[Odd Job]

OK.

So, I phoned LUK technical this afternoon and spoke to a guy called Andy.
He is very experienced and has worked for LUK for many years. I dont know how many years, but he's not some 20 something wet behind the ears guy, he's in his 60's and has a great wealth of knowledge.

So, I explained my own personal quandary. I told him about my very heavy clutch pedal, so heavy I cant live with it. It's painful to drive the car in traffic. That's how bad it is, and I'm not exaggerating, the pedal feels more like the pressure to press a brake pedal than a clutch.

I explained that I'm very concerned about premature failure's especially with the diesel 75's but not exclusively, and several members on here have talked about only a few thousand miles before the concentric slave cylinder has burst.
I asked if there was anything in their technical archive that might suggest a problem, and he checked for me.

He first of all checked to see if there was any bulletins on either the concentric slave or the master cylinders, anything to watch out for, but LUK has nothing on record.
I had him check for recorded failures on this vehicle, and, believe it or not, no recorded failures.
Now before everyone starts to jump up and down, like almost all companies, and even governments, institutes, recording medical issues, etc, there is a criteria for statistics to be recorded. SO, if a particular failure IS reported, but it is deemed to be human error then it wont actually be recorded.


Just a quick example.
I don't know if this is still the case, but, if someone who has a heart attack is over the age of 65, then it isn't recorded on the NHS statistics. The reason being is that at that age organs are reaching their less than optimal condition.
So, if a car had covered 100,000 miles and the clutch failed, that's down to wear and tear. Not down to a faulty product.

Ok.
So, the concentric slave is provided "primed". I.e. you are not expected to bleed the clutch when you fit a new concentric slave. It has a quick fit / release pipe which somehow is supposed to eliminate any air contamination. So there are NO special notes on bleeding the clutch at all.
The same applies to the master cylinder.

We then got onto talking about the criteria for deciding if a dual mass flywheel needs replacing, we spoke about free play in the unit, the degrees of rotation, then the lateral movement, ( DTI gauge is needed for this ) but I digress, not really to do with failure of the CSC ( Concentric Slave Cylinder ). I asked the question could the DMF bring about the premature failure of the CSC, that is a long answer in itself, but for our purposes with clutches which have done very little mileage, just for this we'll say no. Though this isn't exactly true.

So, what could be the issue then?
"Quality of parts! Made in some 3rd world country" might well be the reply, that MAY be true, but I have no proof of that.

What follows next is conjecture, yes, but it is based on Andy's long serving with LUK, his experience on all makes and models, what he has come across, what he has found to be the fault with other vehicles.
I am not saying this is what the problem is, please don't misunderstand.

So, let me explain.

Lets take the clutch master cylinder.
This is a theory.
The master cylinder most of the time wont be replaced.
Brake and clutch fluid is corrosive to many substances, and one of those things is actually the rubber seals in which it is in constant contact with. This is why ( one of the reasons ) brake / clutch fluid will turn dark in colour, because it is slowly dissolving the seals. It also can turn sort of a soapy consistency, and you end up with "lumpy" bits in the system.
So, potentially you may have a new slave cylinder with nice new fluid, which comes pre primed, but when you hook it up to the master cylinder, which is a nightmare to even find, let alone fill, replace etc, you are connecting it up to bad fluid.
Now the fluid in the clutch system actually is a "working" fluid in the motion sense. When you press the pedal the fluid flows and pushes the CSC to operate the clutch.
It wont be long before the bad fluid has mixed with the new and you could get a problem with contaminates damaging the seal, causing it to leak, and hey presto, no clutch!

The potential answer here is to either bleed the clutch BEFORE the new CSC is fitted, so any contaminates are removed from the system before the new slave is fitted, or....
Fit a new master cylinder, which makes an expensive job even more expensive.

Second theory.
The CSC isn't bolted into the gearbox as such. It sits on a guide tube, so if the guide tube has wear on it, then the slave cylinder will be pushing slightly at an angle. This could quite easily cause premature failure of the CSC.

Third theory.
I'm not too sure on this one, but, this may be true for some vehicles on the road, not so sure for ours.
The bushes that hold the actual clutch pedal at the proper spacing and angle when mounted in the pedal box.
If the bushes are worn, then the pedal will be very slightly moving at the wrong angle, which will put undue pressure on other components.
This MAY make the clutch pedal hard to press. But as to premature failure of the CSC I don't believe so. Hydraulics where designed to move things at any angle, where a cable operated clutch has to have a "kind" path to follow.
This is more about a heavy clutch pedal.

To sum up.

There may not actually be one culprit. It may be a mixture of a few things, even things not mentioned above.

But, a car which in case of most diesel 75's are normally on the higher mileage side of things, which has a high potential for other components to be worn as well, when presented with new components fitted onto parts which have become worn, which means they no longer operate in the same place ( angle ) in which they where intended,
i.e. the CSC running at a slight angle because of a worn guide tube, then coupled with a potential contaminated fluid situation from the master cylinder, plus other factors, it's the what has caused the CSC to fail, not it's a badly made / produced / bad materials CSC that's the issue.
If a part has to break it will be the weakest link.