PR: Proprietary Items Speedo Drive Shear Pin

bmetcalf

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During a ride yesterday, my shear pin sheared. This has happened several times over the years, including earlier this year. After the last time, I replaced the old white plastic pinion with a new black one from the VOCSC. I carry a supply of split pins in my tool tray, so I was able to continue and know how fast I was going. Anyway, what could be causing the plot to seize temporarily?

(To those with sharp eyes, I did notice that my air filter had fallen off before continuing. Probably a good thing that I knocked it off and then reinstalled, rather than have it fall off while in the move.)


10 17 2018 jaunt a.jpg
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kettlrj

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VOC Member
During a ride yesterday, my shear pin sheared. This has happened several times over the years, including earlier this year. After the last time, I replaced the old white plastic pinion with a new black one from the VOCSC. I carry a supply of split pins in my tool tray, so I was able to continue and know how fast I was going. Anyway, what could be causing the plot to seize temporarily?

(To those with sharp eyes, I did notice that my air filter had fallen off before continuing. Probably a good thing that I knocked it off and then reinstalled, rather than have it fall off while in the move.)


View attachment 24438,
Hello Bruce, It looks like you have a Shadow clock fitted, in which case, the small angle drive on the back of it is likely to be the prime suspect. They can get stiff to turn if the grease is old. After that check for dry/rusty inner drive cable and finally the angle drive at the wheel which may be running dry.
Regards Richard.
 

Robert Watson

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And that little drive can wear out the housing causing the gear mesh to thrust the gear into the housing and lock it up. I have cured that at times by putting a small "thrust" washer under the gear and realigning the gear mesh.
 

Phil Arundel

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And that little drive can wear out the housing causing the gear mesh to thrust the gear into the housing and lock it up. I have cured that at times by putting a small "thrust" washer under the gear and realigning the gear mesh.
Hi. Robert - reading this reminds me I need to align the gear mesh - any tips on how to do this? The small gear I have needs drilling for the locating pin.
Cheers
Phil
 
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Robert Watson

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I was more referring to the one at the lower end. When everything is worn and you roll the bike backwards one gear will climb on the other and the teeth will bite into the housing jamming the whole plot and shearing the drive pin in the drive gear.
You need to take the whole thing apart which is quite simple and clean it all and then see what happens when you roll the gears back and forth. I found on the one I had trouble with, a small washer fitted under one of the gears did the trick, and that was in 2010 in a hotel parking lot somewhere in Germany. Always look for the local maintenance man when you need common little things such as a drill to borrow or a box full of various flat washers!
 
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