important point made there by chris - some cams have a taper on the end and locate the pulley by friction when the bolt is done up (eg Zetecs) - some dont and rely on the key I was under the impression that valvers (of the mk2/3 golf variety) need the key When I bought my ibiza originally, it had a Brian Ricketts engine and documentation that the engine had recently been serviced to check for (common) wear on the cam and crank keyways. So they must be doing something. The BRM vernier fitted to it was exactly like the one Chris showed above so this method is commonly used by respected tuning houses it seems. Personally, I think I would rather trust a well-modified OEM piece than some of the crap I have seen out there made from cheese Good stuff again Brian but stainless is a bit OTT perhaps...... a nice bit of 5mm ali would have been easier to work surely
Yea I know Rob, it was just there and the correct size , plus, galling wont occur under bolt heads after many tightening cycles Getting my Laser cut plates this eve(6mm steel), I saw one and there a thing of beauty....hmmm.....
I used to make these a few years ago, and done a few for people on here. I used 5mm h30 billet alloy. The only tip I can give, and it's been mentioned above is that if you get it off centre even slightly it's not going to do things any good as it'll alter the tension on the belt every revolution, and can cause premature wear. As for the keway issues. The non keyed shafts rely on a taper fitment. From en engineering point of view, on an interference shaft (usually 1 thou per inch) the keyway is there for alignment,and shouldn't be relied on for drive at all, thats whats the interference fit is for. As for a clearence fit, there is some drive on the key, as well as using it for location. I know the engineer I use shims his keyways to adjust timing, then adds a small shim behind the same size of the amount of material removed.
This one's had the inner and outer sections seperated after the mechanism has been fitted. So it should be concentric to start with, until it's adjusted the first time, when you start to get the consequences of the play in the locking screw clearance holes. That could be corrected by putting a peice of pipe, plastic will do, inbetween the two halves. If you had the pipe, it would be easy to make the seperation cut fit the pipe exactly, with a lathe.
The above pic, if done correctly will work no problem and shouldn't be out of round even if the holes are too big, because the disk should be a nice fit in the outer part of the pulley (2-3thou cleaerence to allow it to move). The inner part is fixed and bolted in position before machining the 2 halfs apart, so in theory, will stay central even if the outer elongated holes are too large.
OK, i missed that as i only looked at the back picture. So that must mean you need to tidy the surfaces where the plate meets the inner and outer pulley parts, and then match the plates to them? As they are rough cast surfaces normally IIRC.
Just to share my experiences, I have got a 16V adjustable pulley that is made just like this, except it is one sourced from BBM in the US. (I got it from there because I got my 16V G60 parts from them also.) It is made using an OEM sprocket cut into two pieces just like above, and made in entirely the same way, except the disc is all CNC machined. The two pieces were certainly cut BEFORE the disc was inserted though (i.e. it wasn't milled like that one above). And you know what? Even though it looks perfectly concentric, it obviously isn't, because on each revolution the cam belt makes a 'whoop' noise at a certain point in the revolution. The belt isn't too tight. To stop this noise I have to loosen the belt to a point where it's definitely too loose. The noise is most definitely down to the pulley, it can't be anything else. The belt itself is a proper good quality item. Soon I am going to junk the vernier sprocket and fit a standard one to cure it. I think the time and effort put into making the sprocket above is excellent. It's very important though that the pieces really are perfectly concentric; even my CNC made item isn't perfect enough.
Just for clarity/those not realising, the pictures I posted are off an ex-Reeves engine, used hard from '98-2000, and beyond, and so pretty much ticks all the boxes in terms of reliability from that alone. The broken keyway is a separate issue, nothing to do with the vernier.
Just incase anyone is wondering where the rest of this is, photobucket stopped working yesterday as bandwidth was exceeded, I had to update so all is well again, ill throw up the rest of the pics either this eve, or in the morning, thanks folks.
Designed up some plates and got a batch laser cut, handy to have sure. I just need to fit integrated vernier pointer and get some more 12.9 bolts before I can put one of the lasered ones together. The tolerance on these is +/- 0.15mm, there pretty amazing and ''talking points'' to say the least. Enjoy. Ill shoot up finishing and assembly pics of one of these and my own first plate tomorrow eve when I get some more bolts.
Prototypes The thread kinda started off as a prototype and then evolved into the finished piece at the end. I have to say, Im liking everything about them, the vernier pointer included Ill be making my tea even with the laser from now on!!!!!!
Nice work. What material did you use in the end? It would be good to do them in something lighter than steel, to avoid adding rotating mass to the engine - not really a big concern unless you're building something pretty extreme though. Does the same disc work with 8v and 16v pulleys?
Trev - just an idea. Have you checked to see that it hasn't been mis-assembled? Maybe the inner and outer parts of the original pulley are in the wrong relative position? That might make it slightly egg shaped?
thanks Mike, I went with a high carbon steel in the end. As i said, although they are fine I just dont like the idea of aluminium plate there, after a few torque cycles I have noticed the alloy to get de-formed or galling occur at slots. I dont like the idea of this, probably ok, but I just feel not in that area. Weight can be reduced in the other pulleys, valve train, or other rotational mass to compensate Im sure. If I was building an all out extreme job I could re-cut in something more fancy if I wanted, but that would be an extreme case after all the above weight loss was done too. Ill just draw up another file for the 8vs, these would work with a little fettling but id prefer to have it clean sheet for the 8v too in order to take all minor differences into account.
