GrandDaddy Clone Project

[JDW]

Well, my 11 year old son and I decided to start a project, and "go kart" won out.

We're building a 2-person, off road kart. After looking around the web for a bit, we decided that the GrandDaddy cart from SpiderCarts was close, but not quite perfect. After a little more digging, I came across a plan in the SketchUp galleries, and we decided on a combo of the two plans. Both are attached below.

I've welded most of my life, and am relatively handy, and I thought this would be a good chance to teach my son how to do some basic non-wood construction. Initial box frame is welded up, and my Harbor Freight 90 Amp welder did just fine -- although I wouldn't trust anything much beyond the current 14 gauge tubing that we are using for the frame.

Frame is 1" square, 14 gauge tubing. We were going to use round, but I didn't feel like building a tubing bender (although I have plans for that, too) so we opted for the square.

I have a week off and plan to get as much done as possible. Since this forum has been such a big help, I decided to keep a project log, and will update this with progress along the way.

 

[OzFab]

Welcome to the forum.

You've made a good start, keep it going...

 

[JDW]

These are going to be the seats. Bought these a while back for a project that never happened, and had them in the attic -- Jegs-branded racing seats. No brackets, though, so I'll have to fab something up, I guess.

 

[PeteNado]

Nice project JDW, keep on posting i'll be watching!

Welcome an good luck!

 

[ed1380]

Looking good. What kind of engine is that?

 

[OasisQc]

what will be the engine ? nice build !

 

[landuse]

Welcome!! You have made a great start. Keep the updates rolling in

 

[JDW]

Thanks for the compliments and encouragement, guys. Much appreciated!

@OasisQc and ed1380 -- We're going with a Predator 212cc 6.5hp for now. Likely with a torque converter (although I'm not sure which one yet.) I'm laying out the dimensions and geometry of the rear engine mount swing-arm to accomodate a larger engine as well, though, in case we want to bump it up at a later time to an 11 or 13 hp Predator.

Question for the group -- are there any standard mods that folks make to the Honda clones / Predator 212 to juice up the output a bit without spending much $$$? I'm assuming a modification to the air intake and enlarging the exhaust port will help, but are there any "standard operating procedures" that folks do on these motors to get more out of them?

 

[landuse]

Thanks for the compliments and encouragement, guys. Much appreciated!

@OasisQc and ed1380 -- We're going with a Predator 212cc 6.5hp for now. Likely with a torque converter (although I'm not sure which one yet.) I'm laying out the dimensions and geometry of the rear engine mount swing-arm to accomodate a larger engine as well, though, in case we want to bump it up at a later time to an 11 or 13 hp Predator.

Question for the group -- are there any standard mods that folks make to the Honda clones / Predator 212 to juice up the output a bit without spending much $$$? I'm assuming a modification to the air intake and enlarging the exhaust port will help, but are there any "standard operating procedures" that folks do on these motors to get more out of them?

If you are thinking of upgrading to a larger engine soon, then I would just get a Comet 40 series TC and be done with it.

You could remove the governor on the engine, get billet parts, advance timing etc

 

[fattony]

I like the plans. I love father and son projects... i look forward to the updates.

 

[JDW]

A lot of cutting and welding today, but now the basic frame is pretty much complete. I think I'm going to have to trade-up from my little 90 AMP HF welder, though... a new Hobart 140 is looking pretty good right now...

I opted to make the angle a little different than in the original GrandDaddy plans. Lots of sitting and estimating to figure out the right size / geometries, but it should work pretty well. This was all done by mocking-up and then installing -- no plans, so not sure what the exact angles are.

The seats fit pretty well, but I will need to figure out how to fab up some seat hardware since I don't have the original seat rails.

 

[souperman000]

Nice progress.

A 40 series TC is good for 8hp and up. The only problem is that they don't fit 3/4" shafts (not that I've seen at least...). If you choose the 6.5hp, then get a 30 series, otherwise, get the biguns now and ride into the sunset.

 

[OzFab]

Lots of sitting and estimating to figure out the right size / geometries, but it should work pretty well.

That's the way to do it; one size does not fit all...

no plans, so not sure what the exact angles are.

The angles are... exactly what they need to be

The seats fit pretty well, but I will need to figure out how to fab up some seat hardware since I don't have the original seat rails.

That shouldn't be too difficult; it won't take much to throw something together from a bit of angle &/or flat stock

 

[JDW]

A LOOOOONG day of welding today, but the frame is just about finished now. Pics of the frame, as well as the wooden jig I made to get the roll-cage angles correct, are below. We decided not to do a front suspension, but I liked the look of the A-arms from suspension carts, so we carried that over for the front wheel mounts as well. It's finally starting to look like a go kart.

I also upgraded to the Hobart 140 welder, and it is AWESOME. It's like night-and-day versus my old AC electrode negative Harbor Freight welder. The DC electrode negative of the Hobart eliminates the sputtering and a lot of the spatter, and the welds are much, much better. Probably knocked 2 hours off of the time today by using the new welder -- just about how long it took me to go to Tractor Supply and pick up the new welder.

 

[OzFab]

That seat is not in its final position correct? It needs to move to the left of the frame (right of pic). That means that the pedals will be offset due to the narrower front, creating a slightly uncomfortable position...

 

[mysteryboy28]

since you've opted for no front suspension, you will need to reinforce the arm extensions with some more square tubing, similar to how i drew it in the picture. otherwise, the first few bumps you hit will bend those arms very easily. do it smart the first time.

 

[JDW]

@Fabroman -- no, that seat isn't in the right spot, it's just sitting on the frame. The angles look odd, but it fits my son pretty well without any awkward angles -- but will be uncomfortable for a guy my size, I think.

@mysteryboy28 -- Thanks for the suggestion and the mocked up pic... much appreciated. I had planned on adding support, but I like your idea better. I'll incorporate something like that in the next round of welding. I still have several supports to add to the frame.