Would you clarify the overdrive operation in my Studebaker and give me some help with the wiring?
Those overdrive units are good but need some getting used to. Many folks are unfamiliar with how they are supposed to work, so diagnosis becomes difficult. Hereís a review. With the overdrive cable pulled out, away from the dash, overdrive is blocked out and will not function. The vehicle will operate exactly as if it has a straight three speed transmission without overdrive. But with the overdrive cable pushed in against the dash bracket, overdrive is available to function. You can push the cable in anytime the truck is either stopped or moving. But you can pull the cable out only when you are stopped or when the engine is pulling the vehicle in direct drive. The governor will not permit overdrive to engage until you get up around 30mph. At that time, the governor closes the ground circuit and allows the solenoid to be energized, engaging overdrive when you let up on the gas momentarily to release the engineís pull on the drive shaft. When you start from a stop with the cable in, it will freewheel as youíve noticed- until the overdrive engages, which happens when you let up on the accelerator momentarily. Or, it will freewheel if the governor cut-in speed has not yet been reached. It will stay in overdrive until you slow down to where the governor interrupts the circuit, or if you press the accelerator all the way to the floor to drop it out of overdrive and return to direct drive. When you floor the accelerator, the kick down switch on the linkage interrupts the circuit momentarily. That allows the overdrive to shift back to direct until you let up on the pedal. This feature allows more speed when you need to pass or climb a grade. When you want to use engine braking to slow the vehicle, first push the accelerator down to kick down. When the transmission drops back to direct drive, immediately pull the cable out. Then you can let up on the accelerator and you will be in direct drive with overdrive locked out no matter what you do.. .because the overdrive handle has been pulled out, disabling overdrive capability. You have to be quick about it, but I have been doing that ever since I started driving Studebaker's over 50 years ago. (I showed my 20 year old grandson how to work it and he thought it was pretty neat, like an automatic fourth gear. In fact, thatís exactly what it is.) Another thing: The shop manual recommends using 40-weight, non-detergent motor oil or 90-weight GL1 mineral oil. If you use EP oil (oil with Extreme Pressure additives), the sprag and synchronize-rs will slip or will not shift as smoothly. Hope this helps. Have fun with that truck: I have a Ď57 1/2 ton that Iíve enjoyed over 33 years and nearly 300,000 miles!
The next 8 pages give you a way to
rebuild the overdrive relay for a car or truck with Borg Warner
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listed Click this
for the web page look under transmission
1936 - 1955 http://www.raylinrestoration.com/TechnicalPages/Overdrive/EarlyOverdrives.htm
1956 - 1963 http://www.raylinrestoration.com/TechnicalPages/Overdrive/Overdrive.htm
This is another way to wire the
overdrive to give you manual control with switches and not just
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In older overdrives there will be a lockout switch in series with the governor switch so if the overdrive cable is pulled out the overdrive solenoid will not be energized. The end have fun with the information.