Replacing The Clutch........again......

I'm actuallly pleased that I did this all over again. No, really!

 Back in 1993 - shortly before my ownership, the car had a new Ferodo brand clutch fitted. In 1997 - several years after I acquired the car - that clutch was deemed to 'not be biting properly' and (at 12559 km on the clock), a Valeo clutch was fitted.  

 

Clutch problems (and/ or a malfunctioning CRC) were the prime suspects when my gearbox input shaft sheared way back in November 1998 and other than a short test drive, my car has not really been on the road again since. You can read about that HERE.

Clutch replacement - 1998/ 99

After reassembly in 1998, the car had a few short test drives but was never really proven to be running okay afterwards. I then laid the car up to do other bodywork, with the speedo showing 23880 km - meaning that the Valeo clutch had only done 11300 kms -  about 7000 miles.

 

The old clutch was removed again, as part of the engine rebuild I did back in 2018. I couldn't confirm anything was wrong with it, but neither could I confirm the three finger plate and mechanism were set up properly. At that time, I was trying to budget for all the work to come and so, reluctantly, just put my old clutch back together. And you can read about that HERE.

A crude attempt to measure the clutch fingers back in 2018.

More recently still, I have rebuilt the CRC unit and so should be able to rule out that as a possible future problem, however uncertainties over the clutch have continued to niggle me. So you can understand why - now that I'm close to putting the engine back in the car again - I really want to be more confident that the clutch mechanism can be ruled-out as a further cause of problems....  

 

Even though the old 'Valeo' branded friction plate had only covered 7000 miles - and still had visible print on it - I decided to replace it this time around in addition to a refurbished three-finger clutch mechanism.

The old 'Valeo' clutch friction plate showed little wear.....

The mechanism is available as a part exchange item and, as they are heavy and expensive to mail out, I planned to collect mine from Citroen Classics at the 2023 UK D rally in June, and needed to have my exchange clutch ready. So late May saw me once again splitting the engine and gearbox.

 

A surprising number of peripheral parts had to be removed first - the camshaft pulley, the centrifugal regulator, the hydraulic pump, the alternator......as well as hydraulic pipes were connects to both bell housing and engine. It felt like a real backwards step - especially as I couldn't even be sure that the clutch i was removing was faulty. I had to keep reminding myself that, in helping to rule out a problem or source of failure,  there was a potential benefit to all of this. And it was a hell of a lot easier to change the clutch now - before I dropped the engine back in.

With the engine on a stand, i supported the gearbox and bell housing with my engine crane - just enough to begin taking it's weight. As the bellhosuing bolts were loosened, I made sure the crane carried the weight of the gearbox.  The bellhousing bolts all undid easily with one exception. There is a long bolt that, as well as holding bellhousing and engine together, also holds the top of the starter in place.

This bolt is only found on bvh cars with a centrifugal regulator

 As soon as I began turning that bolt it sheared with a 'ping'. It didn't even attempt to turn. Luckily - because of the way the starter and bellhousing are fitted. a short length of sheared bolt was left sticking out of the starter. The shear point was the 'air gap' between the starter and the bellhousing.

Sheared bellhousing bolt in the starter motor

With all bolts removed I slid the bellhousing and gearbox away and removed the starter motor. 

With some mole grips I was able to remove the broken piece of bolt.

Bellhousing bolts laid out in order

I would have to deal with that broken bolt in due course.

 

 With the gearbox and bellhousing out of the way the clutch mechanism was removed.

By now it was early June and time for the UK 'D rally'. I duly handed over my old clutch and picked up it's replacement, a new friction plate and various other parts I wanted to buy.

Refurbished clutch mechanism and......

.....new friction plate

Wth  the replacement clutch safely at home, I also set about replacing that sheared bolt. As mine is a bvh car this bolt is 'shouldered' (with hex) and has an extra bit of threading on the tip. I'd need another one for the rebuild so set about sourcing one. There are loads of bvh cars around so that wasn't going to be hard, was it? Wrong! Tracking a bolt down proved very difficult. I couldn't easily find one in the UK or Europe amongst my favourite suppliers.

I got as far as thinking of tapping a length of hex bar to make up a new one with a length of threaded rod(!) before I was saved. In the end, the wider Citroen community came into its own and PaulE way over in Rhode Island in the USA kindly found one and sent it over the pond.

Even this 'new' bolt has rusty threads at the same point mine sheared

And, as so often the case amongst enthusiasts, Paul wanted no payment for it and even covered the carriage costs to the UK himself. So a big thank you to you Paul!

 

I hadn't ruled out a bent clutch fork as the cause of the earlier shaft failure and clutch adjustment problems. The clutch rebuild back in 1998 left the adjuster nut alarming close to one end of it's travel and I worried that - once the car was back on the road and the bvh was set up - I would run out of adjustment as the clutch wore. I'd sourced a NOS clutch fork and, now that everything was apart again, compared it to the fork I had renoved.

NOS ('New old stock') clutch fork

No visible difference. Oh well..... at least I could rule that out then. But why, if the friction plate wasn't worn, had the adjuster been at the end of it's travel? I put some thought to clutch operation and adjustment. After several brain-busting hours  arrived at this conclusion. I wonder if you will agree:

When the clutch is operated, the rod (inside the rubber dust cover) presses on the adjuster on the top end of the fork. This pushes them forwards towards the steering rack.

The adjuster with hex end is shown here as part (3)

The bottom end of the fork moves back towards the engine and press on the release bearing, which in turn, presses on the tips of the three clutch fingers.

The clutch fork moves the clutch release bearing

 

Clutch fork and release bearing (photo credit Carl Kirk?)

Through a lever action, the three fingers then pull back (compress) the springs of the clutch plate  - loosening it's grip on the friction plate.

The fingers release the pressure on the friction plate

If the adjuster on the top of the fork is screwed all the way 'in' (so that the hex end is up against the fork) this pushes the top of the fork more towards the steering rack and nose of the car. The bottom end of the fork pushes against the release bearing more, which moves the three clutch fingers, which compress the clutch springs -  reducing the pressure on the friction plate. In other words screwing the adjuster nut in more, ncreases the (partial) disengagement and so increases likelihood of clutch slippage.

If the adjuster on the top od the fork is screwed all the way 'out' (so that the hex end is at it's maximum distance from the top of the clutch fork, this pulls the top end of  the fork towards the engine. The bottom ends of the fork move further away from the release bearing. When the clutch is operated, the forks have further to travel to contact the release bearing and so the result is that  - at 'full travel' - the bearing may not fully press on the three fingers, and the fingers do not compress and loosen the clutch plate springs. As such, the clutch may not be fully disengaged and may drag. 

Now, as a friction plate wears in thickness and becomes thinner. The clutch plate (under its spring pressure) needs to be able to 'extend' further to continue to exert the right force on the friction plate. To achieve this, the push of the bearing on the three fingers needs to be reduced. This reduction is achieved by screwing the adjuster out.

So from what I can work out, and with my adjuster just about fully 'in', I don't need to worry about not being able to screw the adjuster any further in as the clutch wears, because what i will need to do is screw it out to compensate for wear. Does that sound right??

I also found that the adjuster eyes - that fit on the end of the fork and hold the clutch return spring  - were now being remanufactured.

Clutcher adjuster eye and spring holder

I bought one as the spring had just about worn through the hole in mine and there was a strong chance that it would fail once I pressed the car back into action.

The clutch return spring wears the hole

Being the kind of person I am, I would also have liked to have compared the set up on the new clutch to the old one, but of course I'd had to hand that old one over. Placing the new clutch on a glass plate, I measured the height of the three fingers. They were all within a gnat's whisker of each other but that didn't really tell me much. 

 

One of the 'pluses' of removing the clutch again was that  could properly roughen up the flywheel and clutch plate surfaces. When I refitted the clutch a few years ago  had thoroughly degreased it but, as preparation, had used a wire brush on a drill to clean the surface. I suspect this had the unintended effect of polishing the surface. This time around I used a coarse wire cup on a slow angle grinder to scuff the plate.......

I roughened and cleaned the clutch plate surface

......and flywheel. 

 

Flywheel surface still shows an imprint of the Valeo friction plate pattern!

Both surfaces were then thoroughly degreased.

 

The Citroen workshop manual says that the original friction plates were 8mm thick.  There are (reportedly) some thicker 12mm friction plates on the market. Being thicker, these don't provide enough room for the clutch mechanism to engage/ disengage as intended.

Thick and thin friction plates?
(photo credit Dago Langen I think?)

I compared the Valeo friction plate I was removing and the new unbranded plate  was fitting: bth lked t be the same.....Compressing it's surfaces together, the Valeo friction plate was 8mm thick. So was the unbranded one - so that seemed okay.

I had, once again, borrowed an old input shaft from Peter 'Badabec' Bremner to help align the hole in the friction plate to the hole in the bearing.

Spare input shaft through the new friction plate

If you DON'T do this, you may well find that when it comes to marrying the gearbox back to the engine - they don't line up...... You don't need to use an old input shaft for this alignment. You can use any rod of the right diameter - and even buy special kits of parts to do this. however as eventually you will be trying to line your gearboxes input shaft up, you get a better result if you do the set up with an old spare shaft. And because the splines engage with those on the friction plate, they help to ensure the correct fit.

Offering up the shaft to the bearing in the flywheel

With the friction plate held in place, i fitted the shiny new clutch plate. When fully bolted down, the plate will grip the friction plate tightly in place, so before I reached that point, I gave the input shaft a bit of a waggle to centralise the friction plate - and to make sure I could easily remove the shaft. This all helps to ensure that, once the gearbox is offered up, it's input shaft will slip easily throgh the friction plate and into the bearing in the flywheel.

Friction plate correctly aligned with the flywheel bearing

It's worth noticing here that the new clutch mechanism has strange little copper clips under each of the clutch fingers. I have seen other DS clutches with similar clips but made of plastic.

All these clips are doing is atrifically compressing the springs of the clutch so that you can fit the bolts and screw the plate on. Sometimes it's difficult to spot that these are clips.

Can you spot the clips? (photo credit: Dirk Sassens)

Look carefully and make sure the fingers are free to move. These clips need to be REMOVED before you shove the gearbox back on or the clutch will not operate correctly!

Removing the clips from the fingers

That's it: new clutch fitted

Using the bearing to centre it, I replaced the camshaft dust seal inside the bellhousing. I couldn't remember if i had adequately glued it in place last time.

Camshaft dust seal inside the bellhousing

I carefully aligned the gearbox back to the engine so that the input shaft aligned with the clutch friction plate. It's important to be aware of the camshaft as it passes through it's bearing in the bellhosuing. You want to avoid bending the camshaft. I temporarily removed my bearing to make the alignment easier.

Introducing the gearbox to the engine.....

Last time I did this, the gearbox pushed the engine all around the workshop. so this time i wedged the engine against a wall. Slowly and carefully the gerabox was pushed home. Compared to the last time, it was remarkably easy and went home first time.If you struggle with this, it might be because the splines on the shaft and friction plate are not aligned. Turning a drive shaft or the gearbox - using the hand crank on the end - can help alignment.

Nearly there....

I refitted the camshaft bearing and then bolted the bellhousing back up.

Refitting the bellhousing bolts.

Done! All I have to do now, is put all the peripherals back on again.......

Having said I'm pleased I did this, I just hope the 'clutch snatch' problem is fixed once and for all.