CVTs for Homebuild- School me

[pinestumps]

Hi folks,

I'm starting a smaller tracked build this year and I need a little help on a fuzzy topic for me... CVTs. A lot of people here seem to live and breathe with these units and I'll admit, I've never messed with one before.

I want to use a HF Predator 22hp as the engine and glazing upon the awesomely large amount of info on the forum; I saw 3 readily available choices:

Comet 780
From MFG supply it runs around $388 shipped for a Rec Industries "Tuned" driver and driven. Will this unit be substantial enough for a 22hp engine? Maybe put the red driver spring in for extra caution due to the tracks?

Comet 94C Duster
Around $412 shipped for both clutches. I heard these can handle over 30HP? Will I have to worry about tuning issues on this unit? It appears to be more of a 'universal' clutch, but maybe the tuning won't be so bad?

Comet 1190
Looks to be quite expensive and slim part supply compared to the above two but I am not singling it out yet.

I'm kinda leaning towards the 780 clutch as it is already tuned for a skid steer ATV, just not sure if she will be able to handle the HP. Thanks for the help!

[ARGOJIM]

780's should be fine as they are a proven clutch set up, if you are building weight then I might consider the 1190's. Dusters also seem to work ok for most though they do have a puck tossing issue with the higher rpm guys.

[Noel Woods]

I wouldn't use the Duster on anything but the lightest duty machines. I have thrown pucks before and its not pretty nor fun. Nothing like getting a tow back several miles into a swamp.

[racerone3]

I grenaded a duster in my shop. one hole in the lower tub, and never found one of the pucks

[ARGOJIM]

I grenade a duster in my shop. one hole in the lower tub, and never found one of the pucks

Ok I give, was suggesting duster only from what I've seen.

[racerone3]

Ok I give, was suggesting duster only from what I've seen.

I was agreeing with your puck tossing comment. It was high RPM ... I was doing something dumb

[pinestumps]

Awesome, thanks everyone for the advice on the CVT clutches! This rig is going to be quite heavy at 2100lbs empty, so maybe a small engine/CVT combo is not the best option?

I mocked up the lower steel chassis yesterday on the computer and at quick glance, I don't think my original scheme of using a 22hp/CVT coupled to car transmission is going to work. There's a lot of iron to move, so I'm a bit worried it will be very doggish.
IMG_20190410_174948136.jpg
I think it's back to the drawing board to either build a wee smaller or move up to a bigger powertrain package.

I'm glad I asked the question here on the CVTs or I think I would've broken down in the swamp too!

[Noel Woods]

I would look at a car drivetrain. From the transmission you can adapt a sprocket drive system and integrate a braking system to do the turning. Just use heavy duty brakes.

[phabib]

If I were doing a project from scratch, I'd look at doing a hybrid drive with a a generator running one electric motor per side, and some batteries to provide the power that you'll only need for peaks when you're trying to turn. You can pick up 3 phase motors pretty cheap on the used market and VFDs will let you get speed control. Since the first thing a VFD does is convert the AC input into DC, I think you could put your battery pack into that bus.

The other option might be hydrostatic drive.

[allwheeldrive]

If the CVT is directly mounted to the engine as it should be, only the rated HP of the engine is relative. If a CVT can handle 22 HP and its attached to a 22 HP motor it doesn't matter if the machine weighs 200 pounds or 200,000 pounds since whether it will move is directly responsible by your gearing and not the clutch. If speed is your concern than yes than you can call into question your HP. Likewise you can always achieve sufficient torque as long as you don't mind sacrificing speed. 16HP should net you 6-8 mph top speed at around 3,500 pounds with enough torque to spin the tracks (assuming you have lower gears)