Could've been scary....check those sprocket bolts!

[Splexin]

I have a little story from an incident today.

I'm going out for a ride to do errands, stopped at a traffic light. I start off again and suddenly my bike jerks real funny and I hear a grind, and I'm like OK what's up with this POS transmission it's never done that But after that it was fine. So I think hmm?

I get to my destination and after I get off the bike I look down and one of my sprocket bolts had snapped off! Apparently the bolt came loose and the locking tab got caught on the axle arm (whatever it's called) and basically the motion of the bike tore off the bolt and the tab.

Fortunately following my stalling experience several months ago, I have started carrying a small screw driver, vice grip pliers, and flashlight. I just so happened to have them with me. Not only was the other (remaining) bolt for that locking tab loose, but all my other bolts were a little loose as well! Now when I installed my new sprocket and chain last year I am pretty sure I torqued those down properly. Cause if your sprocket comes off in transit you in big trouble But, perhaps in the course of time and my rough riding they became loose (obviously lock tabs didn't work).

It really could've been scary cause I had almost decided to go on my monthly 60 mile trek, and I can imagine what might have happened during the ride

Needless to say I am adding that to my routine checklist. I will also be applying locktite when I get the replacement bolts.

 

[pamcopete]

The other related scary thing that can happen is loosening of the spokes. If you don't catch it in time, the whole wheel can come apart. More prevalent with the back wheel due to the added stress of acceleration. So, play a tune on your spokes before each trip.

 

[xjwmx]

I have a lot of experience with loosening sprocket bolts... Starting in Poplar Bluff, MO over a year ago and plaguing me ever since.

I've discovered that hammering up the locking tab on three sides will keep them from backing out; won't keep them tight in itself, but will keep them from coming out. Two sides or one side won't. Likewise locktite won't keep things tight; just keeps them from vibrating out.

 

[Street Tracker]

Yes very dangerous for those sombicthes to come out, one must, must I say use lock tight at a minimum and safety wire is the real way to fly when your going fast.

 

[retiredgentleman]

If you found all the bolts loose, I would give some verbal abuse to your mechanic

If those bolts are put in with the correct torque, they don't come loose. I just use a little anti-seize on the bolts and when I check them they are never loose.

 

[jd750ace]

+1 for safety wire. Looks cool, and NEVER comes loose without pliers or mechanical prying.

 

[weekendrider]

+1 Retiredgentleman.
Never been a problem for me.

 

[5twins]

Yes, there is a torque spec given for these bolts in the factory shop manual but it's not easy to find. I found it, I used it, and I've not had any problems to date. I also found it and used it on all the previous bikes I've owned in the last 40+ years. Same result - no problems. I would think that if someone was having an issue with these bolts coming loose to the point where it darn near killed them, they might take the time to find that torque spec too - but I guess not, lol.

When you mount a part using multiple fasteners in a pattern, proper torque does more than just make all the bolts/nuts tight. It applies the same and equal pressure all the way around the part. Just grabbing a wrench and making them all "tight" doesn't do that. Some are tighter than others and this creates an imbalance. As some of you are finding out, that can cause the part to work loose.

 

[retiredgentleman]

The primary safety factor for your sprocket bolts/brake disc bolts/wheel axle bolts, etc. is using the proper torque. The lock tabs,and lock-tite are secondary backup devices.

You don't want to just snug up the bolts with a combination wrench or ratchet and call it good; thinking that the lock tabs and/or lock-tite will prevent loosening.

 

[XSLeo]

I don't think lock tight is such a good idea on those bolts. The lock tight might hold too good and when you remove them next time the threads in the hub might just come with the bolts, it is aluminum.
I used Allen head bolts with flat and lock washers on the sprocket bolts and the brake rotor bolts. A thin coat of anti-seize lets them come out. Been riding the 75 hard a fair amount and have not had any trouble yet.
Leo

 

[XSLeo]

I looked and found a spec of 22 ft/lbs. in the 78 factory book.
Leo

 

[Splexin]

Appreciate the responses guys.

I did use a torque wrench when I installed the sprocket bolts, but I think I only used about 15 ft/lbs. So perhaps that's the reason.

I do ride my bike pretty hard, always trying to beat these 2 traffic lights that turn green simultaneously but are separated by about a quarter of a mile. Most of the time I beat 'em

And not long ago I took a trip where 100 miles of the stretch was 80 mph speed limit.

 

[retiredgentleman]

Appreciate the responses guys.

I did use a torque wrench when I installed the sprocket bolts, but I think I only used about 15 ft/lbs. So perhaps that's the reason.

I do ride my bike pretty hard, always trying to beat these 2 traffic lights that turn green simultaneously but are separated by about a quarter of a mile. Most of the time I beat 'em

And not long ago I took a trip where 100 miles of the stretch was 80 mph speed limit.

Yes, 15 is not enough. I use 27 ft-lbs (10 mm bolts).

 

[5twins]

The hub is aluminum but has steel inserts for the sprocket bolts to screw into. Unfortunately, the holes open into the brake drum area so anything in there (brake dust, water) can enter them. I've encountered some of these bolts that were very difficult to remove, also a mag where they were seized in the holes and 3 bolts had broken off. I highly recommend anti-seize on these bolts. If you put them in dry, you may never get them out in the future.