Huh! What???
Need help picking the right engine for my manco.
- Thread starter Scarface
- Start date
- Status
Huh! What???
Scarface
New member
I deleted the post because about 7 hours gone by and no body said anything so I thought maybe people were getting anoyed with all my questions, so i just deleted it. But I guess I should be more patient and wait atleast 24 hours for a response, guess I was just used to the R/C forums where you ask a question and you will get 1-5 reply's with in an hour. But since I still had the same trouble today I will post what I had up last night.
The speed calculator on this website, does it work correctly for the torque converter and jack shaft setup like I am using or is that speed calc a different kind of setup?
My biggest problem right now is I can not get my driven off my go kart, I took the bolt in the middle of the driven out, and is it just supposed to just come off with alittle bit of pull or am I missing something? I tried pulling but it did not budge I even hit it with a mallet lightly and it still did not move.
Doc Sprocket
*********
You've got to be more patient...
Gearing is gearing. Calculate as if your CVT is just a clutch. You can safely gear a bit higher than you would with just a clutch, but the math is the same. Your driven is likely frozen to the shaft with rust. Try letting some WD-40 or similar soak for a day. Give it a little love with a hot wrench too, but don't overdo it, and avoid beating the heck out of it.
Gearing is gearing. Calculate as if your CVT is just a clutch. You can safely gear a bit higher than you would with just a clutch, but the math is the same. Your driven is likely frozen to the shaft with rust. Try letting some WD-40 or similar soak for a day. Give it a little love with a hot wrench too, but don't overdo it, and avoid beating the heck out of it.
souperman000
New member
Just be patient. people will answer your question. If nothing has happened in say a couple days, then bump the thread. Its a small forum, usually takes a few hours for someone to post. (Also depends on the time of your post.)
Have a look at these. They all work fine
Speed calculator
http://www.diygokarts.com/speed-calculator.html
http://www.rbracing-rsr.com/gearspeed.html
http://www.csgnetwork.com/kartpotentialspeedcalc.html
Tire, gear ratio, RPM and Speed Formulas
http://www.diygokarts.com/vb/showthread.php?t=9591
http://www.csgnetwork.com/gearratcalc.html
http://www.4lo.com/calc/gearratio.htm
Jackshaft ratio calculator
http://www.fasttrackraceway.com/calc/index.php
http://www.affordablegokarts.com/GearCalc.php
Like Toystory says, treat a TC as if it is a normal clutch. You will use the TC sprocket and the axle sprocket for your calculations.
Scarface
New member
Thanks, I will try that monday.
Scarface
New member
Ok so lets say I have that 420cc 13hp predator engine spinning at 5,000rpm's, I have 18" back tires. The sprocket on the jack shaft is a 12 tooth and the one on the axel is 54 tooth, I am getting 59mph out of it.
Now lets say I have the same setup but I have 10 tooth sprocket on the jackshaft and a 45 tooth sprocket on the axel.
Will there be any difference in acceleration or the way it drives or anything, or will they both drive the same way? On the speed calcs it says they both end up being 59mph. Same with an 8 tooth sprocket on the jack shaft and a 36 tooth on the axel the speed says 59mph, will there be a difference in the way it drives?
Now lets say I have the same setup but I have 10 tooth sprocket on the jackshaft and a 45 tooth sprocket on the axel.
Will there be any difference in acceleration or the way it drives or anything, or will they both drive the same way? On the speed calcs it says they both end up being 59mph. Same with an 8 tooth sprocket on the jack shaft and a 36 tooth on the axel the speed says 59mph, will there be a difference in the way it drives?
Doc Sprocket
*********
No difference that you would actually notice. The larger gears would live a wee bit longer as well as the chain because of surface contact area, but on the flipside, larger gears would also equal a bit more weight and rotating mass. Negligible, really.
Scarface
New member
Ok well I want to get that 54 tooth sprocket off the ground, it seems to me that the chain/sprocket gaurd is to low to the ground, so you think a 10 tooth on the jack shaft and a 44 on the axel would be good?
Scarface
New member
Even if I just keep that 12T sprocket on the jack shaft and put a 44T sprocket on the axel instead of the 54T, it then says I will get 70mph with 18" tires and 5000rpm's but will my acceleration be really slow? I don't know what will make my acceleration really slow nor what will just make the tires spin, or does the torque converter balance those two out and a sprocket size isn't going to change my acceleration?
I want me to be able to step on the gas and have the tires spin twice then grab and take off nice but then I don't want the top speed to be 20mph. I kinda need to know what needs to be done to get the results I am looking for. So like punch on the gas spin the tires 1-3 times but then it grabs and then takes off and has good acceleration and top speed of 60mph, that would be great, I just need to know what is going to change driving wise if I go changing a sprocket size higher or lower or changing the tire size smaller and bigger. (18" tires for the back tire is not the offical tire size I am getting, I was just using 18" as an example in the speed calculator, I am not sure what size tire I am getting yet)
I want me to be able to step on the gas and have the tires spin twice then grab and take off nice but then I don't want the top speed to be 20mph. I kinda need to know what needs to be done to get the results I am looking for. So like punch on the gas spin the tires 1-3 times but then it grabs and then takes off and has good acceleration and top speed of 60mph, that would be great, I just need to know what is going to change driving wise if I go changing a sprocket size higher or lower or changing the tire size smaller and bigger. (18" tires for the back tire is not the offical tire size I am getting, I was just using 18" as an example in the speed calculator, I am not sure what size tire I am getting yet)
Doc Sprocket
*********
I believe you're setting your sights a wee bit high. 60MPH and wheelspin just aren't likely (or safe) with what you have. I was running a GX340 and comet 40 combined with 18" tires at 4.8:1, topping out at 46MPH governed to 4200RPM, and even that wasn't the best ratio under the circumstances. You're going to need to be down around 6:1 or deeper to get some decent wheelspin, and you will sacrifice speed. Again, that chassis and componentry are not designed to be safe at 60.
Scarface
New member
Ok I am not exactly sure what it means when you give me ratio's, I just spent 15min looking it up but could not find anything. So what does 4.8:1 or 6:1 mean?
NVM, I think I understand it now, a 6:1 would mean the sprocket on the jack shaft spins 6 times while the sprocket on the axel spins once. But how do I figure out what my gear ration would be if I put like a 12T on jack shaft and a 54T on the axel?
Also I am going to use tires that are like car tread tires that way I can run on road and dirt because dirrt tires on the road will get torn up. So if I am on like the road, I don't necessarily want my wheels to spin but I want to have good acceleration, so I want to be at the point where they won't spin on the road but they will spin somewhat on dirt. So what kind of gear ration should I be looking at but then if it is like a 5:1 then how do I figure out what size sprockets I should be using to get that 5:1 ratio.
NVM, I think I understand it now, a 6:1 would mean the sprocket on the jack shaft spins 6 times while the sprocket on the axel spins once. But how do I figure out what my gear ration would be if I put like a 12T on jack shaft and a 54T on the axel?
Also I am going to use tires that are like car tread tires that way I can run on road and dirt because dirrt tires on the road will get torn up. So if I am on like the road, I don't necessarily want my wheels to spin but I want to have good acceleration, so I want to be at the point where they won't spin on the road but they will spin somewhat on dirt. So what kind of gear ration should I be looking at but then if it is like a 5:1 then how do I figure out what size sprockets I should be using to get that 5:1 ratio.
Scarface
New member
Ok on my jack shaft there is a 12 tooth sprocket and a 54 tooth on the axel, is this a 4.5:1 ratio?
Oh and is this correctly siad?
"A lower gear ratio will give you more torque, but less speed, where as a higher gear ratio is the exact opposite. A 9:1 ratio will give you much higher torque, pulling power, and takeoff but a much lower top speed."
(someone else said this)
Oh and is this correctly siad?
"A lower gear ratio will give you more torque, but less speed, where as a higher gear ratio is the exact opposite. A 9:1 ratio will give you much higher torque, pulling power, and takeoff but a much lower top speed."
(someone else said this)
Doc Sprocket
*********
Now you've got the concept! Divide the drive sprocket into the driven sprocket to find the ratio. Example 12T into 60T = 5:1.
Scarface
New member
Ok but is this statment correct?
"A lower gear ratio will give you more torque, but less speed, where as a higher gear ratio is the exact opposite. A 9:1 ratio will give you much higher torque, pulling power, and takeoff but a much lower top speed."
It says low gear ratio: gives torque takes away top speed.
It says higher gear ratio: give torque takes away top speed.
So which one gives you speed because that statment says the same exact thing.
"A lower gear ratio will give you more torque, but less speed, where as a higher gear ratio is the exact opposite. A 9:1 ratio will give you much higher torque, pulling power, and takeoff but a much lower top speed."
It says low gear ratio: gives torque takes away top speed.
It says higher gear ratio: give torque takes away top speed.
So which one gives you speed because that statment says the same exact thing.
Doc Sprocket
*********
Both are correct. You are confused by the fact that a numerically lower ratio (like 4:1) is referred to as a high ratio. This is because we are referring to a reduction, not an increase. Example-
I was running a 5:1 ratio, but it was too high. So I lowered it to 6:1. It may help to mentally add the word "speed", as in "I was running a 5:1 ratio, but it was too high(speed)...
I was running a 5:1 ratio, but it was too high. So I lowered it to 6:1. It may help to mentally add the word "speed", as in "I was running a 5:1 ratio, but it was too high(speed)...
Scarface
New member
Oh ok, so what kind of gear ratio's should I be looking for or is gear ratios something I am going to have to play with. So when the times comes should I just buy a few sprocket setups and try them then see which one I like? (as long as this sprocket testing can be under $100?)
jman231994
New member
I think you missed something hes saying there toystory, both are the same how he has it worded...
It should be:
Low gear ratio is higher torque and less top speed
High gear ratio is lower torque and more top speed
If I missed something obvious and youve already cleared that up then ignore me hahaha
Scarface
New member
Ok thanks. But how do I know which gear ratio I will like best? Do most people try out a couple different gear ratio's? So in my case I would have to buy different sprockets to see which gear ratio I like best?
EDIT: Also, lets say I have a 12T on jackshaft and a 54T on the axel, and that is a 4.5:1 ratio and that is the ratio i want. But I feel as if my axel sprocket and sprocket gaurd are to low to the ground should I get a 10T sprocket on the jack shaft and a 45T on the axel, that way it is a smaller sprocket and would make for more ground clearance, can I do that?
Doc Sprocket
*********
It's a bit of a gamble. You would do your best to work it out in theory, and then the butt-dyno will tell you if you need to make an adjustment.
As far as sprocket sizes go, yes- there's more than one combination to attain a set ratio. either one is acceptable. Given the choice, I would go with the smaller clutch. This ensures the smallest possible axle sprocket for a set ratio, and leaves the most room for gearing down if necessary.
As far as sprocket sizes go, yes- there's more than one combination to attain a set ratio. either one is acceptable. Given the choice, I would go with the smaller clutch. This ensures the smallest possible axle sprocket for a set ratio, and leaves the most room for gearing down if necessary.
- Status