Can you believe I limped it home on that!

Well it was a nice day outside; cool…barely 50 degrees Fahrenheit. Still it did not stop me so I was out with the 74 Commando Interstate and just hitting some of the twisty roads where I live, which are totally nothing compared to the Asheville NC Rally I went to this summer. We are pretty much considered flatlanders in Southern Ontario. I was just trying to roll the Odometer to the 50000-mile mark just to finish off the season. I was coming up to a T intersection with another M/C rider slowly creepin up behind me. Well just to show off I pull out and give it the boots and all of a sudden there is a lot of knocking and vibration with not much forward motion to the throttle response that I was giving it. I quickly pulled over and stopped. The Other M/C blew by me and was making me some trail dust to chew on. See yah I was mumbling. :x Initially I check the bike over quickly looking for a blown chain but everything was still there. Well I got back on and started off again and every time I tried to put some goose to her I was getting this major vibration and slip on the clutch. I initially thought I had blown some teeth on the Maney belt drive as it was getting close to the 25000 mile mark when I installed it. I had my cell phone and I could have called a buddy to get his trailer but I figured I would try to get her home… or maybe the other way around the bike getting me home. So I was very easy on the throttle and easy on the shifts to keep it moving. I topped it at about 50 MPH cursing speed and I progressed the last 20 odd miles home into the garage.
At first being curious on my guess on the Belt drive, I pulled the inspection cover and slowly looked at the teeth as I moved the engine with the rear wheel in 4th gear. Nothing was out of the ordinary. The belt was still ok. I then did some more investigation and looked about the chain area. To my surprise here is what I found.



As you can see the belt is fine.

New compared to whats left of 24842 miles later.
It’s a 520-chain conversion with just shy of 25000 miles ridden. I think I need to oil the chain a little more often. There is some hook on the rear drum as well. Winter projects come a little too early. May be I will try using Cryogenic hardening with the next kit.
Happy trails.
Cheers,
Thomas
CNN

Hobot award on that rear chain!

25k is pretty impressive for a 520. How often did you lube it? Considering a sealed x ring
for next time?

Thats pretty badly worn, never seen one that bad before, is the sprocket steel or alloy, it looks alloy to me in the pic, I have only replaced my front sprocket once so far in 40 years of ownership and the same with the rear sprocket but have replaced the rear chain a few times, there seems to be something wrong if you have only 24k on it to do that, a well lubbed chain also helps the sprockets last longer and of course runs smoother, chain maintenance is very inportant to me to keep my riding time trouble free except for last year when my chain decided to throw the joining link while giving it a bit of up and go, but that was the first time it had ever let me down on the side of the road, I always carry a joining link on my clutch cable but for some unknow reason I had a Triumph link on there that didn't fit my chain

Ashley

PS I run stock spockets and my last chain that I just replaced had well over 40,000 miles on it and surprised it still wasn't worn out and it didn't have no strech compared to the new chain, but it had a few tight spots in the links.

Onder said:

Hobot award on that rear chain!

25k is pretty impressive for a 520. How often did you lube it? Considering a sealed x ring
for next time?

Click to expand...

LOL
I was thinking of Steve aka Hobot when I took these pictures. I guess we use what we can to the max.
the DID 520 chain is still in good condition from what I can see but the rest took a major dump.
I think I need more lube. :lol:
Cheers,
Thomas
CNN

ashman said:

Thats pretty badly worn, never seen one that bad before, is the sprocket steel or alloy, it looks alloy to me in the pic, I have only replaced my front sprocket once so far in 40 years of ownership and the same with the rear sprocket but have replaced the rear chain a few times, there seems to be something wrong if you have only 24k on it to do that, a well lubbed chain also helps the sprockets last longer and of course runs smoother, chain maintenance is very inportant to me to keep my riding time trouble free except for last year when my chain decided to throw the joining link while giving it a bit of up and go, but that was the first time it had ever let me down on the side of the road, I always carry a joining link on my clutch cable but for some unknow reason I had a Triumph link on there that didn't fit my chain

Ashley

PS I run stock spockets and my last chain that I just replaced had well over 40,000 miles on it and surprised it still wasn't worn out and it didn't have no strech compared to the new chain, but it had a few tight spots in the links.

Click to expand...

Ashley,
I am impressed with your 40 year old front sprocket.:shock: when did you change it out?
In my case.... It was a steel one from Walridge motors. On sale. It was a stock 530 21 tooth which I turned down to 520 spec. I don't think it was an Andover Norton Part though. It was not tagged with an Andover Norton tag. It only came in a clear plastic sealed bag with nothing other than 06-0721 sharpie writing on the package. just a part number.
Cheers,
Thomas
CNN

funny, i'da thought there woulda been plenty of signs/symptoms prior with that amount of wear, chain may look alright but i wouldn't use it again with a fresh sprocket(s)

84ok said:

funny, i'da thought there woulda been plenty of signs/symptoms prior with that amount of wear, chain may look alright but i wouldn't use it again with a fresh sprocket(s)

Click to expand...

my down shifts were not smooth. I didn't catch on until the event. It started happening about two weeks ago.
Cheers,
Thomas
CNN

Sure got your moneys worth out that one :shock:
jug

Onder said:

Hobot award on that rear chain!

Click to expand...

Not without shotgun-drilled holes in the plates!

ashman said:

I always carry a joining link on my clutch cable but for some unknow reason I had a Triumph link on there that didn't fit my chain

Click to expand...

ha ha, proves you're human like the rest of us

Amazing what lack of lube will do. All 3 units , chain and both sprockets destined for the rubbish heap. Looking at the photo is it possible the big nut was installed backwards ? The chamferred side goes towards the gearbox sprocket because the sprocket is dished , not flat ,and the chamfer cuts have more contact area. Hard to see well enough to tell.

i lost a rear sprocket when the chain over stretched , an old farmer had a some chain on a hay baler that got me home 200mi, but the sprocket still had some teeth...

your getting awfully close to friction drive.

That was a pretty common sight on dirt bikes back in the 70's before the advent of the modern o-ring chain. Mixing chain, sprockets, chain lube, sand, and horsepower makes for a great grinding paste. Since sprockets and chain all wear as a unit, it looks like you're out the cost of a whole set. At least you'll be good to go for another 25,000! That's nothing to sneeze at.
As far as lubing it more; difficult as it is to accept, you're actually better to leave an o-ring-sealed chain dry, as it's the grease that attracts grit, bringing us back to my opening statement.

Nathan

You stated that it was a 530 sprocket turned down to fit 520. I don't know if these sprockets are case hardened or not, but I suspect they are. When you removed the hard surface sides it allowed the wear to occur from the sides, narrowing the tooth area and increasing wear rate.
Just a theory.
Jaydee

I'd like to see what the rear sprocket looks like.
Just because the chain is o-ringed doesn't mean the outside of it doesn't need lube too.
That chain looks so clean that it was never lubed before.
Well, now you know what to do.

A quality sprocket will have a definite "ting" sound where one of less quality will have a "tink" sound.

How's the brake drum? I cannot imagine it being worth a damn unless the sprocket was very soft after machining.

jaydee75 said:

You stated that it was a 530 sprocket turned down to fit 520. I don't know if these sprockets are case hardened or not, but I suspect they are. When you removed the hard surface sides it allowed the wear to occur from the sides, narrowing the tooth area and increasing wear rate.
Just a theory.
Jaydee

Click to expand...

That what I was thinking, machining the sproket down to fit takes the case harding off, I don't run a O'ring chain on my Norton but keep them well lubbed and maitained I get very long life out of my chains and sprockets, my orginal front sprocket lasted 30 years before I replaced it, but my rear sprocket lasted only about 20 years, I am still running the the second front and rear sprocket but have replaced the chain a few times, my last chain done over 40,000 miles but have replaced it with one of Andy's chains will see how long that goes.
My Triumph Thruxton has a O ring chain but I still lube it, the lube looks after the sprockets, makes the chain runs smoother over the sprockets, so far my Triumph has over 25,000 on the orginal chain and sprockets, I have never ajusted it since new (nearly 3 years old) and my dirt bike (CRF450X) runs O'ring chain and I am still running the orginal C/S but I also keep the lube up to it before every new ride and I flog the living shit out of it, so to me lube works if I want long life out of my chains and sprockets, I also pull my Norton chain off every 6 months to soak it in kero to give it a good clean then a sock in gearbox oil,. this stops hard spots in the links.

Ashley

ashman said:

jaydee75 said:

You stated that it was a 530 sprocket turned down to fit 520. I don't know if these sprockets are case hardened or not, but I suspect they are. When you removed the hard surface sides it allowed the wear to occur from the sides, narrowing the tooth area and increasing wear rate.
Just a theory.
Jaydee

Click to expand...

That what I was thinking, machining the sproket down to fit takes the case harding off,

Ashley

Click to expand...

:idea: Theory can commonly mean everything but the truth. I can't remember where I heard that quote but you got me thinking.
Jaydee I will put your theory to the test. I will take my milled 21 tooth sprocket (new) to work tomorrow and an unmolested one in 530 dimensions. I have access to hardness test equipment. I will even test the remainder of the old pooched sprocket. I will do a hardness test on both sides and post results. These are all from Walridge motors. I don't think these are Andover but they are stamped made in England. Just a quick edit: I only removed material from the outboard side of the sprockets.

Cheers,
Thomas
CNN

Well I did some tests on the sprockets and found that the material was below the Rockwell C scale and showed an average hardness of 86-87 Rockwell B. I tested areas at the tooth and near the splined center which I did not touch during the machining of the outboard face to bring the sprocket down to 520 chain dimensions. The unturned sprocket gave me the same results. I found no hint of case hardening at all. The outer coating looks like a black parkerized finish for weatherproofing the part only. It is pretty soft carbon steel.
Cheers,
Thomas
CNN

ashman said:

jaydee75 said:

You stated that it was a 530 sprocket turned down to fit 520. I don't know if these sprockets are case hardened or not, but I suspect they are. When you removed the hard surface sides it allowed the wear to occur from the sides, narrowing the tooth area and increasing wear rate.
Just a theory.
Jaydee

Click to expand...

That what I was thinking, machining the sproket down to fit takes the case harding off,
Ashley

Click to expand...

No worries on machining the side of the sprocket, as it should see only incidental contact from the chain's sideplates. All of the load is carried by the teeth faces. If there's a concern for side wear, then there's some serious sprocket misalignment going on.
To quote a well-known chain manufacturer; "Since chain loadings are evenly distributed over all engaged sprocket teeth, tooth breakage or distortion is not normally a problem. It is seldom necessary to use special high strength material."
And; "The hardening process of small diameter, small pitch sprockets is usually a one-step procedure: heat treatment (electrical induction).This method is used to provide a high hardness at the wear areas, plus provide the ability of the tooth to absorb shock loads. This is accomplished by hardening only the wear area of each tooth while maintaining a ductile tooth core which is tough and resilient." When they say "small pitch sprockets", they're talking about motorcycle chains.
Again, I'm impressed at how many miles you got from that chain set. I don't think I'd change anything in your maintenance procedure.

Nathan