Here's the summary I put together of some of the key things to look out for when changing the belts:
I just finished my belt change a few days ago. Here are a few pointers to help make the job go more smoothly:
1. Go ahead and unplug the fan motor connectors, and remove the fan. This will give you a lot more room to work.
2. To set the engine at TDC in cylinder No. 1, remove the rubber cap on top of the distributor, then rotate the engine clockwise by hand until the mark on the camshaft sprocket lines up with the notch in the back belt assembly cover. Then, go to the back of the engine, and on the drivers side, look for the opening in the top of the bell housing. There should be a mark on the flywheel that is visible. If you car doesn't have the window on the distributor, I would go ahead and remove the distributor now, since you're going to have to do that anyway, to ensure that you're at TDC. The rotor should be pointing at about 11:00 oclock, iirc, at TDC.
3. With the engine at TDC, the "O" that's stamped on the upper balance shaft belt sprocket that's peeking through the oval-shaped hole in the cover should be on the top half of the pulley. Then, get a mirror and look at the bottom half of the lower BS sprocket. The "O" on that sprocket should be peeking through a rectangular opening on the bottom half of the sprocket. And of course, the indents in both sprockets should be pointing directly at their respective marks in the plastic housing behind the belt assembly.
4. To remove the timing belt, you have to remove the tensioner. To do this, you have to remove the chrome-plated guide that sits along the bottom of the belt, which is held in by four M6 bolts. You also have to loosen (but not necessarly completely remove) the few bolts in the vicinity of the tensioner that hold the plastic back cover for the belt assembly. Doing this will allow you to pull this cover foreward, which will allow you to maneuver the tensioner out.
5. When installing the timing belt, it should be pretty tight on its upper run, which extends uninterrupted between the camshaft sprocket and the crankshaft sprocket. With the belt positioned correctly, you should count 48 belt teeth between the cog on the camshaft sprocket that sits immediately to the right of the mark on the cam sprocket, and the cog on the crankshaft sprocket that sits immediately outboard of the "105" part number that's stamped in the crankshaft sprocket. In order to get this to happen, you will likely have to slightly rotate the camshaft sprocket clockwise, just enough to move the belt over by one tooth relative to where it want to naturally lay. You will have to overcome to retaining force of the valve springs to do this, and the sprocket will snap back into place after you're moved the belt over. Bulti told me he used a tool he had fabricated to hold the pullies in place while he was turning the M10 bots that hold them in place. I fabricated a tool from some hardware I had used earlier for a different purpose. You may have to get creative, but you will need to figure out some way to rotate the cam sprocket enough to move the belt over by one tooth relative to how it wants to sit if you just lay it in place, as this will leave too much slack in the belt, and will throw your cam timing off. For me, this was the trickiest part of the job - thanks to Bulti for explaining the need to rotate the cam sprocket, and to Porsche96G for confiming the 48-tooth count.
6. Remember that when setting the balance shaft belt tightness and clearance between the bottom of the idler pulley and the pulley below, that the spec for the location of the top of the idler pulley relative to the BS belt is a deflection, not a clearance. It calls for a 0.1 mm deflection, which is way to small to measure accurately. Just make sure the BS belt is slightly in contact with the top of the idler pulley.
The rest of the steps are pretty straightforward. Good luck with the job, and post or IM if you have any questions.
