Front Sprocket Loose?

Gregular · May 17, 2022, 11:24:45 AM

Hello,

I have a 1990 FJ and have done a few mods (wheels, brakes). I recently decided to change the front sprocket to an 18 tooth. When popped the cover off and unbent one of the lock tabs on the lock washer (only one of the two was bent over), I was able to unscrew the bolt with my fingers. It is speced to be tightened at 61 ft/lbs. The threads on both the shaft and the nut are fine. I've had the bike for 4 years and have never had the front sprocket off.

Is it in anyway possible that the nut could have worked its way loose? I would think not considering the one lock tab was completely bent over the nut. Has anyone ever experienced this? I'm somewhat concerned.

Thank you,

Greg

FJmonkey · May 17, 2022, 10:50:43 PM

If the nut turned, the locking tab would have been forced to open up. The spline in the sprocket is taking all the load and cannot spin till the nut and it falls off, the lock tab did its job.

Old Rider · May 23, 2022, 01:07:41 PM

Often the nut is not thightened to the spec 85NM and work it self lose.I have a tip on how to get it tourqued right.Put a piece of wood thru the backwheel on top of swingarm or/ and sit on the bike
on centerstand pressing down brakepedal while using the touque wrench.I also use some grease on the splines and 1 drop of blue locktite on treads.Use blue NOT red or stronger than blue and a new lockwasher

Old Rider · May 23, 2022, 01:34:13 PM

And in fact im doing it a little wrong here in this pic because when using a torquewrench you are suposed to pull on it not pushing like in this pic

Domino · May 24, 2022, 02:50:38 AM

I never knew this. I have learned something new today!

balky1 · May 26, 2022, 03:10:25 AM

Like Monkey said, it probably wasn't tightened in the first place. That nut just by the movement and normal rotation forward will tighten itself (considering you're not constantly riding downhill

) if there is nothing to secure it (lock washer in FJ's case). Some small motorcycles don't have anything to secure the sprocket and it is usually a PIA to unscrew it.

maverick9611 · June 14, 2024, 05:21:34 AM

im changing to 18-40 on a 85 1100. same thing with my nut. I don't think it was ever put on tight.
maybe the thought was the sprocket would float a little bit for alignment? i was quite alarmed

maverick9611 · June 14, 2024, 06:39:03 AM

Quote from: maverick9611 on June 14, 2024, 05:21:34 AMim changing to 18-40 on a 85 1100. same thing with my nut. I don't think it was ever put on tight.
maybe the thought was the sprocket would float a little bit for alignment? i was quite alarmed

https://photos.app.goo.gl/ofn6d1TeXfJ2hpb49

RPM - Robert · June 14, 2024, 10:24:18 AM

At least one of the lock tabs needs to be bent over a flat after tightening. Neither of those appear they were. I have never checked the clearance between the sprocket cover and the nut but you, or whoever did that, may have lucked out that it didn't fall off. There might not be enough room between the cover and the nut for it to completely come off.

CutterBill · August 05, 2024, 09:51:17 AM

Quote from: Old Rider on May 23, 2022, 01:34:13 PMAnd in fact im doing it a little wrong here in this pic because when using a torquewrench you are suposed to pull on it not pushing like in this pic

Another Old Wives Tale. It doesn't make any difference, pulling or pushing. The wrench doesn't know if it's being pushed or pulled; it works the same way.

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Front Sprocket Loose?