Building a "Tarantula" from SpiderCart plans

[SDCoston]

Hi,

4 weeks ago, my 12 year old son reminded me that 2 years ago I had promised to build a go-kart with him (in 2 years). I vaguely remember the promise and my hopes that he wouldn't remember it, given my lack of experience in such things.

Nevertheless, I immediately started doing a bunch of research and, for good or bad, landed on the SpiderCarts website and downloaded a bunch of plans. I then went out and bought a TIG welder / plasma cutter and spent a bunch of time researching "all things welding" on the internet. I decided to build a "Tarantula" model, and started acquiring stuff ... metal, parts, etc.

The cart plans are fairly complete, though I've got some recommendations for additional information that could have been included to help out the extreme newbie builder, like me. I'll expand on those recommendations later if there is any interest here.

I have encountered a few "roadblocks" in my now partially complete go-kart, and am hoping for advice, pointers, or at least direction on where to go to find similar discussions in these forums:

first, I decided to get a larger engine than what was used on the cart in the plans. I went with a Honda 690 12 HP engine with a 1" shaft. This required a torque converter with a 1" bore, so I bought one. The issue is that the mouting plate for the torque converter has a back-side bearing holder that sticks out several inches such that it doesn't fit on my engine horizontally, only vertically. In order to mount the engine this way, I'll have to make some significant modifications to the engine mounting platform on the cart. Before I do that, does anyone recommend something else? ... Like a smaller engine or a different mounting plate for the torque converter?

Second, I'm at the point where I need to mount my front spindle brackets. I bought spindle brackets that came with an extra two inches of room and somesprings to allow a little movement when the front tire/wheels hit a bump. What I am asking of the forum members is some recommendations for the caster and spindle tower angles. This cart will primarily be driven on street and dirt roads.

I'll see if I can figure out how to upload pictures of my project to the forum for people to look at into an album, but for now I put pictures right in this thread message.

Thanks!

Sean

 

[souperman000]

Welcome to the forum.

Could you post a pic of the "bearing holder" that is giving you trouble. I have a feeling it might be for the jackshaft but I can't picture it from your post.

 

[r97]

If you CVT came with a back plate it is likely a Comet 30 series. If so you should return it now if you want to run an engine over 8hp through it. For engines above 8hp you should be using a Comet 40 or 44 series CVT. Also, you said you got a Honda 690 12hp engine. Did you mean a Honda 390 engine which is about 13hp, or did you mean the Honda 690 engine which is a 22hp v-twin? Wait for a member named R-chez to comment (or pm him), he can give you some advice on the caster angles you will want with the springs in place.

Looks like your project is coming along well, I can't wait to see the finished product!

 

[OzFab]

Welcome to the forum.

You're doing good work so far

Good of you to add pics to your thread, we usually have to ask for them. However, you didn't include pics relating to your current dilemma; is it possible to snap some pics of a mock-up so we can properly understand what's happening?

 

[SDCoston]

r97 - you are right that it is a Honda390 13 HP engine and that it is a Comet 40 Series CVT.

I've posted more pics here which hopefully explain my issues. I think I can modify my frame around the engine mount area to accomodate the vertical orientation of the Comet 40 series plate ... just wanted to know if anyone has any other ideas or has encountered this problem before.

Thanks,

Sean

 

[landuse]

Welcome to the forum!! You have done some really good work already.

I don't want to say you are wrong, but I have never heard of a 40 series coming with a backplate before. Are you sure it is a 40 series?

CVT's can generally be mounted any angle. What part of the engine gets in the way when you try to mount it horizontally. If it is the block, then there isn't too much you can do. If it is the tank, then you could always relocate the tank.

You could also scrap the backplate and make your own jackshaft using the same distance between the driver and driven that you have on the backplate.

 

[r97]

I hate to tell you but I'm going to have to agree with landuse. The CVT you have appears to be a 1" bore 30 series. The back-plate, and asymmetrical belt are both key features specific to the 30 series. I would strongly recommend moving up to a 40/44 series CVT, belts will last much longer, your mounting won't be limited by a back plate, and maintenance will be next to nothing.

P.S. Nice motorcycle in the background! Ducati Monster?

 

[SDCoston]

r 97 right again

Again, you are right. I went back and looked at the invoice for my Torq-A-Verter ... it is a Comet TAV2 30-100 218355A, GTC REPLACEMENT 1004.

Wish I had found this forum before I bought it. When it arrived I tried putting the plate on up side down, thinking the jackshaft bearings were supposed to point out the front (yes, I am sometimes an idiot ... but this is the first time I've built anything like this). I ended up "modifying" the plate to make it fit so now I can't return it. Thus I think I will try to make this work for me. I can always buy a new series 40 later if it doesn't work.

Just spent some time on the GoKartsUSA website (where I bought the CVT) looking at the item description which said it fits Honda engines but that it "May require grinding down of the secondary oil filler cap in some 11 and 13 HP engines." This may work for me and allow me to use the CVT without modifying my frame (I'd be super happy)... I'll look at it when I get home from work.

oh, and yes - it's a Ducati Monster ... one of my other toys.

Any further comments about this issue appreciated!

Thanks,
Sean

 

[SDCoston]

success!

I was able to grind down the additional oil fill port and the cap.
This gave me most of the room to mount the plate horizontally.
I still have to put a 3/8" bushing between the plate and the engine, but a much better solution than mounting the plate vertically and having to modify my frame at the motor mount.

I did have a discussion with r_chez about my caster, camber, kpi question. The sticky on these topics was very helpful as well.

I thank all of the contributers to this forum, as the collective experience makes figuring out solutions to build roadblocks an easy process.

I'm moving my thread to the projects section tonight with more pictures.

Thanks again!

Sean

 

[OzFab]

The old saying "two heads are better than one" may be true but, 100 are better than two.
No matter how much experience, knowledge & techincal know-how you have, it always pays to bounce ideas off others