Overdrive Question

[51FrazerManhattan]

I'm new to KF cars and am a bit confused about how to use the overdrive on my car.  I heard that I should only move the overdrive shifter when I am stopped, but guys who remember the 50's say they used it as a regular shifter on their Fords that had overdrive.  What is the proper way to use it?  I've been leaving it in all the time, and the car just shifts into overdrive on its own and shifts out when I stomp on the accelerator, but I would like to make sure I'm using it the correct way.  This question seems so basic that I'm almost embarrassed to ask, but I don't want to tear it up or something. 

Thank you.

[dpledger]

According to the 51 Kaiser owner's manual, the handle to put it in or out of overdrive should be moved one way or the other only when the car is stopped. It can be left either way and will function accordingly. If the handle is in, it will automatically engage overdrive at speeds over 30mph, and disengage when speed drops below 24. One can disengage when more power is required by stomping the pedal to the floor.  So it appears that you are operating correctly. Wouldn't try moving the handle with the car in motion under any circums.

[StillOutThere]

Overdrive should always be disengaged from a standing start (in first gear).  This is an engineering matter of avoiding the initial torque multiplication through the overdrive so it is going to give greater longevity to the bearings of the overdrive unit /case).  So if you have been going down the highway in 3rd overdrive, when you stop for a light, pull out the overdrive knob /handle.  Then when you have accelerated up to speed in third gear once again, push in the overdrive.   That is the basic instruction.

While true that the instruction is ALWAYS to get out of overdrive ONLY when stopped, if you plan your accelerations and decelerations mentally a bit with advance anticipation, you are safe to pull out the overdrive at any time you are NOT IN overdrive, such as after kicking down in 3rd gear or in 2nd gear.  Such times might be a downshift to second when entering a interstate onramp or when passing.  At the time you are out of OD and thus the handle can be safely pulled out.   BUT, you had better have some experience to do this because if your timing is off or you take your foot off the gas, the trans wants to revert into overdrive and moving the lever at that time can cause serious mechanical damage.  For the novice, best to just follow the first paragraph above.

 

[Fid]

Another analysis - It is all about when you can push the cable in or pull it out. With the cable pushed in, the overdrive will operate and the car will "freewheel" independent of the engine. In other words, when you are not accelerating, the engine will not drag the car down.  At speeds above 30 mph you can momentarily lift your foot off the accelerator and the car will go into overdrive. The cable can be left in all the time but read on...
The rule I've heard, and practiced is you can push the cable in when the car is moving but do not pull it out when the car is in motion. The owners manual states the cable should not be operated at all when the car is moving but that's mainly cautionary - you can push the cable in when the car is moving but never pull it out when the car is moving.  I've had overdrives apart and worked on them and it's pretty easy to see why you would never want to pull that cable out when the vehicle is in motion.
One last note - when the cable is pushed in (and you can leave it in all the time, I do) the car will freewheel which means even if you leave it in gear it will roll away!  You must put it in reverse when parked or it can roll away.  If your parking brake works well, the manual says you can park the car in a forward gear or neutral as long as you set the brake but I don't trust that 60 year old parking brake and never have! I always park my OD equipped cars in reverse, that's the safest practice.

[51FrazerManhattan]

Thanks for all the helpful explanations.  I'll keep driving it with the handle pushed in all the time. 

[pnw_oldmags]

I need the help of all you Overdrive Experts.  I am publishing the attached article in the upcoming PNW Traveler.  I would appreciate any comments and corrections you can provide before I published in a week or so.  As I have two 53Ks with non-operating overdrives I am obviously not an expert.  But I am going to be testing voltages as soon as I get home.

[Fid]

It is Bob McBride that makes the overdrive harnesses, not Walter. If your car is '51 or later (save for Frazer) you need to send him the plastic plug in order for him to do the harness for you.
Also, I would add that two things happen when you floor the pedal for kick down - it's true what you state that the normally closed contacts on the kickdown switch open and de-energize the  relay/solenoid. But that does not retract the pawl as engine torque keeps it engaged. What also happens when you floor the pedal is it closes the normally open contacts on the kickdown switch which grounds the coil, through another set of contacts inside the solenoid, (dotted line in the wiring diagram) causing a temporary mis-fire. When the engine mis-fires, the torque drops and the pawl is retracted via a spring in the solenoid.

[84RabbitGTI]

My overdrive also refuses to function after twenty years of flawless operation.  I have done many of the tests, my overdrive solenoid works, 6 volts gets to the plug at the overdrive relay and apparently activates it at the proper speed (according to the light click I hear from the firewall at 28-ish mph) and I was able to power the overdrive solenoid (heavy click) through the blue wire at the plug. My question is has anyone had an overdrive relay go out?  Would that cause the fuse to burn out slowly?  And would it figure that a shorting/failing overdrive relay cause an intermittent activation and de-activation of the overdrive circuit without it causing the fuse to immediately burn out?

[Fid]

I have seen the relay cause intermittent operation of the OD. Check for corrosion on the fuse socket (both ends) an make sure there is no rust, green oxidation etc. on those contacts. Also, the contacts  inside the relay can get tarnished as well. If you feel comfortable doing so, remove the cover and check them - clean with carbon tetrachloride or light sand paper.  Either of the two issues I mentioned would result in a symptom where the relay would click but not pass current to the solenoid.  Also, make sure your battery is fully charged. The solenoid takes about 17 amps to pull it in so if the battery is weak at all, the first component to fail will be the overdrive.
Regarding the fuse blowing; Two things will cause a fuse to blow- a short or an overload. You can argue that it's only one as the short causes an overload. The relay itself would not be the cause of the fuse blowing as the relay simply closes a set of contacts to allow current flow through the solenoid. If the fuse is blowing, it's likely the solenoid is causing an overload. There is a set of contacts inside the solenoid which open as it pulls in.


If these contacts are dirty and causing an arc, that can blow the fuse as it would cause an overload. Same method, clean the contacts with light sandpaper.

Another thing, if lube from the transmission gets into the solenoid, it can create suction and cause the armature to pull in slowly meaning it will take longer for those contacts to open. This too can cause the cause the fuse to blow as the contacts being closed too long creates an overload. Make sure the solenoid is clean and free of oil/grease inside where the armature moves.  If it is full of grease (gear lube) you'll want to check the seal on the trans where the solenoid goes into it.

[84RabbitGTI]

I have had the cover off for some time.  The relay seems to work just fine when power is applied to activate it. The resistance is zero in the circuit to the OD Solenoid when the relay is activated, as it should be.  Nothing appears burned, the wires in the soldered areas appear to be intact and fine.  I cleaned the contact points.  Still nothing.   

[pnw_oldmags]

FID - Thanks for the review and feedback on the Overdrive Overview.  Please do check out the re-write with your corrections.

[84RabbitGTI]

Have you got yours working yet, pnw_oldmags?  Mine still is stubbornly refusing to work.  Any idea where I can get a replacement OD relay?

[retired wrench]

  Some of the older cars would run faster in straight high than in overdrive,due to that if you were going to race you would floor the acc. and when the overdrive dropped out you could pull the cable locking out the overdrive. This is ment as an explanation not a reccomendation.

[84RabbitGTI]

So tonight, following the wiring diagram, just to see what would happen, I applied -6 volts from the battery using a jumper cable to the indicated terminal on the OD relay and the starter motor spun.  The starter bendix did not engage, but the motor started to spin.
OH, SWEET THRILL OF VICTORY!!  I have found the problem with my car.  I had the orange wire connected to the wrong side of the starter solenoid.  Now it works properly again.    My photo below shows how to do it WRONG.