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Borg Warner R-10 / R-11 Tech Tips


Borg Warner Overdrive Tech Tips

The Borg Warner Overdrive R-10 / R-11 electrical overdrive was first introduced in 1940. Prior to the R-10 / R-11 overdrive there was the R-9 overdrive which was a part mechanical part electric overdrive. In this discussion all of the information I give you here is for the R-10 / R-11 overdrive models. I will explain the difference in the two models in this pay attention.   

The Borg Warner overdrive would become an option for 22 different makes and models. Ford was the last to offer the Borg Warner overdrive in 1972 as an option for the Ford F-150 pickup. Ford was also the last one to offer it as an option in a car for the 1967 model year. Studebaker sold the most overdrives options. There were over four million Borg Warner overdrive transmissions sold between their introduction and the last ones sold by Ford in 1972. 

1) Their were 11 different wiring diagrams for the Borg Warner overdrive transmission BESIDES the simple one I provide to you in my overdrive book and in the instructions that are included with the overdrive parts you buy from me. I believe simple is good so that is why I include the original Borg Warner wiring instructions. They are the simplest and least complicated to understand. 

2) The Difference.  The R-10 and the R-11 overdrive models are exactly the same with one exception, the difference is the number of gears inside of the sun gear. An R-10 had three gears while the R-11 had four. The R-11 was used on heavier cars, most typically Packard's and in later years, in higher horsepower V8 applications. The R-10 is by far the most common  and will be plenty strong enough for most antique vehicle applications.

3) Model Identification You can look on the transmission housing next to where the solenoid goes into the transmission and there will be some raised casting numbers cast into the housing. It will say R-10 followed by the transmission identification number which also tells you the application of the transmission. If your transmission is an R-11 it will say R-11 followed by the identification numbers of the transmission. 

4) All of the electrical...Relay, Solenoid, Kick down switch, and most all of the internal parts will interchange between the transmissions. In other words a Ford solenoid and a Studebaker solenoid will interchange with a Willy's or a Hudson. Keep that in mind when you go to the next swap meet.

5) Solenoid Shaft Lengths...MOST but not all shaft lengths of overdrive solenoids measure about one inch in length, if you lay a ruler on top of the shaft and slide it back to the housing of the solenoid. There are a few exceptions...most notably station wagons and convertibles of which some had an inch and a half long shaft due to an extra cross member being present on the frame. Also some Chevrolet pickups from the mid to late 1960's had a two inch long shaft. There were only about 1500 of those made which is good and bad. Good because your odds of ending up with one is slim. Bad because if you end up with one you odds of finding another is not good.

6) Things that wear the most. The two most common things that wear out on a Borg Warner overdrive transmission are the Relay and the Solenoid, which makes sense as they are used the most. A 6-volt and a 12-volt solenoid and relay will not interchange so you need to buy the one that matches you electrical system voltage. Kick down switches are the next most common wear item and they WILL work on either 6-volts or 12-volts. Governors seldom go bad and seldom need replacing, and will work on either 6-volt or 12-volt applications. 

7) Solenoid wiring terminals...with the solenoid in your hand with the shaft facing out in front of you...the right hand terminal is number four and connects to the relay. The left hand terminal connects to the kick down switch. A small amount of solenoids had a third wire that was a ground if yours is one of those check your shop manual and it will confirm where the third wire goes. Finally...most solenoids had screw in terminals, a few had internal connections with wires coming out of the solenoid. Wiring connections for both are the same.

8) There were two solenoid manufacturing companies, besides Borg Warner, both Autolite and Delco manufactured solenoids. All will interchange and as long as the shaft length matches yours and the operating voltage is the same.

9) Checking Solenoids...The best way to test a solenoid is to apply battery power directly to the number four terminal and ground the case. As soon as you touch the case with the ground, the solenoid shaft should snap out. You can do this while the solenoid is in the vehicle OR while on the bench. Either way should make the solenoid work.

10) Solenoid Installation...This is the most important tech tip of all so play close attention! The first thing you need to do is replace the seal in the transmission housing. That way you won't have any transmission oil leaking into the solenoid and ruining the solenoid.

When you get ready to install the solenoid the first thing you want to do is line up the solenoid shaft so the flat spot is at the 12 o'clock position. Next apply battery power to the number (4) terminal on the solenoid. Then ground the case of the solenoid which will make the solenoid shaft extend out. Now carefully slide the solenoid shaft past the seal  (a little white grease or Vaseline in the center of the seal and on the end of the solenoid shaft works wonders) until the shaft engages into the pawl in the transmission. Once it is engaged turn the solenoid to secure the pawl into the grove of the solenoid. Release the ground and the solenoid shaft should retract... and if you got the pawl into the groove at the end of the solenoid shaft correctly the solenoid itself will be pulled towards the transmission. If you always install your solenoid this way you can be 100 percent sure the solenoid is installed correctly. Line up your bolt holes and you are done.

This method also works if the flat spot on the solenoid shaft is clocked at a different location than the original. The rule is you always want the flat spot on the shaft to be at 
12 'clock position when you insert the shaft into the transmission. Once the pawl is in the groove rotate the solenoid as necessary to line up the mounting holes.

11) Overdrive Lockout Cable. Remember when the cable is pushed in towards the dash, the car will go into overdrive at about 33 mph. If the cable is pulled all the way out away from the dash, the overdrive is "locked out" and the transmission will not go into overdrive at 33 mph. If you are having trouble with overdrive engagement check the cable at the transmission to be sure the shift lever is being moved all the way back towards the rear of the transmission. Kinks in the cable can reduce the travel at the transmission shift lever causing the transmission to not engage properly.

12) Don't Cheat !! It is tempting to connect the solenoid to a toggle switch and by-pass the relay, governor, and kick down switch. If you do that you have to remember to NEVER start out in first gear or reverse in overdrive or you will crush all of the needle bearings in the sun gear. That will be really expensive. You will know when you do it because of the sound it makes but by then it is too late. You are looking at a $400 to $600 repair bill if you can find the parts which will have to come from another overdrive transmission because there are no new parts available.

I have had dozens of customers over the years say "I can remember" or "I put a light on the dash..." or any other of a dozen excuses. Eventually they all forget and have the repair bill to prove it!

14) What About Gear Oil?  You want to use GL-1 gear oil in your overdrive transmission and in the front transmission. When you buy a gallon of gear oil you will have about a pint left over after you fill both transmissions. depending on how much you spill on the floor filling the transmission. There is a passageway between the two transmissions but you must fill BOTH transmissions. Do not use tractor oil or any GL rated oil higher than GL-1 as the detergents in the modern gear oils will attack the bronze bushings and parts in the overdrive. And most important of all DO NOT use synthetic gear oil. It is two slippery and the sun gear will not engage. You will have to disassemble the transmission and get all of the synthetic residue off of the internal parts. That is not a fun task!

If you want to learn more about the Borg Warner Overdrive order my Overdrive Book available in the "parts" section of the website. It will be money well spent.

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Since 1987, Fifth Avenue owner, Randy Rundle, has been making antique, classic and special interest vehicles more reliable and fun to drive.