BSA Goldflash Dynamo Sprocket

[peter]

I have to overhaul the breather on the BSA Goldflash 1954. To do this, you have to dismantle the intermediate housing and the timing cover. To dismantle the intermediate housing, you have to remove the dynamo gear, but now I'm having problems because the dynamo gear won't come loose. My question is: is the gear really on a cone and how much pressure can I apply or should I try using heat? Many thanks for your advice.
 Peter

[berger]

keep the puller very tight get a piece of brass and a hammer and strike it on the flat bit on the gear it should come off unless it has loctite on it for some reason

[CheeserBeezer]

I suggest, don't remove the gear. Remove the timing cover with the gear still attached. When replacing the inner timing cover use a spare intermediate gear to set the cam timing, remove the spare gear, then fit the timing cover with gear. Alternatively, the advised BSA method is to remove the inner cover with gear still in place, heat the dynamo gear then hit the end of the shaft with a soft faced hammer or aluminium drift. If you use a puller on the dynamo gear you will most likely distort it, particularly if you haven't applied heat.

[limeyrob]

Agreed, take it off with the gear still on and get it on the bench.  The short answer is , yes you can put quite a bit of force on, its not the end of the world if you have to straighten the pulley .

[CheeserBeezer]

Agreed, take it off with the gear still on and get it on the bench.  The short answer is , yes you can put quite a bit of force on, its not the end of the world if you have to straighten the pulley .

I'd say that distorting the pulley should be avoided at all costs. I'd be interested to know what acceptable engineering procedure could be employed to straighten it sufficiently for the chain to run without horrible tight-spots. The best thing to do is fit a belt drive of course. That pulley can be removed with a couple of timing cover screws, and the dynamo pulley removed with a magneto puller. Happy days!

[berger]

no need to distort anything cheeser that sprocket will take enough tension with a 3 legged puller to enable it to be whacked like a car ball joint taper and it will drop off unless it's been glued up. also what if he hasn't got a spare timing gear to play with. i have always got them off with a short sharp shock-------pink floyd 

[Colsbeeza]

Peter, I found Cheeserbeezers second method works better. Don't forget to replace the cork spacer/washer beneath the sprocket.
Col

[bikerboy]

Col

I gave up putting that washer in years ago and have never had oil come thru there, well nothing to mention anyway. I found all that happened is over a period of time that washer fell apart and filled the compartment up with cork

[Swarfcut]

   Trying heat with that puller in place is worth a go first.  Without a spare timing gear to hand, another alternative is to remove the inner cover complete, and use a puller to remove the timing gear from the idler shaft. Extract the key, and the shaft will slide through. Now you have just the dynamo pulley on its taper. Only hammer alloy castings (and magneto armatures) if you are rich, to paraphrase a Forum Member.

 Well supported on the bench, ever increasing levels of foul language, threats, violence and heat should ensure removal without damage. Some examples are well defiant.

  Small Cork washer under the drive pulley is more to control end float on the idler shaft rather than a true oil seal. Scroll in the bush keeps the oil out, unless some fool has fitted a spurious part or one from the crankcase location. Bushes are the same size, scrolls are mirror images. Dynamo chain runs in grease, not oil fed from crankcase.

 Swarfy.

[peter]

Hello everyone, thank you very much for all your advice, I did it as Cheeser Breezer suggested and it worked perfectly. Now I still have to look for the right breather cork gasket but it's always the same as it always is  , I have 3mm 5mm 6mm gaskets but it should be a 4mm or 5/32" one.
Thank you again Peter

[limeyrob]

What I don't get about these cork washers is that I'll bet just about every engine is 5/32.  So why make 1/16, 1/8 and even up to about 1/4?  There's no way BSA would make parts that varied so much. I must have a pile of these about 2"" high. all too thick or too thin.

[Colsbeeza]

Peter, Limey, there is a lot on the forum about the idler cork. As Swarfy said, it is more about camshaft endfloat. I would suggest mainly about endfloat. I would read up a bit before you decide it isn't necessary. Mine needed a cork of 3.1mm thickness to take up the endfloat. I suspect if too thick, that may be the cause of cork breakup which some experience.

https://www.a7a10.net/forum/index.php?topic=16474.msg141024#msg141024
Col

[Swarfcut]

    A further note may explain.  Small cork washer....Idler shaft.   Big washer...Camshaft gear.

    The small one under the dynamo drive is preventing float on the idler shaft. The one in the cam gear is keeping the gear pressed against the face of the outer camshaft bush, locating the cam lobes under the appropriate follower. It is also acting to press the breather bush flange against the inner timing cover face, and ensure  alignment of the timed breather holes in the bush with the crankcase exit duct. When assembled correctly, there will be no endfloat on the breather bush or cam. Too thick a cork washer and the breather bush will bear heavily on the timing cover, and the cam will be stiff too turn. Choose a cork which fills the gap and is compressed lightly on assembly. Sanding down a thick one to suit is fine, and ensure the drive peg and it's depth of engagement in the bush are adequate.

 But Rob's right, there should not be much variation in parts, but may have been a way for BSA to recover inner covers machined a little too thinly at the breather bush location.*


 Swarfy.

 *Ford used this trick on engine main bearing housings, overboring the block/cap assembly to avoid scrapping a mis machined block. Main bearings were used with an oversize on the outer diameter, as well as being available as an undersize for reground cranks. Found that out the hard way....

[limeyrob]

At the peril of being shot down in flames.. I don't think the cork disc has any role in setting the cam shaft end float:
The cam shaft movement towards the T/S is set by the collar on the shaft running against the bush.  The cork disc would push this away.
The camshaft movement towards the D/S is set by the rear of the camshaft gear running on the face of the bush.  The bushes are flanged both sides and are a pair 67-0686.  The cam shaft end-float is set when the gear 67-0337 is pulled up against the shoulder on the cam shaft and no adjustment is possible.
The cam should spin freely with a few thou float when the gear is on, the cork and breather are superfluous to the end float.
The cork should be the thinnest to just keep the breather in contact with the case.