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Front Sprocket Loose?

Started by Gregular, May 17, 2022, 11:24:45 AM

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Gregular

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
Previous Bikes:

1978 Kawasaki KZ200
1980 Honda CB750
1982 Honda CB650
1983 Honda GL650
1992 Yamaha FJ1200

Current Bike:

1990 FJ1200

FJmonkey

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.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

Old Rider

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

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 :smile:

Domino

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

balky1

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  :biggrin:) 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.


FJ 1100, 1985, sold
FJR 1300, 2009

maverick9611

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
85 fj1100

maverick9611

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
85 fj1100

RPM - Robert

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

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.
Never Slow Down, Never Grow Old.

Current Stable:                                                     
FJ1100                                              
FJ1200 (4)
1999 Yamaha WR400 (street-legal)
2015 Super Tenere
2002 Honda Goldwing