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Clutch pedal-loss of hydraulic pressure when hot


jon beer

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Hi there, i've owned my 2995 Z, with 48,000 miles on the clock for about 5 months now. I rather stupidly let my son drive it a while ago, he was revving the engine too hard, even reversing to turn around, and after about twenty mins hard driving, and another high revving reversing episode, the clutch got very hot, smelt hot and smoke was seen!!

the clutch peddle was not returning, only bout halfway, i had to get my toes behind it to get back where it should normally be, but it did get us home.

The next morning, after cooling down, it was behaving normally, and has done for quite a while now, until yesterday, a very hot day, i noticed the symtoms returning. I think i am losing some hydraulic pressure when it gets hot, maybe through a seal or two, hopefully slave cylinder! The clutch itself is not slipping, which i reckon is good news, i am wondering if any of you guys have experienced anything similar??

Any comments would be greatly appreciated, Thanks. :)

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If your Zed is the model with the slave cyl. on the outside of the gearbox, and not the internal concentric slave, then I would recommend the following.

 

Replace the rubber hydraulic hose with a braided one and swop out the slave cyl.

Flush out the old fluid which will now be boiled and bleed as required adding new fluids.

 

Slaves, lines and fluids all in stock and good to go same next day.

 

Alex.

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I had exactly the same issues, it was the master cylinder on mine although I only discovered that after changing the slave first. Change both and be done with it, the clutch bleeding is a real PITA and is what takes up most of the labour time so that's what you really want to minimise IMHO.

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  • 11 months later...

I would just like to add to this for the benefit of other searching the web and stumbling in to this old thread...

 

Never confuse dot 5, with dot 5.1 - dot 5.1 belongs to the same family as dot3&4 and they're pretty much totally interchangeable

DOT 5 IS NOT GOOD don't ever use it unless your absolutely sure you know that it's right.

 

DOT 5.1 is aka SuperDOT4! it is your regular mix of glycols and glycol ethers (as in DOT3) but has more chemically complicated (or just MORE) additions of borate esters which is what seperates DOT 3 and DOT 4.

 

 

 

 

I change clutch/brake fluid at the same time as my oil, and although I don't notice them degrading, they always feel very noticeably more firm, sharp and full after fresh fluid.

 

I'm doing the brake fluid on the Zed I've just recently bought in the near future, I changed the oil when I got it just as a precaution but after this hot French weather today (30-32°C) and 10kms of stop start traffic, the slack in my pedal got greater and greater till I was literally not getting any action till the pedal was an inch and half off the deck! I checked the clutch fluid and its actually slightly BROWN in the bottom of the res. - this will take a few weeks to flush. Brake fluid looks clean as a whistle but what the hey it's cheap enough. DOT 5.1 for me, not that I even need it - DOT 3 would do for me I'm sure.

 

As some of you will already know, new Silicone Ester based fluids have been developed (by Castrol) that ARE miscible with dot3/4 (so I'm told, dont take my word for it!)

They have a minimum dry boiling point of 310°C as opposed to 260°C of DOT5 & DOT5.1, and 230°C of DOT4, 205°C of DOT3.

Read in to Castrol SRF if you've not heard of it and are really looking for an edge (it's patented so you won't find it else where, and since they developed it and its new, would you trust anyone else?) You'd have to check all the compatibility and read all the bumpff I've never (after 8 years of racing) run in to any issues with regularly changed dot 4 (twice a season).

 

Anyone here know anything of this fancy SRF?

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I'm doing the brake fluid on the Zed I've just recently bought in the near future, I changed the oil when I got it just as a precaution but after this hot French weather today (30-32°C) and 10kms of stop start traffic, the slack in my pedal got greater and greater till I was literally not getting any action till the pedal was an inch and half off the deck!

How odd, it was in France for LM a couple of years back that I had my clutch issues, and it was the master cylinder. I still say change both master and slave together.

 

As far as brake fluid goes, I've used the Endless RF650 which has an even better spec than the Castrol, and whilst it's ridiculously expensive it's also the best stuff I have ever used in my life. I wouldn't use anything less any more given the choice, although I do appreciate that for 90% of people something like the Motul PBF600 would be enough of an upgrade too for much less.

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  • 1 month later...

Have a look under the passenger side (if it's a right hand drive)

Your looking for the bit I have circled on the gear box if you have this then it is the external type if not it will be the internal :)

 

Clutchslave.jpg

 

some Zeds are not this colour underneath :lol:

 

 

I did the slave cylinder and changed to a braided line and new fluid on my last 350 sorted me out :thumbs:

 

:pmzmanalex:

 

for prices I'm sure he has them in stock and good to go :)

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The sooner you get the bitch up and running and stop being a complete picture whore the better :p I think Keyser is bored now :lol::)

 

Have a look under the passenger side (if it's a right hand drive)

Your looking for the bit I have circled on the gear box if you have this then it is the external type if not it will be the internal :)

 

Clutchslave.jpg

 

some Zeds are not this colour underneath :lol:

 

 

I did the slave cylinder and changed to a braided line and new fluid on my last 350 sorted me out :thumbs:

 

:pmzmanalex:

 

for prices I'm sure he has them in stock and good to go :)

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The sooner you get the bitch up and running and stop being a complete picture whore the better :p I think Keyser is bored now :lol::)

 

You try and be helpful and all you get is abuse!! :boxing:

 

I wasn't being a pic whore at all!!!!!

 

 

 

 

 

IMG_3507.jpg

 

 

 

how did that ^^^^ get here ?????

 

:lol:

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I set you up, you post pics :D I was wondering if you had any of the rebuild process..................................................... :surrender:;)

 

The sooner you get the bitch up and running and stop being a complete picture whore the better :p I think Keyser is bored now :lol::)

 

You try and be helpful and all you get is abuse!! :boxing:

 

I wasn't being a pic whore at all!!!!!

 

 

 

 

 

IMG_3507.jpg

 

 

 

how did that ^^^^ get here ?????

 

:lol:

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Hi - I had a knackered clutch on my 2005 45k miles roadster and a dropping pedal when hot. I had the clutch and twin mass flywheel changed - £1k later - the clutch was good but the pedal still dropped when hot. I got a Hel braided hose for approx £20 and replacement fluid - job done. Mr Clutch in Basingstoke didn't charge for fitting the hose and replacing the fluid. Good service. :D

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