A80 (1983) Master Cylinder ?
 

http://i23.photobucket.com/albums/b3...Picture021.jpg

I've been ill since before Christmas so haven't had a chance to do anything to the cars. Just checked the timing belt on the Audi today and it's ok for now.

Took it out this afternoon and remembered how much fun they are to drive.

The brake pedal sinks if pressure is held on it for more than a few seconds (not all the way to the floor). It stops the car ok, the servo is working fine, but I suspect it might need a master cylinder. Are they still available, or does anyone know if any others (Golf ?) might be compatible ?
Can you get seal kits for them ?

If it's the master cylinder I think it is then eBay had a genuine one last week for £10 - I nearly bought it! Ebay is probably your best bet - I got a new one for 99p! It wasn't the right one for my car but was an Audi one - it fitted and works fine, just had to bend the pipes slightly.

http://cgi.ebay.co.uk/New-Lockheed-B...QQcmdZViewItem

Nice one. Thanks for telling me about that. Just did a buy it now.

Much appreciated.

I know it's a bit late but did you check it is compatible with your car? It should be okay but the one you bought may have a pressure switch for the brake light (which can be left unconnected if your car doesn't have one - generally used on earlier models). The other thing is that the brake resevoir on your 80 may have smaller lugs (bits which press into the master cylinder - the older resevoirs have larger lugs), I do happen to have a spare if you get stuck!

Well that was the quickest ebay delivery ever. It turned up yesterday while I was out. Looks like it's exactly the right one. I'll have to check and see if the holes where the resevoir fits on are the same. Got a few other odds and sods to sort out as well. There's a slight exhaust blow somewhere. It sounds like it's at or near the join from the downpipe to the centre section. The ground was too wet to have a look today, but I'm sure it will be a lot quieter when it's fixed.
I changed the brush pack / voltage regulator but it hasn't cured the slightly glowing alternator light problem. Think a trip to the reconditioners is in order.

Did someone on here say to check the engine earth strap ? I had a quick look for it today and didn't see one. I'll put a jump lead from the body to the block and see if it tells me anything.