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 Understanding clutches (425) 
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Joined: August 2nd, 2009, 11:58 am
Posts: 20
Location: Southampton, UK
Post Understanding clutches (425)
Evening all,

As mentioned in my recent thread, I am in the latter stages of renovating my AZ engine & gearbox. I've been having some issues with the clutch at a very basic level and I'm hoping someone on here can talk me through the basics and help me work out if I have the right clutch and am attempting to fit it correctly!
I had to replace my D*lly's clutch a few years ago when it completely failed on me and I had to abandon the car at a mate's place for a week. I think however, that my mind treated that experience much like childbirth and has blacked out everything about the details and just left the shock at the successful end result!
I apologise for any issues with terminology or blatant stupidity regarding clutch operation.
Image
So, the engine is the 425 and the gearbox has 10 splines and the car is supposedly from late 1955. 1st issue is whether it is designed for centrifugal clutch. Unless I've lost some bits ( :? ) I'm pretty sure there wasn't a centrifugal friction plate in there. Can this just be left out of a model where it was previously fitted? Is the flywheel design specific to the type of clutch?
I have what is claimed to be a reproduction clutch suitable for a 1955-1963 model (w/o centrifugal). It is a diaphragm type rather with cantilever springs rather than the original coil springs. However, when I hold it up to the flywheel the thrust plate will only go to 3.5mm from the surface on the flywheel. Is the following assembly right?
Image
I am also struggling to understand how the clutch disengages when the fork thrusts the bearing forwards. My best guess is that the bearing puts pressure on the thrust springs which allows the pressure plate to move axially very slightly relative to the mounting plate and therefore the friction plate also, even though there is force forwards from the fork.

I might well have the wrong clutch. I might well be misunderstanding what happens when the pedal is depressed. I hope you can understand my description above and can put me right.
Please view all photos in my Photobucket album: http://s1032.photobucket.com/user/Versaldean/library/AZ%20Clutch?sort=4&page=1

Thanks in advance for any help offered :D

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Image '86 Image AZ '55
Yamaha Diversion (XJ600s) 1992 & Puch Maxi S 1977 & VeloSolexes*many 1953-~1970


March 6th, 2015, 11:10 pm
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Firing on two.
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Joined: October 22nd, 2014, 10:59 pm
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Location: South-Limburg
Post Re: Understanding clutches (425)
Your gearbox is for a non-centrifugal version. The coal bearing is unsuitable for the modern diaphragma spring clutch. I would have a check if there is a special clutch roller bearing sold with this type of clutch spring


March 6th, 2015, 11:25 pm
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Joined: August 2nd, 2009, 11:58 am
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Location: Southampton, UK
Post Re: Understanding clutches (425)
Thanks for a quick response AZL57. Good to hear that I at least was correct about non-centrifugal :).
I'm not really sure what you mean by coal bearing vs roller in this context. Is this one which was supplied as a kit with the clutch a coal bearing?
Image
The old one seemed to simply be a ring, no bearing.
http://www.franzose.com/shop/citroen/citroen-2cv/2cvold/outside-of-the-engine/clutch/release-ring-clutch-for-all-citroen-2cv-ami-dyane/

Do you have a picture of what I should be looking for?

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Image '86 Image AZ '55
Yamaha Diversion (XJ600s) 1992 & Puch Maxi S 1977 & VeloSolexes*many 1953-~1970


March 6th, 2015, 11:33 pm
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Firing on two.
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Joined: February 11th, 2009, 12:32 am
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Location: Chichester, West Sussex
Post Re: Understanding clutches (425)
I understand how to put one together, but beyond that I'm happy to accept that their function and operation is solely down to magic.


March 6th, 2015, 11:45 pm
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Joined: August 2nd, 2009, 11:58 am
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Post Re: Understanding clutches (425)
One of the main questions I have is whether the plate on the clutch which bolts to the flywheel should be flush with the lip on the flywheel to which it bolts?
If it should be (I think it should) then I guess I must have the wrong clutch because the thickness of the friction plate and distance between clutch mounting plate and contact surface means there is 3.5mm between these points.

Can you shed any light Sam?

Perhaps I should be asking if the flywheel looks like the right one for the gearbox?

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Image '86 Image AZ '55
Yamaha Diversion (XJ600s) 1992 & Puch Maxi S 1977 & VeloSolexes*many 1953-~1970


March 6th, 2015, 11:54 pm
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Joined: August 2nd, 2009, 11:58 am
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Post Re: Understanding clutches (425)
By 'right' I mean 'original'. The gearbox, clutch and engine appeared to have been rusting together and presumably worked at one stage.

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Image '86 Image AZ '55
Yamaha Diversion (XJ600s) 1992 & Puch Maxi S 1977 & VeloSolexes*many 1953-~1970


March 7th, 2015, 12:01 am
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Firing on two.
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Joined: February 11th, 2009, 12:32 am
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Location: Chichester, West Sussex
Post Re: Understanding clutches (425)
I would recommend ditching the graphite ring in favour of a 'normal' bearing - club cassis do a conversion kit which I used on mine.

I think what you're asking is the same thing that worried me, to do with the 'height' of the bit with splines in when placed on a table? I'll post some pics...
I was also worried that the bit that bolts to the flywheel was too 'sticky out', you just have to bolt it RIGHT up so its level with the lip, and not 'riding' on the lip.


March 7th, 2015, 12:32 am
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Firing on two.
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Joined: February 11th, 2009, 12:32 am
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Location: Chichester, West Sussex
Post Re: Understanding clutches (425)
Apparently different friction plates - but not an issue, although this might have been to account for having the short input shaft.
Image

Things bolted down, but not enough (top) and properly bolted down (bottom):
Image
Image


March 7th, 2015, 12:37 am
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Post Re: Understanding clutches (425)
Ah, that could be helpful. Worthing trying a bolt-it-up test. When I hold it up it looks a lot like your middle pic. If something compresses when you do the 6 bolts up to give pic 3 that would put my mind to rest.
I don't think I was thinking about what you describe with pic 1, although I had noticed it. When I held up all 3 parts to the flywheel it looked a long way for the spline to have to reach, I guess this is why the splined section of the friction plate is longer.
I was worried about the thickness of the friction bit itself, but your pics give me hope that something compresses when you tighten the bolts. I guess I'll give it a go and see. Engine isn't quite going yet so no rush for a speed test.
The contact between thrust springs and bearing doesn't look great to me but that might be what AZL57 was saying and I'll look for the conversion Sam mentioned, might be the same thing.

Thanks for the help. I'll try out some of this over the weekend. Fingers crossed!

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Image '86 Image AZ '55
Yamaha Diversion (XJ600s) 1992 & Puch Maxi S 1977 & VeloSolexes*many 1953-~1970


March 7th, 2015, 12:59 am
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Agony Aunt - You have a car problem? Speak to Ken

Joined: March 6th, 2009, 1:40 am
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Post Re: Understanding clutches (425)
A better photograph of the release bearing would be helpful, since it's difficult to tell from the one you've already posted whether it's a graphite bearing or a ball bearing type.

Given that this is a new clutch kit, one would hope that it's the latter, since a graphite type would survive about 5 seconds if introduced to those diaphragm fingers... :lol:

Regarding the fit of the cover/pressure plate to the flywheel, I seem to recall that Peter (2CViking) has previously commented on poor quality control with these kits, either here on on FB, mentioning that the OD of the cover plate was too large to fit into the housing on the flywheel.

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March 7th, 2015, 3:08 am
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