Jackshaft questions

[G.W]

I'm not building anything with a jackshaft, but when I did it took me a long time to figure out the gearing. I figured I'd ask a few questions so I can learn about these incase I need to use one again.

My number 1 question is if I have the same tooth sprocket on both sides, is the gear ratio just the engine sprocket to the axle sprocket, or is it something different?

 

[BrownStainRacing]

I'm not building anything with a jackshaft, but when I did it took me a long time to figure out the gearing. I figured I'd ask a few questions so I can learn about these incase I need to use one again.

My number 1 question is if I have the same tooth sprocket on both sides, is the gear ratio just the engine sprocket to the axle sprocket, or is it something different?

If you got a 10t on clutch going to a 10t on the jackshaft, that is 1:1.

Now if you got 10t on the otherside of jackshaft to a 50t axle that is 5:1.

1 x 5 is 5:1.

If any 1 of the jackshaft sprockets are different, then you have to start the math over again.

I seen a jachshaft calculator somewhere, can't find it now.

With a jackshaft, you can fine the correct gear ratio alot faster, and cheaper.

 

[G.W]

One more question. How much HP would a 1 inch shaft handle with 2 sprockets on the outside with no end support bearing (kinda like stock mini bike jackshafts)

 

[BrownStainRacing]

One more question. How much HP would a 1 inch shaft handle with 2 sprockets on the outside with no end support bearing (kinda like stock mini bike jackshafts)

Have to see a pic.

If it's the stock coleman, baja jasckshaft, then stock engines with eventually crack the plate.

I got a PMR jackshaft on my grands son's mini.

I used it on a 7800 rpm 196cc without any problems, it should have been around 12hp.

 

[G.W]

Yes, that's what I'm talking about. I wasn't talking that specific jackshaft, just somthing similar. I don't have much sprocket space on my go kart axle, so I might need a jackshaft on my 16hp engine, and a jackshaft like that might be my only option.

 

[BrownStainRacing]

Yes, that's what I'm talking about. I wasn't talking that specific jackshaft, just somthing similar. I don't have much sprocket space on my go kart axle, so I might need a jackshaft on my 16hp engine, and a jackshaft like that might be my only option.

I think it bearing placement that's important when it comes to jackshafts.

I've seen stock big blocks bend the jackshaft with 2 bearings, and big modified engines not hurt anything thing with 3 bearings and smaller diameter jackshafts.

 

[Master Hack]

Your question was about gearing, but in typical DIYGK fashion, we take off in tangents and bury ya in useless info overload.
Always keep sprockets as close as possible to the bearings. While not always practical, just remember the farther away from the bearing, the more leverage the chain has on the shaft.
choice of material is important also. A 1inch piece of material salvaged from some chinese crap is not as strong as 1018 for instance.

if you haven’t got the shaft yet, you can be bored by this crap:

Shaft Design | Material , Types , How to Design Shaft - Learn Mechanical Engineering

Shaft Design | Material , Types , How to Design Shaft Introduction to the Shaft:- • A shaft is a rotating member, usually of circular cross section, used to transmit power or motion. • It provides the axis of rotation, or oscillation, of elements such as gears, pulleys, flywheels, cranks...

learnmech.com

 

[G.W]

I haven't ordered anything. Just playing with ideas. I planned on ordering high quality parts for this because of the HP

 

[Master Hack]

I haven't ordered anything. Just playing with ideas. I planned on ordering high quality parts for this because of the HP

Cool, but since this is DIYGK, you get the required info dump.
that way your simple idea becomes a friggen nightmare that takes up may more time than if ya just jumped in!

 

[G.W]

I'm hoping to have the outside sprocket no further than 2 inches from the bearings. That is if I go with a jackshaft.

 

[Master Hack]

That should work, with the right material.

 

[G.W]

Here's an idea. A solid shaft that is well supported, and a tube with the sprockets welded on it with bearings in it. Would this work well? I could probably support the end much easier that way

 

[Master Hack]

If i understand this correctly, No. keep it simple. That is going to weigh more, be more complex, mo problematic. Copy what ya see being done elsewhere, don’t re invent the wheel, or shaft in this case.

 

[Master Hack]

Don,’t over think it. Get the right material call it good. If yer thinkin big power then ya better rethink the whole thing.

 

[G.W]

I was just thinking about that because the old big wheel bikes use that and have about the same HP