Clutch pushrod broken.

[JEK]

Haven't heard of this before.......

My daughter and son-in-law, who also have a ZT-T CDTi, pulled up out side our house yesterday. When the clutch pedal was depressed to take it out of gear, the pedal went totally down to the floor.
Result....No Clutch.
I checked it out only to find that the pushrod from the clutch master cylinder had broken at the pedal shaft. It looks as though it is a round plastic end which goes over the shaft as I found half of it lying on the floor.

So, anyone know if you can fit just a replacement pushrod and, if so, are they different...i.e. petol, diesel??

The clutch had been working well prior to this so I think it's down to the pushrod only.

[HarryM1BYT]

So, anyone know if you can fit just a replacement pushrod and, if so, are they different...i.e. petol, diesel??

The clutch had been working well prior to this so I think it's down to the pushrod only.

I was examining that a couple of weeks ago, mine is worn on the pivot hole in the plastic. As near as I could tell with it still in place, it is a molded onto the shaft part, the shaft is also fixed into the master cylinder, so no obvious way to replace it apart from swapping the complete master cylinder.

[JEK]

I was examining that a couple of weeks ago, mine is worn on the pivot hole in the plastic. As near as I could tell with it still in place, it is a molded onto the shaft part, the shaft is also fixed into the master cylinder, so no obvious way to replace it apart from swapping the complete master cylinder.

That's a bit of a bummer then!
Imagine making the thing of plastic?
So, it's a whole new master cylinder just to replace the pedal pivot!
What a hassle.

Thanks for the response, HarryM1BYT. Much appreciated.

[HarryM1BYT]

That's a bit of a bummer then!
Imagine making the thing of plastic?
So, it's a whole new master cylinder just to replace the pedal pivot!


It seems so.....

I would actually like to get my hands on an old master cylinder, just to see if the push rod end could be taken out, the end threaded, then the plastic part replaced with something more robust made from brass.

[T-Cut]

I would actually like to get my hands on an old master cylinder, just to see if the push rod end could be taken out, the end threaded, then the plastic part replaced with something more robust made from brass.

I knew I'd seen photos of a dismantled master cylinder, so after searching through the forum archive I located some images by Gerfix. Here they are:

http://i245.photobucket.com/albums/gg46/gerfix/Component-Parts.jpg

http://i245.photobucket.com/albums/gg46/gerfix/Disassembled.jpg

Now it seems to me that the pushrod is floating in the end of the piston. It appears to be located in the yellow end piece, so it may be just a push-in fit. I suppose the rod could be threaded to fit a more robust eye, but the overriding problem with these units are the seals. Would it be really worth the effort?

TC

[Brek]

PM me your address I'll post you one, I have one spare.

[JEK]

PM me your address I'll post you one, I have one spare.

Brek,
Thanks so much for your kind offer.
Unfortunately, the son-in-law has decided that he is just going to have to get a new unit as they are going up to Scotland on Friday with the car and he won't have time to strip down his cylinder to replace the push rod.
I assume that your's was from your V6.
The difficulty could be that if he doesn't get the seals back in to the cylinder correctly, he could be back at square one.
Thanks again. the offer was nuch appreciated.
JEK

[Brek]

no worries, I took mine apart to have a look at it for future reference, not sure if there is any issue reassembling or not as not qualified although I fitted one out of a scrappy myself.

[HarryM1BYT]

PM me your address I'll post you one, I have one spare.

I would appreciate that if that would be OK?

I'm wondering if it might be possible to fabrication some brass to replace the plastic part and maybe see if I can source some replacement seals from somewhere.

[Brek]

yeah thats cool harry, pm me were to post it. I have two spare master cylinders from scrappies for £20 each :D so they will see the car out I imagine, the one I removed originally is surplus so it might as well go to a good cause.

[HarryM1BYT]

yeah thats cool harry, pm me were to post it. I have two spare master cylinders from scrappies for £20 each :D so they will see the car out I imagine, the one I removed originally is surplus so it might as well go to a good cause.

PM sent, thanks.

[HarryM1BYT]

Brek's faulty item turned up today. No sign of any obvious problems, other than some obvious wear on the plastic eye pivot on the right hand end of the pushrod in the picture - the same pivot wear which mine is suffering from, but no leaks on mine or other issues.

How it works...

The main barrel of the piston is hallow and has a small hole at its mid point between the two seals at either end. The hole allows for the admittance the fluid from the 'tank', when bleeding it or to make up for any loss of fluid in the pressure side.

On the left of the cylinder is a one way valve (the small black peg + spring + white cap). The valve opens to allow fluid to fill the pipe on the pedal up stroke, then seals on the pedal down stroke.

Only the left hand seal (lets call it the high pressure seal, the dark grey ribbed area) and the above valve will come under any pressure as the pedal is depressed. The seal at the left hand end of the piston only seals against oil at atmospheric pressure.

The bellows shape on the actual pushrod on the right, is the dust seal.

The pushrod has a ball joint at its left hand end, which locates in a socket on the piston end, the white plastic part on the piston's end. The pivot eye is molded onto the end of the pushrod, where it attaches to a peg on the pedal.

From the above, there can be several possible failure modes of the master cylinder.

1. Failure of the valve to seal on the downstroke.

2. Failure of the high pressure seal.

3. Failure of the low pressure seal

4. Wear on the plastic pivot eye on the very end of the push rod or actual breakage of the plastic.

Failures 1 or 2 will result in the pedal being pressed and the slave/clutch not being released properly, or the pedal going down and staying down, due to lack of back pressure from the clutch, with no signs of any leakage.

3. Will show up as fluid steadily leaking out via the bellows shaped dust seal.

Wear of the eye as in 4, will show up as some lost motion as you press the clutch and the released clutch pedal being higher than the brake pedal. You press the pedal and there is not much resistance for some distance. Note that even the new items are bound to have some small amount of play in them.

My clutch pedal has around 1" of free play, which means I am probably loosing around 1/2" of clutch movement with the pedal fully depressed. It is not causing me an issue, other than the strain of having flooring the pedal when changing gear.

http://i245.photobucket.com/albums/gg46/gerfix/Component-Parts.jpg

http://i245.photobucket.com/albums/gg46/gerfix/Disassembled.jpg