Hello, I'm new here. I am on the Kettering University SAE Mini Baja team. We build and race mini dune buggies. Our drivetrain consists of a 10hp briggs engine that drives a jack shaft via a CVT which then drives an axle through a chain. Total gear reduction is about 20:1. The problem is that the axle is solid so in turns, the car understeers terribly. I'm looking into using more or less off the shelf ATV parts to correct this. Namely, an independent suspension setup with a locking differential. I don't know a whole lot about ATVs so I'm looking for things like what the lowest gearing you can get, models that use something like this, weight, cost, etc. Thanks a lot.

This is our car, by the way. You can see the current driveline setup here. PIC

 

The rear diffs are solid on all new machines I belive, so I'd look at fronts. Most of the diffs that I'm familliar with are arround 3.2 to 3.8 to 1 . The older polaris's used a chain front driven diff, but they are solid, the 4x engaged on the hubs. Larger rear tire might help your understeer. You might want to look at the yamaha grizzly front diff, it's a limited slip with an electricly acuated locker, but its shaft drive.

 

A lot depends on your budget. If it is limitless (which is unlikely) you could look into soemthing like a Detroit Gearless Locker which allows one axle of the differential to spin faster, but always drives both shafts.. ie - if one wheels looses traction the other wheel still gets power as well. If your budget is tight, stay with the single axle concpet, but split them.. adapt your frame so that each axle has two bearing supports. One shaft will still be driven by your sprocket & chain... the other axle can be driven via a V-belt and pulley concept... Put one of the v-pulleys basically as close to the drive sprocket as possible on the same drive shaft. Put a Driven V-pulley on the other part of the wheel axle. A belt that is a little too long will allow you to use a third pulley to be used as a slack takeup device. use a linkage on the steering wheel to actuate the takeup.. when steering straight, both wheels are powered, when turning, the v-belt slacks off based on how tight you are trying to turn... the thighter the turn, the looser the belt, an thus the belt driven wheel becomes more of a freewheel application. If this makes sense, good, if not, you can send me a message.

 

P.S. remember to make the v-belt and pulley ratios the same as your sprocket ratios.

Good luck.