Underdrive question-no don't want to run it backwards
Posted: September 20th, 2018, 6:55 am
I am building a speedster/rat rod type of thing using as many tractor parts as possible. The transmission is a three speed model A and the rear end is also model A car. In my first test drive, I had a problem I never planned on, it is too fast in low gear. I need to be able to putt around at shows at five miles per hour or so, but it wants to run about twice that.
I seem to have two choices, replace the three speed with a four from an AA or add an underdrive.
Adding the four speed provides a new set of problems. I am not using the A bell housing so I can't switch it to the shallower AA one. I would also have to change the adapter plate I have now because a three speed bolts on with four bolts and a 4 speed with six. If I bolted it to where the three speed is now, I'd have to shorten the drive train by 3 inches.
My other choice would be to add an underdrive, it should bolt to the back of the three speed without problem, but again the drive shaft would have to be shortened. If I found someone to graft the underdrive into the drive shaft and torque tube, would it be a problem for it to run at an angle?
P.S. Installing 4.11 gears in the rear end wouldn't slow it down enough.
I seem to have two choices, replace the three speed with a four from an AA or add an underdrive.
Adding the four speed provides a new set of problems. I am not using the A bell housing so I can't switch it to the shallower AA one. I would also have to change the adapter plate I have now because a three speed bolts on with four bolts and a 4 speed with six. If I bolted it to where the three speed is now, I'd have to shorten the drive train by 3 inches.
My other choice would be to add an underdrive, it should bolt to the back of the three speed without problem, but again the drive shaft would have to be shortened. If I found someone to graft the underdrive into the drive shaft and torque tube, would it be a problem for it to run at an angle?
P.S. Installing 4.11 gears in the rear end wouldn't slow it down enough.