Announcement

**Duncan Skye** · 24 March 2010, 13:52

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Dear Richard,

On getting a restoration heap, I had to separate the engine and gearbox and found that the clutch release bearing had worn a circular groove in the tongues of the dishedrelease spring. That's the many-fingered one which protrudes inward from within the clutch cover itself.

When operating the clutch, the release bearing will move through a smallarc when in the act of depressing the spring. If there is a wear groove there, the release bearing will have to climb the lip as it moves through its arc. Possibly some roughness from that?

Duncan Skye.

**pompey272** · 24 March 2010, 15:25

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Hi i had the same problem with my new fitted clutch the pedal was very jerky on the way up and got that bad it would stick half way and then release itself very dangerous. I removed the gearbox and changed the clutch pressure plate for what was known as modified at the tip of the fingers there is a bearing that makes all the fingers depress and return smoothly i'm sure you can still buy one i fitted mine approx 5000 miles 6 years ago and its been faultless with a lovely smooth pedal hot or cold its a pain dropping the box but you will eliminate a dangerous fault.

Regards

Trevor

**richardthestag** · 24 March 2010, 18:25

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the jerky feeling sounds similar though my clutch pedal nevers sticks. Pulling away with low revs can stall the engine sometimes as the clutch pedal jerky reaction makes it tricky to engage. but it does get there. Did your clutch mess you about all the time? Even when cold etc? Also with the engine off the clutch is dead smooth and light.

looks like the gearbox is coming out again. Anyone in the Wycombe (bucks) area fancy giving me a helping hand as swmbo is not so keen on getting her hands dirty.:P

**Duncan Skye** · 25 March 2010, 07:07

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Dear Richard,

Sounds like Trevor and I have had similar experience there. When I removed the clutch release bearing (that I presumed to be original) I noticed that the replacement bearing had a more rounded 'nose' to it. By that, I mean the circular high part that actually makes contact with the fingers of the diaphragm spring had a smoother curve to its profile, thus perhaps spreading the load and causing less wear.

Reading Trevors' comments on the clutch actually sticking though, suggests it's the bearing carrier sleeve that is gripping on its shaft through lack of lubrication, or the clutch plate itself is sticking on its splines. Is there much wear there? There might be a lack of the tiniest amount of grease at that point also. If a sticky clutch plate is the case, you can get an indication by parking the car car on hard level ground, handbrake off, have the engine at idle, dip the clutchand try and select first or reverse. If going into first is stiffand the car almost wants to move forward, then the clutchplate is sticking. Or if whenselecting reverse, and against light pressureon the gearlever,there's a constant sound of grinding teeth, (repeated selection, without letting the clutch pedal up)then that points to a sticking clutch plate also.

Another clue which swings me away from the 'bearing' suggestion and in favour of the carrier sleeve (that holds the release bearing) sticking, is that you don't notice the stickiness on depressing the clutch. That may be because threre is a greater influence from the hydraulics actuating the system in one direction, but we're relying on (lesser)spring pressure to allow the clutch to re-engage itself. If any of the clutch operating mechanisms are dry and grippy, then they may allbe sufficient to hold the clutch back from engaging smoothly. I'm talking myself into saying it comes down to a lack of lubrication coupled with some slack in the system that should not be there, but I don't know what else. I presume your clutch pedal returns OK and is simply transmitting the feel of the problem, rather than being the problem itself? If not, I think your gearbox will have to come out for a look-see. A light smear of high melting point grease on all mechanical sliding or contact points will work wonders, but don't get any of it on the clutch plate or it's shiny rubbing surfaces. Good luck with it.

**richardthestag** · 25 March 2010, 08:35

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Hi Duncan, Trevor

I think Duncan has confirmed my understanding of the fault being with the bearing carrier dragging rather than anything else.

The clutch disengages / engages as it should
The pedal is smooth on depressing
The pedal is sometimes jerky on returning
Nothing stops the pedal from returning
The pedal operation is smooth when the engine is off

I shall source a new carrier and bearing, replace the pins in the fork and possibly the bushes either end of the cross shaft and try again. While it is apart I shall check that the pressure plate is showing no sign of wear â€“ it has done 9000 miles so should be good for a few more.

Watch this space

Richard

**Duncan Skye** · 25 March 2010, 09:07

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Dear Richard,

Now that you're on that track, you might find that it's just a case of lubrication and nothing else. You should only need to replace parts if they're showing signs of wear, are bent or suspect in some other way.

If you're planning on re-using the release bearing, be content with it if it's smooth running and free of wear on the circular 'nose'. It should be very smooth running and silent when turned, and DON'T try and do what I did - I wastempted to rinse it out in a paraffin bath in order to re-grease it, and just rinsed debris and grit into it, causing a roughness that was not there before. To be on the safe side I had to replace a perfectly good bearing.

When I replaced my clutch plate, it came with an unmarked sachet of grease that looked remarkably like the 'Red Rubber Grease' that Castrol make. If it is that stuff, then a smear of that on sliding surfaces should be OK, but they don't say anything about it's properties on the tub. Alternately, a grease that has a high melting point and additives like graphite, graphite/copper or Moly/Molybdenum can provide an element of dry lubrication that lasts after the oily fractions have dried up.

It would be nice to know that if you didn't replace anything, lubrication was all that was needed.

With best wishes, Duncan.

**V Mad** · 25 March 2010, 09:57

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Slight deviation, but as the clutch release bearing has been a common problem area recently, I wonder if anyone has considered modifying the clutch thrust system to use a concentric slave cylinder?

This replaces the conventional pushrod slave cylinderand fulcrum/fork with aconcentric slave cylinder that pushes directly onto the clutch relasespring.As it is concentric there would be noside thrust to jam the mechanism.

Any comments?

**Duncan Skye** · 25 March 2010, 10:41

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I've not heard anything, but it sounds like a good modification to make.

The only way you can reduce the side loading is to make sure the cross shaft bushes are OK and that the groove in the bearing sleeve that takes the pins of the release fork are lubricated. And that the shaft that takes the bearing carrier/sleeve is lubricated as well.

With best wishes,

Duncan

**DJT** · 25 March 2010, 11:23

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Duncan Skye wrote:

When I replaced my clutch plate, it came with an unmarked sachet of grease that looked remarkably like the 'Red Rubber Grease' that Castrol make. If it is that stuff, then a smear of that on sliding surfaces should be OK, but they don't say anything about it's properties on the tub. Alternately, a grease that has a high melting point and additives like graphite, graphite/copper or Moly/Molybdenum can provide an element of dry lubrication that lasts after the oily fractions have dried up.

I have heard of grease for this application referred to as 'Red Sparkle'. A bit of Googling comes up with:

http://www.aztecoils.co.uk/pdf/tds/T...2009064423.pdf

http://nhfsupplies.co.uk/pdf/batoyle...lubricants.pdf(scroll down to Page 7)

Never used it myself though.

Dave

**Duncan Skye** · 25 March 2010, 12:07

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Very interesting, and the description looks good.. I needed some wheel bearing grease anyway so ordered up a cartridge of that and their 'red sparkle' grease while I was at it. They only do it in 400g cartridges as the 500g tins are to special order and thus rather more expensive. I've asked for data sheets as well, so if therre's any spectacular data there, I'll post it up.

Possibly the SOC shop should stock some of these very interesting lines..

Duncan

**redstag** · 25 March 2010, 15:07

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V Mad wrote:

Slight deviation, but as the clutch release bearing has been a common problem area recently, I wonder if anyone has considered modifying the clutch thrust system to use a concentric slave cylinder?

This replaces the conventional pushrod slave cylinderand fulcrum/fork with aconcentric slave cylinder that pushes directly onto the clutch relasespring.As it is concentric there would be noside thrust to jam the mechanism.

Any comments?

Its been done for TR boxes so I can't see why it couldn't work for the Stag.

http://www.hvdaconversions.com/pgs-final/htob-info.html

Pete

**V Mad** · 25 March 2010, 16:33

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Yes thats the kiddie. I bet that is the smoothest clutch you could get on a stag!

**Ian B** · 25 March 2010, 16:35

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V Mad wrote:

Yes thats the kiddie. I bet that is the smoothest clutch you could get on a stag!

no thats a BW

or better still a ZF

**Ian B** · 25 March 2010, 16:35

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V Mad wrote:

Yes thats the kiddie. I bet that is the smoothest clutch you could get on a stag!

no thats a BW

or better still a ZF

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