sprocket bolts backing out?

D

dob1385

New Member
So I'm fairly new so any help would be much appreciated.

Anyways the billet aluminum sprocket on my bike attaches to the wheel with two bolts.

as I ride they losen and then the sprocket shifts and it results in the chain being thrown.

Its fine when properly tightened, I have used locktite (blue) in liberal amounts with worked for a couple of miles but eventually broke down.

What is the SOP for fastening this bolts in?dnut
 
Are the bolts actually loosening or is the adapter slipping on the hub?

How tight are you making the fasteners and what tool are you using?

If like most hub/sprocket adapters available you'll need to use a torque wrench and tighten those bolts to about 100 inch pounds if they are 8mm or about 5/16". If they are larger, close to 3/8", the torque value will need to be higher.

If the adapter is slipping you need to carefully measure the inside diameter with the two halves bolted together and compare it with the outside diameter of your hub. Use a
good quality caliper for this. The measurements are critical for a proper fit down to the thousands of an inch.

Tom
 
its the bolts that loses, but that makes everything else slip. i don't have a torq wrench. a hefty application of the blue locktite worked for a while.
 
Thread locking compounds are okay when used correctly but they won't keep a bolt that wasn't tightened sufficiently from not doing its job. Buy or borrow an inch pound torque wrench. It is a necessary tool when working on a motorized bicycle.

You didn't answer my questions. How tight are you making the bolts and how are you tightening them and with what?

Tom
 
I'm tightening them as much as I can, with an allen key. probably deficient. how much would the tore wrench cost? if its necessary I might invest'
 
You can pay as much or as little as you want. For a light-use, DIY'er such as yourself, I recommend getting one from harbor freight for around $20 or less. I think you can even get them from parts stores for that much. I do a lot of torque wrench calibrations (among a lot of other stuff...I wear a lot of hats in the military somehow) and the cheap torque wrenches have shown a +/- 5% accuracy. When you're talking 100 in/lbs, that's somewhere between 95 and 105. I call that good enough. And the thing is that they're very consistent as well. So it's not like you check it once and it gives you 95, then again and you get 105, then next time it's 100. It's more like I set it to 100 and I'll get whatever value it gives (say 98) over and over.

Sounds like a rant.... oops


Anyway, if you have over torqued the snot out of the sprocket adapter, you may have murdered some threads. Aren't they just chunks of aluminum? They don't take too kindly to over torquing. If it's stripped, you may need to drill/tap new threads and try again with some bigger allen cap bolts.
 
thank you both for your responses.


I know i haven't striped anything, knock on wood. I wasn't able to get a large

enough amount of tore, not even close to stripping, with my little allen wrench.I

been it was enough to keep it slipping off the hub. the vibration from the engine

seemed to make it back out just a tiny bit which did let it slip and then throw said chain.
If I can buy one for 20 at harbor freight ill go do that

thanks again
 
I have to agree with the previous answers... Either the bolts aren't tight enough, or you have the wrong size adapter for the hub.

If all you have is a hex key?, you can slip a small piece of pipe on the end of it to use as a cheater bar to tighten the bolts properly. ;)
 
thank you again guys.

Im now the proud owner of a new torque wrench from harbor freight. Ironically

that was also the only place in town that I've come across that sells the

permanent thread locker. I'm poor but thankfully 20 dollars is in the range of my

expenditures. I got a half inch wrench.

thanks again.
 
dob1385 said:
thank you again guys.

Im now the proud owner of a new torque wrench from harbor freight. Ironically

that was also the only place in town that I've come across that sells the

permanent thread locker. I'm poor but thankfully 20 dollars is in the range of my

expenditures. I got a half inch wrench.

thanks again.
Click to expand...
Let me warn you once more about using red (permanent) thread locking compound. It will require heat to remove the fasteners. Your sprocket adapter is aluminum and the fasteners are steel. Once you've used that red Loctite you're going to have big problems ever loosening the fasteners again.

The blue product will hold as good as you should ever need on a motorized bicycle. The red is fine if you're working on semi-trucks. That's all I will say on the subject.
Good luck.

Tom
 
advise taken.

I will stick to the blue locktite and the wrench. I do have a torch but its probable better to not have to cook things for removal

thanks again.
 
Good Man. The adapter and fasteners might take some heat but your hub and wheel bearings might not be happy about it. I think you'll find that once you have the fasteners tight, maybe with a little blue thread locker, you won't have anymore problems.

Keep us informed.

Tom
 
Did you say 1/2"?

As in "I bought the 1/2" drive torque wrench"?

That one starts at something like 50 FOOT-pounds! I recommend exchanging it for the 1/4" model.
 
Agreen said:
Did you say 1/2"?

As in "I bought the 1/2" drive torque wrench"?

That one starts at something like 50 FOOT-pounds! I recommend exchanging it for the 1/4" model.
Click to expand...
1/4"? They might not have the range to use for other things. Maybe a 3/8" drive would be a better choice? And a set of Allen head sockets. Metric and SAE.

Tom
 
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just a thought, not that i have one of those... but could he not just change the bolts to an all thread type (no head) and then use a 2nd nut on top of the first?
 
2door said:
1/4"? They might not have the range to use for other things. Maybe a 3/8" drive would be a better choice? And a set of Allen head sockets. Metric and SAE.

Tom
Click to expand...

The HF 1/4" torque wrench has a 20-200in-lb range. Perfect for bicycles.

Their 3/8" drive model goes from 5 to 80 ft-lbs.

The 1/2" drive is 20 to 150 ft-lbs. Waaay out of range.
 
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