14 replies to this topic

[mbolt998]

You're supposed to set the clearance on the clutch release lever to 0.5mm. But when I do that it's impossible to disengage the clutch fully (and therefore to engage gears). It's been like that for as long as I can remember. I've always used the screw to set a "negative clearance" so that the clutch does disengage, and it's all fine-- the clutch disengages cleanly, the biting point is low, and it doesn't slip.

 

Recently I fitted a new slave cylinder (the old one had got kind of sticky after being left for 25 years) so wondered if this issue had resolved itself. But it's exactly the same: set the correct clearance (or any clearance at all) and you can't disengage the clutch.

 

I checked the amount of slop on the pedal and it's not much: less than 1cm before it starts feeling like it's doing something.

 

Does anyone know what's going on here?

[nicklouse]

Sounds like wear in the clevis pins/arm/ball end.

[imack]

As Nick says, plus I'd add wear in the pedal and the WOK where the clevis pins fit and wear in the plunger that the release arm ball fits into.
You don't want to run without any clearance between the release arm and adjustment bolt as the release bearing will be constantly spinning at engine speed and wear itself and the thrust plate out. You'll also wear the crankshaft thrust washers out as they'll be constantly loaded.

[Designer]

Hi,

 

Am I being an idiot or have I missed something here. What clearance are you referring too, is it the adjusting nut outside the clutch housing at the end of the bell? The only clearance I know of is for this adjustment and it says it should be 6mm or 1/4 inch. Is it different for the different types of clutch?

[Chris1275gt]

There are different clearances for pre and verto clutches on big nut your referring to the adjustment this thread is reverting to is the bolt that comes out of the wok and rests on the clutch arm.

Edited by Chris1275gt, 09 May 2023 - 11:28 AM.

[Designer]

Hi Chris,

 

Thank you for clarifying that I thought that perhaps I had missed some adjustment when putting everything back together on my daughter's Mini. The only setting I need to do was the one I mentioned above.

 

Regards Paddy

[nicklouse]

Hi Chris,

 

Thank you for clarifying that I thought that perhaps I had missed some adjustment when putting everything back together on my daughter's Mini. The only setting I need to do was the one I mentioned above.

 

Regards Paddy

Well there is the other one. The big nuts. Back them off press pedal/lever arm. Wind in nuts till touching. Then release arm and wind in the nuts one flat and lock together.

[mbolt998]

Hi,

 

Am I being an idiot or have I missed something here. What clearance are you referring too, is it the adjusting nut outside the clutch housing at the end of the bell? The only clearance I know of is for this adjustment and it says it should be 6mm or 1/4 inch. Is it different for the different types of clutch?

When you look down into the engine bay there's a big lever going into the bell and then up to the slave cylinder. A bit more than half way up that lever there's a 7/16"-head bolt with a locknut screwed into the housing, and the owner's handbook (and the Haynes) says there's supposed to be 0.5mm between the top of that bolt and the lever. As the clutch wears I think that clearance is supposed to reduce which is why you keep adjusting it. But I don't really understand it-- the head of the bolt isn't touching anything if the clearance is set correctly so what's the point of it?

[nicklouse]

 

Hi,

 

Am I being an idiot or have I missed something here. What clearance are you referring too, is it the adjusting nut outside the clutch housing at the end of the bell? The only clearance I know of is for this adjustment and it says it should be 6mm or 1/4 inch. Is it different for the different types of clutch?

When you look down into the engine bay there's a big lever going into the bell and then up to the slave cylinder. A bit more than half way up that lever there's a 7/16"-head bolt with a locknut screwed into the housing, and the owner's handbook (and the Haynes) says there's supposed to be 0.5mm between the top of that bolt and the lever. As the clutch wears I think that clearance is supposed to reduce which is why you keep adjusting it. But I don't really understand it-- the head of the bolt isn't touching anything if the clearance is set correctly so what's the point of it?

 

It stops the arm pushing the slave to far in. And it does touch. The external spring does that.if you did not have the stop you would have to push the piston through lots of dead travel until it reached the operating area.

[KTS]

The 0.5mm clearance should be set with clutch lever pushed forward to the point the release bearing is in contact with the diaphragm.

This ensures that when you take your foot off the clutch pedal the release bearing is not in contact with the clutch

[GraemeC]

If the arm is not touching the bolt once everything is reassembled and the return spring is in place then it has not been adjusted correctly.
This could easily be the cause of the drag as the slave cylinder will have returned too far and the pedal strike not be sufficient to get enough movement at the arm

[MatthewsDad]

Just had same problem on my new mini and clevis pin and ball arm were both worn. I'd imagine they introduce a mm or two of slack in the mechanism.

[mbolt998]

The 0.5mm clearance should be set with clutch lever pushed forward to the point the release bearing is in contact with the diaphragm.

This ensures that when you take your foot off the clutch pedal the release bearing is not in contact with the clutch

Aha the whole thing is starting to make sense now. So under normal circumstances, if you just go and look under the bonnet of a car with nobody pressing the clutch pedal, there should not be a gap? In other words, it's a stop to prevent the lever coming back too far (and causing the clutch to drag). This does make much more sense because it explains why the bolt exists in the first place.

[Lplus]

 

The 0.5mm clearance should be set with clutch lever pushed forward to the point the release bearing is in contact with the diaphragm.

This ensures that when you take your foot off the clutch pedal the release bearing is not in contact with the clutch

Aha the whole thing is starting to make sense now. So under normal circumstances, if you just go and look under the bonnet of a car with nobody pressing the clutch pedal, there should not be a gap? In other words, it's a stop to prevent the lever coming back too far (and causing the clutch to drag). This does make much more sense because it explains why the bolt exists in the first place.

 

Yes, the return spring on the end of the lever arm holds the lever against the stop bolt to ensure some clearance between the thrust bearing and the diaphragm.

[mbolt998]

Thanks for your help everyone. Mystery solved. It turns out I can't read, because it said this in the manual all along (see the bit underlined in red). If I pull that lever out by hand from under the bonnet my clearance actually is pretty much exactly 0.5mm. So by setting that screw to the minimum that the clutch disengages cleanly without dragging I had arrived in the right place. This actually implies my clevis pins etc. are all in pretty good nick.

 

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