How to shift a stubborn eccentric bb

[Polar Bear]

Just as it says on the tin.   Took the bolts completely out, tried to coerce some movement.  Even got a tad brutal.  Nothing.

Now, I know I'm going to have to strip the front end down completely and do something to get this thing moving but having never encountered one before I'm not sure what. 

I have literally 2 hours tomorrow to try and sort it otherwise she'll be relegated to shed ornament for the winter and I'll have to try and sort it out in the spring.   Why is it that these things always happen just when it's least convenient 

[chris]

Warning - Try this at your own risk!

Spray with lots of WD40, then put a 1p piece in each gap and gently thread the bolts back in from the wrong side. Once the bolts are touching the 1p piece, turn each bolt a fraction of a turn at a time. This might just break the corrosion between the alloy and steel. Dont force it if it wont move!

[Polar Bear]

 

I like the big red warning Chris.   I toyed with this very idea about an hour ago but wondered if I was being sensible or utterly stupid.  I bottled.

However, as you've mentioned it and you are the owner of a veritable tandem fleet which I'm sure you maintain, then I will give it a very cautious go in the morning.

Assuming I manage to free the thing, do you smear eccentrics with grease before assemby?
     

[chris]

Assuming I manage to free the thing, do you smear eccentrics with grease before assemby?    

A very thin coat of copperslip assembly grease.

Another thing you could try is tapping the crank with a wooden or rubber mallet to see it you can shift it sideways.

Or, you could always return it to the vendor - not fit for purpose!

[Polar Bear]

Assuming I manage to free the thing, do you smear eccentrics with grease before assemby?    

A very thin coat of copperslip assembly grease.

Another thing you could try is tapping the crank with a wooden or rubber mallet to see it you can shift it sideways.

Or, you could always return it to the vendor - not fit for purpose!

I have some of that somewhere.  A small tube. 

I'll gently, very very gently ease off the shell and try the tapping as well.

Bought secondhand, sold as seen.       

[Ian H]

I think you'd have to lever quite hard to damage the shell. It's steel, you know

There's a hole in the side of the eccentric for levering. Find a bar (allen key?) that fits tightly, then use a spanner or similar to lever against the axle.

Swearing helps.

[Polar Bear]

There's a hole in the side of the eccentric for levering. Find a bar (allen key?) that fits tightly, then use a spanner or similar to lever against the axle.

Had a miserable failure of a go at this already.   

/\  /\  /\  /\  /\  /\

Swearing helps.

Not always...   

But thanks for the tips anyway.   

[Polar Bear]

Ok,  so top tip is the pennies trick.   Many thanks Chris.   I now have two knackered pennies.  I wonder if I'm gonna be in trouble for this!?!

Judicious tapping either side with a hammer through a length of wood eventually caused some movement.  I got brave and cranked an extra quarter turn on the pennies and voila, I could move the thing by hand.

My fettling was thwarted by the lack of the proper crank puller for Stronglight cranks so there's a new addition for the toolbox to be had.

I managed to ease out each side, clean it up and apply a thin layer of lube.  I couldn't find the copperslip so I just lubed for now.  It's gonna get dismantled again in the spring I suspect.   

I took a link out of the chain.  Bugger.  It's too short!      Stupid me.  Oh well.   Link back in, eccentric adjusted to max (if you see what I mean.   Daisy is operable.

Hurrah!!!!!!

Now I just need to swap in the stoker bars, fettle a slight rubbing out of the back wheel and connect up the speedometer.   

Thanks for all the tips and hints guys. 

[chris]

Glad you got it sorted. I had to adjust both eccentrics on the triplet yesterday (the front timing chain was OK, but tightening the rear one introduces slack in the front one), but luckily they hadn't seized.

[Polar Bear]

The penny trick was the deal clincher, thanks very much.   Though, I'll try to find a bit of scrap steel for future fettles.  I don't know if I can afford to keep throwing good money away 

[chris]

The penny trick was the deal clincher, thanks very much.   Though, I'll try to find a bit of scrap steel for future fettles.  I don't know if I can afford to keep throwing good money away 

Use the same pennies next time, just put them in the other way round and they'll come out as good as new!

[Polar Bear]

I have a 'bits' bowl in the workshop.  They went in there for next time...   

[drossall]

Glad I read this. The eccentric on our tandem is stuck and I haven't solved moving it yet. Next time I have a go, pennies it is.

[Polar Bear]

Ah, the beauty and value of shared knowledge.   

[chris]

Glad I read this. The eccentric on our tandem is stuck and I haven't solved moving it yet. Next time I have a go, pennies it is.

I didn't mention that the penny technique is only suitable for steel frames.

[drossall]

That's OK - it's a 531 Claud Butler Majestic II.