Model T Go Kart reverser disc is mounted on the pulley on the right, or the transmission pulley. The whole transmission moves left and right in the photo, to either tighten the belt or loosen and then further press the wheel against the engine wheel for reverse.
The McDonough and Crue Cut Model T GoKarts used a reverser system that was intuitive and simple to use: that is, once you got familiar with the go karts nuances! The basic steps for making the go kart go forward, were the inside lever (on the left hand side) was pushed down and locked into position. This forward movement of the lever arm was intuitive, because it simulates a forward rolling action.
The reverse action used the same lever, but was pulled up and back. When you pulled up and back you could semi engage the reverse so that it was not always on.
All these lever movements however did something in the belt transmission to engage the motor to move the gokart either forward or backwards.
In this article, we are primarily concerned about the reverse action.
When the lever was pulled up, the arm was connected to a shaft with a crank linkage that was connected to the transmission. The transmission is unique in that it pivots about the rear axle and this movement can be used to lengthen the space between the engine and the transmission, thus tightening the belt for forward movement, or the space can be reduced so that the transmission is brought closer to the engine. This is the action that makes reverse occur.
Reverser Action: Shaft on far left turns CW moving the intermediate linkage in the opposite direction. This pushes the whole transmission assembly in the clockwise -leveraged motion – towards the engine.
Transmission linkage: the far left shaft (under the seat) is activated by the hand lever (behind you in the picture). When the shaft is rotated down (CCW) the transmission is made to pull away from the engine. There is an over-center action on the secondary shaft-coupler (middle) that tends to lock the motor engagement in to position. The bent linkage has a purpose in that locking action, and is also that shape to facilitate proper movement. The spring on the link (link 1) is designed for the over center action.
The transmission has a pulley and a reverser disc mounted to it. The pulley is closest to the transmission housing, and the reverser disc is simply mounted on the outside of the pulley. It is important from a design standpoint that the reverser disc was larger, otherwise it would not work, as you’ll see in a minute.
When the handle is pulled up on the clutch arm, the transmission is brought closer to the engine so that the reverser disc is wedged between the V on the second pulley on the engine. This action is causing the pulley and the disc to rub against each other, thus forming a sort of gear (with no teeth) clutch rubbing arraignment. The disc will rotate in the opposite direction of that of the engine and thus make the go kart go backwards.
NOTE: The Model T Go Karts have a peculiar engine rotation to gokart movement relationship. The engine goes the opposite direction from that of the go kart. In other-words, the engine goes backwards, or reverse to that of the wheel rotation. The reason for this is that the transmission has a reversing set up in it to make the engine and wheel rotation opposite. I am guessing there is good reason for this design, and it primarily is for packaging reasons. It could be related to the engine exhaust locations, and carb locations when the initial design was put together. (If you have any information on this subject, by all means let me know and I will update the post). It is just sufficient to know that the engine rotates opposite the go kart direction. This is key to understanding the clutch, transmission, reverser system and when adding a totally new motor. When adding a new motor, it may not be able to use the reverser system as initially designed because of size constraints on the engine and frame interface.
The initial design of the reverser disc used a brake pad material. A brake disc can be developed and machined into the same profile as the original disc, however newer and different materials have been introduced that work just as well.
We supply different types of parts for the Original McDonough and Crew Cut Model T GoKarts at our Model T Go Kart Parts store. To purchase the Reverser disc go to the following page:
