MNDriver

I keep reading to replace the timing belt between 60-90k. Why does my manual recommend it at 104k if everyone else is saying 60-90k?

00A8

gondar

My own feeling is that low rev highway driving in a cool climate and high performance driving with harsh accel and decel inertia forces on the belt are very different, so milage is only one guide. Also the Audi has an unusual number of bends and rollers. A hard part can fail early. A little oil contamination might hurt belt life substantially too. I have dissected timing belts looking for failure markers and have not found much. Early Volvo 960s had a defective TB design with (I kid you not) at one point a 20K interval, increased to 30 after a rubber damper was added to the EXH cog. This was a Porsche design for Volvo. Problem was the long whippy 6 cyl cams generating stress peaks.

JimR

Great answer.