6.5 gh Engineering Project Help

[royjr]

Hello,

I'm new to this fourm, and have searched on it for quite a bit, but I need help urgently.

As a final engineering project, our class is to build a go kart. We only have till the first week of June to complete it. I live in NYC. I've bought a 6.5 HP Greyhound Engine 2 years ago. So as for the engine, im set. But the problem is buying the right parts.

Im planning to make it a live axle, making both wheels turn. I'm probebly gonna order from this website.. http://www.mfgsupply.com/gomini.html .. since it seams to have everything and on the cheap side.

Engine Manual: link

Parts I need.. (correct me if im wrong or am missing parts required)

• centifugal clutch x1
• chain x1
• sprocket x1
• sprocket holder x1|2??
• pillow blocks x2
• axle x1
• wheel hub x2
• wheel x4 (2 rear + 2 front)

I really need someone to help me buy the correct parts and measurements.

1. 35 or 41 chain?
2. one sprocket holder or two?
3. gear ratio? 6:1 or 7:1 or other?
4. will the key provided in the GH work with the clutch or need mod?
5. how exactly does the wheel and wheel hub attach to the axle
6. I dont have any brakes, any simple/cheap brake solution?
7. will the clutch get messed up if I leave the clutch disengaged from the heat created?

Please I know that this is a big request, but I really in need of ordering the parts soon so that I cant have some time putting it all together and testing it. Don't worry about posting excessive information, I need the most I can get.

Have any suggestions for me, please do so, I wont miss to credit those who have helped me in any way on the go kart itself and in the project video to be created.


Thank you guys sooo much.

 

[OzFab]

35 or 41 chain?

Personal choice & depending on what you can get but, #35 will be ok

one sprocket holder or two?

You'll probably need two if you decide to use disc brakes

gear ratio? 6:1 or 7:1 or other?

6:1 will suffice, it gives you a nice balance between good acceleration & good top speed but, your tyre size plays a part in that too...

will the key provided in the GH work with the clutch or need mod?

The clutch should come supplied with a key but, if not, you may need to mod the one that came with the engine

how exactly does the wheel and wheel hub attach to the axle

There are a number of methods depending on your axle: Some hubs have bolts through them that clamp the hub to the axle, others have a nut on the end of the axle & a locking collar on the inboard side of the hub. Whatever method is used, they all involve a key

I dont have any brakes, any simple/cheap brake solution?

You can pick up a hydraulic set for an ATV for as little as $40

will the clutch get messed up if I leave the clutch disengaged from the heat created?

 

[royjr]

Wow, thanks for that info.

Harbor Freight 6.5 HP Engine
Shaft Size/Type - 3/4” x 2-1/4” L / Straight

So I would have to choose a clutch with a bore of 3/4" leaving me with these choices.

• 3/4" #35 12 teeth http://goo.gl/qjlQP
• 3/4" #35 13 teeth http://goo.gl/y0Y6U
• 3/4" #41 10 teeth http://goo.gl/7eai8

1. On the engines shaft there is already a key in the key way that doesn't come out. Will I be able to just put the clutch on the shaft using the current key?
2. Which of the clutches would you recommend?
3. What kind of sprocket would you recommend? http://goo.gl/1t6YY
a. steel or aluminum?
b. and how would you hold the sprocket on the axle, would that be called a sprocket hub? or a locking collar?

 

[gvfc2]

3.b would be a sprocket hub or also called sprocket holder.

on a side not wanna upload a picture of the engine shaft to get a look at the key thats on the engine

 

[royjr]

yea not with me though, hope to get the pics up by tomo

 

[machinist@large]

Wow, thanks for that info.

Harbor Freight 6.5 HP Engine
Shaft Size/Type - 3/4” x 2-1/4” L / Straight

So I would have to choose a clutch with a bore of 3/4" leaving me with these choices.

• 3/4" #35 12 teeth http://goo.gl/qjlQP
• 3/4" #35 13 teeth http://goo.gl/y0Y6U
• 3/4" #41 10 teeth http://goo.gl/7eai8

1. On the engines shaft there is already a key in the key way that doesn't come out. Will I be able to just put the clutch on the shaft using the current key?
2. Which of the clutches would you recommend?
3. What kind of sprocket would you recommend? http://goo.gl/1t6YY
a. steel or aluminum?
b. and how would you hold the sprocket on the axle, would that be called a sprocket hub? or a locking collar?

I may give some answers that you already know; it's just that they seem to come up regularly, but not as neatly organised.

1] The key on the shaft should work just fine; just make sure it's pressed in all the way. Note; also make sure it's in the straight section of the groove; when viewed from the side, the groove (correctly named the keyway, because the key sit's in it) has a radiused bottom as it approaches the end at the crankcase. Normally, if a key is loose in the slot but the pulley or clutch won't go all the way on, the #1 reason is the key slipping back into the radius and riding up in it, causing the bind. You said your key is already pressed in place; easy way to check for that is with a pair of calipers; from the top of the key to the other side of the crankshaft should be the same at both ends of the key.

2] I'll defer to Fabroman for the size (#35 chain, 13 tooth) just remember to use the correct tooth count when you pick out the mating sprocket.

3] On the page you reference from MFG Supply, you'll need the hub in the lower L/H corner; the sprockets are to the immediate right. Both materials will work just fine; if you're not racing it, steel is about half the price.

Hope this helps!!

 

[royjr]

Right now, I'm having trouble with a couple of things, and I'm really freaking out
I am making this in NYC, meaning that its an on-road go kart.


1. Should I go with a Live or Fixed Axle setup? and why?

2. Aluminum or Steel? I'm guessing steel.. and why?

3. Size of Axle, 1"? and why?

4. Size of Chain, #35/#41? Guessing #35.. and why?

5. Would these combinations be correct for a 1" axle and a 3/4" Engine with the 6:1 ratio?

• Clutch 3/4" #35 12T + Sprocket 1" #35 72T
• Clutch 3/4" #35 13T + Sprocket 1" #35 78T
• Clutch 3/4" #41 10T + Sprocket 1" #41 60T

Thanks alot guys, you make my day when I get a reply.

 

[mckutzy]

Steel is about the cheapest and the easiest to weld.
Do know how to weld or do you have a person welding this together?

So are your saying this is going to be a street legal build?

If this is going to be street-able machine, there is going to probably not much we can do for you in the matter of advice, as this all depends on how you state law is going to dictate the parameters of your machine(car/vehicle). (Im guessing) Ie. brakes, lights, tires, belts and other safety equipment ect.
We here, predominantly work with "off road builds". Not to discourage you in your endeavors just wanted to say hey this is approaching out of our territory.

 

[royjr]

Steel is about the cheapest and the easiest to weld.

cool, then steel all the way

Do know how to weld or do you have a person welding this together?

Yes, one of my friend's father is a mechanic =)

So are your saying this is going to be a street legal build?

If this is going to be street-able machine, there is going to probably not much we can do for you in the matter of advice, as this all depends on how you state law is going to dictate the parameters of your machine(car/vehicle). (Im guessing) Ie. brakes, lights, tires, belts and other safety equipment ect.
We here, predominantly work with "off road builds". Not to discourage you in your endeavors just wanted to say hey this is approaching out of our territory.

Well, not street legal, but still a 'on road' go kart. In my school, we have a huge parking lot, not to mention two large courts meaning it will be only used on private property =)

 

[OzFab]

1. Should I go with a Live or Fixed Axle setup? and why?

Both have their pros & cons:
Live axle pro: Better power transfer, brake, sprocket &, therefore, engine can be mounted anywhere
Live axle con: Poor steering capacity
Dead/fixed axle pro: More direct steering
Dead/fixed axle con: You have to squeeze a sprocket & brake setup onto one wheel hub

2. Aluminum or Steel? I'm guessing steel.. and why?

As mentioned, the preference is for steel as it's cheaper & easier to weld but, if you have the cash & the ability to weld aluminium, there's no reason why you can't go that route...

3. Size of Axle, 1"? and why?

AT LEAST! My current build has a 30mm axle! My daughter's kart has a 3/4" axle which has already been bent by hittiing a kerb...

4. Size of Chain, #35/#41? Guessing #35.. and why?

Again, this comes down to personal preference &/or availability of parts...

5. Would these combinations be correct for a 1" axle and a 3/4" Engine with the 6:1 ratio?

• Clutch 3/4" #35 12T + Sprocket 1" #35 72T
• Clutch 3/4" #35 13T + Sprocket 1" #35 78T
• Clutch 3/4" #41 10T + Sprocket 1" #41 60T

Those combo's are perfect...

Thanks alot guys, you make my day when I get a reply.

Keep in mind that we have members from all over the world. Sometimes, you may have to wait a while but, you will eventually get a response...

 

[royjr]

Live/Dead Axle

• Now about the live/dead axle in my situation of where ill be using it on paved roads, I understand that the live axle has higher traction/resistance in turning, while the dead axle setup would be more smoother in the turning.
  
• Does this mean that I wont be able to turn, or just more traction? I'm moving towards the live axle setup because I understand it better. Any ideas? I just want to choose an easier system, that's cheap and also working for me on paved roads

Type of Metal

• Steel it is

Drive Setup

• Chain Size: #35/#41 (doesnt matter)
• Axle Size: >= 1" (so far sticking to one inch)

PS: I also took alot of picture of the go kart just in case you guys might want to see it. I'm going to start it up for the first time tomorrow. All I have to do is add the oil and gas ad I should be good to go (i think).

In the specs, it says:

• 10W-30 (>32*) & 5W-30 (<=32*), so ill use the 10W-30.
• Theres a synthetic type of oil, is that better or just use regular?
• It tells me to use 91+ Octane gasoline and mix it with stabilizer, should I?

Feel free to add any additional/missing information. Please post as soon as you guys can, my deadline for ordering the parts is closing in, and like I said I only have till the beginning of June to complete this go kart. So thanks alot guys and keep up the great work.

 

[mckutzy]

10w30 and regular gas 87 89 what ever gas. Any alcohol blends will eventually rot out the rubber parts, so try to use non alky stuff if you can. I know some states cant avoid it.
Just stick to the live axle. Its easier to set up brakes/sprockets and dont have to worry about a diff or other expensive parts.

 

[royjr]

OK Cool, live axle it is.

Here's what I have so far...
3/4" 1:6 ratio T #35/#41 Max Torque C Clutch
#35/#41 Chain
1" 6:1 ratio T #35/#41 Sprocket
?" x 1" steel axle


Now for the axle size, I think that 1" is good, any suggestions?
That means that a 1" sprocket is good like the combinations I mentioned above, would be the right way to fix the sprocket into the axle? Sprocket holder/hub? Locking collars on each side?

 

[mckutzy]

Sorry I forgot to say, ya 1" will do, get it longer than you need wide. Then cut off what you don't need.
Ya double up on collars onboth sides of the drive line parts, wheels to if you can, brake hubs aspecially.

 

[OzFab]

You can achieve "adequate" steering with a live axle providing your steering geometry is spot on. Even with perfect steering, you will still have a much larger turning circle than a dead axle kart.

Apart from very few exceptions, all sprocket hubs have some type of locking mechanism to hold them in place; whether it be a clamp style hub or two grub/set screws. All hubs have a keyway to make them turn with the axle

 

[royjr]

Cool, so live axle it is. 1" axle.

1. What type of axle should I use? Does it have keyways or does the locking collar remove that requirement?

2. Should I stick with locking collars on each side of the sprocket? Or some other setup (sprocket hub)? Or does it need locking collars and the sprocket hub together?

Wow guys, you've been tremendous help. Keep up the great work. =)

 

[mckutzy]

IMO...
A keyed shaft, A piece of shaft( round bar cold finished steel) with full length milled key way.
Like I said, use 2 collars on each side of the sprocket/brake/wheel hubs(if you can) this will have the best safety factor. Doubling up just helps on the more critical parts(like brakes).

For ex. Collars can keep the key in the way with a hub, if the set screws in the hub come unscrewed. They capture the key on both sides of the hub.The key can walk out on you due to vibration or other forces. The hub cannot Rotate with the key inplace. Now this is with regular collars. They're also have keyed collars aswell. They do the same thing just clamp on the key itself.

 

[OzFab]

Does it have keyways or does the locking collar remove that requirement?

A key (in a keyway) keeps the hub turning with the axle; without it, you're not going anywhere.

Collars stop the hubs from moving along the axle

 

[royjr]

A key (in a keyway) keeps the hub turning with the axle; without it, you're not going anywhere.

So a key is needed in locking the sprockets spin along with the axle

Collars stop the hubs from moving along the axle

And a locking collar keeps the whole sprocket from sliding across the axle.


So I would need to have a keyed sprocket to key in with the keyway groove on the axle and also 2 locking collars on each side to secure it from sliding along the axle.

Cool, now would I need a sprocket hub with this to work?

 

[landuse]

So a key is needed in locking the sprockets spin along with the axle



And a locking collar keeps the whole sprocket from sliding across the axle.


So I would need to have a keyed sprocket to key in with the keyway groove on the axle and also 2 locking collars on each side to secure it from sliding along the axle.

Cool, now would I need a sprocket hub with this to work?

The sprocket hub would be keyed, and the sprocket would generally bolt up to it