August 1st, 2014

Go Kart Chains: Which Kind Should I Use?

On Go Karts you will notice that a lot of the drive systems, on most go karts have, chains.  To drive them, you will have small sprocket at the engine down to a large drive sprocket on the drive axel.  The chain size can vary. 

Chain Definition

The pitch is the distance between the two links and the pitch diameter on a sprocket is actually the centerline of the chain link, between thetwo chain pitches as they go across the sprocket.  The formula for the pitch diameter is:

Pitch Diameter = Chain Pitch/(SIN(180/Number Teeth)

How Do Sprockets Work?

One thing you should understand about chain is that it is designed to run on the sprocket and elongate.  The sprockets themselves are designed to take the chain, and still pull on it even though the chain elongates.  If you look at an old chain you will notice that the chain pitch is longer, expanded by a few thousands maybe thirty thousands at the most, and the chain itself will actually ride up on the sprocket teeth.  

If you think about it abstractly think of the following example:

Take your fingers and spread them apart.  Put your two fingers in a V.   You will notice that the outer part of your  fingers, the top of your fingers are spread apart farther than the knuckle portion. 

Well a sprocket is similar to your fingers sticking up, in that the chain can ride up on the surface of those fingers, if you will, and become longer.  What will happen is the sprocket itself has a certain kind of profile so that it mates with the chain in a rolling style fashion, a camming action, so that it is smooth. 

What Happens When The Chain Elongates?

Once your chain gets too long then the chain will start to come off.  The sprocket teeth will not engage the chain links well, and the sprocket teeth will actually cam off the chain links.  That is the time to change your chain and your sprockets too, because they both have worn out. 

Chain Load Ratings

The chain itself is also rated for a certain amount of tension.  And that tension will be determined by how large your go kart is, and how muchhorsepower you throw into it. 

The pitch of the chain regulates how fast the chain can whip around the sprockets.  Typically a smaller pitch chain will have less mass, will have less chordal action (meaning less flexation), it will yield less noise and will be able to have faster feet per minute than a larger chain. 

There is a law of diminishing returns there, but a smaller chain is more suited for high speed, whereas a larger chain , not so much.   If you think about it, you have centrifugal loads that are pulling on the chain as it is flinging around the sprocket that it is engaging.  This centrifugal load too, has and effect on how well the chain engages the sprockets. 

But we are not going to be really too much concerned about that, we are more concerned about the rating of the chain.   For all intensive purposes the chains that we would be dealing with would be 3/8ths to ½ of an inch pitch.   Which is #35 and #41 chain. 

Chain Rating Calculation

In the Go Kart Building 201 Coarse, there is a chain rating calculation.  Using the program, which will tell you how much load is being exerted by the engine into your go kart drive train, you can figure out the tension in the chain, and the apply it to the chain calculation.  

Chain Lubrication Is Essential For Good Chain Life.

The next question is:

 -What about lubricating my chain?
 -What about using a chain that is pre-lubricated?  
 -Can I ride my go kart out in water?
 -What do I have to do to make sure it does not rust?

Lubrication is very important for a chain.  And believe it or not lubrication can be a detriment to chain.  It depends on the environment thatyou are running it in. 

Abusive Environments For Chain And How To Lubricate Your Chain

For example:  If you are running your chain in an environment which is very sandy, and you have oiled the snot out of your chain, the sand will tend to collect on the oil and then become ingrained inside the chain.  The best thing you can do in that instance is to not oil your chain. Just leave it. 

If you know you are going to be riding in sand, the best thing would be to leave the chain to dry out, then after you are done driving in sandthen lubricate it.  If you know you are going to be riding in a sandy environment all the time, you may want to reconsider oiling your chain at all.

But for most of us, when we are riding our go karts we would like to have our chains oiled.  And there are several ways you can do that. 

Good Chain Lubrication Practice

First of all before you even put the chain on the go kart, it would be a good idea to soak it, for at least a 24 hour period, in a bucket of oil. What this does is it allows the oil to impregnate itself into the chain.  There also are several type chain lubricants that you can use, Teflon additives and so forth. 

Chain Dynamics And Elongation Due to Depleted Lubricants

What happens actually in a chain, is that it has a rolling action, as it engages and disengages the sprockets.  It is in tension, and it is likea hinge on a door.  It rolls around as it is pulling.  That is how the chain wears out.  And that is actually why a chain becomes elongated.  Not that the bars of the chain become lengthened.  It is because the joints themselves have become worn out and start to lengthen the chain. 

If you were to actually to take the chain apart you will see that the pin looks almost eccentric and the barrel itself is worn out too.   If the chain is that bad it is time to replace it any way. 

Chain Lubrication Systems and Practice

Running a chain at high speed also causes the chain to wear faster.  Lubricating your chain is very important.  One of the things that I do, with my gokart is, I take the positive ventilation crankcase (PVC) hose and I actually route it towards the chain so it spills onto the chain while you’re driving.

Also it is a good idea when you are done with riding, that you  oil down your chain.  Surface oiling, does not really do anything for you.  All it does is it oils the side bars of the chain so they are not rusted, but other than that you should oil the joints. 

One thing to just remember is that surface oiling does not really do anything for your chain, and you may be surprised that your chain will wear out relatively quickly. 

Undersized Chain Effects And Maintenance Issues

I personally have a chain on my go kart, which is I calculated is on a small side; and have confirmed the calculation, because I have been wearing one out about every year and a half if I ride the go kart pretty hard.   And I do, I ride it up towards 35 mph, and that is pretty high speed for that chain, and it is pulling on it pretty hard.  I have also worn out sprockets, drive sprockets in particular, on the clutches. 

It is important, that when you first put your go kart together, that you get the chain tension set up properly.   I was being on the cheap side myself, and I just stuck on whatever I could grab.  I had a clutch that existed, it had a small pitch.  And I did not have any large pitch sprockets; I did not want to spend the money, so I figured I would just run through chain. 

If you want to be cheap, that is an option, but the best thing to do is if you want your chain to last longer, is to actually get the chain sized up correctly from the start. 

Chain Types, Oiless, Rust Resistant, Motorcycle Style Chains

There are various style chains, I had mentioned an oiless chain, it is used on motorcycles where you actually do not oil the chain.  The chain has been pre-lubricated before you buy it and it has o-ring in it.  That is a pretty expensive chain.

There are stainless steel style chains.  I in my past have actually used chains in my profession.  I used to do chain calculations.  One of the things I used to work with was conveyor chains.  And we used stainless steel chains to convey material and you did no have to lubricate the stainless steel chain.  You just had to make sure that it was sized properly.  They would clean these chains with power washers and so on.  

I  have never seen a stainless steel chain ever on a go kart.  I am not saying it would not work,  I just have never seen one on a  gokart. 

There are different chains that have been treated so that they do not rust.  They have a zinc paint coating on them.  And they are designed so that they do not rust.  As far as high speed is concerned, Tsuabaki sells a chain like that for motorcycles. 

I have been experimenting with the style coating (dip spin process) that is used on these chains and it works pretty well.  It works a lot better than zinc dichromate which can be scratched off with a finger nail and then expose the steel to rusting.  This zinc coating material actually sacrifices itself and forms a covering above scratches and prevents rusting from occurring.

Rust Resistance And Proper Chain Care

Really, rust resistance should not be on the top of the list, in my opinion.  Don’t park your go kart outside if you can help it.  If you are, then cover all the parts that would rust and get rain on them.  If they are going to be exposed to the elements, then it would be a good idea to just coat them with some sort of waxy style material just to keep the water and the moisture off of the chain and other moving parts.

Conclusion:  “Which Style Should I Use?”

So the bottom line is, on chains, “Which style should I use?”  I would recommend first of all that you figure out what the tension is going to

be.  What kind of load are you going to be putting on this chain?  Then I would size up that chain, and figure out through those calculations what size chain are you going to use.

Secondly, in the next step, I would figure out which lubrication system am I going to be using.   And make sure you are faithful in lubricating the chain.

 

 


 
 

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