Predator 420cc Go Kart 40 series torque converter and china amazon reverse gear box

[@rayzor285]

I love your precise calculations. "Just some china reduction who tf knows" ☠️

[@nonyabidness6492]

He's the "send it brother" friend we all have

[@reecejackson8689]

Hi mate great video! Quick question for you… I’m just curious as to how you get to your suspected gear ratio of around 50:1? Surely if you’ve got a 10 tooth on the torque converter and a 20 tooth on gearbox input Then 10 tooth gearbox output going to a 60 tooth on the axle Is that not around a 12:1 ratio?

[@myskiis2fast4u]

The torque converter has a variable ratio and the china gear box has a ratio thats quoted somewhere online. I dont know it. I sat there one day and counted how many times i turned the crank (spk plug out) to one tire rotation. With the torque converter belt in its lowest setting (obviously) i was at 52 turns of crank pulley to one tire revolution. Rounded down cause me and my good friend miller did the counting😂😂😂😂

[@scottwiggins2364]

Your supposed to remove the backplate and run the driven side of the torque converter on the reverse gear box. The gearbox should be mounted about 3" forward. Remove the torque converter plate. Takes some doing for correct alinement.

[@myskiis2fast4u]

@@scottwiggins2364 i would tend to agree with you except for the fact my gear ratio is purposely around 50:1. Theres no way i could get that if i didnt reduce it on the way in. You are right though if your application doesnt require such a low ratio like mine.

[@jamesrussell2936]

The gear ratio for the 40 series is: If Driven pulley is 7.5" diameter: 1:1 High, 2.43 Low If Driven pulley is 8.5" diameter: 1.24:1 High, 2.83:1 Low I found this in a Comet 40 series pdf. I don't remember where I found it.

[@steverigter3772]

I like your style man! I have the same attitude about the way shit is "supposed" to be and the way I'm gonna do it! Thanks for the video, I'm trying to decide if I should buy on if those gearboxes because the monster kart I built is now to heavy to pick up and turn around by hand. But that's what happens when you decide to put 2 37" wheels off a Nissan Titan on the back of a kart, which is set up like a scorpion!

[@myskiis2fast4u]

Thats insane.....man....you prolly need like 100:1 gear reduction..... The gear box is so far holding up to what id consider moderate abuse and usage. I tow around shitty pee filled hay in with the car every weekend and it does it without a problem. I think the weak link in the gear box is that super long input shaft. Theres no way this box will hold up to having a clutch on it. You need that input gear against the housing as far in as u can get it. Good luck

[@nathangold3054]

Is the gearbox still holding up a year later now? I'm putting one behind a predator 459 and I'm trying to gauge how long it might last for me. :) I have that same gearbox behind a 301CC and it's mounted vertically just like yours, and I haven't had a bit of problem with it being vertical.

[@myskiis2fast4u]

Im consistently towing with it and doing woods trails almost daily. Im shocked its handled as good as it has. Im running a really low gear ratio though as not to put a whole bunch of torque through the gears. My setup only does like 15mph max before the valve springs float. Its been very good this far.

[@NathanLeeShow]

Which chains & gear pitches are you running there? #40 or #50? Torque converter came with option of #35 or #40 gear. Gear box came with #35 primary, & #40 secondary. I’m hoping to use #50 or #40 chains all around but can’t find the right gears, looks like you were able to?

[@myskiis2fast4u]

#40 sprockets and a #420 chain. My dirtbikes use the 420 cahin and i had a nice new oring one laying around. Im not super sure of all the pitch measurements but google a #420 and the main difference is the width of the chain. Its considerably larger than a #40 chain. Off memory....i have a 10 tooth on the converter output shaft to a 20 tooth on the input to the gearbox....then i go from another 10tooth output shaft on gearbox to a 60tooth on the axle. With 22" tires...... Way over 50:1 gear reduction. It wasnt built for speed. My max is maybe 15mph. I built it more for working and towing around my property. Lmk if u have any other questions. Will try and help out!

[@myskiis2fast4u]

All my sprockets are #40 sprockets with a #420 chain

[@NathanLeeShow]

@@myskiis2fast4u Appreciate the response. Learning more about chains & pitch, #40 gear with 420 chains seems like right the way to go, nice. I'm guessing you changed out that axle sprocket? I believe I have just about the same buggy/kart as you, a Chinese GK-01 150cc originally... I'm gonna swap out that metric 530 31-T axle gear with a #40, realizing I'll have to machine a flat-plate sprocket. I'm basically mimicking you over here haha. Nice project.

[@myskiis2fast4u]

I dunno what mine started with. My neighbor gave it to me...and someone gave it to her. It was an abortion of non working parts....had a 30 series converter and like a 12:1 gear ratio. It would shred a belt in about 3 seconds. The ONLY thing i actually kept was the rear axle and sprocket and 420cc motor. The rest was built. So things ive learned....that swing arm is super cheesey. Definitely put atleast a middle cross member in it to keep the swing arm from spreading. My pillow blocks would literally walk out the swing arm inches until i tied it together in the middle. U can buy all these sprockets online. I was looking for email receipts to try and point u but i cant find them!!! The rear sprocket hub is prettty generic. I would start with set screws first but then u will need to weld it in. The 420 has some torque! I made a few other videos too...one showing how to grind down that china gear.box input shaft to .625" and another in the 40 series converter primary clutch springs. The 420 i have hates to idle. I think the flywheel / magneto too light. I had to use the heavey weight red primary springs with the stock weight china rollers. Setup works good for me. My idle is stable and i can shift that gearbox. Lmk if u need any other pics or videos...... It definitley was a project getting the setup reliable......

[@simplydub]

Fixing to attempt this same thing with my boy. Thanks for the video

[@MCscarfacematt]

well here i am being paranoid about driving my golfcart with this box because it clicks i can hear the same clicks here and i see youve said you tow with it almost daily so i should be good it doesnt click in reverse and ive already driven home in reverse once when i turned the golf cart input shaft to dust leading to the reverse box and live axle. but yes i have the same issue with going from reverse to forwards

[@myskiis2fast4u]

Hey brother.....so i made another video about the primary clutch weights and springs. My ghetto freight predator motor just hates low rpms. I ordered heavy weights and springs for the primary and now i have NO ISSUES at all cause the primary clutch is finally disengaged correctly. What clutch/torque converter are you using?

[@MCscarfacematt]

@@myskiis2fast4u yeah that sounds like my issue because it only clicks with acceleration from a stop but smooths out at around 15km/h im using a 40 series cvt before the reverse box rounded off by a 65 tooth sprocket on the axle which the roads im mostly on the speed limit is 20km/h and the trails im trying to ride is 15 but there is one 50 and one 80. now the fastest ive had it with the stock transaxle was 52km/h and i was floating valves

[@3dconceptsofutah757]

Thanks for showing this! Bout to do this to a Yerf Dog 420, reverse gear box and 40 series. What's your top speed now and did it hold up? I see some folks mount the driven pulley right to the gearbox. I might try that as I want the top speed around 30mph

[@myskiis2fast4u]

So far so good.....i have a heavy kart and i do a lot of small farm work with it believe it or not. I also have a very hilly property. I haul poopy goat hay and chicken shit from a small pen. I use it as a quad. The gear box has exponentially quadruppled the life of the chain because i finally got the right gear ratio. If you put the driven pulley straight to the gearbox i think it will work but i do believe it will fail sooner than normal. Thats a crap ton of leverage on that small diameter input shaft to gear box....but what the hell the gear box is so cheap just buy a new one. I had to reduce my gear ratio several times in order to get to like 40ish:1 for the torque and speed i wanted..... I go from the torque converter with a 10tooth to a 20tooth input to gear box ....then whatever the gear box is....then another 10tooth to a 60 tooth axle sprocket. My top speed is around 15mph or so. Im not looking for speed. I have very tight trails and i use it as a utility machine towing maybe 200lbs of shitty piss hay..... I also have 22" tires. Theres a lot of trial and error on the gear ratio.... I'll leave u with one more thing that im still working on. Heavy springs and heavy weights for the clutch....these cheap china clutches have poor springs and weights. My predator doesnt like low speed idle and the clutch stays engaged...making it hard to shift that gear box. Make sure your primary clutch disengages good enough cause the gear box DOES NOT like to shift with torque appplied. Any other questions LMK!!!!

[@Cherokee-sz7xi]

I run my FNR box like that. DO NOT fill the box to full! It will build pressure and blow out the seals!

[@myskiis2fast4u]

If you blew out your seals then your vent tube wasnt venting! Physics.....i have well over 200hrs on this setup and zero leaks......

[@ikstrucking3289]

Why not install torque converter driven pulley straight on the gearbox, and make the gearbox sit on adjustable plate, so you can tighten the belt as needed

[@myskiis2fast4u]

Needed the extra gear reduction....

[@norcal8718]

The gearing still seems a little low but it's all about what you need the machine to do so if it works for you then that's a success 👍🏻 Will it do a wheelie?

[@myskiis2fast4u]

Gearing is definitely low!!! Im shocked it doesnt wheelie!... It pull uphill in the woods hard though and is decent for crawling..... I dont have much runway for any real top speed!!!

[@jesse1136]

I've had my FNR gearbox apart and no, there is no oiling system other than just the viscosity of the oil transferring naturally across the mating surface of the gears. I agree that the box should be mounted with the shafts oriented horizontally, but without rebuilding my swingarm completely, there's not much choice. I'm rebuilding a Chinese clone of a Polaris RZR 170 (youth utv model). I bought it sight unseen, and what that meant was it is a janky piece of shit. Original GY6? Gone. Original swingarm? Kinda sorta rebuilt, except by a legally blind toddler with vertigo and a wire welding machine but no adult supervision.

[@myskiis2fast4u]

Its been fine for me....i leak a tiny bit of oil out of the vent. Have about 50 hard hours on it and my only complaint is still around the primary clutch....still not enough weight / idle combo for the ghetto freight motor. Good luck with your build!

[@mikeyacullo]

I used to live in the great gorge condos

[@myskiis2fast4u]

Its nice there....love it up here!

[@mikeyacullo]

Yeah it's cool. I grew up up there. Used to ride my dirt bikes all over them mountains. And on the downhill mountain bike jumps at the top of the mountain lol

[@Chilldiy12]

Do you have a link to that torque converter?

[@myskiis2fast4u]

blastled.com/40-series-driver-driven/predator-420-cc-420cc-go-kart-mini-bike-torque-converter-1-35-40-41-12t-10t

[@myskiis2fast4u]

You have to choose your shaft sizes you want.

[@marcchaffee7751]

wherd u get the gear box ?

[@myskiis2fast4u]

Amazon

[@marcchaffee7751]

@@myskiis2fast4u Thanks ! !