Master Cylinder

[Adam Madrid]

Hi everyone,

My master cylinder is on its way out as the brake pedal is slowly sinking to the floor under moderate pressure. I've bled the system and thats fine so I've convinced myself its the cylinder. I have an old car with 250,000km on the clock. With the engine off the pedal is firm but with engine on it creeps to the floor with pressure. Driving is OK as I never hammer it around. I still want a firm pedal though.

My question is: How do I find out which master cylinder to buy? I go to lots of online shops and they have 10 or more that supposdley fit my car. A4 B5 quattro 2.5 tdi AFB engine.

Is there a code that I have to read on the actual master cylinder first? Or will any of the choices online do?

Many thanks in avance.

Adam.

 

[aragorn]

RHD or LHD?

ESP or non ESP?

Facelift or Pre-Facelift?

 

[Adam Madrid]

LHD, Pre facelift no idea if ESP.. How do I check that?

 

[Adam Madrid]

Im guessing no ESP as I dont have the button for it.

 

[aragorn]

you appear to need 8D0611021B then

 

[Adam Madrid]

Many thanks!

How do you find these things out? Is there a database or website you could share?

 

[aragorn]

Vagcat website exists but its somewhat out of date, and isnt always that clear as often the extra info field is missing. But its free and easy to use.

ETKA is the proper vag parts catalog program, you used to be able to buy disks on ebay, but they dont seem to be on there any more. You probably have to root around the bowels of the internet to find it these days.

 

[Avant1]

Did you bleed the clutch cylinder too ?

 

[Adam Madrid]

Not yet! But I will, thanks for the warning.

 

[Avant1]

Using a pressure bleeder . Opposite rear corner to the master cylinder then work your way to the mc leaving the clutch cylinder to last

 

[aragorn]

the clutch cylinder is completely seperate anyway, theres no way it can affect the brakes.

It uses the same reservoir, but thats it.

Still a good idea to bleed it thru ofcourse, but its not going to be the cause of a iffy brake pedal!

 

[Avant1]

Beg to differ Aragon ... Had endless issues with a soft pedal, changed the brake master , booster etc still no joy . Bled the system as above and resolved the issue . It's the last in a sequence and can cause problems

 

[aragorn]

Nonsense.

You could remove the clutch cylinder and throw it in the bin and the brakes would continue working fine. Infact, thats exactly what they do on Automatics, and guess what, the brakes on Autos work just fine.

The brake pedal is quite simply not connected to the clutch in any way, and its impossible for it to cause issues with the brake pedal.