Technical Stilo 2.4 clutch master cylinder mystery & dilemma

[jonti]

The mystery is why my Stilo got through five or so clutch master cylinders in 13 years or so and 40k miles.
I see lots of threads about floppy pedals and master cylinders, but it's not clear if there are more issues than there should be or I am alone in this.
So here we go again. Reverse is not available when the car is hot, and recently I've depended on the goodwill of strangers willing to push when I've forgot and gone into a cul-de-sac.

 

[jonti]

I am thinking that the cheapo black plastic body expands with heat over time and no longer seals. More recently, a metal bodied MC from TRW or Bosch has become available, which MIGHT support my theory. As why would they change to metal, unless it resolved a problem with the OEM design?

So I bought a metal one for a rainy day and that day has come. But on removing the old one, the new metal MC plunger is too long and won't fit. Looking back at the listing, it states 'LHD'. A few others for sale state this and generally they ALL look this long, apart from Shop for Parts which (for the 2.4) is the correct length, but it's the usual plastic one. Mystery (2) then, is it just the 2.4 MC that is short, or is it shorter on all RHD's? I assume just the 2.4, as there will be a lot of surplus stock. Or are sellers using incorrect library pictures, maybe another mystery.

My dilemma is whether to try putting the short plunger from the plastic one into the metal body. I've removed them both. It seems to be a nice tight fit. But I can't be certain my theory about the case expanding is correct? Maybe it is the seals as they age, although the seals from my old plastic one 'look' ok.........

 

[Maxcaddy]

Bit unclear from the photos, but by saying Plunger you mean the piston and not the operating rod ?, If it is the piston then the cylinder will most likely be different, and probably the orifices will be in different positions, and it wont work. You don't say exactly why you can't fit the later one in its entirety, but if it's fouling against something, can you move whatever that something is ?

If it is the operating rod then as long as the end which contacts the piston is the same, I see no reason why swapping them would be an issue.

If needs be you could fairly easily put together a test rig, and then see what was actually happening when assembled.

 

[Davren]

So I bought a metal one for a rainy day and that day has come. But on removing the old one, the new metal MC plunger is too long and won't fit. Looking back at the listing, it states 'LHD'. A few others for sale state this and generally they ALL look this long, apart from Shop for Parts which (for the 2.4) is the correct length, but it's the usual plastic one. Mystery (2) then, is it just the 2.4 MC that is short, or is it shorter on all RHD's?

For all Stilos, the LHD (Left Hand Drive) clutch cylinder rod is longer that the RHD version. It's because of the location of the clutch pedal, and therefore the cylinder, within the car.
.

 

[jonti]

Bit unclear from the photos, but by saying Plunger you mean the piston and not the operating rod ?, If it is the piston then the cylinder will most likely be different, and probably the orifices will be in different positions, and it wont work. You don't say exactly why you can't fit the later one in its entirety, but if it's fouling against something, can you move whatever that something is ?

If it is the operating rod then as long as the end which contacts the piston is the same, I see no reason why swapping them would be an issue.

If needs be you could fairly easily put together a test rig, and then see what was actually happening when assembled.

the operating rod of the metal bodied replacement MC is longer than the Valeo OEM type MC. So the new one won't work at all, as the rod needs to be the correct (valeo) length to fit between the bulkhead and the pedal. your suggestion of a test is a good one, as I steamed ahead without testing the metal body/valeo rod combo. When the pressure bleeder quickly lost pressure, i realised the contents of the brake fluid resevoir were now in the driver's footwell :-o

 

[jonti]

For all Stilos, the LHD (Left Hand Drive) clutch cylinder rod is longer that the RHD version. It's because of the location of the clutch pedal, and therefore the cylinder, within the car.
.

Thanks for this. So much of the non-Valeo stock for sale appears not for the UK Stilo, as they show the LHD (longer) version.

 

[aschiuta]

the operating rod of the metal bodied replacement MC is longer than the Valeo OEM type MC. So the new one won't work at all, as the rod needs to be the correct (valeo) length to fit between the bulkhead and the pedal. your suggestion of a test is a good one, as I steamed ahead without testing the metal body/valeo rod combo. When the pressure bleeder quickly lost pressure, i realised the contents of the brake fluid resevoir were now in the driver's footwell :-o

Why you dont cut it to the right length for RHD version?

 

[jonti]

Why you dont cut it to the right length for RHD version?

This will be the only way, other than buying the Valeo version. This can only work by cutting a section out and rejoining them, as you need the bobble at the end of the rod that fits into the pedal.

 

[jonti]

I ordered another Stilo master clutch cylinder and this was turned up. From Davren's info. above, it looks to me as stock is now LHD master cylinders which are too big for UK cars. I cut the length down by 9.5cm. Initial signs were good with a firm pedal, but no reverse. Then the pedal went flat, so I'll try again tomorrow. Dry in the footwell though, so no Rug Doctor machine this time, although the hall carpet got a clean as well as the Stilo......

 

[Maxcaddy]

Doesn't look that there's any logical reason why it won't work. Not sure why one push rod couldn't be swapped over for the other, but you've done a tidy fix, so fingers crossed .

 

[jonti]

Doesn't look that there's any logical reason why it won't work. Not sure why one push rod couldn't be swapped over for the other, but you've done a tidy fix, so fingers crossed .

The rod in the plastic Valeo one (which is UK size) is retained using a plastic clip. The metal bodied cylinder (not UK size, too long, but metal may cure my issue) retains the rod with a snap ring. I tried to combine them, but the fluid leaked out the end. Had I not reused the snap ring, perhaps it might have worked, but they are slightly different in detail, including the integral piston.