t 20 trans gearing

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Thread: t 20 trans gearing

  1. #1
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    t 20 trans gearing

    any reason you could'nt run directly from the t20 shafts directly to wheel axles if the sprocket gearing was correct for the tire sizes , etc. johnboy va.

  2. #2
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    JB I've never seen a Max machine, but the short answer is yes. Hustler machines are driven directly from the T20 to the center axle.

    Some obvious things you would have to think about is whether there is clearance to make a direct connection (straight path for the chain to follow), whether the newly relocated chain would be in the way of any maintenance tasks, and whether would would have a way to keep the new chain tight.

    The other thing, which you recognize, is getting the correct ratio. I don't know the tooth counts on the sprockets but the question is whether or not there is clearance between the tub and drive axle for the size sprocket you will need. Of course, if you had to you could adjust the ratio outside the tub with your high boy setup.

  3. #3
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    I geared down my tan Max2 a few years ago by changing the output sprockets on either side of the t20. I went down to a 13 tooth gear and I've really been impressed by how that improved my pulling ability. This is the strongest amphib I have and it has easliy towed out multiple Polaris and Can Am 4 seater quads that were buried to their frames. I've also pulled out a MUD OX hydraulic machine on two occasions that was going no where on it's on.

    The down side, is that speed was diminished a bit but is still quick enough for the conditions I drive in. Top speed went from 22mph to 17 mph, but the machine just pulls and pulls.

    I had even considered a 11 tooth sprocket, but that would probably be too low for most conditions. It would make for some stout gearing though.

    Don't know if this answers your question directly John, but lower gearing whichever way you get there, should help your machine.

  4. #4
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    both answers are just what i was looking for . i'm always thinking of ways to improve my max 2 highboy not only performance wise but simpler maintenance also . i can easily change my main drive sprocket to gear down . like you said noel ..top speed isn't my need ..more power and torque . do you remember how many teeth were on the t 20 sprocket originally before you dropped to 13 teeth ? mainly i was asking this because i really like those russian atv tracked machines where they use a car differential to drive the rear wheels . no chains . just brakes on each wheel hub . of course they are always tracked machines . i'm surprised at how good the performace is with just rear wheels driving the tracks . very little slippage . with my subframe on my max i could do the same .. just driving the rear axles off the t20 with one chain and the right sprockets ratios . am i going to do it ? not sure but fun to think about it . thanks much , johnboy va.

  5. #5
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    one other question ..could the t20 shaft on the pulley side be extended past the pulley ? i know that a bolt holds the pulley on that threads into the shaft which i believe is keyed , correct . could a new longer keyed shaft be made and the pulley be held in place with locking collars ? the reason being is if i went with the above design i could just run both t20 shafts thru the tub and those would be my drive shafts to the rear axles ...with the right sprocket ratios . too weird ? j.b.

  6. #6
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    one other question ... on my max 2 ( and i assume the others ) the driven pulley on the t20 spins counter clockwise , which when going forward makes since ,since the sprocket would turn the same direction . when you shift into reverse the sprocket has to turn clockwise but the pulley is still going counter clockwise . i don,t understand how that works . i always thought the pulley and sprocket were on the same shaft ... i've never torn a t20 apart so not sure how that works . thanks, jb

  7. #7
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    The original t20 transmission in my Max2 had 15 gear teeth, going to 13 seemed perfect. It seems like a 20% gear reduction maybe slightly more.

    I actually did a similar gear reduction on my Coot, which uses an Apex transmission and it only required one output gear to change ratios. I geared the Coot down even lower, its amazing on what it will do as well, you can descend a steep hill in high gear without touching the brake, my disc brake is actually off the machine currently because it stops so well with engine braking alone.

  8. #8
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    Hey JB,
    I assume you are wanting to eliminate the jack shafts of the Max II, Good idea.
    You theoretically could extend the output sprocket past the input driven clutch, but bad idea. too much stress on the case and shaft.
    The input driven clutch is on a shaft which extends the width of the t-20, and the output sprockets are fitted over that shaft.
    The reverse happens when the shift collar (also on the input shaft) slides in or out of the gear set of the planetary set.
    There are some good videos of T-20 rebuilds, here and youtube. http://www.youtube.com/watch?v=tuifk0kE7vg&t=891s
    depending how much torque your engine has dictates how much gearing you can put into the final drive.
    Noel geared down for more pulling power, I geared up for a little more speed, but I am also using the diesel with 47 HP and a lot more torque.
    Hope this helps.
    Mike
    Last edited by mfenmor; 01-08-2022 at 10:12 PM.

  9. #9
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    thanks noel and mike for the input ..now i understand how the shafts and sprockets on the t20 work . i see now my idea is not that great . sometimes it's better just to leave well enough alone . my max highboy has performed well over all these years with very little maintenance needed . i finally got full throttle working on the motor and have plenty of speed ... so with a quick change of the drive sprockets down 2 teeth , i'll see how the power changes and if much speed drops. mike,still wondering about the max 4 lift project ..it was some beautiful designing and fabrication . johnboy

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