MK1 - Possible Rear Crank Gear Play

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camstevens
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Re: MK1 - Possible Rear Crank Gear Play

Post by camstevens »

Hi Allan
I'm sure a shim would work....I'm just wondering the actuall technique of fitting it. Perahaps super glue it to the top of the key (residing in the gear), and try to feather the shim so the gear rides over it when fitting?

cam
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Re: MK1 - Possible Rear Crank Gear Play

Post by allan.walker »

Yes, I see what you mean! That could be worth a try.

Would .001" shim, folded over the front edge of the key (whilst in position in the shaft) so that it passes down each side of the key, possibly work?

Or, even further out of the box.....do you know anyone with a diy plating kit? Plate the key to increase its thickness, then file-down the part that fits into the shaft.....??

Or, obtain a thicker key and file it accordingly....???

Allan.
Last edited by allan.walker on Thu Jul 22, 2021 8:27 am, edited 1 time in total.
camstevens
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Re: MK1 - Possible Rear Crank Gear Play

Post by camstevens »

Hi
Actually, I have a 0.001" feeler gauge strip....I'm sure I can "appropriate" a piece :D

Cam
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Re: MK1 - Possible Rear Crank Gear Play

Post by GuyWalton »

personally I would make a stepped key , but I do have a milling machine , that way it would fit both the crank and the gear .
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camstevens
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Re: MK1 - Possible Rear Crank Gear Play

Post by camstevens »

A success + a non-Success

The refitting of the rear cranksahft gear with new key, .002" shim on gear side of key, plus Loctite 648 went really smoothly with the gear now home and really snug on the shaft. I've got no doubt this part of the process will be a success.

My second exercise has been a dismal and disappointing failure......this was re-dowlling my new chain wheel centre onto a new 40 tooth sprocket. I'm not sure where it all went wrong, but I followed the instructions closely, bolted the two components togther, made sure the holes were aligned, etc, etc,etc. I watched the fitter press the dowells in .....he was methodical and careful, and I trotted home smug in the belief I now had a great product....plus a much desired gearing up. Sadly, the chain wheel centre was deformed around 0.003" - 0.004" out of round.....thus will not fit on the geabox shaft. There is also now appears to be a throw out on the sprocket, which I'm not yet sure is due to the centre being warped, the new sprocket warped or both. I'm sure I cannot recitify what I have.......I suspect it is all now scrap.....even if I procure a new centre, I'm not sure if a buckled sprocket could be straightened. If it means scrapping and new kit, I really need to figure out where I went wrong......has anybody else also suffered this problem? If so, was there a remedy / solution? :oops:

Cam
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Re: MK1 - Possible Rear Crank Gear Play

Post by Paul_Linden »

That doesn’t sound good. Did the centre part come off your bike? I’m really asking if it was working all right before you put the new sprocket on. It’s unlikely that the sprocket was supplied out of true (unlikely but not but not impossible).
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Re: MK1 - Possible Rear Crank Gear Play

Post by camstevens »

Hi Paul
No, it was a new component....and it did fit the shaft/bearing unit before mounting onto the sprocket.

Cam
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Re: MK1 - Possible Rear Crank Gear Play

Post by camstevens »

Hi Paul
No, it was a new component....and it did fit the shaft/bearing unit before mounting onto the sprocket.

Cam
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Re: MK1 - Possible Rear Crank Gear Play

Post by allan.walker »

Oh dear.
What kind of press did the fitter use? I fitted my new sprocket and dowels using my bench vice. Very little force was needed and the result was fine. The sprocket/centre went back in place with no problem and it runs true.
A 20 tonne hydraulic press, perhaps, could distort the components......just a guess. :?:
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Re: MK1 - Possible Rear Crank Gear Play

Post by camstevens »

Hi
I think the issue must lie in the interference I have/had...........there is now way in a million years one could have pressed my pins in with a vice....no way. So...I guess next time around I'll need to ream out the holes to a reasonable interference. OK, next I'll drill out the pins...again.......and see what state my new sprocket is in. I'm sure it could be pressed flat if need be, and I look to source another centre.

Cam
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