutch in, started car, car lurched forward. I know that's not right. Diagnosis? Solutions? Thanks in advance for the help. By the way clutch fork movement is substantial. Tom

[allen]

Peter may be correct that the clutch has seized - if the flywheel, driven plate & clutch cover plate have been assembled together for a long time this may be the problem.

 

Apart from disassembly and a bit of cleaning up, the only other solutions are a bit brutal and possibly risky.

 

There was a thread on this some months ago, but suggestions like jacking up the rear wheels (properly supported on axle stands)starting up, depressing the clutch pedal and repeatedly putting the brakes on. was one of them.

 

May be best to bite the bullet and disassemble?

 

Good luck

 

allen

[Peter Carmichael]

Is the slave starting its actuation with the bearing in contact with the clutch fingers? If you remove the slave actuator from the end of the arm, is there any free movement of the arm from its normal resting place until it makes contact with the clutch diaphragm spring and won't move any more? What is the movement from this point to full travel with the hydraulics reattached?

 

If there is no undue free movement and the arm is moving ~7/8 in then you definitely have a seized clutch. If you can do it, you should arrange to get the car moving and drive around stomping on the accelerator with the clutch fully down - eventually the clutch will free up.

 

So what you do is this. Start the engine. Get some helpers to push the car until it as at the speed where first gear will slot in without the clutch. Then go drive like a hooligan with the clutch down until it sorts itself out. You might like to do a clutchless change to second to make this more practical on the open road.

[Tony Martyr]

Thinking about this system which significantly has not yet run, so we

are not considerering a fault that has develped in a running system.

The clutch yoke is correctly moving in response to pedal movement.

There is no abnormal noise when operating the clutch or when the engine is

running so we can assume that the geometry of the yoke movement is such that

it is not touching the clutch housing and has its fulcrum end fixed in the

right place.

Peter's test 1 indicates that the clutch and 1st gear is engaged without the

engine running.

test 2 indicates that trying to start in 6th produces the normal result and

that the clutch and gear is engaged.

Test 4 indicates that even with the clutch mechanism supposed to be putting

the clutch into disengagement it is, in fact, still at least partially

engaged.

So surely the clutch is, as Peter suggested, seized in engagement after

long storage. Even though the pressure plate is lifting, the friction plate,

which is splined onto the gearbox input shaft, is stuck to the flywheel.

This would mean you can engage gears while stationary but not while the

engine is running because you efffectively have no disengagement of the

drive line.

If this is the case you have to put more torque through the clutch than the

cast iron corrosion can transmit. Peter's suggestion would probably work but

requires some nerve, a bit of unused road and maybe a rescue vehicle, but it would work. The 6000 rpm part is what Peter would do, mere mortals might consider 2000 in the first case.

 

[TomGaval]

You guys are GREAT! Since the car is still awaiting registration approval from the State, and it has not been run in yet except for the dyno, not only will I risk getting caught with an unregistered car, It will be for speeding, and since their are NO other Caterhams in the area, let alone a bright yellow one, I might stand out a little. So I'm going to leave work now and give it a go! Should be a blast. Tom

[ashaughnessy]

I've had a stuck clutch in the past (twice in fact) and resorted to rough stuff. I depressed the clutch pedal fully, put the car in top gear, pressed hard on the brake pedal, then tried to start the engine. For a slight seizure, the starter will free the clutch plate. For a worse seizure, it takes lots of tries (and lots of nerve). Try to start the engine, and it just sticks and whines. Let off and try again. Keep doing this on and off and on and off to a samba rhythym. Eventually it let go (it did for me, anyway). Has the advantage that you don't need to move from your driveway.

Anthony

PS. this was on a four speed xflow.

 

Edited by - ashaughnessy on 11 Oct 2001 10:00:33

[TomGaval]

Thanks, got home last nite and found they had ripped the street up for repaving, and had a 4 inch drop from the driveway to the street. I'll try this method first unless there are any severe downsides? Thanks again for the suggestions guys. Tom

[Andrew Russell]

Tom

I have had my clutch stick on a couple of occassions when the car has been laid-up over the winter months. Very similar symptoms to those described by you. I have always managed to free it off by simply putting car in gear, depressing the clutch pedal and then briefly using the starter motor to 'shock' the plate free.

 

Sounds brutal but isn't really and is without risk to life and limb.....

 

Good luck!

 

Andrew

[ashaughnessy]

Severe downsides? I don't know - I wouldn't like to try it every day. These days, I try and take steps over the winter to make sure it doesn't happen.

Anthony

[allen]

Tom, did it work - let us know how you got on please.

 

allen

[TomGaval]

It appears that the hydralic slave cylinder set up i cobbled together is not adjusted properly, leaking, etc. I am attempting to add spacers to take up the slack. Hopefully, this resolves the problem. Thanks all for the suggestions. Registration came in today, with this issue resolved, my first drive is the only item left on my build check list! I'll update tomorrow. Tom