Manco - American Express Rebuild

[db131]

My son and I are rebuilding an old Manco Kart, and need some help with the axle length (We have no kart experience). The original axle was 36", but it had old 4" slick wheels. He wants to upgrade them to a larger off road wheel. Any suggestions on how to determine axle length? The cart rear frame/hangers measure at 26". We're looking at the GoPowerSports axle kits one has: 8" Live Axle Wheels with 18" Off-Road Tires and the other has 6" Live Axle Wheels with 14" Off-Road Tires. We're leaning toward the 6"wheels, but again, we're open to suggestions.

6" Axle Kit
8" Axle Kit

Thanks,
Dave

 

[redflash]

On my arachnid I have 40 inch axles 1 inch solid. on a 22 inch rear chassis section. I would say that you want about 8 inches on each side of the frame for tire/wheel clearance.....sooooo 42 to 44 inch axle. for any off-roading I prefer 8 inch rims because there are a plethora of tire widths and diameters, and patterns to fit .

Da Redflash

 

[Denny]

I have to second the 8” rear tire selection not only are there tons of tires to choose from but their usually cheaper to buy and easier to find.

 

[panchothedog]

Everything Denny and Flash said. 8" wheels and a 40" or 42" axel. Good tire selection , strength and width for stability, and for off road use you want the ground clearance of the taller tires.

 

[db131]

Are there any other considerations prior to selecting axel size, or is it just appearance past say 42 inches? In my head: 7 inch rim + 26 inch frame + 7 inch rim = 40 inches. I would think 2 inch gap between frame and each rim, so that would equal a 44 inch live axel???
Does that make sense, do I need more or less space, or am I completely missing something?
Thank you all!

 

[redflash]

width of the tire/rim. typically, half the tire width will be beyond the axle stub, and 1/2 overlap the axle. . So a 10 inch wide tire will need at least 1/2 to 1 inch frame clearance. that puts the axle stub about 6-7 inches beyond the frame. We're talking off road tires, not harbor freight weenie tires

Da Redflash

 

[db131]

What's up Pit Crew!!
Ok, a bit of action here on the Manco rebuild, and my sons and I are ready to wrap this thing up as quickly as possible. We need advice with gearing and axle length. We purchased the 8" live axel kit from Go Power Sports (click for link) - 40" axle, Axle Sprocket #420 60T, and 19x7-8 Off-Road Coffin Tires.

Axle Length:
As previously mentioned, the cart is 26" wide. Unfortunately, the axle is too short. GPS offers live axles in 44" or 54". I'm debating which one to go with. The 44" will give me 2 inches per side from cart frame to inner wheel/rim. The 54 will give me 7 inches per side. Thoughts? Is wider or tighter better?

Gearing:
We're running a 212 Predator engine, and we also bought a Chinese made Torque Converter by Billet Lines. The kit from GPS came with a #420 60T drive sprocket and the Torque Converter has a 10 tooth sprocket for a 40/41 chain and/or a 12 tooth sprocket for a 35 chain. We're going to be running 19x7-8 Off-Road Coffin Tires. Now, problem #1, the #420 60T drive sprocket does not fit. I'd have to extend the back of the frame which isn't happening. At this point, I can't even get a chain on the sprocket its so close. So.... Gearing. What should I do?? I know nothing about this except for what I've ready here. I know they're problems with the Chinese TC and I know I need as large of a drive gear as possible to handle the tire size, weight, etc. Please help with any and all suggestions!!

Photos Attached so you can see (a little bit) of what I'm talking about. I appreciate the help you can give, and I apologize in advance for all the questions that are about to come as we finalize building this bad boy!

Thanks,
Dave

 

[BrownStainRacing]

What's up Pit Crew!!
Ok, a bit of action here on the Manco rebuild, and my sons and I are ready to wrap this thing up as quickly as possible. We need advice with gearing and axle length. We purchased the 8" live axel kit from Go Power Sports (click for link) - 40" axle, Axle Sprocket #420 60T, and 19x7-8 Off-Road Coffin Tires.

Axle Length:
As previously mentioned, the cart is 26" wide. Unfortunately, the axle is too short. GPS offers live axles in 44" or 54". I'm debating which one to go with. The 44" will give me 2 inches per side from cart frame to inner wheel/rim. The 54 will give me 7 inches per side. Thoughts? Is wider or tighter better?

Gearing:
We're running a 212 Predator engine, and we also bought a Chinese made Torque Converter by Billet Lines. The kit from GPS came with a #420 60T drive sprocket and the Torque Converter has a 10 tooth sprocket for a 40/41 chain and/or a 12 tooth sprocket for a 35 chain. We're going to be running 19x7-8 Off-Road Coffin Tires. Now, problem #1, the #420 60T drive sprocket does not fit. I'd have to extend the back of the frame which isn't happening. At this point, I can't even get a chain on the sprocket its so close. So.... Gearing. What should I do?? I know nothing about this except for what I've ready here. I know they're problems with the Chinese TC and I know I need as large of a drive gear as possible to handle the tire size, weight, etc. Please help with any and all suggestions!!

Photos Attached so you can see (a little bit) of what I'm talking about. I appreciate the help you can give, and I apologize in advance for all the questions that are about to come as we finalize building this bad boy!

Thanks,
Dave

With those big tires, I would go with this setup.
54t sprocket for the axle
8t sprocket for the t/c jackshaft
7" driven
Comet belt
Aluminum driver fly weights
1 pink driver spring + 1 plain (stock) driver spring, for a 3000 rpm engagement.

This would give it a 21:1 low gear and 7.56:1 high gear.

The extra stall (driver springs) will put the torque to the tires very fast and easily get a 200# rider moving.

The 7" driven will get those big tires moving faster then the 6" driven.

The 60t sprocket would be my 1st choice too, but you jus don't have the room for it.

 

[db131]

With those big tires, I would go with this setup.
54t sprocket for the axle
8t sprocket for the t/c jackshaft
7" driven
Comet belt
Aluminum driver fly weights
1 pink driver spring + 1 plain (stock) driver spring, for a 3000 rpm engagement.

This would give it a 21:1 low gear and 7.56:1 high gear.

The extra stall (driver springs) will put the torque to the tires very fast and easily get a 200# rider moving.

The 7" driven will get those big tires moving faster then the 6" driven.

The 60t sprocket would be my 1st choice too, but you jus don't have the room for it.

BSR,
Wow, that's pretty impressive, thank you! I'm guessing these parts can easily be found via Google. Could you please give a little more dtail to the "7 inch driven". I'm not sure what that means. Also, is there a standard for the Comet belt, or do I have to measure what came as stock on the T/C?

Any opinion on the axle, 44 or 54 inch?
Thanks!
Dave

 

[BrownStainRacing]

Can't help you on the axle length. That's gonna take YOU measuring and mocking up with what you got.

The driven pulley is the bigger pulley for the t/c.

The kits come with a 6" driven, they work good on mini bikes. Not so good on go karts, they will work, you jus gotta run BIG gearing, which you don't have the room.

The 6" has gear ratios from 2.7:1 (low side) to .90:1 ( high side). That .90:1 is OVER DRIVE. Let's look at the math with a 60t/10t (6:1 gear ratio.)

2.7 x 6 = 16.2:1 low side.
.90 x 6 = 5.4:1 high side.

The 7" has 3.15:1 low side, and 1.12:1 high side.

3.15 x 6 = 18.9:1 low
1.12 × 6 = 6.72:1 high

As you can see the 7" will get weight moving sooner, not bog the engine down when going into high, and save the belt too.

Here's some good info about the 30 series, how to measure for belts, what different springs will do, some good reading material.

I find the parts cheaper, elsewhere.

Any more questions, jus ask.

Comet 30 Series Torque Converters | Comet 30 Series Parts

Comet 30 Series Torque Converters for 3 to 8hp Go Karts and Mini Bikes. Comet 30 Series Clutches, Driven Pulleys and Comet Parts. Technical Information.

www.gokartsupply.com

 

[Hellion]

EDIT: Mock it up, indeed. Beat like a rented mule!

Any opinion on the axle, 44 or 54 inch?

The axle you bought would have been sufficient for the actual American Express frame, because it is a standard kart frame but the cage and axle hangers you have added have made it custom now.

I think before you pick our brains on that one, you should have 'mocked it up' by taking the wheels off the current axle and using a stand-in axle substitute (like a broom handle or something) and map out where you want the wheels to sit. You're there and we're not and it's very hard to "do it for you" over cyberspace. You can still mock it up now. I suggest you do that pronto.

The wider the rear axle is, the harder it will be to turn.

 

[db131]

BSR, thank you again. I appreciate the detail and the added reading material!

Hellion, thank you also. I agree with the mock up, which I do plan on doing, but the question I guess was more so coming from an 'engineering' stand point, and do's and don'ts. I can mock it up and think it looks good, but then a guy who understands the engineering will say, "yeah, looks great, but you'll never be able to turn the thing". Those are the bits I'm looking for, or something like- two inches from the frame is still to close, by the time you put 200 lbs on it, and the tires heat and expand from ground friction, then the tires will be awfully close to rubbing the frame (I just made that up, but it's the type of info/help I'm looking for). Trust me, I'll make it look good, but I want to make sure it starts, rolls, stops, and turns!!

Dave

 

[Hellion]

Most karts seem to have way more space between the wheels and the frame than two inches.

I guess you should make sure that there's enough room betwixt the frame and the wheels taking into account tire pressures (for more traction tires might be deflated a little for muddy trails, etc or sand) and ensuring there's room for different/wider tires in the future, if you foresee such a situation.

For 5" between frame and wheel, for example, how much wider will your axle need to be? And will it still fit inside whatever hauls it? I was using a minivan with the seats folded/removed to deliver most of my go karts. They all fit except for the Dingo.