Audi b9 clutch

[Sid2020]

Me and my Audi clutch are not friends, back story is the clutch friction plate exploded taking out several hydraulic lines, new clutch/ pressure plate, concentric cyclinder and new hydraulic pipe fitted, gearbox removed again for seal to be fitted into concentric slave cyclinder that Audi don’t fit into replacement part and took 3 days to even find in there system, all good for a few months then master cyclinder failed, 14 months later clutch delay valve leaking and master cyclinder won’t bleed due to check valve fault which is a design fault in these master cyclinders, I’m looking for info on the cable that bypasses the clutch delay valve a few members have fitted or even better a braided line from master to slave cyclinder 

[Sid2020]

Sourcing hydraulic hose at this time of year has failed so reassembling it tomorrow, have replaced the main seal in the master cyclinder and fitted a new check valve which is the cause of not being able to pass fluid past master cyclinder and thus preventing bleeding, got the seals by ordering a LHD version at fraction of the price, everything seems a exact match except length of the push rod but this part is not being used. Il be bleeding with a pressure bleeder and will repeat a few times giving the peddle a good work out in between bleeds. Il update on how this goes

[Sid2020]

LHD version v RHD, longer is LHD 

[cliffcoggin]

Why would one push rod be longer than the other? Is the floor pan a different shape on either side?

[Sid2020]

My only guess is that as the Clutch pedal would be against the A pillar instead of the transmission tunnel so it must be mounted differently, the master cyclinder twists into a alloy bracket  bolted to the firewall/bulkhead from what I can see so is likely this would be different for LH and RH drive cars 

[Steve Q]

Keep us posted on how you get on. Doing great work so far. 

[Stevey Y]

On 12/22/2024 at 8:18 PM, Sid2020 said:

Me and my Audi clutch are not friends, back story is the clutch friction plate exploded taking out several hydraulic lines, new clutch/ pressure plate, concentric cyclinder and new hydraulic pipe fitted, gearbox removed again for seal to be fitted into concentric slave cyclinder that Audi don’t fit into replacement part and took 3 days to even find in there system, all good for a few months then master cyclinder failed, 14 months later clutch delay valve leaking and master cyclinder won’t bleed due to check valve fault which is a design fault in these master cyclinders, I’m looking for info on the cable that bypasses the clutch delay valve a few members have fitted or even better a braided line from master to slave cyclinder 

Hi for what its worth I had this problem over about two years, multiple master cylinder changes multiple brands of cylinder, finally cracked it as it was all about the fluid used, I was of the opinion that all DOT4 was the same, ITS NOT, finally settled on Comma ESP 4 and a new LUK cylinder along with a complete flush of the braking system with Comma, gravity bled the clutch slave cylinder with a auto fill top up bottle and two years and 80k later no problems with the clutch pedal hitting the floor first thing in the morning, an oil/fluid technician I spoke to said that the cheaper brands of DOT4 contain an acidic compound which causes the seals to degrade and wear and in his opinion the Comma is as close to genuine Audi fluid as you can get.

Steve.

[Sid2020]

Great tip Steve thank you, il be off out to  get some before I start, looking back this makes so much sense, when I replaced the clutch the original master bleed fine but failed a few months later, replaced with Audi unit, gradually developed a dragging clutch and couldn’t bleed thru the master either direction, replaced with febi unit and exact happening again, pulled 2 of the failed units apart and what was obvious is that the rubber in the check valve had swelled preventing fluid from the reservoir entering the cyclinder piston, it was trapped behind it. this clearly didn’t happen to factory installed unit with 90k until I replaced the clutch and used different fluid and have continued to use different fluids since 

[Sid2020]

Master cyclinder fitted today, syringed out most the brake fluid in reservoir to save mess and also just normal Dot 4, pressure bleed using Comma Dot 4 esp/Lv fluid so time will tell now, got a few pictures of the mounting plate incase anyone benefits from them 

[Stevey Y]

18 hours ago, Sid2020 said:

Master cyclinder fitted today, syringed out most the brake fluid in reservoir to save mess and also just normal Dot 4, pressure bleed using Comma Dot 4 esp/Lv fluid so time will tell now, got a few pictures of the mounting plate incase anyone benefits from them 

Hi as per my conversation with the tec he reckons that VAG changed their seal compound back in 2010 as they were getting too many warranty issues, the seals are a mixed compound using Neoprene to aid longevity but this is prone to a reaction with the other types of fluid on the market which is why they always demand you use manufacturer brake fluid, it wont cause the degradation, I did think at first that I was the only victim of this but then my daughters Q3 had the same problem within a year of having a new clutch both clutch master cylinder  and slave cylinder were knackered, had a chat with the garage that had fitted the clutch and just slipped in what brake fluid do they use and they showed me a bottle of silver hook fluid, just about the cheapest universal yo can buy, got it back to mine and changed the master and slave cylinders, no small effort at my age even with the aid of the son in law, we bled the brake circuits as well with ESP4 and touch wood no problems for the last six months, gravity bleed in g is the best method once you have a pedal allow it to settle and just crack the slave cylinder bleed off with no pedal pressure and watch all the little bubbles come out they tend to congregate in the slave cylinder and then as air rises try and go back up the pipe towards the reservoir, I also got caught out by the radial seal in the slave cylinder and had gear oil leaking out of the bell housing which contaminated the driven plate so I had to buy a new plate Driven and Pressure, their other favourite leak is engine oil from the seal behind the ring gear, rear crank seal and thats a real mission as it has the crank sensor pick up attached to it.

Steve.

[Sid2020]

Thank you for sharing your knowledge and experience Steve, my pedal feels a lot better this time round, Just hope my slave cyclinder has survived the misadventure as don’t fancy taking the box out again. When my new clutch got covered in gearbox oil a old friend advised soaking it in full fat coke for 10 minutes to clean it, seems to have worked as that was 18months ago and of all my problems,  slipping hasn’t been one 

[Stevey Y]

2 hours ago, Sid2020 said:

Thank you for sharing your knowledge and experience Steve, my pedal feels a lot better this time round, Just hope my slave cyclinder has survived the misadventure as don’t fancy taking the box out again. When my new clutch got covered in gearbox oil a old friend advised soaking it in full fat coke for 10 minutes to clean it, seems to have worked as that was 18months ago and of all my problems,  slipping hasn’t been one 

Hi the Coke is a good shout, that works on blocked DPFs god only knows what's in it or what it does to your innards when you drink it, my original replacement would have probably worked after cleaning but it then got another coating of engine oil from the crank seal, considering that when the pressure plate is engaged the grip pressure is something like 5000nm it takes a lot to get them to slip, ran my car over 278k so a lot of the problems I have ever had you probably wont ever experience, low pressure EGR coolers and the valve that sits on them are another mission but this can be avoided by using regular dosing of Wynns or Dipetane EGR cleaner as these have a Hydrocarbon rich formulae, Hydrocarbon by nature absorbs a lot of moisture which then burns with the Hydrocarbon.

Steve.