How much 'throw' does a clutch release bearing need?

[novarally]

As you may or may not know, I'm in the process of fitting the hydraulic clutch system from a Daewoo Lanos onto my Nova hillclimb car.

The Lanos uses a Vauxhall-derived engine and gearbox, although it's clear that there are some fundamental differences - more details will appear on my 'Project' thread soon.

Anyway, I need some technical expertise please.

Today I have removed the engine and gearbox from the Lanos I purchased, and have been playing about with fitting the clutch slave cylinder and actuation arm from it onto my F13 gearbox.

The actuator arm fits fine, but gives very limited 'throw' as it stops up against the gearbox casing. Hopefully this will be clear in the photos below.

This photo shows the Daewoo arm installed on the F13 gearbox;

http://i285.photobucket.com/albums/ll66/hillclimbescort/016_zpsc5e2242c.jpg (http://s285.photobucket.com/user/hillclimbescort/media/016_zpsc5e2242c.jpg.html)

And this is the position of the arm with the clutch released, and the corresponding position of the bearing;

http://i285.photobucket.com/albums/ll66/hillclimbescort/017_zpsf69b523a.jpg (http://s285.photobucket.com/user/hillclimbescort/media/017_zpsf69b523a.jpg.html)

http://i285.photobucket.com/albums/ll66/hillclimbescort/019_zps8d1c4281.jpg (http://s285.photobucket.com/user/hillclimbescort/media/019_zps8d1c4281.jpg.html)

And this is the clutch engaged, again showing the lever and the bearing;

http://i285.photobucket.com/albums/ll66/hillclimbescort/018_zps02a977a6.jpg (http://s285.photobucket.com/user/hillclimbescort/media/018_zps02a977a6.jpg.html)

http://i285.photobucket.com/albums/ll66/hillclimbescort/020_zps34a8d915.jpg (http://s285.photobucket.com/user/hillclimbescort/media/020_zps34a8d915.jpg.html)

It's not moving very far before it butts up against the casing, so the release bearing won't 'push out' any further.

Contrast this with how far it would move with the old cable-type clutch arm in place;

http://i285.photobucket.com/albums/ll66/hillclimbescort/021_zps0ea2841f.jpg (http://s285.photobucket.com/user/hillclimbescort/media/021_zps0ea2841f.jpg.html)

What do we think? Is there sufficient movement with the Daewoo arm in there? How much does it need?

With the arm installed in the original Daewoo gearbox there was a little bit more 'throw' but not a lot (I couldn't test the clutch in the car as the release bearing was seized solid;

http://i285.photobucket.com/albums/ll66/hillclimbescort/003_zps3e83e15d.jpg (http://s285.photobucket.com/user/hillclimbescort/media/003_zps3e83e15d.jpg.html)

Rather worn as you can see!

[jimbob-mcgrew]

whats hitting the box, that L-shaped bit of the arm ?

[novarally]

whats hitting the box, that L-shaped bit of the arm ?

Yes, that bit.

I appreciate I could cut it back to let it clear, but I don't see it should be necessary.

[meritlover]

its hard to tell as you have so much going on here. but the bottom line is - not much.

1. i dont believe the OE bearing would come out as far as your second last pic as its nearly right off the sleeve.
2. the lug on arm which i presume is hitting the casing could be ground off, but without knowing how much stroke is remaining on the slave cylinder its too hard to know. There may have to be a stop of some sorts to stop the slave piston popping straight out the cylinder.
3. changing the release bearing will not solve the stroke issue, unless the shape of the forch is such that it points further forward, allowing the bearing to touch the pressure plate earlier in the slave cylinders travel.
4. the leaverage in both arms is clearly different so its hard to tell from the pictures what is actually going on.

[novarally]

its hard to tell as you have so much going on here. but the bottom line is - not much.

1. i dont believe the OE bearing would come out as far as your second last pic as its nearly right off the sleeve.
2. the lug on arm which i presume is hitting the casing could be ground off, but without knowing how much stroke is remaining on the slave cylinder its too hard to know. There may have to be a stop of some sorts to stop the slave piston popping straight out the cylinder.
3. changing the release bearing will not solve the stroke issue, unless the shape of the forch is such that it points further forward, allowing the bearing to touch the pressure plate earlier in the slave cylinders travel.
4. the leaverage in both arms is clearly different so its hard to tell from the pictures what is actually going on.

Thanks for your thoughts, most useful.

The actual clutch release bearing is different between the Lanos and the Nova (the Lanos is larger diameter as it has the bigger gear input shaft), but I must confess I haven't compared the forks. I must do that! Thank-you.

I appreciate it's hard to see exactly what's going on, but I am simply comparing the two lever arms at this stage, as I want to be able to bolt the engine and gearbox back in place.

Everything else can be played about with once it's in the car.

[jimbob-mcgrew]

im guessing that L-shaped piece on the arm is a safety feature, to stop the bearing going too far, and popping off the guide.

is that arm contact spot of the box casing the same as the daewoo ?

[meritlover]

as a rough guide,
take the outermost point of the clutch plate drive boss as it sits on the engine and measure the offset between that and the pressure plate where the release bearing would make contact

Measure the point on the input shaft innermost to the gearbox (where the copper grease is smudged to) and assume that this is the resting place of the plate with the clutch engaged and use the above measurement to roughly guess where the release bearing (and therefor - arm) will sit at idle.

you might find the arm sits further forward than you think and give you enough travel.

are there no wear-marks on the concentric sleeve which might give away the normal throw of the release bearing?

with the length of the slave cylinder and the shortness of the lever, it looks like there would be ample travel although without knowing of these 'fundamental differences' its impossible to tell.

[novarally]

im guessing that L-shaped piece on the arm is a safety feature, to stop the bearing going too far, and popping off the guide.

is that arm contact spot of the box casing the same as the daewoo ?

It looks to be the same, as far as I can tell by eye. Obviously it's very difficult to measure it as it's a curved surface.