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!