I thought I should just point out that certainly with regard to the ABZ engine there is a very important stage in the procedure that I have laboured over many times and lots of people do not grasp it;
Replacing the timing belt requires special locking equipment for the cam shafts, these bolt to the rear of the cylinder heads and hold the cams in an exact position. You then have to undo the cam pulley bolts (you must counter hold the pulley to undo the bolt not let the cam locking equipment take the load, damage will result!) Then you have to "tap" them with a dead blow hammer (special plastic mallet) to release them from the taper, them set the pully bolts to half a turn back from just touching the pulleys. Once you have fitted the belt and tensioners then you re-torque the pulley bolts (again you must counter hold the pulley whilst you tighten)
What this is actually doing is reetting the position of the pulley to the correct position, this is required as they are on a plain taper and they slowly "creep" round slightly out of time.
Whats wrong with that you ask? well when you fit a new belt without following this procedure the problem is made worse as the new belt is not stretched and the slight slippage (creep) now becomes an issue. On the Alfa Romeo V6 this is often the kiss of death just after the timing belt has been changed but these are much closer running than the Audi A8 ABZ V8.
My point is that universal pulley locking tools should not be used and this important step in the procedure skipped.
"If ignorance is bliss then it is folly to be wise"
An excellent procedure is available at
www.audipages.com
Incidently I do have these tools but they cost me £500 , if anyone would like to use them I may be willing to come to some arrangement.