Chain Wear

G

ghwallice

Hero member
Location
Ipswich
From a technical perspective, why does a chain wear in a way where it has loose and tight spots??

And, what is an acceptable difference/wear limit between loose and tight? Like, I set it up for say 40mm on a loose spot, and in a tight spot it's only about 20mm (with a subjective few kilos pressure with my hand), so 20mm difference.

(I do wash my chains with diesel and lube with 80/90 gearbox oil)

Regards, Greg
 
Hi Greg, I know I'm not answering your direct question but....

check first thst it's not your rear sprocket running eccentric.

Find a tight spot and put a paint mark on the spocket at 9 o'clock (rearmost) then rotate the wheel to the next chain tight spot and see if the paint spot is at 9 o'clock again. If so, bingo. Naturally, the loose zone will have the paint spot at 3 o'clock.

HTH Paul
 
We are talking secondary chains running in the open air and getting water, mud, dust, sand slung at them, aren't we?

Paul
 
Paul Marx said:
We are talking secondary chains running in the open air and getting water, mud, dust, sand slung at them, aren't we?

Paul
Click to expand...

Yes, secondary chain. Like from the front sprocket to the back sprocket. And NO, I do not normally ride my Italians in any of water, mud, dust and sand.
 
Check whether the chain is stretched in certain spots too!

You could manufacture a 'GO'  'NO GO' tool for between the rollers - just a bit of steel or whatever filed down would do the trick!
 
SimonR501 said:
Check whether the chain is stretched in certain spots too!
Click to expand...

That's what I'm asking, from a technical perspective. Why do they stretch/wear in certain spots. The sprocket is not elliptical as Paul H asked me to check. I've fitted another chain and variance in...?.....sag (?) does not exist. If "sag" can be used as a descriptor....
 
A chain is a series of manufactured plates and pins (in basic form).
In use the interfaces where they join are subjected to many forces.
Not all pin to plate interfaces will be identical.
Once one area is stressed slightly more than the rest it will start to wear more than the others, and with time this accelerates, resulting in tight and slack spots in the chain.
 
ghwallice said:
HMMM. Where is this going to go? Not really, it's about 10m long?
Click to expand...

It's because road dirt, i.e. water, mud, dust, sand, will get into your chain and precipitate wear. Unevenly.
But if you don't use the bike on the road, that isn't relevant.

Paul
 
Paul Marx said:
It's because road dirt, i.e. water, mud, dust, sand, will get into your chain and precipitate wear. Unevenly.
But if you don't use the bike on the road, that isn't relevant.
Click to expand...

Oh! just road grime? I thought you meant water, mud, dust and sand, literally....
 
I have an idea it is to do with the differing number of teeth on the front and rear sprockets, at the front the chain curves a lot and at the rear it curves much less, at one end you have xyz number of teeth passing their respective chain links at a given linear chain length speed, and at the other many more teeth in the same time frame, so as to achieve two differing shaft rotational speeds.
CLEM

 
Interesting concept Clem. On a 14/43/102 (Ducati), or 15/44/106 (3CL) setup one would have to work out if the chain "crept", or if there was a fixed relationship. I wonder what the equation is for that?

Diesel? I was told diesel would not deteriorate the x rings, but that kero would?
 
I have modded my post as I had not worded it to describe what I was thinking,
3C should be 19/40 sprockets 15/44? (16/36 if anyone is daft enough to still use battleship door chain 630)
CLEM
 
Interesting question. I'd hazard a guess that it would depend partly on chain quality, plus combo of dirt and contaminants. But in the end, once you have a little variance it will rapidly grow, in the same way that corrugations on dirt roads develop (something we have LOTS of on Australian backroads). The more wheels accelerating over a single bump the more the subsequent 'oscillations' in the power transmission will cause the wheels to create more and more (and bigger) bumps until you get a long series of them with the same effective frequency (think sine wave frequency).

Just a theory ...
 
ghwallice said:
Interesting concept Clem. On a 14/43/102 (Ducati), or 15/44/106 (3CL) setup one would have to work out if the chain "crept", or if there was a fixed relationship. I wonder what the equation is for that?

Diesel? I was told diesel would not deteriorate the x rings, but that kero would?
Click to expand...
I use kero and it has been fine on o-ring chains. It is the only type of degreaser I use for everything (except brake internals) and it washes off with water afterwards.
 
ghwallice said:
Diesel? I was told diesel would not deteriorate the x rings, but that kero would?
Click to expand...

As far as I'm aware, Diesel and kero are very similar. They're both distilled oil products. Kero being a slightly lighter distillation than Diesel.
My Diesel engine car uses normal black O-rings throughout the fuel system. And you can run Diesel engines on kerosene with no ill effect (vehicles in cold climates use a fuel mix of Diesel and kero to prevent the fuel waxing in sub-zero temperatures). So I think it's unlikely that either would degrade the O-rings on chains. Even less likely that one would while the other wouldn't. I'd be happy to use either as a degreaser.

The degreaser you can buy in pressure-pack cans smells like it could be Diesel or a diesel/kero mix. If so, it's an expensive way to buy diesel. But the spray feature is handy.

PS: I just looked up a chemical resistance chart for O-ring materials. Ratings scale is:  A = excellent; B = good; C = fair; D = not recommended.
Motorcycle chain O-rings are made from Buna-N (nitrile) material, which is rated 'A' for chemical resistance to both Diesel and kerosene.

 
90 percent of the chains I replace at work have seized links. I do 1-2 a week. O ring has failed, let water in, grease out. Very rare to see a tight/loose spot, Japanese rk brand seem very good. One customer religiously sprayed his chain with wd40, o rings had fallen out.
 
Good info Marty, I keep hearing stories about what someone does with chain maintenance and getting millions of ks with no trouble. WD40 gets mentioned a lot.
 
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