Audi RS2 timing or belt question

[twoqu]

Yes, my theory is that the relationship between the key position and the timing mark is the same on both pulleys but because they wanted to change the installed duration they timed it one tooth out and thats why the timing marks do not align. They may be other variables but I think one tooth is like 7 degrees so its not a precise guide.
To put the hall sensor aperature, the gap, back into the corect place they had to move it back, hence the RS2 B version. This because the Motronic uses this signal to determine the engine phase. The resident expert on here claims that its basically ignored after starting but there does seem to be some other function to it. My theory is that it is used to base some calculations on and therefore if its not in the correct position the calculations are incorrect.
I think there was an example recently on another members car where the position of the rotor effected the performance due to it not being in the position the ecu was expecting.
All this is purely academic really. As far as we know if it does not have the B stamped on the ring its not an RS2 one. All the rest of the components seem to be RS2.

[twoqu]

Read on from this page (Post 1364)to see how the position of the hall sender rotor can have effects:

http://www.s2forum.com/forum/showthread.php?t=34052&page=91

So it need to be in a plausible position according to what the ecu expects. Oviously that is a heavily modified example but the principle is the same.

[minim]

Yes, my theory is that the relationship between the key position and the timing mark is the same on both pulleys but because they wanted to change the installed duration they timed it one tooth out and thats why the timing marks do not align. They may be other variables but I think one tooth is like 7 degrees so its not a precise guide.
To put the hall sensor aperature, the gap, back into the corect place they had to move it back, hence the RS2 B version. This because the Motronic uses this signal to determine the engine phase. The resident expert on here claims that its basically ignored after starting but there does seem to be some other function to it. My theory is that it is used to base some calculations on and therefore if its not in the correct position the calculations are incorrect.
I think there was an example recently on another members car where the position of the rotor effected the performance due to it not being in the position the ecu was expecting.
All this is purely academic really. As far as we know if it does not have the B stamped on the ring its not an RS2 one. All the rest of the components seem to be RS2.

This is why I think I might have a RS2 - ADU pulley since It has a different offset on the hall window than the picture sowed earlier in this thread was fitted on AAN/ABY. This without having the "B" marked in the plate tho. If I didn't compare those two pictures I would not be hesitating it but after looking at them it's clear that it's not the same position of the hall window.

Read on from this page (Post 1364)to see how the position of the hall sender rotor can have effects:

http://www.s2forum.com/forum/showthread.php?t=34052&page=91

So it need to be in a plausible position according to what the ecu expects. Oviously that is a heavily modified example but the principle is the same.

Agreed with you then on the function of the hall sensor else he would not get that problem during gear change. But that was caused by a slightly offset sensor due to a wear on the cambelt so it had slack and made the cam go off position during gear change. I have the problem during acceleration with WOT. I now regret that I didn't capture a movie while I had the car running and tested the problem as it's a bit hard to describe. Once I get the cable tomorrow I'll do a check on the hall sensor as the first thing I do with it but after comparing those pictures I have a feeling that there might not be any fault codes.

Wish someone had a picture of a ADU pulley so I could compare the gap I have on mine to that one..

[twoqu]

Or it could be the altered perspective that appears to move the slot as one is at more of an angle!
We need to see a flat view from the rear so we can make a comparsion shot of the regular pulley. If someone has one for sale then perhaps you could ask for a pic. I think I have asked on here before without success.
Is it me or do the holes on the rotor seem to be in different positions. Unfortunately yours does not have a hole in the position that the other pics of the B pulley have but perhaps thats not a good indicator, unlike for example a big stamped B!
I'll check the few pulleys I have to see if they are all the same out of interest.

[minim]

True. I tried to take many pics from different angels without getting it exactly the same as the picture I had.. Almost impossible without having a picture shot straight from above.

They are in a different position yes. Mine is straight across each other. If I can't come to any conclusion I am tempted to just order one to be on the safe side and to take pictures to document the differences.

Do Audi technicians have access to CAD drawings of parts found in ETKA. I guess not but it would be a lot of help if it was possible to get access to something like that.

[twoqu]

Right! Both my pulleys have the holes in the rotor at approx 4 and 10 o'clock with the key position at 12 o'clock but the pic Dave supplied has them at 2 and 10 o'clock! Which is a bit odd as you would expect them to assembled on a jig to position them accurately so all the holes on the AAN/ABY should be in the same place. If I am not mistaken you pulley is also at the 4 and 10 o'clock position. If you want a better pic to compare yours to I'll get one. If everything is in the same place then we will have to assume its not an RS2 pulley I guess, unless we can obtain the same sort of pic for a genuine RS2 pulley!

[twoqu]

Is it me or does the pic Dave supplied from the rear an actual RS2 pulley? There does not appear to a B but the hole at 2 o'clock seems right as thats the one visible in the other pic from the front!
Thats why its appears to move bacause you are actually doing the comparsion between the different pulleys. See what you think.

[UrS4boy]

Now I have removed my cam sprocket and tried to take some pictures of it. It's hard to get the exact angle to compare but I made a short video of the first attempt here. It does look like I have a offset on the housing but the key and the mark on the wheel looks like it's at the same spot. Will work on a better picture for it. Edit: Sorry for not asking to use your picture first UrS4boy, I just came to think of it now. Please let me know if you want me to remove the movie from youtube again.

That video worked for me. You had the key and the timing mark the same on both sprockets but the shutter window moved (presumably 10 deg) between the two. Since the small hole also moved (10 deg?) I presume that the shutter wheels are identical *EXCEPT* they rotated it the 10 deg for the RS2 sprocket *BEFORE* the spot welding to the toothed belt pulley was done.

[minim]

Could you try to take a picture straight from above on one of them so I can re size them and make a overlay like I did in that video again just to see if key, mark and hall window match up? It would make it a lot more accurate to do it on a picture taken above without an angel like on the first comparison. If your pulleys are for AAN/ABY and my pulley match up to them I'll just grab a new one.

Another thing... they haven't made a change to the hall sensor and mounting plate afterwards then so that my hall sensor is taking the offset instead of the pulley so that the same pulleys can be used? I don't know if that made any sense or if it was possible to understand

[twoqu]

But what are we comparing. It seems logical that the holes are for alignment. The holes apear to be in different positions, again logical because the relationship has changed. There is efectively one pulley hole difference. We are close to decision. We now need to identify Dave's pulley!

[UrS4boy]

Robin: I took your photo and resampled it larger, then ran a red line from the timing mark through the center of the sprocket to the opposite edge. For the sprocket on the left, the line just touches one of the edges of the shutter opening. For the sprocket on the right, the line passes through the main part of the shutter wheel, missing the shutter opening (presumably be 10 deg).

[UrS4boy]

Is it me or does the pic Dave supplied from the rear an actual RS2 pulley? There does not appear to a B but the hole at 2 o'clock seems right as thats the one visible in the other pic from the front! Thats why its appears to move bacause you are actually doing the comparsion between the different pulleys. See what you think.

I suggested that one of my photos was an ADU (it was archived as such *AND* the backwards "B" can clearly be seen at about 11 o'clock on the shutter wheel. The other photo is from an AAN.

[twoqu]

Look identical to yours I am afraid! If thats not good enough, PM with your email and I'll forward it!

[UrS4boy]

But what are we comparing. It seems logical that the holes are for alignment. The holes apear to be in different positions, again logical because the relationship has changed. There is efectively one pulley hole difference. We are close to decision. We now need to identify Dave's pulley!

Those small holes could simply be for a VAG cam sprocket holding tool (so you can provide a counter force when removing the cam sprocket bolt).

[twoqu]

The diagonal pic is one tooth out I think! Both those pulleys are identical. The one without the key is from an AAN the other is from an ABY. I have only just noticed that the mark on the inside of the pulley is aligned with one of the holes. Its clearer on the cleaner pulley. That makes sense to aid alignment when attaching the rotor ring.