Predator 420cc on a Kandi Spyder 150gka-2 Question on Ratios

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gr8hairy1

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.... that issue.

How much room do you have in front of your engine?

.....

Not much at all... maybe a few inches.

I am very jealous of the replaced rear swing arm that kevbo22 posted. So much room to do whatever you want!
 

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kevbo22

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I am very jealous of the replaced rear swing arm that kevbo22 posted. So much room to do whatever you want!

It came out pretty good, thanks.
Its not so roomy any more however. I put in a FNR gear box, and with the 40 series, brake caliper, hub and disk and battery box, it pretty much eats all the room up.

But it works great.
 

gr8hairy1

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It came out pretty good, thanks.
Its not so roomy any more however. I put in a FNR gear box, and with the 40 series, brake caliper, hub and disk and battery box, it pretty much eats all the room up.

But it works great.

Wow oh wow forget my silly ideas. That is hands down the best setup. Even if I could fiddle with the design and get something to work, I know I'll always be wishing it was setup like yours. Definitely would need a redesigned swing arm like yours to fit the height of the jackshaft box (such an obvious idea now that I know about it).

So....uh.....did you make it yourself? Usually doing it the first time is the hard part, making something the second time is easy and quick ;) ;)
 

kevbo22

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Wow oh wow forget my silly ideas. That is hands down the best setup. Even if I could fiddle with the design and get something to work, I know I'll always be wishing it was setup like yours. Definitely would need a redesigned swing arm like yours to fit the height of the jackshaft box (such an obvious idea now that I know about it).

So....uh.....did you make it yourself? Usually doing it the first time is the hard part, making something the second time is easy and quick ;) ;)

I did do it, yes. Thats the first and only one I did. A little pre-planning went a long way for me. Looking back on it, it really wasn't hard to do.

I unbolted the rear swing arm and put it on a furniture dolly (where it still sits in its entirety in my garage) and just welded up a square, but on the side that attaches to the frame, i notched out the end and welded tube in for the swing arm mount. I made sure to weld on the new bearing hangers so the axle would be at the same place, and also made sure to weld the shock mounts at the same place as on the original swing arm.
 

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gr8hairy1

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Kevbo22

Thank you such for the info. I don't think I'll be able to convince myself to go any other way than what you did.

How did you keep all the connections in the same place but still have the clearance for the jackshaft box and the extra room above the engine?

By the way, what gear ratios are you using?
Edit: Nevermind, finally clicked that you said you put in an FNR Gearbox. While I'd love one, my budget does draw a line somewhere below that lol
 

kevbo22

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Kevbo22

Thank you such for the info. I don't think I'll be able to convince myself to go any other way than what you did.

How did you keep all the connections in the same place but still have the clearance for the jackshaft box and the extra room above the engine?

By the way, what gear ratios are you using?

Well the clearance really came from removing the gas tank and using the one that came with the buggy.

So my gearing is a little wired cuase im using a FNR so I calculated it like a jack shaft gear ratio and I think its right.. but this is what it is:
First gear in FNR 10 tooth
second gear in FNR 13 tooth
Gear out of FNR that goes to axle sprocket 12 tooth
Axle sprocket 60 tooth
This would be 6.5 ratio

And like I said I think thats right, But that FNR does have some "idler" gears, so not sure if thats how it is calculated.
 

mckutzy

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Any piece of 1" keyed shaft will do...
Could get fancy with one with threaded ends, but the above will be just fine...
Get plenty of shaft collars for the wheels and such...
 

gr8hairy1

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Any piece of 1" keyed shaft will do...
Could get fancy with one with threaded ends, but the above will be just fine...
Get plenty of shaft collars for the wheels and such...

Good deal. Thank you much. That's what I was thinking, but was looking for confirmation.

On a related note, I am having a really tough time finding a sprocket hub. I'd like to get a large sprocket for now so we can at least enjoy the go kart while building a new rear end.

I'm looking to find a (something around 60t) sprocket for 428 chain, as well as some way to mount it onto the axle hub. The axle hub bolt hole pattern is 2.25.

I haven't found anything....
 

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kevbo22

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As promised in our PM, here are the dimensions. I couldn't send the image via PM, so im posting it here. Hope it helps if you decide to go this route.
 

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KingCobra

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Does anyone have any recommendations on where to get an axle this go kart? I'm not sure what I'm supposed to be looking for.

Ebay will have great deals and you will need at least a 42". Go 44" X 1 1/4" or 1" if you must. Seek out wheel hubs for the 1 1/4" axle first to make sure you can find them. Plan ahead and then after your research is completed and you can assemble the axle you want, then order it.
 

mckutzy

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A quick search on your sprocket... It is a JT sprocket... They are at least relitivly common... Now you just need to find your bolt pattern and desired tooth count...
 

gr8hairy1

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A quick search on your sprocket... It is a JT sprocket... They are at least relitivly common... Now you just need to find your bolt pattern and desired tooth count...

I can't find this bolt hole pattern anywhere. 2.25 in a big sprocket doesn't seem to exist. Since the sprocket I'm looking at getting will be temporary use, I could see about welding it to the sprocket hub, as long as the sprocket is steel.

---------- Post added at 12:48 PM ---------- Previous post was at 12:47 PM ----------

As promised in our PM, here are the dimensions. I couldn't send the image via PM, so im posting it here. Hope it helps if you decide to go this route.

Awesome awesome awesome! I'm excited about getting started on this. May take a few months, but it'll be worth the wait!

---------- Post added at 12:49 PM ---------- Previous post was at 12:48 PM ----------

Ebay will have great deals and you will need at least a 42". Go 44" X 1 1/4" or 1" if you must. Seek out wheel hubs for the 1 1/4" axle first to make sure you can find them. Plan ahead and then after your research is completed and you can assemble the axle you want, then order it.

Tubular is good enough for a kart this size? I was hoping to go solid core (because I figured overkill removed worry of screwing anything up) at 1.25 inch, but I could only find that in aluminum. The thickest solid steel able I've been able to find is 1 inch. There is an amazing lack of info on axle selection.


---------- Post added at 12:54 PM ---------- Previous post was at 12:49 PM ----------

Good advice! Thats exactly what I used:
http://www.bmikarts.com/1-14-Tubular-Steel-Axle-14-Wall_p_510.html
I picked this axle just because of what you said!

What hubs do you have for your axle? Did you go splined or keyed? With shoulder/without shoulder? Pros and cons of what the ends of the axle should be are still really really confusing for me. There's either not much info out there or I am searching all the wrong words...
 

mckutzy

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Kart specific no.... Industrial use there's a fare amount...

For what it's worth, 1" is plenty, keyed all the way... Just mount all items on existing hubs(there easy to find), and it'll put together with common bearings... It's pretty simple setup.
 

gr8hairy1

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Do you think that would be enough to stop the belts from shredding? If so that'd be great.

My torque converter gear is 10t and the current axle sprocket is 42t, giving a ratio of 4.2:1.
53t brings that up 5.3:1. The last belt was nearly destroyed after 2 miles of driving straight and easy, and it finished shredding while driving a little bit around the yard. I know there's no guarantee on anything, but I'm ok with a "good chance" lol.

Today I measured out what a 60t sprocket would look like on the go kart and it would be extremely tight. I'm guessing 1/4 to at most 1/2 inch clearance from the front of the motor mount platform.
 

mckutzy

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Idealy you should be 6:1 or more... But ya that does some times promotes problems as for ground clearance....
Typically in this situation you'll need a jackshaft to augment the final ratio, and gain clearance.
 

gr8hairy1

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I have a tricky decision I'm trying to make. Unfortunately, I can't find one clear winner of an idea.

bob58o is amazing and sending me an 8t sprocket for the driven pulley on my torque converter. I agree with him and ezcome-ezgo that it could make all the difference to running this kart without a jackshaft(for now). The biggest chain that sprocket is rated for is 420 (as a side note I can't even find an 8t sprocket for 428 chain).

I'll be replacing my axle sprocket, so I could change it to a 420 sprocket and chain. There are two downsides (that I am thinking of). Plus a 3rd potentially bad idea.

1. I can't find a 420 steel sprocket that is at least 56t. I can find a hardened aluminum (Aluminum 7075-T651) sprocket in 420 that has the tooth count I want. The problem is I can't find a clear answer on how much force is too much for an aluminum sprocket. This go kart is very heavy and has large tires. Most of the things I have read were about using aluminum sprockets on dirt bikes. Though I know people have used them on side-by-sides as well. That and people seem to be polar opposites on aluminum sprockets...either love them or hate them...nothing in between.

2. (and it may not be that big of a deal) but 420 is not quite as strong as 428. This is a heavy go kart, but I don't know enough about engineering.... to even know what to look up to understand what kinds of pounds of force will be getting applied to the chain or sprocket with a near (6/7):1 ratio on a 700+lb go kart with big tires.


(Good idea/Bad idea)
A potential 3rd idea would be to use both 420 and 428. 428 chain is a touch wider but has the same spacing, so it would fit onto the sprocket. Using a 428 chain would let me have a steel axle sprocket in the size I want, and have a 420 driven sprocket. Obviously, that's not the best idea....but it is steel all around.


Final Note
The other thing I am keeping in mind, is after building a new rear end for this kart, I would like to reuse as much as possible in putting together an extra wide mini trail bike with the original 150cc motor and potentially the sprocket and chain I am looking at buying now. Kill two birds with one stone kinda thing.

Please please, any thoughts and ideas would be appreciated.

P.s.
If anyone was wondering, I found PBI has blank sprockets. For 428 chain, steel goes up to 57t. The aluminum ones can be custom ordered for very little extra money (center hole, bolt size and pattern).
http://www.shop.pbisprockets.com/category.sc?categoryId=56
 

bob58o

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I didn't get that sprocket shipped today. I will tomorrow before work.

#420 chain works great on #41 sprockets.
Find a sprocket, Then find a hub that matches the sprocket and axle.
https://www.ebay.com/itm/60-Tooth-4...d=222693308215&_trksid=p2047675.c100005.m2219

---------- Post added at 06:50 PM ---------- Previous post was at 06:09 PM ----------

And if you run 60:8 along with a quality belt (like Genuine Comet), you have a chance.
22" Tires are big. Might work with 420cc and the undersized TC.

And if you are re-doing the rear end, and if you can fit a 7" rear pulley on the TC, instead of the 6" pulley (not sure which you actually have now, you might have a 7" - I dunno?), then I THINK your final reduction would be ((60/8) * 1.12) = 8.4:1 with 60T,8T,7" Pulley<-now we're talking. Instead of ((60/8)*0.90) = 6.75:1 with 60T,8T,6" Pulley.

I say I think, because I'm not 100% sure the reductions when using the 1" bore 30 series Driver Unit. Also not sure how using the 1" bore Driver Unit affects belt length. The bigger driven pulley needs a longer belt, but unsure about that Driver Unit.

PS
I'll also send a #41 5/8" bore 9T C type sprocket for a 5/8" shaft incase you have trouble fitting / aligning the chain on the TC with the B type.
 
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