The vacuum hoses nn both of my A4 (1996 2.8, 1998 1.8T) feel brittle.
They both show good vacuum (I think), at idle 25mm on the 1.8T, 20mm on the 2.8.
But the cloth layer disintegrates when touched, the inside rubber feel flimsy to say the least (pushing them onto the nipples is almost impossible because they are so wiggly).

I would like to start replacing all those hoses.

What material do I need to get?
- specs (ID, OD, wall, other)?
- sources?

Are both cars using the same?

 

http://www.ecstuning.com/Audi-B5_A4-...Hose/ES250319/

That will work for both cars, and you'll never have to worry about replacing it again. Just do one hose at a time so you don't get confused about what goes where. Pull one off, cut a length of silicone hose to match it, and replace it. This was one of the first things I did to both my A4's. Just a bit of insurance against vac/boost leaks

 

Chris, do you remember the i.d. Of the lines?

 

Looks like 3.5mm is the ID, 2.0mm the wall.
There are several online place (including ebay) that offer 3.5mm ID silicone (NOT for fuel or oil), but with larger wall (which I like much better than the 2.0 from ECS; price shipped (10ft) is around $20 (ebay cheapest 3mm wall is $17 shipped for 10ft).

Some sources ("specialty" i.e. German parts) also offer the cloth braided (wear) OEM style (high price, ca. $5/ft).

http://www.germanautoparts.com/Hardware/Hose has both at average price.

While ordering hoses: what other hoses/diameters should I get as a precaution (shipping cost)? 5mm? Fuel (rubber) or air (silicone)?

 

Update: I had ordered some silicone 3.5mm line. Worked good, but not as flexible as the original material (can be an issue with the spaghetti pile on top of the TB when sharp radius' are required). Kept searching and go my hand on a good chunk of the original German (Contitech) braided rubber 3.5 x 2 mm lines (paid $1/ft plus shipping).

If someone is in need, PM me with how much you need and zip for shipping (until I run out, naturally).