Any tips for getting sprockets off the axle?

[msaspence]

I’m refurbishing a model b and replacing all the moving parts. I’m struggling to get the sprockets off the axle though. I already broke one fly wheel cog tool and have ordered another and I’m wondering if anyone has any tips for loosening them before I break this one too

[Carl Watts]

Are you trying to undo it in the right direction?

Not removed one myself but thinking about it its a left hand thread.

Hold the sprocket and turn the shaft clockwise from the flywheel side.

[msaspence]

The manual says turn counter clockwise and certainly the threads on the replacements I have are standard thread.

I've ordered some WD-40 specialist penetrant and a blow torch.

[Carl Watts]

Depends on what side of the axle your trying to turn.

Would have thought a bit of WD40 left to soak would be enough. Personally wouldn't waste alot of time on it just buy a new sprocket and axle.

[c2jonw]

It's a right hand thread. Heat and penetrating oil should get it. I've removed dozens of them. JonW

[msaspence]

Personally wouldn't waste alot of time on it just buy a new sprocket and axle.

Yeah me too but they don't sell Model B axles online, maybe over the phone but Concept UK aren't taking orders over the phone at the minute.

[msaspence]

It's a right hand thread. Heat and penetrating oil should get it. I've removed dozens of them. JonW

Any tips for not breaking the fly wheel cog? or just a case of don't apply too much pressure and more oil and heat?

[c2jonw]

Any tips for not breaking the fly wheel cog? or just a case of don't apply too much pressure and more oil and heat?

I assume you mean the cog tool, which is a large hex nut with a one way clutch in it. I guess just more heat cycling and oil. Good luck! JonW

[Carl Watts]

Just pulled my spare Model D shaft with the sprocket still attached out of my spares box.

Also have the Concept 2 removal tool which is a large hex nut and a one way bearing in it.

The first thing to note is the tool has a recess in one side of it so its not symmetrical.

To gain the most surface area to grip to on the shaft the tool is designed to put on the flywheel side and the recess side goes on first.

Undoing the sprocket on the flywheel side requires the nut to be turned anti-clockwise. Sorry cannot edit the above posts that are incorrect.

The best way of holding the sprocket was with the use of an old chain wrapped round the sprocket and offset (side by side) in the jaws of a vice and done up as hard as possible.

Mine came off without much effort, probably because it had chain oil put on over the years and it had got into the thread and stopped any rust. Ideally reassemble with a bit of anti-seize on the thread and it will be much easier to remove the next time.

[msaspence]

The best way of holding the sprocket was with the use of an old chain wrapped round the sprocket and offset (side by side) in the jaws of a vice and done up as hard as possible.

This is a great tip thanks, I hadn't though of this and I still have the old chain lying around. I'm not sure how much it will help as getting purchase on the sprocket hasn't been the problem its been on the axle, but can't hurt to help. I don't have a vice but will try and add some grip in addition to the removal tool with a locking wrench. I've got a blow torch coming today which I'm kinda betting on, if that doesn't work the old sprockets will have to stay on, they aren't too badly worn, the chain is the main problem.

For all I know the sprocket has been on there nearly thirty years and if the state of the chain is anything to go by hasn't been oiled nearly as often as it should.

[Carl Watts]

Personally I would just hit the sprocket with an angle grinder, it would be off in about 2 minutes.

Just put a flat on it and keep going until you hit the shaft. Doesn't really matter if you even flat a bit of the thread. The sprocket will then just fall off once its had the heat and the tension is gone. Clearly you have rust on the thread so I would suggest that this is your only option. Have done it with bearings, destroy the cage then the ball bearings fall out and the outer ring falls off and just grind one side out of the "Ring" thats left on the shaft and it just falls off by hand.Basically you already have a "Ring" with a few teeth on it and an angle grinder would make short work of it.

[c2jonw]

agree with Carl- grinding is a viable option if you have access to one. Also note that the odds of a new chain functioning correctly on an old sprocket are very remote. JonW

[msaspence]

So my new sprocket removal tool came and even with the heat it wasn't enough.

I managed to get the small cog off by using the larger one for purchase. So I now have an assembled rower with new chain new small cog and new skewer assembly. To be fair the larger old cog runs pretty well, but the smaller one is smoother and I know using the larger one will wear the chain faster.

I did think of grinding it off and I do have a Dremel I could use but I was worried about damaging the thread underneath.