Brakes

[Will Caradoc-Hodgkins]

Took my car out for a cross London run to see daughter and after about an hour of stop go traffic my brake pedal kept going from normal to hard then i found that the brakes were binding?
Could also hear a hollow clunk sound from the near side servo when putting brakes.
I have fitted all new brake system some two years/5000miles ago.
I'm sure I read something about this phenomonon but cannt recall where.
After lettig her cool down brakes were back to normal so managed to get home.
Any thoughts on this would be appreciated.
Cheers
Will

[Aldeburgh]

....."Took my car out for a cross London run to see daughter and after about an hour of stop go traffic my brake pedal kept going from normal to hard then i found that the brakes were binding?..."

Same thing was happening to my S3, and Harry has a similar but worse problem with his. He fixed mine but I cant remember exactly what he did with it... new servo or something. Seems a commonplace thing though.

[Heuer]

If it is anything like the S1 system the servo is likely to be OK but the reaction valve on the end of the master cylinder may be suspect. This tends to fail and leave the brakes locked on. Are you having to top up with brake fluid? Any puffs of white smoke from the exhaust? If so it is going into the Reservac. Best bet would be to replace the entire master cylinder although I have no experience of the S3 so others may have a different view. Be aware it will eventually leave you stranded with the brakes locked on although you can release them by opening the bleed valve. Safer to get it fully checked over.

[Will Caradoc-Hodgkins]

Well got a new brake reaction valve repair kit,?20, from SNG so will fit today and see what happens.
We will see