Need help with Multiple Design Decisions

[slapshot2205]

Alright I have had this go kart for about 4 or 5 years now and its been an experimental process but I have reached a point where I need some advice before I move forward but attached are some pictures since they are 1324 words (2011 Net Value).


Here are my questions:

On the Axle Should I support it with 4 bearings instead of the 3 I currently have supporting it?

Should I purchase smaller width wheels for the rear?

Down the line I would like to upgrade the engine which is a stock Honda GX 160. How much power would a better intake, exhaust, GX390 Carb, 18 lb valve springs get?

Should I stick with a clutch or go back to by old TAV2? Also which is the best place to buy a TAV2 drive unit with everything included (AKA Washer, Bolt etc) Current Gear Ratio is 10 to 54 (stupid fast ) (Not Driven Unit)

The goal for this thing is a hybrid street and light offroad use so I can experience a little bit of everything to give some context for the questions. I would still like it to maintain upper 30 to lower 40s in terms of speed.

Things I will not do:

-Single Wheel Drive
-Trying to stick with the Self Contained Differential because Cornering is fun with it.


Feel Free to ask questions and your input is valued.

Thanks a lot.

 

[Doc Sprocket]

Hi, Slapshot (you a hockey fan?), welcome to the forum!

The axle looks like it's supported fairly well. That said, while I was studying your pics, I think I caught a hint of differential- If this is what I think it is, you should go with 4.

Narrower rears won't do much for you, but the diameter of them is a point worth noting. With tires that big, you certainly are better off with a CVT.

Sorry- I just re-read things- you do have a differential, don't you? Go with four bearings- both half-shafts must be properly supported.

Let it be known that if the steering geometry is set up correctly, you can steer quite well with a live (no diff) axle- and offroad, the traction difference is night and day.

 

[slapshot2205]

Yeah I am a hockey fan. Played for at least 12.

I had a feeling about 4 bearings and I just think it would be a good idea to do that.

I had a live axle at first and it had some wicked crazy bend. I replaced it with a differential because the thing kept turning off around corners it wasn't till way afterward that I realized it was just the low oil switch..... I may switch back because 1. Its Cheaper. 2. Its longer. Ill stick with the diff right now however.

Im thinking I might go back to a CVT unfortunately a case of mistaken identity was made and I think the bucket I originally put the Drive unit in was thrown away.... NEED TORQUE AHHHHH I just and correct me if I am wrong am scared of revving a CVT above 3500/governor regulated.

 

[Doc Sprocket]

A CVT will survive well above the governed RPM, you have no worries there.

 

[oompaloompa543]

I have the same streaker except mine is tan. You are the only other person I've seen with this model

 

[slapshot2205]

Bringing this back from the dead with a few updates.

I switched from a differential to a live axle because of safety issues and also it seems that a live axle will be better for the off road applications I am looking to do in the future.

I went ahead and bought the CVT and switched over from the clutch. Instant gratification by having torque throughout the rev range and not just power at the high RPM.

Points for the future:
-New front tires (No treads equals no grip especially with those grippy back tires)

-Balancing the weight a little better. (It is pretty much distributed 30/70 to 20/80 toward the rear which in turn gives me no grip on the front because the tires cant grip the road.)

-New intake system of sorts. Going to try something a little different than just slapping on a better filter. Actually going to try some sort of ram air/CAI. I understand the carb operates off venturi so I cant have too much pressure going into the carb. Tried out a very primitive system at first, (Ill Post a picture) but I need to take into account, idle, where the engine isnt pulling a big enough vacuum to draw air down and I have to find a way to filter the air coming in.

-Going to try and model the go kart in Inventor and do so stress and force analysis on the axle to see what types of modifications I should do if I attempt to go with a higher rev set up at some point.

 

[mckutzy]

Interesting build, looks good.
On the intake Idea, take a look at a previous thread of mine, I did a similar kinda thing with the air box thing. There is a few problems with it running, Im having to set the choke at half way point in order to run and idle.
http://www.diygokarts.com/vb/showthread.php?t=13794

 

[questseeker]

just an idea why not tube the axle and go with two bearings and put the drive off the other side of brake less bearing less resistance just make sure key way is deep enough

 

[questseeker]

will post pic my cart rear end later looks like a lot of steel for nothing on yours or maybe just up grade to steel of different grade

 

[slapshot2205]

just an idea why not tube the axle and go with two bearings and put the drive off the other side of brake less bearing less resistance just make sure key way is deep enough

Can you rephrase this cause I am having a hard time trying to get what you are trying to say. I get the two bearing. All the steel mess under the go kart came with it when I got it. Keeps the frame nice and rigid and helps with the hard cornering forces those tires generate. If you rephrase it or draw a simple ms paint picture it might help explain though. (I am picture oriented so I understand that better)

 

[Doc Sprocket]

I think you've done a pretty righteous install. There's a couple areas for potential improvement that I see, but would require more fab work. In the meantime, I'm sure your kart has become a whole new driving experience for you!

 

[slapshot2205]

Interesting build, looks good.
On the intake Idea, take a look at a previous thread of mine, I did a similar kinda thing with the air box thing. There is a few problems with it running, Im having to set the choke at half way point in order to run and idle.
http://www.diygokarts.com/vb/showthread.php?t=13794

Yeah I looked at your post and a filter change would probably do that some good seems like it would want something more free flowing but I can understand budget restrictions. Decent free flowing filters are expensive.

What I am going for with mine is trying to get it to increase air flow at speed. I could probably set the idle higher but I don't want to richen the mix too much cause it wont be pulling as much air. (although it really wouldnt hurt much other than the fuel economy) When I am running an am at speed I am pulling plenty of air since the intake faces the flow, its the inevitable stopping that makes me worried. I could probably butterfly valve it near the bottom of the tube, so at idle its wide open but at speed it closes.

Toystory_4wd- Suggestions? I'm all ears and open to cool ideas. I have some of my own right now but its figuring out how to do them on a budget. By the way it has become different a lot similar to the original design with some good tweaks.

 

[Doc Sprocket]

My suggestions are strength related. According to the principle of leverage, your axle is a bit more prone to bending than need be. To make the most of what you have, I propose the following:

Move the sprocket and brake rotor inboard of the framerails, rather than outboard as they are. Then, either move the wheel hubs as close to the framerails as tire clearance will allow, or (if you don't want a narrowed rear track width), fab something up that will allow you to reposition your bearings toward the wheels as far as tire clearance will allow. The idea overall is to largely reduce the leverage the tire has on the axle, by keeping the unsupported axle as short as possible.