Dynamo driving sprocket removal

[RichardL]

I'm trying to remove the large dynamo driving sprocket on my barn-find A7. Using heat, a cheap puller (to the point of bending the tightening handle in half), Liquid Wrench and a hammer = no happiness. I've probably bent the sprocket teeth a bit, but I'm not concerned with that, as they could be straightened if I wanted. I don't have a copper drift, as some books suggest, but I can't imagine that exerting more force than the puller at its extreme. Any additional thoughts?

Another thing I tried to do unsuccessfully was to remove the inner timing cover with the large sprocket still on the idler spindle. Everything pulled out about 1/8" and stopped. Even though I know that the cover should come off with the oil pump in place, I removed it just to be sure there was nothing weired. As far as I know the idler should just come off wth the cover, but it ain't. Again, any thoughts?

Thanks for your help.

Richard L.

[bsa-bill]

Hi Richard
Excuse me if I'm telling grandma how to suck eggs
Well it's a taper, the trick with them is not to try and pull it off with a puller (not to the extent of bending the handle at least) but to put pressure on the sprocket then give the end of the puller a good sharp clout with a hammer.

[morris]

A taper can be a PITA to shift. Maybe you could try drill two holes in the sprocket left and right to the shaft and tap a thread. Then make a strip of metal thick enough with two holes placed across the shaft. That way you're pulling closer to the shaft so the sprocket deforms less.

[muskrat]

Why is it that "should" not always works .
I agree a puller done up tight and a sharp blow "should" move it. Mine does. Try heat as well.
 If all the screws securing the inner cover are removed the cover "should" come off with the idler gear attached. Mine does. The inner part of the idler pinion might have gum build up preventing the teeth from sliding out. Try turning the motor back and forth while pulling on the cover.
Anyway you've got all winter for that. Why aren't you out riding the A10
Cheers

[duTch]

  Every time someone asks stuff like this, I feel like I need to go through the actual motions to get in my head what is actually happening- but then I come good...

Even though I know that the cover should come off with the oil pump in place, I removed it just to be sure there was nothing weired. As far as I know the idler should just come off wth the cover, but it ain't. Again, any thoughts?

 Not quite sure what you mean there, well I do, but not the 'weired' bit....

I've had success with slipping  a metal flat bar under either side of the sprocket(thicker than the gap plus end float, if yea kenow what ah means) and tapping on the loosened nut, a bit of heat may help.????

     Bugga - shanghaied at the pass......

[bsa-bill]

Morris makes a good point. pulling on the outside of the sprocket may deform the sprocket such that it is deforming and nipping on the taper - catch 22

[duTch]

 Well yeah, but that's kinda what I was driving at, by using a (suitable) bit of flat bar of the right thickness (or two half thicknesses, to create a wedge type effect), it distributes the load over more of the circumference, then tap the nut.....

[Nigeyp]

After all the help on Hydraulicking which I can now rule out- I am looking at the dynamo chain as the culprit.
 Having read the BSA instructions it advises if no puller - apply a spanner to the dynamo sprocket nut and give it a sharp blow in an anti-clockwise direction with the chain in position (real mechanics then BSA chappies").

[RichardL]

Thanks for your thoughts gents.

Bill,

After sitting all night with the puller on and with Liquid Wrench trying to work (on the dynamo sprocket, that is), I  went out this morning and whacked the end of the puller. No go. I didn't try to kill it with the hammer because it seems this process actually gets the screw and claws going in the same direction, to little affect.

Morris,

Without stepping into the garage, this minute, to check for sure, I doubt there is adequate flatlands on the sprocket for the holes. If there is, I might go that route.

Muskrat,

Now you're making me think I didn't hit it hard enough or heat it hot enough. The 1/8" gap made when trying to pull out the cover is enough to see the idler can slide in and out a tiny bit when pulling on the sprocket spindle. So, next thing I try might be to wedge the cover open, block behind the cover and sprocket and then whack the end of the spindle (nut on, or wood block). Yes riding is better than fighting, but it was rainy early yesterday and I'm a rain wimp. Besides, did you notice the time of my last post? Midnight.

Dutch,

Since I'm responding in sequence, it seems like I just described to Muskrat what you suggested. Great minds think alike (and, occasionally, mine comes along for the ride). This will definitely  be my next approach.

Bill (again),

I'm wondering if any kind of deformation wouldn't actually help when it comes to breaking the hold of rust or corrosion.

Nigeyp,

Hadn't heard that one, or thought of it, but think it unlikely to overcome 20 or 30 years of rust/corrosion. Nevertheless, everything is still on the menu until the job is done.

Thanks again guys. Other thoughts still appreciated. I'll let you know what happens, but it may not be today.

Richard L.

[Greybeard]

I have a couple of very useful tyre levers that came in a Volvo toolkit; they get used for all sorts of tasks. When I needed to remove the dynamo drive sprocket on my machine I used the duTch method: the two tyre levers were pushed under each side of the sprocket with the slightly angled ends wedged close to the sprocket boss. Bearing in mind that force was being applied to the inner timing case and also I didn't want to damage the threads I tapped the loosened sprocket nut with light but sharp taps. I had already applied heat to the sprocket boss before this.

Leave it; do something else; when you come back to it the sprocket will come off easily.

[a10 gf]

900°C gas torch on the part to be removed, followed by -65°C electronic cooling spray on the part it's to be removed from... then a little punch with a small hammer (when using a puller tighten it, give it a few small punches). Always worked here. Should result in a happy little 'click' when the parts unbound :O)

Amount of heat and cold to be applied with care, planning and consideration, of course. Repeat a few times if necessary.

[Topdad]

worse case back up plan Richard , I've got both cog and sprocket ,they have your name on 'em if needed , I'm with graybeard and E ,leave for a while then attack while its napping , think only gundge is keeping the inner on ,I've had to take it one off and suport carefully and then hit with large hammer onto wood onto loosened nut , best of luck, BobH.

[pjm01]

I had similar experiences ... attempting to remove THAT sprocket. Consulted my neighbour (who used to be a toolmaker) and he loaned me 2 fine steel wedges. These were LIGHTLY driven behind the sprocket (close to the spindle) and the shaft nut given a sharp tap .... result. Best not  be too brutal. If you are going to buy a new dyno chain then I'd suggest it's inspected carefully .... the NEW chain I purchased from a 'regular BSA spares supplier' was amazingly poor quality and not worth fitting.   Peter M

[RichardL]

Peter,

I just tried a variation on the wedge theme by using drill bits slightly larger in O.D. than the gap. Drove one in under each side of the sprocket. Applied heat until the sprocket was about to cherry. Hit sprocket with hammer then hit the nut with hammer. No go.

e,

I don't have electronics freezing spray and I wonder if I could even get enough on the spindle to matter.

I think I've decided there is enough landing zone to drill and tap holes for a custom puller. After I attack it again with other brute force, I think that the custom puller is my next direction. Just in case I must, will there be an angry outcry if I decide to thoroughly trash this original part by taking a cutoff grinder to it?

Richard L.

[morris]

Just in case I must, will there be an angry outcry if I decide to thoroughly trash this original part by taking a cutoff grinder to it?

Nope...