Author Topic: AAZ camshaft woodruff or no woodruf? Help. (Read 7126 times)

haybayian · « **Reply #15 on:** May 25, 2008, 10:08:11 am »

Quote from: burn_your_money

In all the diesel VW engines I have ever taken apart the cam is slotted for a key but the pulley is not. It`s my opinion that if you used a key in this situation you would be reducing the surface area of the cam and cam pulley and thereby increasing the chances of it slipping. I think this would be especialy true after adjusting the timing several times and causing many indents in the cam pulley.
Plus, I`d expect the cam gear to be off center and would cause timing belt tracking issues.

Thanks for your point which makes sense, in theory. I guess the only way to find out why VW designers thought of a woodruff key at this place would be to ask them. On my own specific cam sprocket there was a slight indentation on the inside edge of the taper but no damage to the extent you are suggesting. The bore was intact and no ovalization could be detected. Considering that this cam dated back (presumably) to 1993, I doubt that forcing the sprocket over such a small woodruff key could possibly lead to an off centered sprocket and belt tracking problem. But not being an engineer I can only speculate and if my timing belt starts acting up I will certainly look back into this key issue. I will try to test this question on some European forums and try to catch a German or French VW engineer who may give us an answer.

Turbinepowered · « **Reply #16 on:** May 25, 2008, 11:16:26 am »

It's possible the camshaft has a key because they grind the diesel cams from the same blanks as the gas cams during manufacturing? Maybe? Would certainly be in keeping with the rest of VWs "use as many pieces for multiple purposes as possible" build philosophy of the Seventies and Eighties.

haybayian · « **Reply #17 on:** May 25, 2008, 12:39:37 pm »

Quote from: "Turbinepowered"

It's possible the camshaft has a key because they grind the diesel cams from the same blanks as the gas cams during manufacturing? Maybe? Would certainly be in keeping with the rest of VWs "use as many pieces for multiple purposes as possible" build philosophy of the Seventies and Eighties.

Perhaps, except that (to be the devil's advocate) the other VW 4 cyl users of this cam blank would be gasers and these seem to have a cylindrical sprocket mating assembly (not cones) perhaps of a smaller size. It would make no sense for VW to go into the trouble of cuting a keyway on a tapered end (destined to AAZs and AHUs) if it is not going to be used. IMO in the process of fabricating the shaft it seems to be a useless operation. So thanks guys :lol: I don't think that I have my answer yet.

mdonau · « **Reply #18 on:** May 25, 2008, 12:43:15 pm »

hi,

cam-wheels on gassers are mounted like the intermediate-shaft-wheels,
so the blanks are not the same.

the key is -my guess- for fixing the cam in the right position for machining,
no further funktion.: fix it at the cam-end and loosen the wheel when adjusting timing when changing the TB.

remember: the conical surface has to be clean an degreased.. else the
pulley can slip, only the clamping force tranfers the power.

greets, Michael

haybayian · « **Reply #19 on:** May 25, 2008, 02:01:12 pm »

Quote from: "mdonau"

hi,

cam-wheels on gassers are mounted like the intermediate-shaft-wheels,
so the blanks are not the same.

the key is -my guess- for fixing the cam in the right position for machining,
no further funktion.: fix it at the cam-end and loosen the wheel when adjusting timing when changing the TB.

remember: the conical surface has to be clean an degreased.. else the
pulley can slip, only the clamping force tranfers the power.

greets, Michael

Danke,
The keyway cut in the cone shape camshaft end seems logical indeed from a machining stand point

.... hummmm! except for one thing: the other end of the camshaft has already a more functional slot (TDC No 1) that would be plenty for machining cams. I guess only VW could explain all this!

I enjoyed visiting your webpage.
Haybayian

Tintin · « **Reply #20 on:** May 25, 2008, 03:30:23 pm »

VW diesel (TD and TDI, also ALH) valve are close to the piston, that need a perfect timing on the cam, there are no other possible reason.

PD motor have an adjustable cam pulley like ALH pump pulley with 3 bolts to set the cam timing, It's not for esthetics.

The first VW cylinder head motor that I have repaired in my life.... 10 years ago, 1.6TD with head gasket failure, I planed the head, I install a 1 notch thinner head gasket, and I reinstall the cam pulley exactly at the same place as when I remove it, I reuse the old timing belt, result = 1 week later all the valves had to touch the piston, not much, but enough to rebuilt the head....... however I used the same method as if there had been a key.

haybayian · « **Reply #21 on:** May 25, 2008, 05:05:30 pm »

Quote from: "jimfoo"

No key, friction fit on mine as it has to be to time the crank to the cam.

Thank you very much to all of you. The response was unanimous: no woodruff key. I still don't know why Haynes did not bother to expand on the existence of a keyway on this engine, and I will probably never know why AAZs have been built with such a confusing camshaft. I have pulled out my camshaft sprocket, removed the woodruff key and tomorrow I will go through the timing routine for the fourth time .
Thanks again.
Haybayian