gr8hairy1
Member
You are awesome! I super excited. I'll definitely be posting the results.
Predator 420cc on a Kandi Spyder 150gka-2 Question on Ratios
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You are awesome! I super excited. I'll definitely be posting the results.
gr8hairy1
Member
bob58o, you inspired me 
with your comment about replacing the hub. My first thought was that the hub comes attached to the axle from the factory. Potentially it is only welded on, but if cutting it off goes poorly, there's no coming back. The kart is out of commission until I can afford a new axle and everything that goes with that.
But that got me thinking about putting on a new hub on the opposite side of the axle sprocket. Then I became doubtful because the axle has no key or splines to keep the hub in place. It could be welded, but I do not have a welder(yet
). Buying out the time to transport this kart in itself would take awhile (I have no truck or trailer).
While trying to think of hub designs that could work, I thought about the two hubs sandwiching the sprocket in place. I realized that all I really needed was some way to press the sprocket (really hard) into the old hub.
Final chain of thoughts led me to using a disc of steel that bolts to the new sprocket on a farther out diameter and bolted from the steel disc through the center of the new sprocket onto the old hub. A spacer would need to be added to prevent the new sprocket from being pushed over the old hub, to keep everything aligned.
I was thinking of where to get a steel disc for this idea, and I found in the box of parts that came with the kart, an old worn out sprocket from the kart. Smaller than the new sprocket and with all the right measurements to bolt to the hub!
The link to the 60t sprocket bob58o just posted is the perfect size. I'll need to (grind out/cut out) the center to just past the bolt holes, but everything should line up.
I know this will put extra force on the bolts that would be going from the old sprocket through to the hub, but I should be able to find a small steel plate that could be used as a rock solid spacer for the middle.
Any thoughts on the pros and cons of doing this?
Attached is a scribble I did trying to picture everything and see the details on paper.
with your comment about replacing the hub. My first thought was that the hub comes attached to the axle from the factory. Potentially it is only welded on, but if cutting it off goes poorly, there's no coming back. The kart is out of commission until I can afford a new axle and everything that goes with that.But that got me thinking about putting on a new hub on the opposite side of the axle sprocket. Then I became doubtful because the axle has no key or splines to keep the hub in place. It could be welded, but I do not have a welder(yet
). Buying out the time to transport this kart in itself would take awhile (I have no truck or trailer).While trying to think of hub designs that could work, I thought about the two hubs sandwiching the sprocket in place. I realized that all I really needed was some way to press the sprocket (really hard) into the old hub.
Final chain of thoughts led me to using a disc of steel that bolts to the new sprocket on a farther out diameter and bolted from the steel disc through the center of the new sprocket onto the old hub. A spacer would need to be added to prevent the new sprocket from being pushed over the old hub, to keep everything aligned.
I was thinking of where to get a steel disc for this idea, and I found in the box of parts that came with the kart, an old worn out sprocket from the kart. Smaller than the new sprocket and with all the right measurements to bolt to the hub!
The link to the 60t sprocket bob58o just posted is the perfect size. I'll need to (grind out/cut out) the center to just past the bolt holes, but everything should line up.
I know this will put extra force on the bolts that would be going from the old sprocket through to the hub, but I should be able to find a small steel plate that could be used as a rock solid spacer for the middle.
Any thoughts on the pros and cons of doing this?
Attached is a scribble I did trying to picture everything and see the details on paper.
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ezcome-ezgo
G'me sumthin to write on
I think it would work, as long as it doesn't create alignment issues.
bob58o
SuckSqueezeBangBlow
Well I'm a big fat liar. I cannot find the 8T I mentioned. I'm sorry. I think you would of had issues with the alignment anyway (when using beefier than #41 chain), because it was B style. I did ship you the 9T sprocket. Addressed to "Resident". It should be there in three days. I can PM you a tracking number later.
420cc
22"
60T Rear
9T Front
30 series TC
6" Driven Pulley
is
18:1 at TC engagement
6:1 in highest gear.
Should give you around 39mph at 3600 RPM.
The engine should have the torque for that gearing and tire size.
The TC is still questionable.
Get a GOOD BELT and hopefully it lasts quite a bit longer.
The 8T will be better for you than the 9T. 12.5% Better. Sorry I couldn't find it.
If you don't use the 9T, you can ship it back if you feel so inclined.
420cc
22"
60T Rear
9T Front
30 series TC
6" Driven Pulley
is
18:1 at TC engagement
6:1 in highest gear.
Should give you around 39mph at 3600 RPM.
The engine should have the torque for that gearing and tire size.
The TC is still questionable.
Get a GOOD BELT and hopefully it lasts quite a bit longer.
The 8T will be better for you than the 9T. 12.5% Better. Sorry I couldn't find it.
If you don't use the 9T, you can ship it back if you feel so inclined.
gr8hairy1
Member
No worries! You've helped me so much in just information alone, plus with the 9t sprocket!! I'll see how it goes with the 9t to see how the belt wears. I bought some higher strength kevlar belts that people reviewed as lasting much longer.
Too bad it's a 1in shaft out of the engine. A 3/4in driver would reverse the ratio to 1.2:1 in highest gear...
---------- Post added at 06:47 PM ---------- Previous post was at 06:46 PM ----------
Since this kart will be toeing the line on tearing up belts, what would be the safest way to drive it for now? Trying to stay under full torque converter engagement (having fun with acceleration) or trying to stay at higher speeds for longer? Does it matter?
bob58o
SuckSqueezeBangBlow
Well the 30 Series with 3/4" DriveR Unit and 6" DriveN Pulley is 2.68:1 in LOW and 0.90:1 in HIGH.
The 30 series 3/4" DriveR Unit with 7" DriveN Pulley is 3.13 in LOW and 1.12 in HIGH.
Do you know if using the a 1" DriveR Unit changes those ratios????
I'm not sure I've seen ratios for using the 1" DriveR. Not sure if it changes it. I don't know much about the 1" DriveR 30 series TC's.
gr8hairy1
Member
You're right. I had looked at those numbers thinking they were for a 1" bore.
So then it "might" be even more unfavorable for low gears.
I say "might" because if the overall size of the driver pulley is the same, fully engaged "should" be the same.
It is a bit odd how with as many gearheads there are there's no definitive information on the ratio differences of torque converter pulley sizes. I get that in the big picture it's a small difference, but that's never stopped people from other pointless debates lol
bob58o
SuckSqueezeBangBlow
There is no debate, I was just lazy earlier.
Comet provides this info.
And now that I made sure, I will parrot it to you.
30 Series
http://www.bmikarts.com/pdf/comet_30series.pdf
30C/31D6 2.68:1 LOW
0.90:1 HIGH
30C/31D7 3.13:1 LOW
1.12:1 HIGH
30C DriveR Unit bore is 3/4" or 1". Doesn't seem to matter. Same ratio.
203814A 3/4 Bore
203603A 1" Bore
DriveN unit bore is 5/8" or 3/4". Doesn't matter. Same Ratio as long as pulley is same OD.
31D6 is 6" DriveN
217610A is 5/8 Bore
217779A is 3/4 Bore
31D7 is 7" DriveN
217611A is 5/8 Bore
217778A is 3/4 Bore
40 Series
http://www.bmikarts.com/pdf/comet_40series.pdf
40C/40D 2.43:1 LOW
1.00:1 HIGH
40C/44D 2.83:1 LOW
1.24:1 HIGH
40C DriveR unit bore either 7/8" or 1" Doesn't seem to matter. Same ratio.
203015A 1" Bore
203016A 7/8 Bore
Driven Unit Bore 5/8", 3/4" or 7/8". Same Ratio
40D 7.5" DriveN unit
209151A 5/8 Bore
209133A 3/4 Bore
209139A 7/8 Bore
44D 8.5" DriveN unit
209631A 3/4 Bore, Threaded Post and Cam
---------- Post added at 02:38 PM ---------- Previous post was at 02:06 PM ----------
If you want a debate I AM very interested in, it is "how it shifts". I want extensive testing done on amount of DriveN unit Preload (which hole you set the spring in) and which Driven unit Spring (how long it stays in lower gear before "shifting"). I want video showing RPM, MPH, and the entire TC while driving in various conditions. Fast Accel. Steady Cruising. I want this video with various Preloads and springs. I want this video on Heavy big wheel'd buggies and small minibikes. I think it would be great. LOL. Not really a debate. I want data!
I tried but my phone shook too much and was too close to the TC to get a good video.
I'll have to settle for a video of the tachometer displaying GPS mph and work backwards to get gear ratio. Sorry
gr8hairy1
Member
There is no debate, I was just lazy earlier.
Comet provides this info....
....
....
....If you want a debate I AM very interested in, it is "how it shifts". I want extensive testing done on amount of DriveN unit Preload (which hole you set the spring in) and which Driven unit Spring (how long it stays in lower gear before "shifting"). I want video showing RPM, MPH, and the entire TC while driving in various conditions. Fast Accel. Steady Cruising. I want this video with various Preloads and springs. I want this video on Heavy big wheel'd buggies and small minibikes. I think it would be great. LOL. Not really a debate. I want data!
I tried but my phone shook too much and was too close to the TC to get a good video.
I'll have to settle for a video of the tachometer displaying GPS mph and work backwards to get gear ratio. Sorry
That is not off topic! I think that is the most ON TOPIC thing I have heard in a long time! I would love to get that info along with video recordings....
Anywho, I got the sprocket you sent. Thanks again so much! Fits like a glove! Depending on how belts go I may be quickly be switching to an 8t. If so I'll send the 9t back your way. Also, the 60t sprocket arrived. It's a big one. Good weight but nothing crazy heavy. I also bought some heavy duty 420 chain that's supposed to be able to have 4,000lbs tensile strength.
The 2" spacers on the rear axle are on really tight. I'll have to borrow some air tools from my family.
Now that I got the axle and tires off, I see there is quite a bit of welding that was done on the wheel hubs (on both sides of each wheel hub). I'm not so sure how cleanly I'll be able to remove the hubs, with the idea of re-welding them after replacing the sprocket.
The good news is my next paycheck is going to be bigger than expected. I should be able to order an axle and all the hubs I need (wheel, brake, sprocket). Though they might not arrive until January(ish).
I would still like to try to get it working with the old axle in the meantime. It will all depend on how easy the hubs come off and how much time I have to work on it. If I can get the old axle up and running next week, I will do it. Otherwise I'll wait for the new axle.
What would be great is if there was a safe way to cut the axle in half and fabricate some way of hooking it together so that it doesn't require cutting the welding on the hubs each time I need to replace something.
Any ideas or is that just plain stupid?
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bob58o
SuckSqueezeBangBlow
I'm not sure cutting the axle in half is a good idea if you plan on using it again.
I may fully understand the plan, but I wouldn't cut it. And if I did cut it, I would surely weld it back together before using it.
I may fully understand the plan, but I wouldn't cut it. And if I did cut it, I would surely weld it back together before using it.
mckutzy
Well-known member
I would look into replacing the whole axle assembly... I know that sounds like alot... it might be...But the whole thing is welded shut.
The bearings are held captive by the welded on hubs for the wheels, aswell as the brake and sprocket... any wear on any of those.. the whole lot need to be turfed....
Depending on how badly the wheel hubs are welded on.... one might be able to slit the weld bead with a zip blade on a grinder, and knock it off the shaft.... but that still means youll have to cut the thing to press/hammer the slug out....aswell as for the other hubs..
Overall its not looking good in my opinion....
The bearings are held captive by the welded on hubs for the wheels, aswell as the brake and sprocket... any wear on any of those.. the whole lot need to be turfed....
Depending on how badly the wheel hubs are welded on.... one might be able to slit the weld bead with a zip blade on a grinder, and knock it off the shaft.... but that still means youll have to cut the thing to press/hammer the slug out....aswell as for the other hubs..
Overall its not looking good in my opinion....
gr8hairy1
Member
I had some time on my hands so I decided to see what could be done.
It took more work than I would've liked, but then again, so does most stuff.
Took quite a bit to get the hubs off. I would like to think re-welding wouldn't need as much, but I understand not wanting it to break. They definitely needed to be welded. The splines were almost 100% gone. Once I broke the welds both hubs could spin freely.
I wasn't sure what to do to enlarge the hole on the new sprocket. I tried with a dremel tool just to say I tried. Wow, that did not work (kind of expected that though). But that got me wishing the sprocket hub center was smaller, which then made me realize I can easily use the angle grinder on that. I don't understand why I didn't think of it before. It went pretty quickly and I put out the fires from the sparks .... almost as quickly as they started (3 times
)
(note to anyone attempting this: have the axle spinning as much as possible to help keep the hub concentric. I think it would've gone much better if someone had been there to spin the axle for me or even to hook up a motor or something to get it spinning)
It fits great and I'm not worried about how centered it is, because as long as I get the bolt holes decent, it should be balanced enough for what RPM's it will have at the axle.
What's going to be hard is getting the wheel hubs to be straight with the axle. Still trying to figure out a way to do that.
On a side note, I measured the width difference between the rear axle and the front axle. As best as I could tell the rear on this kart is 6 to 7 inches narrower on each side than the front. To get the middle of the front tire to match the middle of the rear tire I'll need a 55 inch rear axle! I think I may just try to get the outsides of the tires to be the same distance. That would make going up ramps onto a truck or trailer easy and I would know where ever the front of the kart can fit, the rear can too.
It took more work than I would've liked, but then again, so does most stuff.
Took quite a bit to get the hubs off. I would like to think re-welding wouldn't need as much, but I understand not wanting it to break. They definitely needed to be welded. The splines were almost 100% gone. Once I broke the welds both hubs could spin freely.
I wasn't sure what to do to enlarge the hole on the new sprocket. I tried with a dremel tool just to say I tried. Wow, that did not work (kind of expected that though). But that got me wishing the sprocket hub center was smaller, which then made me realize I can easily use the angle grinder on that. I don't understand why I didn't think of it before. It went pretty quickly and I put out the fires from the sparks .... almost as quickly as they started (3 times
)(note to anyone attempting this: have the axle spinning as much as possible to help keep the hub concentric. I think it would've gone much better if someone had been there to spin the axle for me or even to hook up a motor or something to get it spinning)
It fits great and I'm not worried about how centered it is, because as long as I get the bolt holes decent, it should be balanced enough for what RPM's it will have at the axle.
What's going to be hard is getting the wheel hubs to be straight with the axle. Still trying to figure out a way to do that.
On a side note, I measured the width difference between the rear axle and the front axle. As best as I could tell the rear on this kart is 6 to 7 inches narrower on each side than the front. To get the middle of the front tire to match the middle of the rear tire I'll need a 55 inch rear axle! I think I may just try to get the outsides of the tires to be the same distance. That would make going up ramps onto a truck or trailer easy and I would know where ever the front of the kart can fit, the rear can too.
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ezcome-ezgo
G'me sumthin to write on
That's good work. Why did you cut off the tip of the axle? Someone will correct me if I am wrong, but I think having a wider front track than rear will help the steering dynamics of a live axle kart.
gr8hairy1
Member
Yes, please, if anyone has thoughts on the pros and cons of changing the rear axle width on an off-road kart I would be most thankful. Most everything I have been able to read is focused more on racing karts and being on pavement.
I cut the tip of the axle off, primarily because I knew the splines were not good on the axle. The guy I bought this from told me that was the reason they were welded. Without decent splines welding would be needed. If the one end is going to be welded, might as well do both sides. That, and the one on the other side was already gone from when they had first done the welding.
gr8hairy1
Member
Well, that didn't work out....or rather I don't feel like investing in making it work.
Part of the problem is I can't find any alternative hub sizes for this sprocket. There are two sets of mounting point diameters. One is at 2 7/8" and the other one is 3 1/2". I can only find hubs for 2 7/8".
3 1/2" is too far out to meet up with this go kart's stock sprocket hub. 2 7/8" is very close (stock sprocket is 2 1/2"). Without having any machining tools I think the only way to even try to drill it out is to drill at an angle where the bolt holes slightly match up when the sprockets are laid on top of each other. Whether it's drilled straight on or at an angle, the drill bit has unequal angles working on it and with both sprockets being hardened steel, it's very easy to snap the drill bit.
I think it 'could' be done, but likely each hole would end up breaking at least a few drill bits. I pretty quickly broke my 1/4" drill bit trying to drill the first hole. With having 3 undamaged holes I'm not worried about the sprocket being off center.
Additionally, the direction the drill bit takes is very hard to control without a drill press. If someone had a drill press and some high-quality drill bits, it might be more doable.
The problem is the 2 7/8" bolt hole pattern would be ruined for mounting on a standard sprocket hub. There is the 3 1/2" mounting diameter, but I can not find any 3 1/2" sprocket hubs for a high torque application like this.
I could go the original route and grind out the center of the sprocket, drill holes to bolt the 2 sprockets together, and then mount using the original sprocket bolt holes. Though I haven't been able to find any large bolt hole diameter (4" or bigger) heavy duty sprocket hubs, so again, I likely would only be able to use this sprocket with this axle.
I would be more tempted if I wouldn't be able to afford a new axle and hubs for a while. I suppose if I could've gotten a blank sprocket this large (60t) it would've made drilling holes much easier, though the stress would come from trying to keep the sprocket concentric and have a means to drill a large enough center hole.
With the higher probability of screwing up the only mounting points I can find hubs for, I think it'd be best to wait for the new axle. I get paid on the 10th. So sometime after that, I will be ordering the new rear axle and all the needed parts. Hopefully by then I will have figured out what a good width for the rear axle would be.
I include all these points in case anyone tries doing something similar on this type of go-kart axle so they can learn from my mistakes. I personally am very proud of my idea to use the old sprocket as an adapter to attach the new sprocket. I wish I could've done it just to see that work.
Part of the problem is I can't find any alternative hub sizes for this sprocket. There are two sets of mounting point diameters. One is at 2 7/8" and the other one is 3 1/2". I can only find hubs for 2 7/8".
3 1/2" is too far out to meet up with this go kart's stock sprocket hub. 2 7/8" is very close (stock sprocket is 2 1/2"). Without having any machining tools I think the only way to even try to drill it out is to drill at an angle where the bolt holes slightly match up when the sprockets are laid on top of each other. Whether it's drilled straight on or at an angle, the drill bit has unequal angles working on it and with both sprockets being hardened steel, it's very easy to snap the drill bit.
I think it 'could' be done, but likely each hole would end up breaking at least a few drill bits. I pretty quickly broke my 1/4" drill bit trying to drill the first hole. With having 3 undamaged holes I'm not worried about the sprocket being off center.
Additionally, the direction the drill bit takes is very hard to control without a drill press. If someone had a drill press and some high-quality drill bits, it might be more doable.
The problem is the 2 7/8" bolt hole pattern would be ruined for mounting on a standard sprocket hub. There is the 3 1/2" mounting diameter, but I can not find any 3 1/2" sprocket hubs for a high torque application like this.
I could go the original route and grind out the center of the sprocket, drill holes to bolt the 2 sprockets together, and then mount using the original sprocket bolt holes. Though I haven't been able to find any large bolt hole diameter (4" or bigger) heavy duty sprocket hubs, so again, I likely would only be able to use this sprocket with this axle.
I would be more tempted if I wouldn't be able to afford a new axle and hubs for a while. I suppose if I could've gotten a blank sprocket this large (60t) it would've made drilling holes much easier, though the stress would come from trying to keep the sprocket concentric and have a means to drill a large enough center hole.
With the higher probability of screwing up the only mounting points I can find hubs for, I think it'd be best to wait for the new axle. I get paid on the 10th. So sometime after that, I will be ordering the new rear axle and all the needed parts. Hopefully by then I will have figured out what a good width for the rear axle would be.
I include all these points in case anyone tries doing something similar on this type of go-kart axle so they can learn from my mistakes. I personally am very proud of my idea to use the old sprocket as an adapter to attach the new sprocket. I wish I could've done it just to see that work.
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gr8hairy1
Member
following your build. Your buggies rear assembly is almost identical to what I started with, same size motor too, except I opted for twin jackshafts to drop the final to 7.6:1 and changed to smaller #41 chains
Glad to be of entertainment ;-)
If you have larger rear tires I have a question for you. Are you happy with that gear ratio? If you had to do it again would you still go with the same?
Also, I'm guessing with a dual jackshaft setup you have a 40 series torque converter? How often do you go through belts?
Are your rear tires the same width as the front? Would you prefer the rear to be wider or narrower?
Adultlife
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I am still building it, and waiting on a jackshaft kit from eBay, but hopefully this weekend or sooner I can answer that question yes 40 series and I hope I don’t go through belts with my 7.6:1 ratio and 20” tires. I reduced tire size when I bought the new maxxis’s. The rear track width is narrower than the front and I read from the manufacturer that they do that because the live axle makes it hard to turn without understeer and that rectifys it somehow , idk, I like the width though, it fits in my truck still , >53 inches
yes 40 series and I hope I don’t go through belts with my 7.6:1 ratio and 20” tires. I reduced tire size when I bought the new maxxis’s. The rear track width is narrower than the front and I read from the manufacturer that they do that because the live axle makes it hard to turn without understeer and that rectifys it somehow , idk, I like the width though, it fits in my truck still , >53 inches
ezcome-ezgo
G'me sumthin to write on
Can't say enough about step drill bits for easy and accurate drilling in metal.
gr8hairy1
Member
Great point on easily fitting in a truck bed.
I'll be following your build too! Here's hoping you can make some mistakes for me so I can learn what not to do lol. Though I suppose no mistakes is best. But where's the fun in that?
---------- Post added at 08:22 PM ---------- Previous post was at 08:19 PM ----------
Very true. I forget about stepped drill bits often and I don't know why. I think the only time I've ever seen them break is when they are really dull, on a strong drill, and drilling on something hardened.
As long as you could find one narrow enough and had a drill press, I bet it could be done.
Though I'm hoping to get a welder before a drill press.
---------- Post added at 08:53 PM ---------- Previous post was at 08:22 PM ----------
I have an answer for the axle width! And I think it will make many people happy. For science!
I plan on ordering the longest axle I can from BMI. They have a custom axle option that goes up to 55 inches. They say you can special order, but I feel 55 inches is the limit for me. Since the extra width will be on the outside, I can easily move the wheel hubs in for a narrower width.
I can replace the steering wheel with a nut and use a torque wrench to show the differences of force needed to turn the wheels to help quantify the results (obviously not going to be doing any high-speed testing).
Plus, with ordering the axle that big it'll force me to figure this out and not let me be lazy and skip it. I'll create a separate thread for showing the results.
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