Make a 12-Speed Transmission from a 6-Speed Transmission?

My Friend Suggested this Idea, Some Transports have a similar Idea where you have your normal First Gear to lets say Sixth Gear then you shift another gear handle and you start all over again from Seventh Gear to Twelfth Gear and again up-to your eighteen gear(Or what ever the Transmission goes upto). Well You know how Most Lawn Tractors have one Belt from the Engine to the Transmission? Why not put two and make the Engine Pulleys and/or Transmission Pulley A Different size and Independent Clutches, and then put a Lock on Each Clutch so they stay Engaged while the other is dis-engaged(verse-visa). If you don't really get what I mean I Quickly made a Picture in MS Paint.



If you wanted to make it so it worked like a 12-Speed you would probably need to find out the proper pulley ratio's etc. I thought this could be a great idea for A Mudding and Trail Tractor where the trail or mud hole is a far distance from your house.

Problems I could see is wearing out belts quicker because one will be a dummy until you make it upto speed, But If one Pulley breaks on you then you could always drive home on the other pulley.

You could always figure out to connect two transaxles together like the offroad crowd does with what's known as a doubler transfer case (basically two transfer cases mounted together).

But that would basically give you 36 gears. But this idea may be workable. I've got some spare parts that include a 5 speed and a 3 speed. First gear in both would be super low. Maybe like 20:1.

I had thought of doing something similar with one of my MTD's - i put a 3 speed manual trans in it , then planned on leaving the variable pulley in it - theoretically it should net 6 plus gears - just had an issue with belt allignments - ill have to drag it out and tinker with it sometime .


Best way to make a multi speed machine? Go kart clutch. Dealing with multiple belts and clutches would be too much of a power drain - not to mention the pulleys probably wouldnt line up either.

i could actually see your idea working but the only problem is if the power is going through the top belt you will need to somehow make that belt not touch the other pulleys and just float because if it is touching a spinning belt, or its spinning and touching a pulley spinning a different speed it will wear through that belt in one spot in no time
if there was a way to rig it up like that on the tranny and use a clutch of some sort where its either locked in and turning the belt or its spinning freely and allowing that belt to spin one speed and then the power coming from the engine spin a different speed
does this all make sense? it does in my head but i dont know if i made it clear to everyone else lol

dangeroustoys56 wrote:

I had thought of doing something similar with one of my MTD's - i put a 3 speed manual trans in it , then planned on leaving the variable pulley in it - theoretically it should net 6 plus gears - just had an issue with belt allignments - ill have to drag it out and tinker with it sometime .


Best way to make a multi speed machine? Go kart clutch. Dealing with multiple belts and clutches would be too much of a power drain - not to mention the pulleys probably wouldnt line up either.

Yeah everything would have to be custom built and and you would have to probably lift the rear end

Jordan wrote:

i could actually see your idea working but the only problem is if the power is going through the top belt you will need to somehow make that belt not touch the other pulleys and just float because if it is touching a spinning belt, or its spinning and touching a pulley spinning a different speed it will wear through that belt in one spot in no time
if there was a way to rig it up like that on the tranny and use a clutch of some sort where its either locked in and turning the belt or its spinning freely and allowing that belt to spin one speed and then the power coming from the engine spin a different speed
does this all make sense? it does in my head but i dont know if i made it clear to everyone else lol

I think i understand what you mean, like if your in the 7th-12th gear section the 1st-6th gear would be sagging down and riding on the belt thats turning. What could work is a peice of sheet metal between the two belts so they dont touch. Or do you mean when its in 1st-6th and the belt for 7th-12th is resting on the pulley and wearing out?

dagr8tim wrote:

You could always figure out to connect two transaxles together like the offroad crowd does with what's known as a doubler transfer case (basically two transfer cases mounted together).

But that would basically give you 36 gears. But this idea may be workable. I've got some spare parts that include a 5 speed and a 3 speed. First gear in both would be super low. Maybe like 20:1.

That seems harder but it would work more efficently. I think I know what you mean and your idea sounds the strongest and would have a really low gear ratio for 1st gear transfer case and 1st gear rear end.

W1ldyOvvnZ wrote:

Jordan wrote:

i could actually see your idea working but the only problem is if the power is going through the top belt you will need to somehow make that belt not touch the other pulleys and just float because if it is touching a spinning belt, or its spinning and touching a pulley spinning a different speed it will wear through that belt in one spot in no time
if there was a way to rig it up like that on the tranny and use a clutch of some sort where its either locked in and turning the belt or its spinning freely and allowing that belt to spin one speed and then the power coming from the engine spin a different speed
does this all make sense? it does in my head but i dont know if i made it clear to everyone else lol

I think i understand what you mean, like if your in the 7th-12th gear section the 1st-6th gear would be sagging down and riding on the belt thats turning. What could work is a peice of sheet metal between the two belts so they dont touch. Or do you mean when its in 1st-6th and the belt for 7th-12th is resting on the pulley and wearing out?

i meant if its running power through the top belt the bottom one will probably be spinning along with the tranny and loose around the engine like most clutches work but the belt will rub on the engine pulley and with them going different speeds it will wear out the belt too soon, so to fix it youd need to think up a way that you can get the belt far away from the pulley so they dont touch at all

i was thinking about this for a long time after i first read your idea...i figured that using 2 electric PTO pulleys would do what you need have them wired separate but attached to the motor somehow, this will allow one to drive the tranny and the other will float with the belt tight like you will need and theres no clutch to mess around with then to switch to the other range just turn off the one pulley and turn on the other
i know its going to suck power back but it will allow good operation and its not very hard to build because you wont have to even have a clutch with it because turning them both off will allow them to 'float' when not being used

The problem with electric clutches is they are on & off only. When regular driveline clutches engage they allow the belt to slip some. Using an electric clutch would be like "popping" the clutch with every start, and would be hard on the entire driveline, and inevitably break shift keys in the trans.

AcreFarm wrote:

The problem with electric clutches is they are on & off only. When regular driveline clutches engage they allow the belt to slip some. Using an electric clutch would be like "popping" the clutch with every start, and would be hard on the entire driveline, and inevitably break shift keys in the trans.

yeah probably so i guess itll still need a regular clutch to take off

Jordan wrote:

AcreFarm wrote:

The problem with electric clutches is they are on & off only. When regular driveline clutches engage they allow the belt to slip some. Using an electric clutch would be like "popping" the clutch with every start, and would be hard on the entire driveline, and inevitably break shift keys in the trans.

yeah probably so i guess itll still need a regular clutch to take off

Unless you made your driveline almost bulletproof, but also those electric clutches are expensive, I had to replace one on my fathers mower and it costs like $300 for one of them. You would end up putting around $600-650 into it when your finished with the project.

I know my fathers friend suggested using a comet clutch(Snowmobile Clutch) and he said it would take about 3hrs to install it(Non air tight seal). But it could be used somehow with the lawn tractor rear end and have almost an unlimited gear(I know that's not 100% correct but that's all i could think of how to describe it for now). You wouldn't need the lawn tractor rear end to make it an "unlimited gear" but you would use that and the clutch to make the tractor have lots of torque at low RPMs and fast tractor at high RPMs, and if you wanted you could do what some automatic ATVs do and make it air tight and have a vent line(for cooling the air and whatever else it is used for on ATVs) so when your in water the belt for the clutch doesn't slip and then run a chain drive from the clutch to the rear end(you wouldn't need the standard lawn tractor clutches because the primary clutch (the one that connects to the engine) will work like the cheetah clutches(used for go-karts, etc.)).

Yeah electric clutches arent cheep - for my 86 GTII i looked up for a replacement clutch ( didnt need one was just curious) - was about $400 for a new one- i have a spare off my GT6000 tho.

A simple manual clutch could be made tho for the electric clutch - idler pulley on an arm with a tension spring and a lever hooked to it , to avoid the inital turning on - would be super easy for a side input shaft trans setup.

When comming up with the 4x4 idea for my GT6000- never crossed my mind about electric clutch engagement 'jolt' - if the belt is long enough the jolt shouldnt be too bad - the setup i came up with would put a jackshaft across the chassis , and 2 belts or possibly a belt and a chain.

More i think about it, in my setup, id need some sort of manual clutch to shift gears in the front trans - the electric clutch would only be to power the belt/trans.

dangeroustoys56 wrote:

Yeah electric clutches arent cheep - for my 86 GTII i looked up for a replacement clutch ( didnt need one was just curious) - was about $400 for a new one- i have a spare off my GT6000 tho.

A simple manual clutch could be made tho for the electric clutch - idler pulley on an arm with a tension spring and a lever hooked to it , to avoid the inital turning on - would be super easy for a side input shaft trans setup.

When comming up with the 4x4 idea for my GT6000- never crossed my mind about electric clutch engagement 'jolt' - if the belt is long enough the jolt shouldnt be too bad - the setup i came up with would put a jackshaft across the chassis , and 2 belts or possibly a belt and a chain.

More i think about it, in my setup, id need some sort of manual clutch to shift gears in the front trans - the electric clutch would only be to power the belt/trans.

Thinking of the "jolt", how do they manage not to shock the system for your normal mower(not a modified mower)

Most 'shift on the fly' setups actually have the clutch intregral with the shifter - why you dont need to press the clutch while shifting.

You can get a decent 'jolt' on the old tractors - once i impromptu raced my freind with my stock 11HP dynamark ( he had a JD) - i revved up the tractor , put it in first and popped out the clutch - front end went skyward and i rode a wheelie for about 5 feet.

Most new tractors are setup for comfort , not a whole lot of power.

you are missing a gear, reverse. it would get pretty annoying having two reveres the hole time.

McHandyMan wrote:

you are missing a gear, reverse. it would get pretty annoying having two reveres the hole time.

A low and High Gear, for reverse, You wouldn't need to shift from low to high in reverse, If you wanted to you could put it into 12th gear(forward) from neutral without the engine bogging like a manual truck

dangeroustoys56 wrote:

Most 'shift on the fly' setups actually have the clutch intregral with the shifter - why you dont need to press the clutch while shifting.

You can get a decent 'jolt' on the old tractors - once i impromptu raced my freind with my stock 11HP dynamark ( he had a JD) - i revved up the tractor , put it in first and popped out the clutch - front end went skyward and i rode a wheelie for about 5 feet.

Most new tractors are setup for comfort , not a whole lot of power.

I pop the clutch on our 04 JD all the time its got some new technology so I disconnect the seat safety stand up over the steering wheel with the tranny in fifth, my foot on the clutch, and my neighbor grabbing the back of the seat and leaning way down with his feet on the hitch. Then I release the clutch and jerk my self back into the seat while my neighbors jerks back on the seat and that front end goes way up there. We rode a wheely through all his trails and then on the top of his four wheeler jump we stood up on it again and popped the clutch. lets just say we havent done it since and the steering wheel broke in the process.