28 replies to this topic

[whawes]

I've replaced my clutch plate, diaphragm housing and release bearing and am having problems.

At first I put everything together and had a functional clutch (pushing the car in gear with the clutch pedal depressed did not move the engine). Something evidently wasn't right though, because with the clutch pedal up the plunger in the flywheel housing was trying to turn with the engine, which was consequently impossible to turn over more than three quarters of a turn.

I took everything apart and re-examined all the parts. I discovered that the new thrust plate in the end of the diaphragm housing is different to the old one. Here is the new diaphragm housing as supplied:



And here are the two thrust plates. The one on the left came off the old diaphragm housing, the one on the right is the new one:



I know, I should have noticed before... doh. The old thrust plate has a dimple to accommodate the pin in the centre of the clutch release bearing, pictured below:



I put it all back together with the old thrust plate. Now the engine turns independently of the clutch plunger, but the clutch doesn't engage at all. The clutch arm moves, but the engine still turns with the clutch pedal depressed. I've tried adjusting the throw out stop, which makes no difference. The clutch pedal is noticeably light, which I imagine is due to it moving only the clutch arm and not rest of the clutch assembly. The clutch arm now comes to rest approx 4mm from the clutch return stop with the clutch pedal up, whereas before it sat on the return stop.

Looking at both thrust plates side by side, it's evident that the new one is raised about 4mm in the centre. When fitted, this raised part was pushing against the clutch release bearing with sufficient pressure to operate the clutch. With the old thrust plate there is an extra 4mm of space between bearing and thrust plate, so only the pin in the centre of the bearing can touch the thrust plate. It's not to be doing so with sufficient pressure though.

What's the reason for the clutch not engaging? As far as I can see, either

1) the pin in the centre of the release bearing is worn (although wearing by several mm seems unlikely)
2) I need some kind of spacer behind the old thrust plate (again, doesn't make a lot of sense as the clutch worked fine before with an identical diaphragm housing)
3) I've got major brain fade and something needs adjustment (probable)

Any ideas?

Edited by whawes, 03 March 2007 - 01:45 PM.

[whawes]

After chatting with a few parts suppliers, it appears there are two types of clutch release plunger for the pre-verto clutch. This is the one I have:

http://www.minispare....aspx?pid=32626

This appears to be an old design only fitted to very early A+ engines. My engine falls into this category so that would make sense.

The newer type plunger looks like this:

http://www.minispare....aspx?pid=35354

The difference between the two appears to be that with the old one, the inner part of the release bearing spins with the clutch, whereas with the new one, the outer part does. Hence the little collar and pin in the centre of my old release bearing and the different thrust plate.

I'm going to order the newer plunger/bearing and see how I get on. Fingers crossed

[Guess-Works.com]

I'm glad you posted that picture up, as I have a bearing supplied in a clutch kit with the same inner.... always wondered how it connected, but if I get one like that I just drift the inner part out and put it onto what I know as the std plunger ( the second in you two shown items )

[whawes]

I'm glad you posted that picture up, as I have a bearing supplied in a clutch kit with the same inner.... always wondered how it connected, but if I get one like that I just drift the inner part out and put it onto what I know as the std plunger ( the second in you two shown items )

I always try to post up answers to my own questions where possible, so glad it's been of use!

Yes, the collar and pin come out easily. The pin is free floating and can be removed by hand, the collar just drifts out as you state. As far as I'm aware the bearing is the same for both cases. My situation is pretty much the reverse of yours, in that my old bearing had the collar and pin fitted, whereas the clutch kit I bought contained just a bearing like this:

http://www.minispare....aspx?pid=34305

And a lockwasher like this (says verto on the description but I am told it fits both non-verto and verto plungers):

http://www.minispare....aspx?pid=38018

If you have the brass coloured plunger in my earlier post, then you don't need the lockwasher as the bearing just taps into place. There's no danger of the plunger being pulled out of the bearing in operation because all the clutch pressure goes inwards. The lockwasher is only used with a different plunger:

http://www.minispare....aspx?pid=32985

Apparently this setup allows the bearing to float on the plunger, which is supposed to allow everything to align better and improve clutch operation. I might try this if I get any problems with the non-floating setup.

With either of the newer plungers, the outer part of the bearing spins with the clutch. With the old plunger I had, this remains static - it's the pin and inner part of the bearing that spins instead.

I was also confused initially about how the newer plunger is prevented from falling outwards out of the flywheel housing. Turns out the answer is that the lug on the end of the clutch arm does a pretty good job!

Edited by whawes, 05 March 2007 - 12:01 PM.

[The Matt]

I was in a similar scenario, using an Allegro (I think) A+ engine and box. It had the earlier type plunger, but when I went to fit my newer cutch and flywheel assembly I changed to the later type plunger. I still have the old one somewhere I think. But I have noticed that the new thrust bearing is slack on the new plunger, which is concerning!I'm not talking about a little play here, I'm talking about it being like 2mm too big for the shaft. Will have to investigate tonight whilst I think about it. I might even go back to the original setup for the box

[Guess-Works.com]

MMM, make sure you plunger is not a verto type.... which has a grove for the O ring in it...

So there are actually three types of plunger...

The original A series, long shaft no grove

The Verto, long shaft with grove for O ring

and now...

An A+ variant for a diaphram clutch which has a massive cup on the end to hold the bearing by the outer race ( and reading between the lines, never fitted to a Mini, only to a metro... infact just read Metro manual... this type is fitted to Metros which dont have a return stop on the clutch arm, commonly described as the adjustment screw )

Edited by GuessWorks, 05 March 2007 - 12:14 PM.

[The Matt]

MMM, make sure you plunger is not a verto type.... which has a grove for the O ring in it...

So there are actually three types of plunger...

The original A series, long shaft no grove

The Verto, long shaft with grove for O ring

and now...

An A+ variant for a diaphram clutch which has a massive cup on the end to hold the bearing by the outer race ( and reading between the lines, never fitted to a Mini, only to a metro )

I have this type, which is listed as a pre-verto, to allow float, but it seems like alot of float! Sorry, this is thread hi-jacking!

[whawes]

So there are actually three types of plunger...

The original A series, long shaft no grove

The Verto, long shaft with grove for O ring

and now...

An A+ variant for a diaphram clutch which has a massive cup on the end to hold the bearing by the outer race ( and reading between the lines, never fitted to a Mini, only to a metro )

Yes, I'd go along with that. I don't have an engine number, but I'm reasonably sure it's an early A+ lump from a Metro.

[whawes]

Oh, and as MMM says, the two types of "standard" plunger (with and without lockwasher) both seem to be for pre-verto setups.

Edited by whawes, 05 March 2007 - 12:23 PM.

[The Matt]

Next question has to be about release bearings then??? Are there two pre-verto sizes, with a different inner bore?

[Guess-Works.com]

Again reading between the lines ( on the minispares site ) yes it's loose on the plunger...

[whawes]

More problems!

The clutch is now operational to the point that the car can be driven, and works without any judder or odd noises, but slips with anything more than very gentle operation of the throttle.

Everything has been assembled in accordance with the Haynes manual - clutch disc has hub facing inwards, primary gear splines were greased lightly, timing marks on all parts align, etc.

There is no grease/oil etc on the friction linings or pressure plate.

Throw out stop has been adjusted as per Haynes manual - depress clutch pedal fully, wind nut in until it touches clutch cover, release pedal, wind in one further flat and tighten locknut.

Return stop has also been adjusted as per Haynes - 0.50mm from contacting clutch arm.

After reassembly I noticed that the clutch arm, which had previously been resting on the return stop, was approx 10mm away from the return stop with the clutch pedal up. Maybe this is normal but it does seem quite a big difference, particularly as the old clutch disc was only worn about 1-2mm. I'm struggling to explain what would cause the 10mm gap, short of the clutch plate being in the wrong way round, or perhaps the diaphragm bolts not having been tightened enough. I can't really see that the clutch would work at all under either of those circumstances though.

I'm stumped. Any ideas? Could it be something else like the the clutch plate sticking on the primary gear splines? Or am I just missing something obvious?

[whawes]

Anyone? I've found one other thread that seems to be an identical problem:

http://www.theminifo...;hl=clutch slip

Tried IM'ing the OP to see what the solution was but no answer yet

[whawes]

Today's update. I unbolted the slave cylinder and removed the pushrod. The release arm then sat noticeably closer to the return stop, as though the pushrod had been holding it out for some reason. Sliding the slave cylinder back into place along the pushrod (i.e. to the left), significant resistance is encountered with the bolt holes on the cylinder approx 5mm-10mm to the right of those on the flywheel housing. Presumably this is the point at which the clutch would start to disengage.

With the pushrod disconnected, I got the front of the car up on axle stands, started it and put it into second gear. Both wheels were spinning and *seemed* to speed up relative to the engine, although it was difficult to tell for sure.

I stopped the engine, put the front of the car back down on the ground and started it up again in neutral. Tried to select all the gears and couldn't (take this to be a good sign, i.e. that the clutch is fully engaged).

Finally I removed the pushrod from the release arm and examined it. It consists of a rod with approx 20mm of thread on one end, which has a ball screwed onto it. The ball end goes inside the slave cylinder. Presumably the thread offers an extra way to adjust how far the clutch release arm is allowed to return when the clutch pedal is released. The ball part is about 10mm from the innermost point of travel along the thread. Adjusting the ball to take up this extra 10mm or so should, as far as I can see, allow the slave cylinder to be refitted with the clutch release arm in the position it currently occupies, i.e. 10mm or so further in than prior to removing the slave cylinder. This in turn should mean that the clutch will now be engaged fully with the slave cylinder attached. If this is the case it would rectify my slipping clutch. Except the thread on the pushrod is far beyond re-tapping, so I need a new rod anyway!

Does the above describe a normal pre-verto slave cylinder/pushrod? The only diagram of a slave cylinder I've found in Haynes is on page 6.4 (dark blue manual). From the overall shape it appears to be a pre-verto cylinder, but the internals look nothing like those of the cylinder I've removed, which is pretty much just an empty chamber, without a spring or any of the other parts shown in the Haynes diagram. Bearing in mind my earlier experience with the clutch throw out plunger, could this be either a very old design of cylinder, or a Metro design? Does anyone know?

by the way, I'm not trying to waffle for the sake of it - hopefully this stuff will actually be useful to someone else in future!

[icklemini]

It consists of a rod with approx 20mm of thread on one end, which has a ball screwed onto it. The ball end goes inside the slave cylinder

that aint a standard mini push rod :s

all the ones i've seen are just a rod with the clevis hole where it connects to the arm - can measure the length for you if you like...