As a former IKF (International Kart Federation) racer, engine mechanic in the military and currently 45 years aerospace general machinist & tool and die maker, it warms my heart to see a young guy with mechanical skills and a brain put them to use. Kudos to you young man.

I stumbled across this video and watched it and I enjoyed it. I am a retired professional fabricator that ran my own fabrication shop for 30 years. I commented to my wife that this kid is quite impressive. It’s nice to see young folks building and designing things like we old guys used to do. Keep it up 👍 you are practicing a dying art.

Holy shit I knew this was doomed from the start. first off, That's a Peerless 700 series transmission from a Lawn Mower, which is a solid transmission when used correctly, they were VERY common in professional Lawn Mower Racing, and can hold a lot of horsepower, however there is a long list of things this guy has done wrong. 1: When overspeeding the transmission as much as he did, he should have used a thinner grease or oil as that thick grease will simply sling off the gears and no longer coat them at that speed. #2, mounting the trans sideways like that is just asking for trouble, since the casing is not made for the linear force at that vertical angle. #3, these transmissions are not made to shift on the go, especially with a centrifugal clutch like that. there's no syncro gears, so you're essentially just jamming the gears together, destroying them, hence the "rough shifting" he mentioned in the video. If he set up a manual clutch that stops the input shaft completely in between shifts, he might be able to get away with shifting on the go. #4 as you can clearly see in the driving shot where you can see the back of the kart, he placed the chain tensioner on the wrong side of the chain, so all of the torque of the motor is pulling on the tensioner, and bending the frame, probably pulling the input shaft at a weird angle, contributing to snapping it off completely, as shown in the video. What could he have done to prevent all of this, and still have a cool 5 speed Kart? #1, use a thick oil in the trans, #2, mount the trans the correct direction, and use a right-angle gearbox to adapt to the kart motor, #3, use a manual clutch that slow down or completely stop the trans input shaft between shifts, and #4, avoid overspeeding the trans too much by using a larger output sprocket in order to get the ratio you need, instead of a smaller input sprocket size.

I really enjoy seeing young, innovative people doing their thing. Don't stop, please. You give us old genX guys some hope and some satisfaction, knowing the things we love and understand will live on. Thanks, Bubba.

Man this world needs more young innovative young people like you. Don't listen to the looser saying it was a waste of time or you should of... They have no respect and envy your skill. Nice work.

Use 75w-140 gear oil in the gear case. Add a drain and fill port. Shifting will be much smoother and you will get more power to the wheels.

All I can say is, I am damned right impressed. This is what we as young teens did when I was growing up 45-50 years ago. Now 63, It is so refreshing to see a young man living life clean and not being tied to an electronic screen of some sorts. Kudo's young man... you have the whole world in the palms of your hands.

A suggestion, when you ramp the music up, maybe a little less. Every time the music ramped up I had to turn it down, and then back up to hear you speaking.

Shifting technique with a sequential is important to the life of the gearbox. You don't need a clutch, you just need to go from a state of load on the transmission to a state of decel. You want to shift inbetween those two where the gearbox has no load on it. For instance, hard on the throttle, light tug of the shift lever, quick lift of the throttle and it'll drop into the next gear. For a down shift, gentle press forward and tap the throttle. It'll fall into the lower gear.

Elegant fabrication and attention to details. And an impressive grasp of design flaws. No shame in breaking parts; it's called research and development! Stay after it, young man; you will go far!

That young man has my respect because he is making something constructive of his life. Thumbs up man!

I used the same gear box in my lawnmower racing days. You need to open it up and remove the grease and close it up with RTV around the edges and put gear lube in it. You can get it in there after removing the neutral safety switch on the top of the case. The grease flings off of the gears when you run it at such high RPMs and you will burn up the trans pretty damn quick with the grease and not the gear lube. PS a lil will leak out of the 4 brass bushings, but there's not much you can do about it.

Hi, I had a Go Kart when I was a kid, in 1965. I started with a Soap Box Derby Cart that my cousin dropped off when he was done with it. It was wooden and had foot steering. Living on a dirt road, it wasn't much fun to push it around, so I took Dad's lawn mower apart and put the frame and everything including the "reel mower blade" under the back end of it. Eventually the "reel" blade was taken off, and as you would expect it only went about 3 mph but I was encouraged by self propulsion. So, I improved it when I found an old Radio Flyer Wheel that the rubber had came off of and used it for a pulley. I drilled holes through the Soap Box Derby Wheel and bolted the Radio Flyer Wagon Wheel to it. I went directly from the engine to the "wheel/ pulley" with a belt using a centrifugal belt clutch on the 3 hp engine. That was a major improvement, it went about 25mph. On my first trip down my street, when I turned the corner the board the engine was "nailed" to broke and the engine fell off and it went tumbling down the street with me by the throttle cable. Then, somebody put a Go Kart frame made out of 1 1/4" water pipe up for sale for $20. I combed the ditches for 2¢ & 5¢ beer & pop bottles, did odd jobs and mowed grass until I could buy it. That one got an 8hp Briggs & Stratton CAST IRON engine with a centrifugal chain clutch. 10 teeth on the clutch and 40 teeth on the axle #35 chain with 4.10 x 3.50 x 12" tires. It went 50mph. I lived on a dirt road, so all of my early Karts had 3 or 4 inches of ground clearance and needed to be able to handle dirt and grass. My last Kart was a low rider with rack & pinion steering. It had an 8hp Aluminum Briggs with a milled head to increase compression ratio, 2 spark plugs running from 2 car coils using a motorcycle battery for ignition. 2 spark plugs made 2 flame fronts acting like advancing ignition timing. Geared 4 to 1 at about 6,000 rpm that Kart went about 55mph. Lots of get up and go, and low center of gravity made it a blast to run. But by then I was moving on to cars. It was a great beginning though and I attribute it to my advancing into automobiles which ultimately landed me at The General Motors Proving Ground in Milford Michigan doing experimental work in advanced engineering. I'm retired now. The last thing I worked on was the Hydrogen Fuel Cell, and I just saw a UKposts video where Mary Barra GM CEO is going to veer away from battery powered EV and go to Hydrogen Fuel Cell powered EV. That's some heady shit right there boy! I hope you can gain something from what I have written here. ben/ michigan

It's awesome to see there's still people in this world who still use there hands and amagination .....just make sure you pass it down to your kids....teach them.....

Nice work and video, I really think the grease was your limiting factor. Use 80w-90 and make sure you touch up your seals and seal the case. Probably have better luck. Some single seal bearings would also help. I would like to see you try again. 👍🏽

One of the best vids I've seen on UKposts in ages. Love to see these young kids work with their hands instead of goofing on video games. Nice work.

I'm not surfing through all the comments to find out if anybody mentioned this but _you used 'way way' too much grease_ in that transmission. Stuffing it like that causes pressure to build up inside, enough too blow out and break the housing as you found out. I seriously doubt the input shaft broke because of the tensioner you made, much more likely the pressure build up was the cause. I'm a retired engineer, I've worked with tons of gearboxes like that over 40 years. Just saying not bragging brother, I really love your adventure with the Go Cart 👍😁

Peerless 5 speed transmissions can be converted to gear oil instead of grease. Faster, better shifting, and it's easier on everything because grease is too thick for going fast. These are used for racing lawnmowers all the time and that is where I heard about the gear oil conversion

2 things stick out about the failure. 1 use bigger gears, less torque lost on small diameter sprockets, don't go huge but a 15-17 tooth would reduce parasitic power loss at that point. (I'm not a certified engineer, just some random dude that stayed at a holiday in express a couple times). 2nd, Outer shaft support. Run a nose off the outside with a bearing to reduce stress on the cast aluminum housing that failed. (I'm a welder/machinist/tool maker) having a "nose support" like on a coyote motor crank support for running a blower as well as timing chains to keep the crank from snapping off. Your weak point doesn't look to be the gears themselves, but the housing. Reinforce the shaft and housing on next go round. Good luck man! Stuff like this makes me hopeful for the next generation of gear heads.

I'm 67, I like this kid, reminds me of me in 1966, keep going kid, do it, you just might end up an Automotive Engineer, like me. How Cool is that!

Bro if we grew up in the same neighborhood we’d be best friends 100%

AFTER 50 YEARS IN THE BUSINESS, IKNOW TALENT AND YOU HAVE IT YOU DO GOOD WORK KID STICK WITH IT

Trial and Error equals Progress, cool vid, good job, keep going, and be safe

Impressive young man. Great to see another generation has the itch to improve what they have.

I'm 68 years old and this is exactly what we were doing back in the day. Actually I still have scars on my left foot from riding my mini bike in the field and getting it underneath a chain-link fence because I was going to fast and didn't quite make the turn. I dragged it for a pretty good distance before I could shut my mini bike down, Of course my mom freaked out from my ripped up foot, oh well, She took me to the hospital which was nice of her LOL.... guys, you're living the dream and you're going to be okay, I couldn't even begin to guess how many people out here are so absolutely proud of you guys.

Awesome project. Love all the negative comments from the game boys who never get their hands dirty.

I'd be curious to see how this worked. Those transmission required Bentonite not grease. Also landscapers killed these in one season my trying to change gears on the fly. They were only effective when stopping the machine changing gears and then proceeding. I do applaud his skills in design and building this cool little cart.

Nice, impressive fabrication. Great job. YOu have a bright future ahead of you.

Glad to see this, especially now. Nice work engineering parts to make it work, for the most part! Also, shout out to your community on not being dickheads and letting you cruise the streets. No harm, no foul.

7:35 Are you sure you used enough grease?

That gearbox needed more grease 😂

Dude! Your channel is so underrated! You deserve more subs. I can tell you put a good amount of effort into these videos with the carts and the video editing. Props to you!

Sweet build man! I've always loved things with engines and adding a transmission to something that wasn't meant to have a transmission is awesome. Not to mention that your music selection is pretty good too

Tip from an old fart. Level out your audio levels so the voice is not low compared to the music. Very good for an old mechanic to see the younger generations keep up what we tinkerers started with back in the days :) So young and already welding and fabricating working prototypes. Impressive sir. I wish you the best in not burning out early, keep your interests alive by having many factors to fiddle with is my absolute best tip to never get anything finished ;) Also helmets are cool, brain damage is not. One impaired driver heading towards you and you are done for sir. Helmet!

I love to watch people who love doing what they love.

Great enginuity, young man. You will have a good future and a lot of fun in life.

Hey dude great build! Sorry the transmission gave up but I really worried about that in put shaft when you have it apart! It didn't look like it would put up with much. The one thing I would have suggested before it broke was less grease in the gearbox I understand why you filled it but they're not designed for that and I think it had more pressure inside then you realize and that aided the breakage of the case and the shaft support! Greece is a great thing but so many people over Greece the hell out of stuff and it causes all kinds of problems just my opinion my friend but great build I enjoyed the video thank you

Don’t let the negative comments stifle you. You are learning by doing and failures give you as much information as successes. 60 years ago I built three, none as innovative as yours. Great to see you building and having fun and success doing it.

You my young fabricator, are headed for greatness. Keeping custom builds alive with dudes like you is a good thing. Most kids your age are afraid of grease under the nails. You have a great mind. Bet it runs in the family.

7:30 Don't overdo it with the amount of grease, too much grease and the gearbox will overheat. Usually the manufacturer states a certain weight of grease to put in.

It's not the Clutch. It can't handle the Stress of the Street's Rapid Acceleration. This Transmission is one big Granny Gear for a Lawn Turtle.

Way too much grease, it'll absorb power, and then get very hot. Thick oil may have been better as long as the shafts have seals fitted.

So great to see a young man with natural mechanical skills like my self, I’m 64, great video

You’re a pretty damn good fabricator man!! Love to see builds like this

Young man, This old man is now smiling thanks to you. Did the same when I was your age. Keep developing your fabrication skills, which are fantastic. Stay humble and honest. You just learned that a transmission designed for a lawn mower is not appropriate for your inted use. Press on. Use your imagination and you will succeed in life. Be careful on the road, there are others using it who don't have your driving skills. Have a blessed day my friend.

The chain snap can be eliminated by putting the tensioner on the slack side of the chain, not the pulling side. Also, an outboard bearing on the transmission input shaft will take the side load off the input shaft bearing. Also, centrifugal clutches are tough on transmission gears, the engagement chatter tends to break things.

Your mind is like a Doctor of Mechanics. Seriously, I hope you realize your worth in life, because the talent you have is worth a fortune. Don't let anyone tell you otherwise, or cheat you.

I'm with the last guy. Too many young people with their eyes glued to a screen these days. This thing you do with tools and knowledge....That's cool. Keep up the good work. People notice.👌

This is the mindset of the folks in the late 40’s and early 50’s that gave us what’s known as hot rodding. Respect to you sir!

Dude whatever you do never give up . I'm old enough to be your grandfather and my younger brother and I had some go-carts when we were younger and man we would have a blast . Had he still been alive we still would be doing our thang . There's nothing like having fun and being young so don't forget to never give up .

Alot of the people are talking about sideload, but the biggest issue with a peerless 700 is they MUST be used with a clutch. They are designed for sideload but not rammerjammin into the next gear, the neutral you were getting was the shift forks not slipping into the next gear, and instead the gears spinning around them. They absolutely need to be used with a clutch

Clutch and a synchro is what you need to take the pressure / load off the gear changes.

I'm a retired design engineer who worked at NASA's manned space flight center. I did some hot rodding when I was young. I can well remember what it was like to be young. You have done very impressive work here. You have multiple skills, and those skills are really important, and valuable. The key to good engineering is to think about how things will fail. If you design the failures out, what you have left is success. I'll give an example: when you are doing plumbing, if what you think you are doing is getting water from point A to point B, you are in trouble. What you are actually doing is keeping water out of the rest of the room. That means you have to be certain that your joints don't leak. In other words don't ask yourself "How can I make this work?" ask yourself "How is this going to fail?" Now lets talk about why the gear box was popping out of gear. Why would you expect it to stay in gear? Your shift lever didn't have any sort of detent system to hold the transmission in a particular gear. The torques from the motor apply twisting forces to the structure holding the transmission in place, and vibration is going to cause your shift lever to move from where you left it. When you design your detent system to hold your shift mechanism in place, think about how torques, vibration, thermal expansion, and contraction are going to affect it, and design around those problems. Expect each part to only do one job. A Swiss Army Knife looks like a good idea, until you try to eat a steak with one, and you find out having a fork at one end, and a knife at the other doesn't work very well. Now I want to talk about something no young man ever considers; safety. Humans can run about 17 mph, and the rule of two times the maximum expected stress shows up in our bodies. In other words, any sort of accident at or above twice that maximum body speed (call it 35 mph) is a potentially fatal accident; the human body simply comes apart in such collisions. The connections to the organs break down, arteries are torn loose from the heart, for example, and the body bleeds to death internally. Keep going, have fun, but stay safe. Think about what a tire blowout at high speed would do. Get tires rated for twice your maximum speed.

I’m not that old, late 30s, but what I can say is the world needs more youths like you. I’m guessing your late teens. Sorry if your not. Nowadays kids are too worried about gaming or internet trends. Not too many interested in mechanics, engineering and fabrication. Keep it up man!

I made a go cart once out of a mower that had that same transmission. I put a bigger sprocket on it, and a smaller diameter pulley on the input. I had the same results, it broke off in the same spot as yours. I had a belt clutch, that loosened the belt. I think the housing is weak in that spot. The gearbox isn't thick enough. Gearing it up increases the pressure on the thin part of it, and that's where it breaks. After I broke two of them I realized it wasn't strong enough. I used to fix mowers and I had a ton of extra parts. I think you will have better luck with a motorcycle engine that already has a clutch and transmission. The case won't break when it's shifted. If you're bound and determined to try the same type gearbox, you might need a clutch made for a v belt to cushion the shift somewhat. Otherwise it's just going to break again. The original belt drive from the mower had a longer belt, which had some give to it. The mower I had used an 8 HP engine. As long as about five of the horsepower was being used to run the blades, everything worked out. But when it all was being used for pulling, the box couldn't take it. Just thought I would give you a heads up.

It appears the shaft of your gearbox was mounted onto the case of the gearbox. This can only withstand so much torque before shearing off, the neutral you were experiencing was the gears separating due to the casing of the gearbox cracking.

the gearbox is designed for a lawn tractor that goes 5 to ten MPH tops when you geared it up to 50 MPH it subjected the gearbox to strains way beyond it's ability and it self destructed ... get an engine trans from a small dirtbike that will stand the strain ...!

Great job young man. If you don’t break things once in awhile your not trying hard enough. Smash it mate. Smash it hard. Cheers

I bought one with a older 250cc Suzuki engine years ago. It already had 5 speeds in the engine. Would easily pop a wheelie. Very dangerous. Why don't cart racers use motorcycle engines? Changing gears adds to the fun.

As others have suggested, bone yard bike motor/tranny. My suggestion is a Kawasaki 3-cyl, 2-stroke w/a 5-speed. Talk about TORQUE!! I'm very impressed with your talent and determination!! Keep it up!

I have been wondering where creativity had gone in young people today. This young man gives me hope that it's still here. Regardless of outcome of this project, the learning experience was something he could not have gained playing video games or playing soccer. Activities like this should be promoted by adults but it rarely happens. Keep up the good work young man. It will pay off one day!

Well I'm certainly impressed with your talent. Of my almost 50 years in the automotive industry I've only worked with a handful of people over the years that we're as creative as you and all of them had many more years of experience. Well done !

You've got a hell of a future ahead of you man. Was really impressed you nailed the gear ratios first go. You've got some skill for fabrication that's for sure. Screw the haters, it's fun to do stuff just to try something different

What a great video. I'm so pleased to see a young man making productive use of his time versus sitting around playing games. He is steps ahead of others his age, understanding mechanics, using a welder and power tools. I work with adults who don't understand anything about their cars other than it goes or it doesn't (must to out of gas). I look forward to what you'll build next and thumbs up.

Extremely impressed with your skills brother! I instantly subscribed 😁 looking forward to your future projects✊

Young man... It's good to see that you dive into creativity. I'm 63 years old and I grew up riding Mini bikes and gocarts. You are too cool young man!!!!!

it dropped into neutral because of all of these factors probably: 1 too much power for the gearbox. You will have to calculate your torque to match the rated torque for the input for the gear box. Use a correct gear ratio based on the engines max power to match or under the max of the gearbox 2 yea..you need a better clutch and 3 the case was probably flexing. mount points are put in places that allow the enclosure to "flex" in a balanced way. . not enough space to explain that here.. in short you'll want to mount the gearbox the same way- (direction power is applied, distance from the power and orientation to the torque) to get the best out of it. or gussie it up by welding xtra supports and material on the case.

Dude…I’m impressed that you saw potential to improve performance and was able to engineer it into your cart. That how things evolve..keep on tinkering!!!

I see a full boat scholarship to your engineering school of choice. My compliments on your quest for engineering more speed. You are a credit to your generation. Keep your videos to add to your entrance exam. Best of luck to you.

Well you dont know if you dont try. Dont listen to negative comments, those people probably never have and never will be able to fabricate or build anying in there lives. Cool project 👍

I owned a garage for many years. I wish there was more kids like you in this world. Keep up the good work you’ll go far in life.

Many years ago my friend and I put an AMF Harley 175 motor on a cheap go kart frame with no shocks and a cheesy drum brake designed for like a 5hp motor. After driving it around for a while in terror and almost dying we tore it apart before we did die.

The clutch on the engine is centrifugal so it won't disengage until the RPMs drop enough for the clutch shoes to release. They remain engaged even after release of the throttle due to the speed of the mechanism becoming the driver of it. So, like a manual transmission on a car, the clutch needs to be mechanically disconnected via a separate system not tied to engine/subsystem RPMs. I have a hunch your transmission broke due to either the casting inability to handle the torque applied or bearing seize due to lack of lubrication. Finally, keep it up young man as we need tinkerers like yourself. I'm 62 and had my own self built go-kart when I was 12 with a 6HP Tucumseh salvaged from a rototiller. I had a lot of fun with it. I became a packaging machine designer/builder/programmer because of always being inquisitive about things mechanical.

Hey kid, how ya doin'? I'm a new subscriber with years of mechanical experience since I was 7 years old & I'm 25 years old now, that Geerbox was designed for axial loads and will fail when placed under lateral load-forces. You can find Geerboxes designed for lateral load-forces on there outboard shafts. Looking forward to watching more of your videos so keep up the good work, you'll learn as you go.

Actually found this video by accident. Very creative thinking. I used to build basically the same thing as what's called racing mowers. All though mine I called go mowers. Seemed Craftman manual shift transaxles were the easiest to manipulate for the projects, and had a tremendous amount of fun back in the day. Unfortunately, as you found out, lawnmower transmissions just don't make the cut. They will work, but usually not for long. The input shafts on them things always wear. Although for your configuration you at least had it laying over so more grease could flow to that bearing. On most transaxles, I would wear the bearings out to the point the input shaft would be wobbling. I had even used a heavy duty and new Peerless on one. I've had gears break and go through the case, wore pullies into 2 halves. Countless belts. Seems they do alot better gearing moderately. I had one that would clock 60 MPH. Later ones no more then 30-35 tops.

Fantastic work and fabrication, this is content worth watching from beginning to end! you deserve many more of views!!!

Not bad for a test go. You should definitely try this again with a proper way to clutch between gears. This looks like is has potential for sure.

You're a good kid, you give me some hope for the future!

Me and a few of my friends used to build racing lawnmowers. The rules were pretty simple. other than larger pulleys, and some type of gas pedal arrangement, basically everything had to come off of some kind of a lawnmower. that type of transmission is OK but if I remember correctly, there isn’t a lot of bearings in it. The main shaft that holds your gears have bronze bushings and that’s it. Also, I believe reverse is a pretty flimsy chain drive. It’ll work, but the bushings will be worn out before too long. The transmissions we never did destroy were the Spicer six speed slide shifts. They are pretty easy to recognize because the mower has the gearshift between your knees and the shift pattern is R. N. 123456 in an arc. Those things don’t have any space between the gears so you can’t really miss the gear. You can skip a gear, but it just goes into the next one. On the mowers, we would only use the clutch for first gear and reverse. All the other gears it was just mash the gas, let up, slam it into the next gear, mash the gas again. But they are transaxles so a little different setup.

I had a Skat Kat minibike when I was your age. It had a torque converter instead of a transmission. Working on it with my dad taught me everything I needed to know about engines when I got my first car. Have fun and stay safe.

Hey man, loved the build! You've found the key... one learns nothing by laying down some cash and buying a rig, but learns immeasurable lessons by building it and solving the problems on your own......

I'm just jealous of the kids workshop and tools.

Nothing like shifting through the gears. A motorcycle gear box is probably your best bet, but "making it work" is so cool in and of itself. Right on man!

You have brilliant future ahead of you! In Australia this video would have used by the police as an example of extremely dangerous and recklessness behavior, calling for the public to report such things.

That gearbox will have so much drag with all that grease ? Surely oil filled would be so much better ???

You’re a smart young man! Respect.

Dang im impressed as hell. Youve got all the skills of an Engineering expert. Get yourself a degree you’ve definitely got what it takes.

You need a counter gear to balance the force of the engine pulling that small rod to one side. After you get that welded back in place use a counter chain so that there is zero angular torque on that little gear rod.

Love your gokart, the angle of your helmet cam is anxiety inducing, just starting down at your lap while you race off to somewhere unseen at high speed.

Too cool....and this kid is amazing with his ingenuity and patience for his age...I was really feeling it when he was building it....Has a lot of knowledge....Keep it up guy

You are lucky to live in a neighbourhood where you can drive these on a smooth public road and not be hassled by anyone, and you probably realize that. My brother welded up a three wheel frame (two in the front) which let him use a complete small motorcycle engine, clutch and trans driving the single rear wheel. This was fairly simple to build, and it handled well as do most two-in-front 3 wheelers.

An awesome reason I'd recommend Moly [ Molybdenum Disulfide ] based grease is the Moly will actually EMBED into the surface of metal parts, so even if _do_ you lose some due to a leak or other would be horror story, the Moly will keep lubricating even under intense heat and save your bacon until you notice the issue! Just beware if your transmission has any Aluminum parts that are a bearing surface with friction on them (not including the housing) that you make 100% certain the Moly grease DOES NOT CONTAIN GRAPHITE! (most moly grease does have added Graphite, like CV axle or bearing grease.) Graphite is HIGHLY abrasive to Aluminum because it's so soft! Other than that Moly is slicker than snot on a two year old!

The same problem with the centrifical clutch is that the engine speed must drop below a certain speed before it will completely disengage. You need a clutch that completely disengages at any engine speed to take the stress off the transmission while shifting gears.

Great video 👍 Really nice edit and a genuine home build project keep doing what you're doing!

Great engineering! Be proud of yourself!

Theory abt transmission fatigue: 1) Gearbox & sleeve bearings not designed for these speeds 2) Your grease as gentleman mentioned below thou acceptable in low speed applications may not be compressing fast enough as it passes btwn gear teeth pushing them apart. 90-80wt typical 3) Axial shock load fatigue, maybe added support on trans'n output shaft . .

Mate your videos are literally the best on UKposts

Next job is make an outrigger/bearing support for the gearbox input shaft. Case breakage was caused by sideways shock-loading due to chain slack/jump. That clutch will not release once it is above a certain revs; only when it starts does it slip. Try to be more positive when changing gear, there is no synchro on that box. Find another gearbox casing and rebuild.

I think you stuffed WAY too much grease in the gear box. I would have thought oil would have been used. Didnt I see a drain plug on the case? If so, it is not there to drain grease :) Good job on the build though.

My experience, lawn mower transmission housing are not thick enough material to handle that level of abuse. Also if you synchronize the gears (bevel the teeth) if done correctly, you won't need a clutch. For go carting a 3 speed transmission works better than a five. you will find the gear is similar, but quicker, less moving parts to fail, less time shifting. Last thing, use a l synthetic oil, not grease, in the gear box.. Good video, show more than pavement and turning tires next time. Enjoyed watching.