Re: 1938 Super 8 1605 - adventures with a newbie

Posted by HH56 On 2023/9/6 22:31:00

No idea what type OD was installed since 38 never had one and having a Super eight, it may even be an aftermarket unit. In 39 they offered the R6 which is called a semi automatic unit and is controlled by a centrifugal clutch which put the unit into OD when the clutch automatically engages it at a certain speed. Electric portion was mainly used to kick it out of OD if you wanted a burst of power. 40 on had full electric units and most trans and ODs thru 50 can be installed on the earlier regular engine cars.

On the speedo issue, cars with an OD unit typically had a different rear axle and speedometer drive gear had a tooth count correct for that axle. If they just added an OD and kept the original axle it sounds like the gear may be the wrong one for the axle in the car.

If it has an indicator light it may have been a typical Borg-Warmer R9 unit which Packard used from 40 to mid 48. When the knob is pulled out OD is completely locked out. When knob is pushed all the way in then it is mechanically and electrically able to have OD engage when the car reaches a speed of around 20 mph and governor enables the electric side to prepare the solenoid for engagement. In the R9 with indicator light, at speed the light comes on as a signal you can go into OD at any time. By releasing your foot from the accelerator briefly to lower engine torque and car speed a tiny bit, things move in the OD unit and the solenoid can finish moving the plunger in to place the unit in OD. As soon as the solenoid is fully engaged and unit is in OD the light will go out.

Once in OD, to kick down accelerator is pushed all the way to floor, kickdown occurs and car drops into conventional gear. You can then pass a car at full power or if OD is no longer wanted, pull the knob out to lock out OD. If just passing a car, as long as car is still moving above speed it will go back into OD when you let your foot off accelerator again.