NOVICE Predator 420 Off road Build

[Joe-dan]

Considered Features: 420 predator with FNR gearbox, Torque converter, live axle, rear end suspension, single seater.

Goals: MAD offroad skids, get off my *** and weld something.

Assets available: MIG welder, manual pipe bender, AutoCAD, CNC plasma cutter, Chop-saw with metal blade, and hand tools

I wanted to know: what tire size? what gear ratio? what torque converter? what gear box?

Trying to research these questions has been like drinking from a fire hose, but who else would I ask other than DIYGK?

I greatly appreciate your comments, suggestions, and opinions. Even your sarcasm.

 

[chancer]

Cool A new guy that appreciates our Sarcasm!
Welcome!
40 series TC.
Geared 6:1

 

[Denny]

Well since you asked for sarcasm, you came to the right place. You must first decide on the intended use, then tire size and type. Design and build from there. Now go away with you're stupid questions and come back with some answers.

Denny

 

[mckutzy]

Hello and welcome...
Wow got some tools... Nice...
I recently got a new licence for my autodesk, product design suit.. Pretty F-ing cool...

Good to hear about the enthusiasm we need it here... And the included skill...

 

[chancer]

Hello and welcome...
Wow got some tools... Nice...
I recently got a new licence for my autodesk, product design suit.. Pretty F-ing cool...

Good to hear about the enthusiasm we need it here... And the included skill...

Yep and he is a Professional Gun smith!

 

[Jrgunn5150]

Tire size? 22"

Gear ratio? TBD

Gear box? Any Polaris quad from the 80's-90's has a F-N-R box. Machine the shaft down, and stick the driven side of the clutch on it.

 

[Poboy kartman]

Please define "off-road". That could be gentle grades and grass...to mud pitts...to rock crawling.

Welcome to the forum.

 

[Jrgunn5150]

If your idea of off-road is gentle glades, we can't be friends, just sayin.

 

[landuse]

20" tyres, comet 40 series, no gearbox, 7:1 ratio

 

[Joe-dan]

I brought a box for the sarcasm but it looks like I'll have to make a couple trips. I also traded in my stupid questions for some answers. You would not believe the exchange rate.

Intended use: Dirt track and mild "off road" use. IE: cow pastures with little to no elevation variants greater than +/- 3' with the occasional drainage ditch or furrow. I would like to do my best to wear out all the parts, make a lot of noise, and to do lots of burnouts and doughnuts. No gentle glades to be found and it's south Florida so lots of rain and mud.

This Saturday I'm flying a few acres to make a topo map to layout a dirt track. The property belongs to a family friend and I'm assisting in their efforts to build the track. That's what started this endeavor. I'll upload pics this weekend.

Tire size seems to be split between 20" and 22" I make the assumption that it should be a knobby style tire, but I don't know enough about them to begin selecting an actual type.

TC seems to be a 40 series comet.

As for a gearbox I hear either a modified Polaris or no gearbox at all. You expect me to either drive like i know what I'm doing or get out and push when I have to back up? I'm an entitled millennial! Any other options for a gear box that can handle the 13 hp? I only ask because when it comes to salvage parts there's no guarantee that I can find one.

Gear Ratio looks like a split between 6:1 and 7:1. If I want MAD skids then I want high torque and that means a steeper ratio like the 7:1? Or am I not seeing part of the puzzle?

I knew you guys here at DIYGK would help out and be generally awesome and you totally came through. Thank you for the input it's greatly appreciated.

---------- Post added at 07:51 AM ---------- Previous post was at 07:49 AM ----------

@mckutzy

Getting a CAD license is like being given a mad engineer's license. That's awesome. If you need any CAD help I would be happy to oblige.

 

[landuse]

I brought a box for the sarcasm but it looks like I'll have to make a couple trips. I also traded in my stupid questions for some answers. You would not believe the exchange rate.

Intended use: Dirt track and mild "off road" use. IE: cow pastures with little to no elevation variants greater than +/- 3' with the occasional drainage ditch or furrow. I would like to do my best to wear out all the parts, make a lot of noise, and to do lots of burnouts and doughnuts. No gentle glades to be found and it's south Florida so lots of rain and mud.

This Saturday I'm flying a few acres to make a topo map to layout a dirt track. The property belongs to a family friend and I'm assisting in their efforts to build the track. That's what started this endeavor. I'll upload pics this weekend.

Tire size seems to be split between 20" and 22" I make the assumption that it should be a knobby style tire, but I don't know enough about them to begin selecting an actual type.

TC seems to be a 40 series comet.

As for a gearbox I hear either a modified Polaris or no gearbox at all. You expect me to either drive like i know what I'm doing or get out and push when I have to back up? I'm an entitled millennial! Any other options for a gear box that can handle the 13 hp? I only ask because when it comes to salvage parts there's no guarantee that I can find one.

Gear Ratio looks like a split between 6:1 and 7:1. If I want MAD skids then I want high torque and that means a steeper ratio like the 7:1? Or am I not seeing part of the puzzle?

I knew you guys here at DIYGK would help out and be generally awesome and you totally came through. Thank you for the input it's greatly appreciated.

---------- Post added at 07:51 AM ---------- Previous post was at 07:49 AM ----------

Getting a CAD license is like being given a mad engineer's license. That's awesome. If you need any CAD help I would be happy to oblige.

Yes, the tyres should be knobby tyres. This will give you grip. As for the gearbox (if you really want one), Comet has a FNR gearbox that you could buy. Not cheap though. And why do you need reverse? The only time people need to reverse is when they don't know how to ride and get themselves into tight spots . Do you not know how to ride properly?

The higher the number in the gear ratio (7:1 as opposed to 6:1), the more torque you have and less speed.

 

[Joe-dan]

No, I don't know how to ride properly.

I will take this knowledge and run with it, much like I do with scissors.

 

[mckutzy]

Depending on your setup/skill/budget... A common offroader trick, is use a starter/flywheel for your "reverse gear".

Ya the CAD is pretty fricken awesome. Will do so on the help..

 

[bob58o]

Did you buy the Pred 420 yet. There's a new engine on the eBay market that a few people recently purchased. Much cheaper.! 420ccc electric start $190. Or $160 recoil start. I've been waiting to hear about them, but haven't been reading much here lately.

---------- Post added at 11:37 AM ---------- Previous post was at 11:31 AM ----------

Depending on your setup/skill/budget... A common offroader trick, is use a starter/flywheel for your "reverse gear".

Ya the CAD is pretty fricken awesome. Will do so on the help..

Will that have enough "oomph" to get something stuck out of the mud?
What kind of starter motor?

 

[Joe-dan]

I haven't purchased the predator yet. Can I get a link for the one on eBay?

How does the starter integrate? Pics maybe?

 

[mckutzy]

Heres a link to the Idea, amongst many I saw...
Switch to neutral... might need a switch cover for the button... press for reverse.
http://www.minibuggy.net/forum/projects-progress/15906-reverse.html

Others Ive seen, had a ring gear attached to the diff or transmission.

I don't know what car they're from, but im assuming an import or the like.

 

[bob58o]

http://m.ebay.com/itm/PowerLand-PD3...3D282022990644&_trksid=p2056116.c100408.m2460

---------- Post added at 01:24 PM ---------- Previous post was at 01:24 PM ----------

http://m.ebay.com/itm/PowerLand-PD4...3D282060565692&_trksid=p2056116.c100408.m2460

---------- Post added at 01:25 PM ---------- Previous post was at 01:24 PM ----------

http://m.ebay.com/itm/PowerLand-PD4...3D282054302854&_trksid=p2056116.c100408.m2460

 

[KartFab]

what tire size? what gear ratio? what torque converter? what gear box?
22" knobby with 8" rims, gear ratio 6:1, torque converter 40 series, gear box: Comet FNR

make sure to get the right size driven unit for the comet FNR (i think its 3/4" bore IIRC)

For gearing, some will say gear this way or that way. From experience, this is what I have to say

1) 6:1 gearing (9t/54t)with that size engine on a large 2 seater go kart is really fun, and it still climbs hills pretty decent, staying in low gear. Its really fun though when the ground isnt as steep and it levels out picking up speed to go 40 mph

2) 6.75:1 gearing with 18" tires is really really built up for torque and just destroys hills. It basically goes full speed up the hill if you want, and flings rocks and crap everywhere. Not so fun when the trails are flat because the speed is only about 30 mph.

Just giving you some things to think about with gearing. The good news though is that you can modify gearing with the jackshaft sprocket. So maybe get a 72 tooth axle sprocket and modify your gearing that way. 72, 60, and 54 teeth 40/41/420p axle sprockets are common.

 

[Joe-dan]

Ok, I'm desperately trying to hold this down in my mind.

I get the jack shaft and the ratios allowing for torque.

I've never even seen a torque converter in person, not one like these anyways.

The powerland engine bob58o suggested and the predator 420 have a 1" shaft I found this comet 40 series on ebay, whats the "drive" and whats "driven"? I assume the driver is the one that interfaces with the engine. Then that would mean the 3/4" drive would go to my gear box and the gearbox is connected to the live axle?

I'm thinking about splitting the difference between the 18" and 22" tires.

 

[Jrgunn5150]

Have you ever seen a snowmobile, or Polaris quad? Same idea. Golf carts also use them.

Some weights, some springs, some rpm, booom, movement.

Driver's go on the engine crank, and drive the driven. The driven will mount to a jackshaft that in turn has a sprocket. Sprocket has chain to axle, you do burnouts.

Using a gear box, the driver goes on the crank, the driven goes on the gear box, and for the money, I'd rather have a Polaris one, but that's just IMO, then the gear box has a sprocket coming out. Chain from sprocket to axle, burnouts AND Rockfords.