CRC Rebuild.......again.......

 Well. I finally (I think) dealt with the 'riddle of the seals'. And corrected a mistake.

 

All back together. Again..........

I covered the overhaul of a Clutch Re-engagement Control (CRC) unit in a post back in September 2018. You can read about that HERE.

 

I then discovered where the 'spare' and unused seal in the CRC rebuild kit went. You can read about that in my June 2019 'riddle of the seals' post HERE.

The unaccounted-for seal always bugged me

To add to my CRC woes, Timo contacted me and pointed out that in my original rebuild post, I'd seemed to have fitted one of the spring assembiles the wrong way round! I investigated by pulling apart another CRC unit and it looked at though Timo was right! You can read about that in my post from December 2019 HERE.

 

At that point, what I hadn't done, was remove the CRC from my car to check that spring assembly and replace that seal. I wasn't looking forward to pulling it off the car again and it's taken me until now to do it.

The CRC fitted to the car

The two jobs I needed to do meant almost a complete disassembly of the CRC. I say 'almost' because I didn't need to remove the caps from both chambers - just the one with the incorrect spring set up - and because there is an adjuster screw that shouldn't be tampered with. This was a job of two halves. The CRC sperates in the middle. the seal replacement involved one half and the spring replacement involved the other.

A game of two halves....

I tackled the spring problem first as that seemed easiste to deal with. Carefully holding the body in a vice I used a suitably sized socket on the end cap to push it in very slightly. This takes pressure off the circlip. In my original rebuild I had drilled a small 'key hole' to help press out the circlip that retained the cap. An older photo - but like this.

Removing the circlip holding an end cap

 With the circlip removed, the cap was removed by VERY CAREFULLY pushing on the pin inside the unit. Sure enough, when I took out the spring and it's thrust washers, I had indeed assembled them wrongly! I think I had (wrongly) assembled the parts in this chamber  like the spring in the other chamber. I should have looked more carefull at my disassembly photos all those years ago.

WRONG! Not like this......

Relative to the end cap, the parts should fit in this order:

The correct order of the parts....

The order of the parts was corrected and, with a brush of LHM the parts were refitted. I used a socket and vice to push the end cap on slightly further in than it's resting place. With the circlip refitted, I carefully pushed on the end pin inside the CRC againto push the cap back against the circlip. DONE.

Next I moved on to that hidden seal. I was curious to see how I'd get on! Don't forget that I had a spare CRC unit, so if I messed this up, I had a plan 'B' up my sleeve.

Plan A and Plan B (they ARE both the same size....)

The CRC I had chosen to rebuild back in 2018 was one I'd bought for a few Euros at Citromobile that summer. I chose to rebuild that one as it was the tattiest of the two I had and the one that would benefit most from some tlc. It had a large amount of silicone sealent cruedly smeared all over it.  At the time, I wasn't aware of the 'secret seal' and I assumed this silicone was because the gasket joing the two halves was leaking. My rebuild included a gasket replacement, so no more leaks - right? It was only when I discovered where the unused 'O' ring seal went, that I realised the silicone might be because of a leaking shaft seal - and would have been no fix for such a problem. The silicone had been smeared over a bigger area than just the gasket area. All around the shaft in fact. As such, if there was a shaft leak, then my original rebuild would still leak......

Telltale sign? The silicone sealent strongly suggests a shaft seal leak

To replace the 'O' ring seal, the shaft needs to come out - or virtually all the way out. The shaft is sealed in the CRC body at one end. This end is capped with a metal press-fit cap. The inner circumference of the cap also acts as a kind of bearing - supporting the shaft end.

 

The technique I followed was to remove the cap to expose the other, hidden, end of the shaft. The shaft can then be pressed out. The shaft has a cam in the middle that fits tightly on to splines. The CRC body holds back the cam and the shaft is effectively pushed through the cam and off the body. It was 'MichaelR' who first alerted me to the whereabouts of the extra seal. He had used mole grips to pull the cap out. 

MichaelR used grips to pull the cap off (Photo credit: MichaelR)

There is not a lot of exposed end to grip and this looked quite messy - damaging the cap. Timo refined this: he welded a threaded length to the end of the cap and then would it out simply by tightening a nut on the thread. 

Timo used a nut to wind the cap out. (Photo credit Timo)

And that is what I did.There is some hardened 'goo' around the slotted adjuster (that should not be adjusted) and the cap. I'm assuming these are to provide a fluid-proof seal against LHM leaks. Anyway the cap end was exposed and tickeled with a grinder to provide a clean wekding surface. I didn't want to mistakenly weld the cap in place, so chose a size of threaded rod that sat comfortably on the top of the cap and allowed some room for weld - on the top, not the sides of the cap. I think I chose M6 size, or maybe M5.

 

It took severeal attempts to weld a rod on. the first time I tried it, winding the nut on simply pulled the threaded rod off the cap. In the end I left the end on a countersunk screw. That provided a stable base for welding (the threaded part stood vertical) and also the thin edge of the countersunk screw head succumbed more readily to my welds and joined to the cap.

Threaded stud welded to the cap

The rest was very easy. I used a suitabe socket to sit over the cap and threaded rod. As Timo did, using a washer and nut I wound out the cap.

Using a nut to wind the cap out

It was like pulling a cork from a wine bottle and came out very easily.

The cap removed - not shaft end beneath

As the CRC body is made of alloy, I wanted to provide as much support around the shaft as I could when I pushed the shaft through. I used a wooden spacer with a large diameter hole cut through........

Making a wooden spacer

......so that, when pushed out, the shaft had somewhere to go.

Using a bolt that fitted neatly in the recess where the cap had been removed........

I used a bolt to press the shaft out

........I used my vice as a press to press on the shaft and push it into the wooden block. This gave me more control than hammering on the bolt and, I reasoned, was less of a 'shock' to the body - less risk of distortion.

Pressing out the shaft - into the wooden block

There was that pesky 'O' ring seal! 

The shaft seal - exposed

Shaft with seal - note the splines for the cam

And there was the cam left behind.

All the bits

 

Refitting was easy. The unused 'O' ring seal from my old rebuild kit was brushed with LHM and fitted to the shaft. It definitely sat more proud than the old seal. I'm so glad I changed it.

 

I cut the stud off the CRC end cap and tidied the cap up - ready for reassembly. It looked good as new. Next thing I did was check the face of the cam - no obvious flat spots or other wear. Nothing that would make it stick. With the help of a little more LHM the shaft was located in the body - picking up the cam along the way. I first wiggled the cam to make sure it was correctly aligned to the splines.  At this point it is VITAL that the cam is fitted on the right way! if it's 'upside down' the CRC will not opereate (and may not even go back together). I referred to drawings and my other CRC to make sure I got this bit right!

A schematic of the CRC. Note the way the cam is fitted

 Other than making sure the cam is the right way up, there is no correct rotational orientation of the cam on the shaft - but the position of the shaft and cam need to be set up when refitting the CRC to the car. A pin is used to 'lock' the cam in the right position. 

The cam. Note splines and also the 'setting' hole for setting up the CRC

Using my vice again, I slowly pressed the shaft into the body and through the cam. When the cam is fully engaged on it's splines the shaft cannot be pushed further. using a vice to gently push the shaft in stopped me forcing the shaft too far.

Using my wooden block over the exposed end of the shaft again, I located the cap over the end  of the shaft hole. Wiggling the shaft so that it centred in the hollow in the cap, I used my vice to squeeze the cap and wooden block together. I mixed up some Araldite and used that to seal the end cap against fluid leaks (I think).

I won't cover further reassembly here. That's all in my original post from September 2018.

I part-asembled the parts and gave the CRC a few coats of paint (being careful not to get panel wipe or paint inside the lubricated parts of the CRC).

Masking and painting......

I think this time around I will fit the1968 flector and see what happens.These are spring-loaded two-part affairs.

Short-lived flector design (photo credit unknown)

They seem to have only been used for a couple of years (early 1966 to early 1968) before Citroen reverted to the earlier one-piece 'cartwheel' version. Perhaps I will find out why!

Earlier (and then also later) style of flector

 

Drawing to a close, something I want to point out here is that, before and after my initial rebuild, the shaft turned very easily against the spring tension. In fact in one of my posts, I'd shared video from Youtube of someone with a 'knotty' shaft - a shaft that got stuck and didn't spring back easily: this video HERE. I had attributed this to a worn spot on the cam and the thinking being that 'loose' = 'correct'.

Now that I've come to change that seal, I find that the shaft is fairly tight and can barely be rotated by hand - It is able to resist the spring tension. In conclusion I can see that a shaft that rotates freely and DOEs spring back, or a shaft that does what the one in the video does, is not 'knotty' but a shaft with a worn seal - and at risk of leaking at some future point.

I'm confident that, when fitted, and when taken alongside the springs inside the CRC, the combination of the  springs on the throttle linkage, plus those on the carburetor will be enough to cause the CRC shaft to rotate as it needs to.

One final thought. On Facebook someone told me that you don't have to do any of the above! All that stuff with welding and caps. They said that by pulling on the shaft end, this exposes the seal which can be winkled out. I have to say this is one of the first things iItried before I pulled tha cap off. Pulling the shaft only exposed a dark ring. That may have been the edge of the seal groove but, if so, gave no scope to replace seal. In fact I think all I was seeing was a ring of dirt and the seal remained deep inside and out of sight.

Gently pulling on the shaft didn't expose the 'O' ring seal....

If you could expose the seal simply by pulling on the shaft, wouldn't this mean that the seal could leak? From what I can see, the only way to expose the seal without removing the cap, would me applying significant pulling force to the shaft so that it pulled it free of the cam inside. And that is what Manfred Wolf did: he gripped the shaft and used two screwdrivers to lever against the body.

Levering the body (photo credit: Manfred Wolf)

That seemed to be enough to expose the seal.

And there is that seal again (photo credit: Manfred Wolf)

The levering technique is basically the same as the pushing technique - where you push the shaft through the cam. Pushing involves removing the cap as above, pulling leaves you with a gnarled shaft I would think. Pushing is more involved but less destructive and (I feel) the more conventional/ expected route.

I suppose you could weld a threaded length to the exposed end of the shaft and wind it out by tightening a nut. I'll save that thought for my next rebuild!

Front Suspension Cylinders - Strip Down and Overhaul

I have rebuilt and refitted the front suspension cylinders. The suspension arms and anti-roll bar went back on the car some time ago. I'm not sure why, but I'd moved on to refitting pipework before I put the suspension cylinders back on. All fitted now.

Front suspension cylinder refitted

Many years ago I'd noticed that the car had an obvious LHM leak coming from somwehere around the left side wheel arch.

Tell tale signs of leaking LHM

I soon realised that the cause was a split boot. Pulling the car apart ore recently I'd found the other boot not leaking but badly craked. Both boots would need changing. I bought a couple of Suspension cyliner rebuild kits from Citroen Classics a few years ago and now was the time to use them. The kits were a mixture of modern-sourced parts - plus a couple of old Citroen parts - the large 'O' ring seals in the caps.

A suspension cylinder rebuild kit

Instructions for rebuilding suspension cylinders were not included in the original manual 814. You can find some instruction in English for rebuilding rear cyliders at Operation Dx.433-3 in earlier manual 518. If you are in search of instructions for front cylinders, you can find these at Operation D.433-3 in volume 3 of French language manual 583. From manual 583, here is the detail of a later style suspension cylinder:

Suspension cylinder parts

In the diagram above:

    Part 11 is the piston

    Part 7 is the sealing nut on the end.

    Parts 6 and 10 are the felt washer and O ring inside the nut.

    Part 5 is a thick metal thrust washer

    Part 8 is the white Teflon seal inside part 9, another O ring.

 

Before I started the rebuild, I'd been keeping dust and dirt out of the cylinder ends using the smart blue caps that Peter Bremner made on his 3D printer. I'll also use them again when the cylinders are refitted - but before I fit spheres.

 

With the Ligarex clips removed from the large ends, the boots can be pulled off to reveal the pushrods and end nuts of the cylinders. The pushrods remain attached to the boots by the Ligarex clips at the other end.

Pushrods and cylinder nuts revealed

Unlike the rear suspension units, the pushrods and ball bearings of the front units are inside the rubber gaiters and lubricated with hydraulic fluid. The cups, rods and pins of the front suspension cylinders are different to those of the back and I don't know how readily available they are.

 

The nuts that close the ends of the cylinders and hold the seals in place are screwed up pretty tightly. The technique is to carefully grip the nut in a vice and then remove the body from it by using some kind of tool around the boss on the other end (where the hydraulic pipe connects) to turn the cylinder body. The manual recommends wooden jaw liners with a 'V' cut in each.

The manual recommends soft jaws in a vice

You can't grip the nut too tightly in the vice for fear of distorting it and pinching it on to the body even more tightly. And there is the risk that if that happens and you manage to get it off - it won't go back over the piston and/ or seal properly.  Unfortunately, if the vice isnt tight, the nut twists with the body as you try to rotate it. A bit of trial and error is needed to find something to line the vice jaws so that you don't need to tighted the jaws too much but still have enough grip on the nut.

Seperating the nut and cylinder

I used soft aluminium jaw liners and some pieces of rubber. I wiped the cylinder body down with panel wipe so that the rubber gripped it without slipping. Eventually was able to loosen the nut. 

Loosened end nut on a suspension cylinder

Inside the nut was a felt dust seal. This sat in a recessed groove.

Removing the felt seal from the nut.

 There was also a rubber 'O' ring that seals the nut to body join.

Seals inside the cylinder nut

Beneath the nut was a thick thrust washer over the cylinder piston.

Thrust washer (on the piston)

The thrust washer and piston were removed. Inside the circumference of the open end of the body was a white Teflon seal - within an 'O' ring that sat in a recesed groove.

White Teflon seal and 'O' ring in the cylinder end

These provide the seal againt the massive hydraulic fluid pressures at play in the suspension system. Some leakage was always anticipated - which is why the rubber boots have a return line back to the reservoir. It was at this point that I found this.....

That's a bit blurry. This is better. 

Do you recognise it?

It's a thin sliver of hydraulic pipe seal that has found it's way into the suspension cylinder. These get 'shaved' off the seals by the threads when the pipe flare nuts are screwed in or removed. When working on the car, if you disconnect hydraulic lines you need to remember to remove and replace old seals - but also to fish out any slivers of rubber. If you don't these can compromise the working of various slide valves and they can block pipes. In my case, this sliver would have found it's way back to the reservoir from the cylinder and been picked out by the filter.

Here are the parts of my two cylinders laid out.

Suspension cylinder parts laid out

The instructions for the old style rear cylinders in manual 814 warn that several parts and paired and shouldnt be muddled between cylinders. I wasn't sure that was the case with the newer design front cylinders but it didn't hurt to be cautious and I put a couple of discreet marks on things to help ID them.

I carefully marked the parts to help ID them

All the parts were cleaned in petrol and I put the pistons and bodies through my ultrasonic cleaner.  I gave the piston a light polish to make the surface that little bit smoother - hoping it would reduce wear and tear on the new Teflon seal.

 

I didn't bother to disassemble the push rods as I wasn't sure whether replacement pins were available. That's when I found this.... the cups and pins on the pushrod ends were different. 

Different cups on the pushrod ends

Both the cups and pins are different. For the pushrod on the left, the 'fat' pin sits in a slot and then a clip around the circumference of the cup stops it slipping out. The ends of the 'thin' pin of the other pushrod sit in two holes. The difference in pin diameter also means that the pushrods themselves are different. Overall there was about 3mm difference in overall length - partly attributable to different cups but also partly down to different length pushrods.

Two pushrods, two lengths....

A bit of a trawl through the parts manuals revealed that there seems to have been a change in parts late 1970 - for the 1971 model year cars. The shorter rod (right hand side in my photo above) looks to be the original 1968 pushrod from my car, whereas the other one is from a 70s car. My receipts show that I did have a cylinder replaced back in the day, but I can't remember why that was necesary. Anyway, different they were!.

Refiting is the reverse of disassembly. The new felt seals need to be soaked in clean LHM for a few hours before being fitted in the nuts.

Soaking the felt seals in LHM

 I fitted them in the recesses in the nuts - making sure they were not twisted and sat squarely.

New felt seals fitted

The 'O' rings were brushed with LHM and also fitted inside the nuts.

'O' ring for the nut - an original spare part

Rebuilding is pretty straightforward and some may not bother with the workshop manual instuctions - especially if they are in French. However there is a particular  - and simple -  technique for safely fitting the white Teflon seals without damaging them. 

Teflon suspension cylinder seal

I have seen elsewhere on the internet, photos of people trying to fit the Teflon seal by inserting them in the cylinder bodies with the 'O' rings and then trying to push the piston through the middle. With that technique there is a danger that you fold or twist the Teflon seal - causing a crease and ruining it. Here is how the manual says it should be done - and it worked:

 

The rubber 'O' for the cylinder body was brushed with LHM and fitted in it's seat. 

Rubber 'O' ring in the cylinder body

The piston was brushed with LHM and the teflon seal was carefully slipped over the open end of the piston.

Teflon seal on the piston

The piston, smeared with LHM, was carefully slid into the cylinder body. The top of the piston extends from the cylinder and so the Teflon seal was still visible at this point. I moved it down the piston to the rim of the cylinder - where the 'O' ring was sitting.

 

Next the thrust washer was brushed with LHM and slipped over the piston. Carefully pressing down evenly on the thrust washer pressed down on the Teflon ring which suddenly 'popped' into place  - between the piston and the iinner circumference of the 'O' ring seal.

As if by magic, the white Teflon seal was fitted

Taking care not to twist the felt seal, the nut was slipped over the piston and screwed up hand-tight. I slipped the nut end back into my vice - again taking care not to over-tighten it. The manual says a force of between 95 Nm and 120Nm sould be applied when tightening the body to the nut. I had no way of measuring that directly so I tightly gripped a large hex-headed nut in another vice and set a torque wrench to 100Nm to get an idea of what applying that force felt like. I then tried to apply approximately the same force through my adjustable spanner. It was all guess work and I can only really say that I felt I did the nut up pretty damn tight.

 

I painted a green band around the top of the cylinders. Why? Well I needed to repaint the extension piece that fits to the top of the left hand cylinder anyway. But I don't really know why I painted the bands -  other than that there were signs of paint when I took mine apart and I wanted to take them back to the state I think they would have been in originally.

Extension piece and painted band

I'd bought a single replacement suspension boot from Chyparse -a parts supplier in Holland -  back in about 1998. I'd never gotten round to fitting it(!). Now that I needed to replace the pair, I bought two new ones. The various parts sellers often sell a cheaper  'standard' quality version and (because the 'standard' ones aren't very flexible and don't last), a better/ best quality version.

 

The pair I bought most recently were 'best quality' apparently. Now I looked at them, i discovered they weren't a 'pair' at all. One was noticibly softer than the other which was stiffer and less springly. I suspected this harder one might actually be a 'standard' quality one....The old Chyparse boot was closer in feel to the softer/ more flexible of my new 'pair'. What to do? In the end, I decided to fit the two new boots and see if - as suspected - the hard/ less flexible one gave in first. If it does, I always have the Chyparse gaiter as a spare. I also decided to refit the two different suspension pushrods and cups.

Not a pair........

With my decisions made, before I fitted the Ligarex bands, I did a 'trial fit' of the cylinders on the car. It's important that the boss where the hydraulic line joins the cylinder is lined up with the hydraulic pipe. That should be pretty straightforward if you loosely refit the pinch bolts that hold the cylinder in place - as they will line up the cylinder. On my car, on the left had side the boss faces backards - towards the cabin. On the right hand side the boss faces forward towards the bumper. Relative to the cylinder position, it's also important that the slot through the cup of the pushrod is lined up to the split pin holes in the suspension on the car. With the boot joing these two parts together, there is one last check to make: that the overlflow outlet of the boot is lined up with the rilsan overflow pipe on the car.

 

With the alignments made, I fitted the Ligarex bands. Over the gaiters themselves, I fitted new rubber belts so that the Ligarex bands did not bite into the boots.

Ligarex bandings fixed

The only fiddly bit of fitting the cylinders was fitting the split pins through the cups at the bottom. I used new split pins but they were a tight fit in the holes so needed to be lined up perfectly. 

Split pin at the base of the suspension cylinder

With that done, there are two bolts and lock nuts that hold the sides of each cylinder. These are not meant to be done up tightly. These have pointed end. They should only be done up hand tight so that the pointed ends engage in the dimples in the cylinder bodies. Then the lock nuts are tightened.

If I get a suspension leak from one or other boot, I have a spare to fit. When I'm setting up my front anti-roll bar, if that proves difficult then I will have to try and remember that the two suspension pushrods are not quite the same length.