Pay particular attention to the "Pre-Load Idler", where it says 0-1mm.

That is the amount of deflection the idler should cause to the belt, and not the amount of clearance, so that idler should just be touching or slightly deflecting the balance shaft belt when properly adjusted, and .5mm off the belt/idler assembly below it.

I usually tuck a credit card under it to set that clearance, then I can just focus on the top one.

John, I think I've got that bottle...

I'm sure I did mine ccw so it would give me the right clearance on the idler. But as I age...

OP - Note that if the belt rides on the idler it'll whine like a hungry toddler with his pant full.

++++poop/plop http://forums.pelicanparts.com/support/smileys/wat6.gif

So when I put the balance pulleys on and align the marks the keys should be in about the 10-11 o clock position? Because that's what they're doing when I just put them back on.

Look at the picture in post 4--the pulley keys are at 12 o'clock (the little black squares on top of each shaft).

J_AZ

Yes but I believe the picture is rotated. There is no way that the key can be at 12 o'clock and the notches line up.

They will line up exactly as pictured if you follow the Clarks-Garage procedure.

Timing Belt and Balance Shaft Belt Installation

Both of my 924Ss ---BB many times removed and replaced---exactly as shown---notches at 12 o'clock.

J_AZ

Hmmm well I will try again. There just didnt seem to be any combination that would make it work.
Do the balance pulleys have different part numbers?

Note that each sprocket has 2 keyways and is stamped with an O and a U. Over and Under. You can't go wrong: keyways up, notch on sprocket aligned with timing mark. Have a look at the first pic posted in this thread.

What can happen is that rotating the tensioner can pull the bottom sprocket out of time. If so, you can gently slip it one tooth or so back I to time, or compensate by installing the lower out of time and pulling it into time as you rotate the eccentric tensioner.

My top tbalance timing notch is literally at 12 o'clock so how can the key be at 12 o'clock too?

The notch is in the 12 o'clock position
http://forums.pelicanparts.com/uploa...1382212808.jpg

Here this better explains my problem.

This is the upper balance shaft. You can see that when the key is at 12 oclock, the notch is waaaay off.
http://forums.pelicanparts.com/uploa...1382214930.jpg

Same for the lower.
http://forums.pelicanparts.com/uploa...1382214958.jpg

Should I line up the notches or the keys? There is no possible way they can both be aligned

If that last picture is right, I think you have installed the sprockets on the wrong shafts. The one marked with an O should be on the top shaft (upper - Oberen) and the U should be on the bottom shaft (bottom - Unterste). Swap them around and perhaps it will all come good.

Both sprockets are exactly the same. Neither have a U on them either.

I have just been out to my old block and had a look. The upper shaft timing mark is at 12 o'clock, therefore the keyway cannot also be at 12, it has to be slightly counterclockwise (10 or 11). You appear to be right regards the picture in the PWM - it has been rotated clockwise a few degrees. If you look at the Clarks diagram - that shows a more acute angle between the shafts and is much closer to the actual reality of a fitted engine. The rule is the keyways must always be up, but they cannot be at exactly 12. However, the notch on the upper sprocket will be.

Yes, some later sprockets did not have a U stamped on them, they used the thin metal cover with holes in to identify the sprockets. On the upper one the O appears in a nice large round notch and two pin ways are also clear. On the lower the O appears in a rectangular slot and the other two pin ways are clear.

Here is a (grainy) photo taken from the PWM. It show the upper shaft, as you can see the O (visible in its nice round notch) is at about 11.

http://forums.pelicanparts.com/uploa...1382220973.jpg

Hope this helps.

Have a read of Clarks ENG-08, they discuss the sprocket id issue and the problems that can occur due to Porsche not stamping U on them..

You're over-thinking this. Keyways up, rotate to align notches on belt install and done. In your pics you look fine. Just align the timing marks.

Mike, here's a link to Youtube video series that goes through the entire process and should clear up any questions you may have. I hope this will get you back up and running in short order. Good luck

Porsche 944 Timing Belt Replacement - YouTube

Thanks everyone.

I ended up just putting it back together with the keys up as far as possible and it works perfect so I'm not stressing it anymore!

^^^ Result - nice one Mike..:):):):)