Bevel Gear Drive: The Vertical Engine Solution?

Question: I have this set of bevel gears that I found when I took apart this transmission on a riding lawn mower, and I was wondering can you use these bevel gears to convert a vertical engine to run horizontally and then run a go kart?

That’s a great question, there are a lot of proponents of using a bevel gear system on a go kart drive using a vertical engine and I am all for the concept but I have some reservations as to how it would actually be put together. To be quite honest I have yet to see a system that it actually works properly and lasts a long time.

The concept that people are proposing is taking a bevel gears which usually are made out of powdered metal and then somehow fixing them to the engine and then fixing the other bevel gear to a horizontal shaft which would be mounted on some bearings. The two shafts would then run perpendicular to each other the vertical engine obviously running straight up and down and the horizontal shaft driving a clutch or a belt to drive the go kart.

There are three major problems with this concept and I will go through them here:

Number 1: The lubrication of the sprockets themselves.

Number 2: The center to center spacing of the sprockets themselves.

Number 3: The actual mounting of the sprockets to the shafting and the engine itself.

The biggest problem, number one, is the lubrication of the sprockets themselves. When a gear set is put together lubrication is the utmost in maintaining the longevity of the gear set. To explain that further the action of the sprockets teeth relative to one another is a sliding action versus a point contact. The sliding action generates heat or friction when the teeth are mating together. The lubrication or the oil medium is designed to keep the teeth from rubbing against one another and actually peels away the heat energy as a two sprocket teeth mate one another. If oil or lubrication is absent with the sprocket teeth the two teeth will weld to one another or become galled or in a better sense they will act like files on one another and wear away the face of the teeth.

Lubrication is a vital component in gear sets in order to allow larger loads to be put through them. The major problem with lubrication on a bevel gear set that you would basically take off of transmission is that the bevel gear set would be hanging up probably out in midair and you would need to adapt the development an oil bath system. A simple spray can is not going to cut it in this application, but an oil bath is vital or at least the grease packing would be very important for this particular application. In order to contain the oil and the grease a shroud or a casing will have to be developed to keep the oil in a pool and the grease in a pocket.

The alignment of the gears relative to each other is actually just as important if not more important than the oil bath system. The reason for this is that the orientation of the gears relative to each other is very vital otherwise the action of the gear teeth will be more an impact load versus a sliding action. When gear teeth impact one another they tend indent the surfaces of each other and also induced stresses which the gear teeth are not designed for. As a result the gear teeth will eventually shear off or crack off and you’ll end up with teeth missing on the bevel gear set. Alignment of the gearing can be accomplished using basic measurements and doing it by eye, however a machinists accuracy is required for proper alignment of a gear set. In other words the gearbox is needed which is designed by nature to be machined on machining centers which hold tolerances which are really tight. Additionally a gearbox is designed with an oil reservoir and has bearings which are designed to be continually bathed in oil so that the gearbox can bleed off heat in all these vital areas.

From a simplicity standpoint trying to set up a bevel gear drive may appear initially to work okay but will not last much more than a couple of hours before the gears will be destroyed.

And finally the third aspect of using the bevel gears, attaching the gears to the drive system can be quite a challenge. If you take a look at some of these bevel gears that come off a gearboxes they have splines which are designed for a splined shaft. You may be tempted to use the spline shaft that comes out to gearbox, which may work okay in some instances but for most instances it’s probably not going to work.  You’re going to have to develop your own shaft that will mate up to the clutch. Additionally mounting the powdered gear sprocket or bevel gear onto the engine may be quite a challenge. You will end up probably having to weld the bevel gear onto a metal hub which will fit onto the engine itself. The problem that you will discover when you’re welding this gear onto the metal hub is that the gear will not mate squarely to the hub and will probably run wobbly and as a result destroy your other gear when you try to run the system.

So in a long breath paragraph and dissertation on the discussion of bevel gear systems, it is not a good idea because of all the complexities and the lack of lubrication. You will end up with having a system that might work for an hour then wind up destroying itself after that hour and then you wonder what you’re going to do next.

In case you’re wondering “How do you do it?”  the Go Kart Guru has put together a “How You Put It Together Vertical Engine Drive Course.” In this 18 page volume you’ll discover how to us put together a simple yet reliable system that will work on all sorts of go carts. The horsepower ranges can be from at least five to around 12 or even 15 hp.

In this course we also discuss how to set up the drive system so that you can make a go kart climb hills and also hook it up to a torque converter system so you can maximize your horsepower output so the go kart climb hills and do off roading and so forth.

Goto   for  more details.

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  1. i have a honda motor that came off a spray washer, iam mounting it on a go cart. cant get it to idle down.
    it stays at halve or wide open throttle.i have bought
    many honda brackets to fis this problem but they dont work. i notice this carb. does not have a air gas needle valve or idle mixture screw.any help or thoughts woul be appreciated.
    gc 160 honda engine

    thanks wayne zimmer

    • The carb on this power washer is set for 3600 rpm all the time (at least the governor is set for this speed). The needle valve is set at the factory. The performance of this set up should not affect what you are trying to do. The problem you are having is that the governor is set high. Typically this means that the spring to the governor mechanism is tighter than on lets say a snow blower or roto tiller.

      To get past this you need to look for adjustments in the governor mechanism, which is the spaghetti maze of systems which we talk about in this article: How Does The Governor Work On Go Karts Or Small Engines?

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