Jackshaft moving out of bearings

M4X1MUMW0RF

New Member
Oct 8, 2018
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A few months ago, my jackshaft moved out of the bearings enough so the 9-tooth gear fell off while I was riding the bike. Not a pleasant experience. After taking the transmission apart, I could push the jackshaft out of the assembly with my hands. I put new bearings in the assembly and used a bearing press to put the jackshaft back in. Yesterday, I noticed that the 9-tooth gear was riding right next to the transmission plate... the jackshaft moved outwards again. I disassembled the transmission and could again push the jackshaft out with my hands. I am convinced that there is something wrong with the jackshaft so I am going to order a new jackshaft assembly. What could be the reason this is happening? Did I just get a bad jackshaft? Has anyone else had this problem? Thank you!
 

MEASURE TWICE

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Jul 13, 2010
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Picture of your set up would help. My jackshaft kit I bought was not for any specific motorized bike. I did a DIY type bike with Briggs Edger 3.5hp engine custom. Note I used bearings with snap ring. The snap ring holds it to not move in one direction. This is since the snap ring is slightly larger than the bearing outer diameter, The opposite side of the hanger which the snap ring bearing sits in, is held from the opposite side by a 1 piece split collar. The other set screw collars that have a set screw that hits the keyed round stock makes servicing near impossible. Split collar use a set screw that I tighten and use blue Loctite on which allows servicing but keeps it together. Attached links and my set up shown. Hope this helps, otherwise get pictures of what you have.

https://motorbicycling.com/attachments/img_4996-jpg.65395/

https://motorbicycling.com/attachments/img07621-20120330-1758-jpg.46514/

https://motorbicycling.com/attachments/cam24432-jpg.84308/

https://motorbicycling.com/attachments/cam24431-jpg.84307/

https://www.grainger.com/product/DAYTON-Black-Oxide-Steel-Shaft-Collar-1L661

https://www.homedepot.com/p/Climax-...d-Mild-Steel-Set-Screw-Collar-C-050/203025022

https://azusaparts.com/product/prec...g-with-snap-ring-58-id-x-1-38-od-x-716-thick/

https://azusaparts.com/product/jackshaft-kit-complete-for-35-chain-58-x-14-long-shaft/
 
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MEASURE TWICE

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Jul 13, 2010
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PDF Manual for Sick Bike Parts Shift Kit, I found.

It does mention using Loctite. Also noted that the Lock Rings on the Bearing should be on the outside of both plates. The other way around it cannot work at all. The instructions also mentions about filing a flat spot on the jackshaft for the second set screw on the gear that is at right angles to the one inline with the keyway. On a similar note I have to mention I had a set screw go missing, well knowing I tightened it on my DIY bike pulley. I also had a slight misalignment of two pulleys, but with a belt it is more forgiving that a chain. The belt did not come off but the shaft went a slight amount sideways when the set screw on the pulley holding it down on the key in the keyway slipped. Maybe there is a way to use the split collars also on a Sick Bike Part Kit Jack Shaft. If not, the regular checking things are tight as maintenance and having in alignment using those shim washers should be fine.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&ved=2ahUKEwje_KuV8vrdAhXzHDQIHeqkD-EQFjANegQIABAC&url=http://www.aaamotorizedbikes.com/manuals/SBP2%20Manual001%20Rev%20A2.pdf&usg=AOvVaw0iqV9VqcsU9HAVVjc4v79V
 
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