First offroad go-karts build

Status
Not open for further replies.

JPGraphX

New member
Messages
118
Reaction score
0
Location
Quebec
Hello all!

I'm starting a project with one of my friend. We want to build a go-kart that is going to driven mostly offroad (winter's coming). We have old wheels from a lawn mower and I just bought a Genuine Comet 40 series. I'm looking for a 13hp snowblower motor, that I should buy really soon. I have a lawn mower motor, but I don't want to convert it to horizontal..

I'm going to keep this thread up to date as my project progress.

First, I have some questions that I think you might help me with.

1. How are you calculating your gear ratio when you have a Torque Converter? Are you considering it 1:1 ?

2. What is the belt going on a torque converter, where should I find these?

Thanks!
Jean-Philippe Guerin
 

lyfesaver

Member
Messages
142
Reaction score
0
Location
Dallas, Texas
As I only ride off road myself and I would like to ask a few questions before answering yours and adding some other info I may have.

The main question I want to ask is when you say "off road" what exactly do you mean? I have made assumptions before only when they said off road they meant dirt, or dirt track. To me "off road" means trails where you run into sand, mud, fallen trees, rocks, roots, puddles, etc all while making serious inclines or turns.

What you want to do with it will determine a lot about the design and configuration.

How important is comfort?

-Lyfe

What is more important to you, top end or torque?
 

JPGraphX

New member
Messages
118
Reaction score
0
Location
Quebec
Ok, for me offroad is everything that is not on asphalt.

For winter: Snow (we do ice fishing, so it is mostly flat)
For summer: Trails, but easy one, no fallen trees or big rocks, hehehe!

Comfort is not very important, I was thinking about a lightly padded seat and MAYBE some spring under it. But I don't plan to add suspension to my kart.

Torque is more important than top end, but I would like to go more than 20 mph ;)
 

lyfesaver

Member
Messages
142
Reaction score
0
Location
Dallas, Texas
Okay, so you want mild off road kart, or an aggressive yard kart. Do you have the frame already or are you building one from scratch? Reason i ask is some things you are going to want on a kart that will be on the trails (even mild trails) like brush guards and clearance regulators of some sort.

This post should answer your question on drive ratio, as other things need to be considered: http://www.diygokarts.com/vb/showthread.php?t=26445

As for the TC that is a good one, and the belt will be determined by your mounting of the engine. But there are many sizes so it wont be difficult to get the one you need.
 

OzFab

New member
Messages
15,615
Reaction score
4
Location
Warwick Qld, Australia
This post should answer your question on drive ratio, as other things need to be considered: http://www.diygokarts.com/vb/showthread.php?t=26445

Well, yes & no, it provides a lot of basic info but, I haven't had time to add all the relevant info regarding TCs yet...

As for the TC that is a good one

IIRC, a TC has a starting ratio around 2.5:1 & a high speed ratio of 0.9:1 (feel free to correct me)

I'm building frame from scratch with 1-1/2" square tube (1/8" thick).

I would like to suggest larger, thinner wall material, maybe 2" 14 gauge (5/64" wt); thick wall material doesn't add much to the strength but, it adds a lot of weight... the one thing you don't want...

If this is to be a build log, would you like it moved to the appropriate section?
 

JPGraphX

New member
Messages
118
Reaction score
0
Location
Quebec
Well, yes & no, it provides a lot of basic info but, I haven't had time to add all the relevant info regarding TCs yet...

IIRC, a TC has a starting ratio around 2.5:1 & a high speed ratio of 0.9:1 (feel free to correct me)

Exact. I'm a mechanical engineer (my goal is not to look cool *how to say this?*), but I know how to calculate gearing ratio. But I was wondering how you deal with a TC. Are you calculating ratio as there was no TC?

As for my frame I already bought my material. I look on the forum and saw many recommend this. I'm not a very good solderer so it is better with more wall thickness hehehe. :lolgoku:

Thanks,
JP
 

firemanjim

Just kartin' around....
Messages
5,228
Reaction score
1
Location
Houston Texas
1.5"x .125" ?! :smiley_omg: It's gonna be heavy..... That size material is normally used in a big off road type buggies and like sandrail chassis, race car chassis... Those things have lots of power to push the weight around.
IIWM, I'd only use that material to build the main base of the chassis. Then switch to .06"-.09" material...... Save some weight, less work the engine has to do......
 

lyfesaver

Member
Messages
142
Reaction score
0
Location
Dallas, Texas
Okay, you got your material. Kind of stinks that you got something so heavy, but you got it and it is what it is. Look at this way, you are putting on a 13HP engine so that will help. If you were planning on using a 5-6.5 then I would say buy new material.
Also, if you have not gotten the engine yet, maybe look at the Duromax 16HP. It is 420cc with (or without) electric start and brand new they are under $300. I don't know which 13HP engine you are looking at and how much you will be paying for it, but it is just an idea.

I am going to use my Baja Blaster 65 as an example, so hang in there with me while i work this out.

First let me talk about why I asked about comfort. It was to determine how much suspension to add to the kart, not to determine "shocks or no shocks", but how much. Any off roading without suspension is ludicrous. Seriously. Unless you are on pavement or a well manicured lawn or dirt track, you NEED suspension. It will suck without it.



As you can see in the pic above, this has front shocks (back you will see in a moment) but also take note of the clearance wings (do not know official name of those). Even with light trail riding you will more than likely need something like those to keep crap from getting into the wheel and axle mechanics. But onto the suspension. This kart has some robust shocks on it to handle the aggressiveness in where and how I ride, but you do not need something that extreme.

@Gran_Pann has a dirt track cart that is awesome and he has these shocks on it that are tiny and probably do the job for him (and would for you) very well. Maybe he can suggest a make/model.

Also, in the pic above you can (sort of) make out that this kart uses upper and lower control arms as well as rack steering. These are advanced karting mechanics that you will not need, but if you can swing it, you wont be disappointed.



Again same for the back when it comes to shock size. I am actually thinking about going bigger and giving it more movement in the rear shocks. I would go with large ones on the rear. They are 19.99 brand new so it wont add much to the budget.



Again optional, but if you can swing it, independent rear suspension makes a world of difference when trail blazing (again, even the milder stuff that you plan to do).
Just some ideas to keep in mind. Tips from a guy who only karts in the trails =)
 

JPGraphX

New member
Messages
118
Reaction score
0
Location
Quebec
Hello,

Thanks for all your great information, this is clearly going to be useful.

I don't have a big budget. I'm still looking for a motor, and if I find a 10hp, this is what I'll buy, but I aim for 13hp.

As for my frame, 1-1/2 square tube 1/8" thk is 2.25 lb/ft. Let's say my frame need 30' my frame is going to be less than 70 lb. Not bad..

I'm going to design it with 3D CAD, I'll be able to show you what I want to build.

As for suspension, I'm going to take a look at what I can do. I need to think about my options.

Thanks again,
Jean-Philippe
 

lyfesaver

Member
Messages
142
Reaction score
0
Location
Dallas, Texas
Right on. Anxious to see what you design. And again I can not stress this enough. Without any suspension you will feel every, little, bump. =) If you want to go rack steering and duals control arms, etc for real cheap. Hit up a salvage yard that has some EZ Go carts (golf carts). Those pieces can be stripped and used on almost any kart build. And you can probably get axles, suspension, steering and control (probably wheel too if you wanted) for less than 100$. You can try golf cart dealers for their scraped ones, but you will most likely pay more (as they know what they have).. maybe $200 for it all.. but you will also probably get used parts that have been taken care of better.

Good luck!
 

JPGraphX

New member
Messages
118
Reaction score
0
Location
Quebec
For my rear axle I'm going to machine it myself. I'm project manager in a machine shop. I have access to CNC, milling, lathe..

My first try was on a golf carts, I (almost) bought 2, but someone just bought them 1 hour before me..

Thanks for all the tips. :)

JP
 

OzFab

New member
Messages
15,615
Reaction score
4
Location
Warwick Qld, Australia
Are you calculating ratio as there was no TC?

Correct

As for my frame I already bought my material. I look on the forum and saw many recommend this.

Well, what's done is done so, the fact that you're a mechanical engineer means you have the ability to design a minimalist frame & still maintain structural integrity :thumbsup:

I'm not a very good solderer

I hope you mean "welder" :lolgoku:

...so it is better with more wall thickness hehehe. :lolgoku:

Well, yes & no; as you would probably know, thicker material means you need a hotter weld but, thinner material is a lot easier to burn through... six of one...
 

Poboy kartman

Senior Moments Member
Messages
12,461
Reaction score
1
Location
White Settlement Texas
Correct



Well, what's done is done so, the fact that you're a mechanical engineer means you have the ability to design a minimalist frame & still maintain structural integrity :thumbsup:



I hope you mean "welder" :lolgoku:



Well, yes & no; as you would probably know, thicker material means you need a hotter weld but, thinner material is a lot easier to burn through... six of one...

Stand at attention when spoken to soleder you should know the army doesn't weld to individuals.....but depends on the cohesiveness of the unit.....
 
Status
Not open for further replies.
Top