Any ideas for a rear sprocket that's about to be toothless?

[StepThruPanAm]

Hey guys,

Seems like a stretch I know but has anyone ever successfully prolonged the life or bodge-fixed a rear sprocket that is badly worn and about to become a smooth circle? Plenty of oil is the only thing I can think of so far...

Thoughts appreciated.

[mollydog]

There are a few "bodges" to be done but best thing is to get NEW sprockets and chain ASAP. Also, keep in mind, your worn sprocket will have EATEN your chain and the front sprocket as well.

So, no point buying just a new rear sprocket, putting it onto a worn out chain and worn out front sprocket. Disaster in short order.

You need ALL NEW everything.
In future, you might consider keeping an eye on your sprockets and carrying some spares on board. One good tip is to change out your front sprocket about every 10,000 miles. I carry a spare front sprocket on all longer rides. Will extend chain life by about 20%.

The front sprocket is always the first to wear ... once worn will accelerate wear on both chain and rear sprocket. It's a system! and it's all quantifiable.

You may find a spare sprocket from a random bike of the correct pitch but the bolt holes won't line up. Try to RE-DRILL new holes in the sprocket to line up with those on your hubb. Can sometimes work.

Only other thing you can do ... and it's really a stupid thing ... is to tighten up chain (probably already done?) and oil the Hell out of it ... and ride on. Go easy, who knows, you might make it!

You could also have a machinist grind (by hand) out the sprocket, kind of reshape it so it will last a bit longer. Doesn't have to be perfect, just last enough until you can buy ALL NEW sprockets and chain.

[backofbeyond]

Originally Posted by mollydog

Only other thing you can do ... and it's really a stupid thing ... is to tighten up chain (probably already done?) and oil the Hell out of it ... and ride on. Go easy, who knows, you might make it!

The one time it happened to me that's exactly what I did - I think the chain was good for about c sharp eventually. But I only had to do about 50 miles so it was good enough and got me back.

[Gipper]

If you really cant find a replacement sprocket, as a last resort you could get a workshop to add a thick bead of weld all around the outside edge and then grind out the shape, This is pretty tricky to do correctly, they have to make sure the new shape engages the chain correctly and make sure that whoever does it gets the diameter and number of teeth correct or it will change the gearing.


As Mollydog says, the rest of the chainset will be pretty screwed already, if you can order a new set and have it flown to you, this will be the best option - just watch out for customs fees for importing parts.

Good Luck!

[*Touring Ted*]

There is nothing to do but replace it.

[Warin]

Buy new chain sprockets as others have said.

Bodger fixes here won't last long, and if you have equipment then you have access to mail .. so get some new ones. The only thing that can be done is to tighten the chain.. if you make that too tight the chain will break, in any case it will give up soon.

[StepThruPanAm]

Thanks guys, the biggest problem is our imminent Myanmar crossing! Non-refundable...

My partner's CT110 rear sprocket is about to spit out a bunch of teeth and surprisingly there aren't any compatible parts in Asia.

I was on my way to the Honda shop this morning armed with the old sprocket (still attached to half the hub) and didn't make it far past the front gate of the hotel when I saw a Lifan shop (Chinese Honda clones). The guy there dug around and found an XL125 sprocket with correct pitch, correct tooth count and even a pretty good looking hole pattern for the bolts. Unfortunately the hole in the middle of the sprocket is too small to fit it over the hub. I sat looking at it for a while and gestured that it was no good unless I could get the centre of it machined out. No problem. He could get that done by an acquiantance in an hour and a half. How much? 350 Baht for the sprocket and another 100 for the machining ($18NZD total), this is why I love Asia! I considered going and seeing what the Honda shop had then just decided to get this guy to do his thing on it. Legit Honda sprockets still seem to go for around $100 and I was pretty sure I'd need any of those machined as well. A CBR150 sprocket would probably have been the closest thing they'd have in stock around here and they'd likely be the most expensive and probably made of undrillable superhardened steel. I guess our new sprocket will lose a bit of structural integrity but I think it was the best option. We'll see how it comes out

[navalarchitect]

Glad you got it sorted. A fix I've heard of, but never witnessed, is to get another sprocket with suitable teeth and then cut the centre out of it and weld in the centre of the original sprocket. If facilities are limited you might also get away with simply welding the new sprocket on the outside of the old one (assuming enough clearance) - chain alignment would not be great but I think it might work ok for awhile.

Sent from my SM-P350 using Tapatalk

[Warin]

Originally Posted by StepThruPanAm

I saw a Lifan shop (Chinese Honda clones). The guy there dug around and found an XL125 sprocket with correct pitch, correct tooth count and even a pretty good looking hole pattern for the bolts. Unfortunately the hole in the middle of the sprocket is too small to fit it over the hub. I sat looking at it for a while and gestured that it was no good unless I could get the centre of it machined out. No problem. He could get that done by an acquiantance in an hour and a half. How much? 350 Baht for the sprocket and another 100 for the machining ($18NZD total), this is why I love Asia!

I hope you got a new chain too.. and a front sprocket too at those prices!

At those prices I'd be getting some servicing done. Oil change, check tyres, air filters, brakes etc .... errr I'd be doing -the work.. but get the parts from those guys.

[richy-rich]

could you find a whole new wheel to give you a sprocket ? the axle diameter would be the problem. How far to go, find a swingarm to fit your bike an the new wheel haha. Possibly you can file out the central hole in the new sprocket if the machinist is pie in the sky

[Threewheelbonnie]

Very old thread, but no one mentioned the real bodge: turn it round. Nut off, remove, turn over so the side market out is in and replace using packing as required. There is usually a bit more wear available in the "pushed" face of each tooth hence the final hooked look as the "pulling" side takes more hammer. I've never had to do it on a bike chain, so no idea if it gets you a hundred miles or a thousand.

Given you get a few thousand miles warning, I wonder how you get in this predicament though. I've always fitted new for any trip of even half the chains expected life. You can always use the last 25% of a worn set when you get home.

Andy

[Tomkat]

For sure anticipating problems is better than solving them! For a long ride it makes sense to carry a spare set of chain and sprockets - if this would tend to cause weight problems then at least a chain and front sprocket, as this has fewer teeth in engagement with the chain and invariably wears fastest.

Turning a sprocket round could make a small difference (enough to get you to the next town perhaps) but only if installation features allow it, for example no countersunk bolts.

[mollydog]

Originally Posted by Threewheelbonnie

Given you get a few thousand miles warning, I wonder how you get in this predicament though. I've always fitted new for any trip of even half the chains expected life. You can always use the last 25% of a worn set when you get home.

Andy

Well that's the real problem ... clueless riders. I've been on HUBB 10 years and see travelers repeat the chain/sprocket disaster OVER AND OVER, despite my rants on bike prep and data regards chain & sprocket wear and taking spares.

Too many still take chain/sprockets for granted and haven't a clue how to read a chain/sprocket for wear. Most want easy, short cut answers and don't want to have to put too much time, money or effort into their bike ... their lifeline to travel.

[mollydog]

Originally Posted by Des Senior

For sure anticipating problems is better than solving them! For a long ride it makes sense to carry a spare set of chain and sprockets - if this would tend to cause weight problems then at least a chain and front sprocket, as this has fewer teeth in engagement with the chain and invariably wears fastest.

Turning a sprocket round could make a small difference (enough to get you to the next town perhaps) but only if installation features allow it, for example no countersunk bolts.

Yes, when in middle of nowhere with no help, try anything to keep you going!

You could carry spare chain & sprockets, BUT, most times if you begin trip with NEW, HIGH QUALITY chain & sprockets, carry TWO spare front sprockets, a rider can go 15K to 20K miles (on most bikes) on that chain and rear sprocket.

Riding LOTS of mud and rain can shorten chain/sprocket life.

Most know, it's front sprocket that wears out first and once worn, causes wear on chain and rear sprocket. AND ... if you can keep the front sprocket fresh, then you extend chain and rear sprocket life. Cheap, easy solution.

I replace my front sprocket every 7 to 8K miles and carry a spare front sprocket on board. Last chain (just replaced it) was a high quality DID VM-2 X Ring chain. It lasted 24K miles ... and could have done another 5K miles easy! Used 3 front sprockets over this 5 year, 24K mile period.

If you buy a cheapo budget chain, you will get HALF that number if you're lucky. Same with sprockets. I prefer OEM Suzuki on the rear and either OEM Suzuki or JT on front sprockets. Once on the road, may be hard to find quality
chain and sprockets. But if you take care of your drive system and start with TOP QUALITY components to start ... it's very likely you can make it 20K miles or at least to a location where New, high quality name brand components are available.

[markharf]

Originally Posted by mollydog

Well that's the real problem ... clueless riders. I [snip] see travelers repeat the chain/sprocket disaster OVER AND OVER, despite my rants [snip]

Surely there are possibilities aside from "clueless riders." And just as surely, no one here considers their own periodic "rants" on to represent the final word on a subject? All we really get to do is offer our observations and experience for others to make use of, or not--as they choose.

Personally, I don't change front, rear or chains as often as you claim is necessary. (Nor do I meticulously clean or oil chains, but that's another story.) I get good service life out of all of these, with what strikes me as a good balance of care and neglect.

Every so often I've gotten over-optimistic, and ended up changing out parts under less-than-optimal conditions (think: subzero cold in a dark parking lot, or torrential rains and tropical humidity), but then again there are dozens of occasions on which I've not done so and gotten along just fine--on five continents and in scores of countries.

YMMV, but I hope that's helpful. Kudos to the OP for exploring the available options and finding, as one does, a workable solution!

Mark