[s-cars] (s-cars) UrS4 slave cylinder

[trgreen at comcast.net]

The FAQ at the top of the UrS4/6 forum on quattroworld.com has what you need for instructions, Mike.  I  believe you will find enough details to just send him there to read.  If he is tall enough or uses a stand he can reach the slave cylinder on the bellhousing side from the engine compartment.  Removing the line from the cylinder will let the fluid run out so a container should be available and some Dot4 fluid available for replacement.  The bolt retaining the cylinder is easily visible at the back end of the cylinder.  I have also seen some guys put a plug on the new cylinder to close off the port for the line before installing the cylinder.  This allows you to depress the piston and then put the plug in place to create a hydraulic lock to keep the piston depressed.  Otherwise you must depress the piston when pushing it into place straight in the access hole and holding it to install the bolt.  Bentley recommends a new bolt but I think you can get by without a new one if the old one is in good condition. 

You can take the new  cylinder to an auto parts store to fit a plug.  It should be the same as a brake line fitting. 

There is a flexible section of this line that should be inspected also.  If you have loosened the bleed port before installing the cylinder it should be easy to open to bleed the system after refilling the brake fluid reservoir.  Gravity does most of the work here along with some pedal actuations, so no fancy technique is needed to get a good pedal and most of the nasty fluid will have drained on its own accord.