I use the Comet 40 series torque converter clutch system with a Comet 44 D driven clutch http://www.hoffcocomet.com/comet/aftermarket-torque-converters.asp This combination provides for a very heavy duty automatic and torque sensing drive system without the need to shift gears. I find this system to be more reliable and durable than conventional motor cycle clutches that can be strained by hill climbing and the large 25 inch rear tires that require lots of variable torque. This drive system has been used for many decades in the snowmobile industry and also in many industrial applications with great success. These clutches are made to take a real pounding and its nice not to have to try to coordinate a foot or hand leaver manual clutch system and having to shift five gears like on many motorcycle applications. This is not very much fun in hilly areas or where trail riding demands constant speed changes. The rear shocks are heavy duty 17 inch hydraulic coil-overs and are made for large ATV applications that can take much more weight than this type of buggy weighs.