Shifter kart - axle

[Lance15]

I'm in a welding engineering program and for are sophomore year we are tasked with a project of anything we want. I choose to build a shifter kart thinking that it would be a great learning experience to figure out the mechanical side of things. I have completed the chassis and got an engine (Honda cr80) but am lost on figuring out an axle and the components involved with an axle. I have attached an image of my chassis for hopefully a good reference.

The chassis rear end is 27 inches wide

I was wondering if someone could help me out in finding everything I need to complete the axle. I got tremendously confused when it came to bearings, hangers, etc. I plan to brake the front of the kart making it so I can burn the back tires out but not sure if that's smart to do or not. If someone could help I would greatly appreciate it!

 

[Denny]

That’s the easy part. 1” solid axle pillow block bearings 1” Gokart Supply, Go Power Sports, BKI, Manufacturers Supply, Amazon and E-bay are some of the bigger suppliers look around. Front brakes only are not a good thing. You need rear brakes too for stopping control.

 

[Lance15]

That’s the easy part. 1” solid axle pillow block bearings 1” Gokart Supply, Go Power Sports, BKI, Manufacturers Supply, Amazon and E-bay are some of the bigger suppliers look around. Front brakes only are not a good thing. You need rear brakes too for stopping control.

Thank you for the response!

What goes on the axle from preventing it from going side to side? or will the pillow block bearings do that?

 

[Denny]

Double split collars or my personal favorite pieces of emt conduit cut to the proper length for spacers.

 

[Lance15]

Double split collars or my personal favorite pieces of emt conduit cut to the proper length for spacers.

Awesome, I'm understanding it now since its in simpler terms.

One last things. For the sprocket for my chain. Should I just weld the sprocket onto the axle or what would you recommend?

 

[Denny]

Never weld anything to the axle! They make Sprocket hubs that you can bolt the sprocket to. Make sure you get a fully keyed axle.

 

[madprofessor]

Heavy Duty Aluminum Sprocket Hub (1" Bore) - Black | 433968 | BMI Karts And Parts...........I recommend this hub because it has a split that squeezes down tight to the axle, not just a setscrew.
1/4" x 1/4" Keystock (12") | AZ8403 | 8403 | BMI Karts And Parts...........Cut to length with a little extra sticking out of both sides.
#35 Split Sprocket | 6335** | BMI Karts And Parts...........Recommending splits instead of solids because nothing has to slide off/on the axle to change gear ratio with a different number of teeth.
double split locking collars | eBay..........Nothing to slide off, like the splits above. Put these on both sides of everything.
1" Steel Live Axle | 4000** | BMI Karts And Parts..........Order the length you need from the list.
#35 Standard Roller Chain 10 FT With 1 Connecting Link (jeremywellindustry.com)............Get a chain breaker to cut to length.
UCP205-16 Pillow Block Bearing 1" Bore 2 Bolt Solid Base (2PCS) (jeremywellindustry.com).............Nothing better, stronger, forgiving, reliable. They're all rated at 4K rpm, but will take a lot more. The zerk fittings are there for a reason, grease up early and often.

 

[Lance15]

Thank you both!!

I will update this discussion with pictures as I go.

 

[Denny]

Mad, he’s using a bike engine. He’s going to need to use steel components. He said he wants to do burnouts. That will involve clutch drops. He is going to have to use whatever size chain the counter shaft sprocket is. Is grade will suffer if it breaks the first time out.

 

[madprofessor]

Okay Lance, I just reread your starting post. Honda cr80............Total mystery to me. Except the Honda part. How many cc's is that, and how much horsepower. Denny said bike engine and burnouts, so that sounds like it's out of a motorcycle (bike, putt, iron, crotch rocket, whatever).

 

[Lance15]

Okay Lance, I just reread your starting post. Honda cr80............Total mystery to me. Except the Honda part. How many cc's is that, and how much horsepower. Denny said bike engine and burnouts, so that sounds like it's out of a motorcycle (bike, putt, iron, crotch rocket, whatever).

Realistically it might not have enough power to do burnouts. The motor is only 80cc's but it is a two stroke (20.39 horsepower at 12,000 RPM's). The goal for it is to be a shifter kart which is a kart that has a clutch and is usually front braked so you can whip the rear and take sharp corners but besides that its a normal go kart.

Appreciate the concern Denny and thank you mad for continuing helping me out!!

 

[redflash]

interesting plan, but in my humble opinion.... I know honda gives those specs..... but unless that motor is brand new and factory juiced I 've never seen a standard 80 cc have 20 hp. more like 12-13 for a 2 stroke. and second, you'll be doin good to crank that engine to much over 8000 rpm. So again, in my humble experience, I don't see wheelies or burnout in your future with that engine. In addition, if that motor came off a mini bike....the bike probably weighed maybe 160-180 pounds max. If the kart can fit an adult it will surely be over 300 pounds....and then an adult butt of 180-210 pounds...so you possibly pushing somewhat over 500 pounds..........eehhh no wheelies.

Da Flash

 

[Lance15]

interesting plan, but in my humble opinion.... I know honda gives those specs..... but unless that motor is brand new and factory juiced I 've never seen a standard 80 cc have 20 hp. more like 12-13 for a 2 stroke. and second, you'll be doin good to crank that engine to much over 8000 rpm. So again, in my humble experience, I don't see wheelies or burnout in your future with that engine. In addition, if that motor came off a mini bike....the bike probably weighed maybe 160-180 pounds max. If the kart can fit an adult it will surely be over 300 pounds....and then an adult butt of 180-210 pounds...so you possibly pushing somewhat over 500 pounds..........eehhh no wheelies.

Da Flash

oh I know that's what the rated specs are I know I wont be able to get that out of it but that's what its rated at. I know it wont pop wheelies and I don't want it to pop wheelies. Once set and done the kart should only be around 170 lbs. without a person.

Thank you for your humble response!

 

[madprofessor]

If shifter kart means a manually shifted tranny of some sort as I've always thought, not just a manual clutch, then good for you as higher gears are great for more speed. Thing is, if you need to wind out some crazy rpms to get the powerband up and humping, the higher the gear ratio the less rpms you'd be able to wring out of it. Not really understanding the whole point of chainsaw engines and such to power gokarts, although when I was a kid people put little McCullough engines in really lightweight gokart frames with 1-wheel peel and a scrub brake and supposedly could have a ripsnorting good time with it. Spin the power tire bald, scrub the middle of the brake tire bald.

 

[Functional Artist]

oh I know that's what the rated specs are I know I wont be able to get that out of it but that's what its rated at. I know it wont pop wheelies and I don't want it to pop wheelies. Once set and done the kart should only be around 170 lbs. without a person.

Thank you for your humble response!

It's not how big/powerful you are
...it's all in "how" you "work it"

My !ARRIBA! kart is only ~2.5HP
...& does wheelies quite easily

 

[redflash]

Oh, that Kart looks reeaaal comfortable.... and definently NOT off road !

 

[Functional Artist]

Um...I don't see a road
...& where's the video of your "reeaal comfortable" kart, doin' wheelies?

 

[redflash]

your front lawn aint rippin through the desert in nevada ( real off road), dude ! And that kart is so short your sittin on the rear axle...yeah its a wheelie you win !

 

[anderkart]

Lance,
Before you start buying parts; we need to calculate your gear ratio and how many teeth you'll want your axle & counter sprockets to have. ~ I can help but need more info:

1- What year is your CR-80 engine?

2- How many teeth does your CR-80 counter sprocket have now?

3- How many inches tall are your rear tires going to be?
(Guys that race CR-80 shifterkarts typically have 11" tall slicks)

4- What approximate top speed would you like to achieve?
(It could be geared anywhere between the 45mph-70mph range)

 

[Lance15]

Lance,
Before you start buying parts; we need to calculate your gear ratio and how many teeth you'll want your axle & counter sprockets to have. ~ I can help but need more info:

1- What year is your CR-80 engine?

2- How many teeth does your CR-80 counter sprocket have now?

3- How many inches tall are your rear tires going to be?
(Guys that race CR-80 shifterkarts typically have 11" tall slicks)

4- What approximate top speed would you like to achieve?
(It could be geared anywhere between the 45mph-70mph range)

1 - CR80 is a 1998 (Putting a new top end on it)

2 - 15 teeth currently (I want to put a slightly bigger counter sprocket in so the rear sprocket can be smaller. I want to try to gear it for more torque then top speed. In my head since the kart has smaller tires then a dirt bike taking one chain link out is way more significant then what it would be on a dirt bike? Please correct me if I'm wrong.)

3 - Yes 11" tall slicks is what I want to run on it.

4 - 55 - 60 MPH range. (In my area there would be few chances of really getting it to top speed so I would prefer to go with more torque but still keeping a good balance between top speed and torque.)