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Old 04-19-2020, 10:32 AM   #1
mrlaser
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Default 1951 Ford overdrive

I have a question re: the Borg Warner OD. I recently read this (paraphrased) post on another forum:

If your OD is not working electrically just mechanically, with the cable pushed in to activate the OD, the transmission will be freewheeling when you take your foot off of the accelerator. The engine will return to idle even if you are still moving at a normal highway speed . When you again depress the accelerator, the engine RPM's will "catch up" and again power the car. In other words, the OD may not actually go into OD with the planetary gears powering another gear, but simply allowing the transmission to freewheel.

Again, I am paraphrasing the original post, but if this is accurate, how would you test the system, assuming that all the correct electrical and mechanical connections have been made? In this case, all the components are new or NOS and the transmission was professionally rebuilt.

When driving, this seems to be the situation that I am experiencing. When the accelerator is firmly depressed there is no apparent return to the lower gear. On the other hand when cruising at 40-45 MPH with the accelerator depressed,the engine sounds like it is operating at a lower RPM than when the cable is not the OD ("on") operative position. I have never driven a car with this system and recognize my ignorance on this subject. Any advice would be appreciated. Thanks in advance.
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Old 04-19-2020, 11:00 AM   #2
rotorwrench
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Default Re: 1951 Ford overdrive

It's an electrically operated system so it needs to have functional switches, relay, and solenoid for it all to work properly. When the cable is pulled out, the lockout rail effectively moves the sun gear out of mesh an blocks the operating solenoid pawl that does the shifting of the OD planetary. In other words it works pretty much like any manual 3-speed when locked out. When you shift the car into reverse whether the cable is pulled or not, there is a mechanical mechanism in the reverse shift that pushes the lock out rail so that is will always be locked out in reverse.

The firewall mounted relay is the control relay that turns the operating solenoid on & off. The free wheeling clutch has to be there for the overdrive to shift so it has to be fully functional when the unit is locked in with the cable pushed all the way in. The governor on the tail housing has a simple switch to turn the system on when it reaches on speed around 23 MPH.

Ford recommended using the OD as a semi automatic transmission when driving around town. You just leave the car in second gear and only use the clutch when you stop. Starting in second is possible when the car is not loaded too heavily. This way a person can drive away from the stop and let up on the throttle above 23 MPH and it will shift into overdrive. It's basically operating as a 2-speed transmission with a clutch. Whether this works or not depends on the speed limits where the car is operated and is not necessarily the best way to operate it if conditions don't match up well with those speeds.

There are a lot of tests that can be done on the system if something isn't functioning as it should. I would recommend getting the shop manual for the type car you have. there should be a full section of the overdrive system that includes the test procedures. Jumper leads and a test light is all that is required to perform most tests.

The operating solenoid only has two terminals on it but they both perform different functions. Grounding is provided by the drive train to battery ground connection. One terminal is an ignition coil kill circuit for the downshift function and the other is to function the operating solenoid to shift the transmission into and out of overdrive.

There are other threads on here that have wiring diagrams or you can find them on line. If the system is going into overdrive then the kick down switch under the throttle pedal has to be depressed all the way to get it to downshift out of OD. It will also drop out of overdrive when the speed of the vehicle drops below the ON Speed of the governor. It should be out of overdrive any time you come to a complete stop. When it shifts in, you will notice the drop in rpm. If you don't feel it going into overdrive planetary gear then it isn't working correctly. The kick down switch, governor switch, and relay all have to be working. Some of the older units also have a rail switch in line with the governor switch control that can give problems. Later models eliminated that switch as redundant. It can be bypassed if it's not working properly.

Last edited by rotorwrench; 04-19-2020 at 11:19 AM.
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Old 04-19-2020, 11:23 AM   #3
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Default Re: 1951 Ford overdrive

Simply put, if the transmission is "freewheeling" above 30 mph with the handle pushed in, it is not in overdrive.
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Old 04-19-2020, 12:55 PM   #4
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Default Re: 1951 Ford overdrive

The way I always check is to accelerate up to ~40 mph or so, and by this time will be in 3rd. Let up on the gas pedal, you should feel the car go into a higher gear (lower RPM, less acceleration response when you hit the gas) as long as the OD is not locked out. Then, if you kickdown by stomping on the pedal, you should feel the opposite when the car goes back to normal 3rd (lower gear: increased revs, increased acceleration response)
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Old 04-19-2020, 11:46 PM   #5
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Default Re: 1951 Ford overdrive

First I want to clarify the purpose of that handle labeled "overdrive". It does NOT "turn on" the overdrive when pushed in! It just allows the overdrive to operate as designed when pushed in (its normal position). All overdrive functions are electrically operated only. This cable is properly called the "lockout cable". Its main function is to provide more engine braking on a downhill grade. It essentially turns an overdrive trans into a standard three speed trans when pulled out, as mentioned in an earlier post. Any early '50's to mid '60's MOTORS or Chilton's etc. manual will have a wiring diagram and troubleshooting instructions.
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Old 04-19-2020, 11:53 PM   #6
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Default Re: 1951 Ford overdrive

The 3 on the tree manual with OD will free wheel by design. Put your e brake on when parked on a hill. Always ran mine on the 53 around town with the od off/out. Great transmission. Everything well, it cruises 70mph all day long with low rpms to the engine on the hwy, engaged.

RotorWrench post is very informative.


.

Last edited by Tinker; 04-20-2020 at 12:11 AM.
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Old 04-20-2020, 07:46 AM   #7
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Default Re: 1951 Ford overdrive

When you get past 30, let up on the accelerator and listen for a thunk, what it sounds like to me, that will be the OD shifting in. Sometimes it is easier for me to hear it in second. Someone wrote earlier about driving around in 2nd OD. While that is possible it is not recommended. OD cars came with a 4.11 ratio so being a little lower you could start off in 2nd and shift to third without the clutch, and then let up on the gas to shift to OD. Depress the gas to shift out of overdrive, let up to shift in again.
If it is just not shifting out then your switch may not be addjusted properly or the grounding circuit is not working. The points need to be shorted to remove power from the input shaft to let the solenoid drop out.
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Old 04-20-2020, 08:57 AM   #8
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Default Re: 1951 Ford overdrive

Thanks so much for all of your input. I suspect that there is an electrical or a component issue. I have the wiring diagram and the wiring harness is color coded the same as those described in the factory manual. Would anyone have a specific online reference for a proper trouble shooting procedure? Unfortunately my reference library is rather limited. Thanks again.
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Old 04-20-2020, 09:26 AM   #9
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Default Re: 1951 Ford overdrive

I answered my own question. This is a fantastic article with a complete troubleshooting guide.

https://fifthaveinternetgarage.blogs...verdrives.html
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Old 04-20-2020, 10:18 AM   #10
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Default Re: 1951 Ford overdrive

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Last edited by Black Fifty; 04-20-2020 at 10:21 AM. Reason: info already posted
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Old 04-23-2020, 07:47 AM   #11
mrlaser
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Default Re: 1951 Ford overdrive

After doing some of the testing outlined in the above mentioned article, it appears that the solenoid is not functioning. When battery voltage is applied to the #4 terminal and the a ground is applied to the case, the expected (hoped for ) "clunk " does not occur. My question is,until I have a working solenoid, is there any concern about driving with the OD cable pushed in and the transmission continuing to freewheel? The car is actually more pleasant to drive when the engine's RPM's are allowed to drop when not accelerating. The gearing with the OD rear end is such that the RPM at 45-50 make the engine sound like it needs that other gear included in the Borg Warner OD. On the other hand, I don't want to do any harm to the transmission by keeping the mechanical part of the OD setup in use if it is not advisable. Thank you for any advice that may be offered.
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Old 04-23-2020, 11:46 AM   #12
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Default Re: 1951 Ford overdrive

Quote:
Originally Posted by mrlaser View Post
After doing some of the testing outlined in the above mentioned article, it appears that the solenoid is not functioning. When battery voltage is applied to the #4 terminal and the a ground is applied to the case, the expected (hoped for ) "clunk " does not occur. My question is,until I have a working solenoid, is there any concern about driving with the OD cable pushed in and the transmission continuing to freewheel? The car is actually more pleasant to drive when the engine's RPM's are allowed to drop when not accelerating. The gearing with the OD rear end is such that the RPM at 45-50 make the engine sound like it needs that other gear included in the Borg Warner OD. On the other hand, I don't want to do any harm to the transmission by keeping the mechanical part of the OD setup in use if it is not advisable. Thank you for any advice that may be offered.
You won't hurt the trans but your brakes will take a beating because you won't have any engine braking. Do a back-to-back test; first with lockout cable pulled out, then with it pushed in and see the difference.
Have you checked the glass fuse on the relay? They can look good through the glass but can be broken at the end behind the metal cap. Use an ohm meter or test light to check.
Check the solenoid with an ohm meter also. An open circuit will show infinity. Remember to check between the heavier wire and the case.
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Old 04-23-2020, 12:39 PM   #13
mrlaser
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Default Re: 1951 Ford overdrive

Thanks for all the suggestions.

I did check the fuse ( separately) and also found battery voltage before and after the fuse on the relay with the ignition in the "on" position. If I remove the solenoid for bench testing and it is not working, will I be able to reinstall it until I get a replacement? I watched a YouTube video showing the instillation of the solenoid which indicated that the plunger needed to be extended (using battery activation) when installing it. I would like to be able to continue driving a bit while waiting for a replacement. The speed limits here in my neighborhood vary from 25 mph to 45 mph and the braking system is new. I'm hoping that bit of driving won't be too hard on the brakes. Thank you all again.
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Old 05-14-2020, 03:27 PM   #14
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Default Re: 1951 Ford overdrive

I have the original R10 BW overdrive which was installed at the time of the factory build. As noted in the above posts, I have been unable to engage the overdrive in spite of now adding a new solenoid, new relay, new wiring harness , and new kick down switch. The governor is nos and was installed during a professional transmission rebuild. With the OD cable pushed in, the transmission freewheels normally. When 30 mph is reached and the gas pedal is momentarily released, no shift into OD takes place. In Randy Rundle's Overdrive Manual, the governor is tested by removing its cover, separating the points ,and grounding the cover. Unfortunately, on my car there is insufficient floor pan clearance to be able to remove the cover screws to accomplish this test. BTW, with the key on, both the relay and the solenoid click simultaneously when the TH terminal on the relay is grounded. I have ordered a proper sized wrench to remove the governor should that be necessary. I would appreciate any other suggestions for an alternative means of testing the governor without the necessity of removing it. Also, does anyone know what type of nylon (??) gear is attaches to the governor"s shaft? Thanks in advance for any suggestions.
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Old 04-23-2020, 08:44 AM   #15
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Default Re: 1951 Ford overdrive

If the solenoid is non functional, a person still needs to make sure the firewall relay and the switches are working too even if the operating solenoid it bad. It's easy to remove the solenoid and do further inspection and testing on the bench. Most of the electrics were placed in a swampy area so they deteriorate faster due to that. Sometimes they just need a bit of TLC to restore function but a person won't know until they tinker with them a bit.
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Old 04-23-2020, 09:50 AM   #16
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Default Re: 1951 Ford overdrive

It won't hurt the transmission to drive with the handle pushed in. Keep both sections of the transmission filled with oil and park with the transmission in reverse, as it will roll forward in any other gear.
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Old 04-23-2020, 10:10 AM   #17
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Default Re: 1951 Ford overdrive

Mr Laser

A caution in testing the selonid. On the bench use the voltage from the vehicle battery or a heavy duty charger. 6 volt lantern batteries or 3/4 amp chargers don’t provide sufficient current to operate the selonid, causing false test results.

The selonid is usually not the cause of OD trouble.

Hope this helps,

Tom
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Old 05-14-2020, 05:54 PM   #18
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Default Re: 1951 Ford overdrive

The governor is the last permissive in the circuit. The kickdoen switch is the first and only on a 51. If you unplug the wire from the governor and ground it with the key on you should hear the relay and the solenoid click. If you do not then I would investigate the kickdown switch. Make sure you have the kickdown switch wired correctly. The upper most terminal should connect the governor to the relay.
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Old 05-14-2020, 06:57 PM   #19
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Default Re: 1951 Ford overdrive

Grounding the wire will check the wire but not the points in the governor switch. Unscrew the governor and pull it out so you can check the points on the bench. If they open and close and have continuity when closed then the governor switch is OK. The flyweights should be secure and move easily. The gear should be metal. The governor shaft is held in the gear by a spring ring. Gear lash may be visible from the speedo gear side. If it has the wrong gear then there would be a problem. These governors were used on a lot of different cars and some had different gears depending on the transmission they were set up for.
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Old 05-15-2020, 06:16 AM   #20
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Default Re: 1951 Ford overdrive

Thanks for the replies. I do now have a properly sized wrench and will remove the governor for testing. I also will recheck the kick down switch for proper wire placement.
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