Megane R26 slave cylinder broken again

[Martin Watson]

anyone have any suggestions on this, my 2nd slave cylinder has failed after around 1000mls, first one lasted around the same, it failed on my first of 2 days at spa, so pretty pissed off with it now, i feel there has to be an underlying problem, i'm running an SMF and R clutch,and SRF fluid, i don't want to get it sorted for it to fail again, both slaves were genuine Renault.HELP
Ive been told that @Red21 may have some suggestions, any help would be much appreciated.

Bit of background on the car, i sold my mint R26.R as i didn't want to keep hammering something that nice on track 5 or 6 times a year, i bought a rather nice GW R26 from a lad on RS megane, its had a 250 turbo, decat, milltek, ktec induction kit, 630 injectors, SMF and .R clutch, AST 5100 suspension, fitted and setup at AST, carbon bonnet, ktec bolt in cage and a nice brake upgrade with 250 callipers,mapped by Paul, 300 & 300, it goes and handles just how i want it now, just need to get to the bottom of the slave cylinder problem, i'm waiting for it to be recovered from Belgium, its going straight to Mark Black so he can strip it and have a look, thats 2 slaves in less than 2000miles!

 

[Red21]

Have you got any pictures of the first failed cylinder as need to know if it is ball bearings failure or fluid leakage, & also the clutch assembly.

I have seen on an Espace where the DMF was replaced with a SMF & clutch kit and suffered repeated slave failure. This was due to the overall height of assembly being too small which allowed the slave move just a few mm to far past it's operating range and thus damaging the seals.
The only option was to fit a DMF and correct clutch.

Another possible cause is crank shaft end float due to worn thrust bearings, but this is generally associated with selection problems, noises and other issues but it is still worth checking.

There are other possibilities but I will wait until I see some pics.
Rich

 

[Martin Watson]

Its still in Belgium at the moment, gearbox engages gears really nicely, no funny noises, i'll send a few pics once its off and take it from there. I'll get the bearings checked when its off.
Cheers for the reply, i'll keep you posted.

 

[Red21]

This is going to be strange, but I have been speaking to a friend/fellow competitor who have a Megane 230 in their workshop that has also suffered a slave cylinder failure a year or so after having a SMF conversion.
There could be other factors involved but it's odd.

 

[Duncan Grier]

Agree with Rich on things to rule out but with another separate case I would be measuring oem setup v the smf

DG

 

[NJH]

You see its when I read posts like this I am glad I had a new standard clutch and slave cylinder fitted to my R26 this week.

Mind you the bite point is amazingly low on this new clutch, its got me thinking if the clutch hydraulics need bleeding again as I am tending to push the peddle all the way down often till I can feel the end stop. It has a strange squidgy feeling at the top of the travel which feels a bit odd to me. The explanation given above by Red21 sounds very plausible in those terms.

BTW inspecting the old cover plate confirmed what I felt was helping mine to slip, one of the finger springs had broken off and 2 more where bent away. Seems to be common place these days for manufacturers to spec cover plates that are weak and don't last.

 

[DaveL485]

This was due to the overall height of assembly being too small which allowed the slave move just a few mm to far past it's operating range and thus damaging the seals.

Thats a very good call Rich. Can the slave be spaced forward a little?

 

[Martin Watson]

there are loads of people running the same setup as mine with no problems, what could cause the height issue?

 

[Red21]

there are loads of people running the same setup as mine with no problems, what could cause the height issue?

It could be a variation in production tolerance of either flywheel or clutch assembly especially if they are supplied by two different manufacturers and not developed as a complete set up.
Just to put a spanner in the works (no pun intended) but thinking what else could cause a similar issue is cracking of the gearbox casing around the slave mounts.
It's a long shot but if the pressure/cover plate is uprated to much the extra strain may crack the case allowing movement in the wrong direction.
I think we need to wait until the box is out before we speculate any further.

 

[DaveL485]

Is your pedal significantly heavier on the new clutch? Just wondering if there is increased strain on the system with the stronger clutch. Again, long shot and unlikely. I'd defo be looking at what Rich suggested first.

 

[Martin Watson]

not any different to the standard DMF, it'll be getting a good going over until we know whats causing it, cheers for the reply's and help.

 

[DaveL485]

not any different to the standard DMF, it'll be getting a good going over until we know whats causing it, cheers for the reply's and help.

Really interested in how this develops, please keep us updated. My money is on the over-extending slave.

 

[Martin Watson]

Just got to get the car back from Spa now, cover is with kwik fit who have just told me it may take 3 weeks!, i'll be going to get it myself, expecting a call back as I've just told them that won't be happening.

 

[andybond]

Which slave are you using @Martin Watson ?

 

[Martin Watson]

OEM valeo one, both times.

 

[andybond]

Its it splitting ? Leaking or just not working ?

 

[Martin Watson]

when the first one was taken off, it had split, i assume this one will be the same.

 

[andybond]

How was it bled when changing ?

 

[Martin Watson]

It was filled with fluid before fitting then the usual pump pedal like mad with the bleed valve open, it did need a lot of bleeding, but was fine before it failed, there is no warning, pedal goes to floor and thats the end of that

 

[andybond]

No chance its air in system ? Worth trying a reverse bleed ?