40 Series Torque Converter Maintenance

40 series torque converter maintenance
40 series torque converter maintenance is simple. If you have an old go kart torque converter that needs to be serviced, this article will show you how to do it step by step. In addition to cleaning, most old torque converters need new belts as the old ones tend to crack and become narrow (reducing low end torque and top end speed). You can get a new torque converter belt, as well as 40 series replacement parts here.

This video will show you how to disassemble, clean, lubricate, polish, and reassemble a comet 40 series torque converter. You will need simple hand tools, and some wire attachments to get rid of rust, dry molybdenum spray for lubrication. Just watch the video, it takes too damn long to explain it.

If you found this information valuable, go ahead and like it, comment, and share. If you end up needing comet 40 series torque converter parts, you may be able to order what you need rather than replacing the whole unit.

This is part of the maintenance section of KartFab.

42 thoughts on “40 Series Torque Converter Maintenance”

  1. Also, I got a 16 HP Kohler Command that I am gonna mount to the Kart and getting. Should I go with the 40 series or 44 magnum? I know the belt width is different but what does that really do? And what sprocket sizes should I run? I would really like to do donuts in the dirt and sand.

  2. I removed the governor in my pred 212, was disappointed, didn’t notice a big difference. Barely noticed anything. Is that normal on a governor delete?

  3. I have a small homemade dune looking buggy. That a neighbor made. It had a 8 hp motor. I bought a honda Gx 390 motor. The rear left axle has a big pulley with a torque converter rated for a 8 hp motor . From all the questions & answers I read from your sight. Do some carts use a chain system & 40 series torque coverter? I do not have the front pulley for the front shaft. Can you help me out? Just asking ? Thank you

  4. Can the driven part be made to work in the opposite direction? I am adapting a 13hp Honda motor to a Club Car work cart and the driven pully is on the wrong (right) side of the axle for the Honda’s direction of rotation. (Hope I’m making myself clear enough).

  5. My name is Tom I bought the live axel plans. I have been fabricating all kind of things for the past 40 years. Where can I find a diagram of a front end suspension that gives the measurement on how to make it, shocks, upper and lower A arm measurements, and steering arms, And how it attaches to the kart? I bought the Predator 670 engine. So my wife and I could go street and off road riding. Most of time I can just look at picture of what I want fabricate and make it. Can you help me to

    1. Tom, have a look at some mini buggies that are on the market. Heep the tie rods in the same plane (angle) as the a-arms with the steering wheel straight. You will need to center the rack and pinion.

  6. Hello, if I order the Deluxe Upgrade Live Axle kit is there a good way to add a reverse gear to my go kart?

    1. You can but i dont give out any instructions. The only reverse gear I know of is only rated for 8 hp. chinese for the trailmaster go karts. The driven unit of the torque converter is what attaches to the reverse gearbox. This is also on the same website that the parts kit is for the go kart parts in the plans. just gotta search reverse gearbox.

  7. I have a carter talon 150 cc . I have replaced the carb , petcock , spark plug , gas tank and intake . The go kart will run all day at full throttle as long as it is up on jack stands but as soon as I put it to the ground at full throttle is bogs down and kills . I also have check and it has good compression any suggestions

    1. could be a vacuum seal issue with intake gasket(s), jetting, or dirty carb. Think back to see if you changed anything, anything you touched.

  8. Hey kartfab I have a question I have an 07 Joyner with no engine I am trying to put a 440cc 18 HP duromax engine on it with a 40 series on it , in your opinion what sprocket and tire size would you use ? Do you think I’ll have a problem with the torque converter and the axel?

  9. Jag har en
    DuroMax 16 HP Go Kart Log Splitter Gas Power Engine
    Utväxlingsförhållande 6:1

    Behöver jag en 30 el 40 serie?
    momentomvandlare (30 eller 40-serien

  10. I don’t have any comments but I have a question can you file down the rivets on a 40 series torque converter my belt keeps catching on to the inside rivets

    1. If your belt is catching on the rivets, then you have a serious alignment problem. If you google “comet belt chart” you will notice that the center to center distance has almost no margin of error. My two cents? Your belt is too short or your center to center distance is too large for your belt.

  11. I have a predator hemi 212cc engine I’m upgrading. I’m assuming after the upgrades it will be in the 12-14 hp range. Would I need to upgrade the torque converter from a 30 series to a 40?

    1. No, you won’t be making that much HP typically unless you do a lot of modifications to alter your compression ratio and run it on race fuel. Also, the torque converters (30 or 40 series)are a bad idea for High rpm applications. If you are going to rev high, you are going to need a centrifugal clutch or disc clutch.

      1. How many rpms would you consider high? I’m slightly building a predator 212 and would like to get from 5500-6000 rpms. Will a 30 series let me do that or should I invest in a 40 series with a 3/4 bore? Thanks

  12. How often should I clean and lub a 40 series clutch? Got a new 40 series and after about 10 hours total of driving time in a couple weeks it wants to hang up a little after driving it hard at slowing down. It pops back in place at almost stop.

    1. as often as it needs it. What you are describing could just be an issue with idle speed. If it takes time to pop back into place, then you may need to bump your idle rpms down.

      1. Hi i have a 420cc predator and im ordering a 40 series with 1 inch drive and 5/8 driven,then also getting 16inch 5/8 jackshaft with 3/16 keyway that matches my driven also ordering the reverse kit and 2-5/8 pillow bearings since my transmission on golfcart is on left when facing from front which is odd cause ezgo carts aee on right but anyway this causes me to need the jackshaft what do you think ? Does this sound like im heading in right direction?

  13. Thanks for your input, I found that the motor I have for the dune buggy is a Chinese motor, and found the new side case for the transmission, 114 dollars us. So I will be in business. Because that is what mounts to the rear of the frame. Now on to building a gokart with a predator engine.

  14. I just bought a frame of a I guess Bahamas style off road go cart, no use able engine. Has coil over shocks front and bac, rack and pinion steering, disc brakes, two seater, roll cage. Well built and heavy, took 4 guys to put it in the back of my truck. Knob by tires etc. Had a water cooled engine, but broken mounts,dual chanel drive to a live axel. I want to put a 16 or 18 horse motor with a series 40 torque converter. But how do I know that the axel will accommodate the torque converter? I can send a photo. Interested in your opinion.

    1. It’s Baha style, and had dual chain drive off of a motor I have never seen, with a transmission for forward and reverse. And probably not usable instead of a torque converter.

    2. check out diygokarts on google, they can answer your question because you will have a lot more! axle isnt the problem but gearing. Typically 6:1 gearing with 22″ or smaller rear tires is fine.

      1. I did some research on the motor, 250 cc water cooled Honda, not usable now, because the mount hole toward the rear of the engine near the live gear, is broken, and can be welded, and need to check engine usability. My question is what about air cooled motor and torque converter instead of the water cooled? The axle is bigger than 1 inch diameter, will a torque converter work, or do I need a different axel?

  15. My murray gokart briggs and stratton 6.5hp engine needs torque converter and mount. Im looking for parts and instructions or ideas. Like to surprise my son with a nice gift.

  16. Thanks a lot! i am new to engines because i am 15 and at school, your videos help more than any other, Keep making them, you are giving me great grades and helping me become the master mechanic i want to be! Thanks man

    1. 30 series is for 5-8 hp engines, has either a 3/4″ or 1″ bore and is ok for most go kart applications. 40 is for 8-18 hp engines, has a 1″ bore, and is heavy duty.

      1. Does the 40 series not have a larger drive diameter allowing it to use more rpms than the 30 series? Also. I plan on running 15 in tires on my small yard kart. I was looking at running a ratio of 6-1. Will the TC change the final ratio? Should I gear a bit smaller to obtain faster speeds while using a TC? I would like to be able to run 50mph. I have Predator 212 with stage 1, billet flywheel and rod and governor removed. Thanks

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