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Repairing Twin Stick overdrive

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farna View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jun/12/2019 at 6:57am
Yes. There are two shift arms on the transmission for the three speed, then ANOTHER short shift arm further back on the OD unit itself. It's shorter than the three speed shift arms and may be harder to see, but it should move. As TomJ pointed out, they used a big solid wire cable, sort of like a thick choke cable. It's common for them to rust and seize then break. Remember, they are over 50 years old. Not surprising to break a cable that's been under a car for 20 years, let alone 50!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote al1630 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/12/2019 at 3:39pm

So, here's my transmission. The red circle shows the levers for the 3 speed, correct? Is the lever in the blue circle with nothing attached to it the overdrive lever? Moving the OD stick back and forth, nothing moves under the car.
1963 Rambler American 440H
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2019 at 12:16am
hard to see from your small photo, but yeah.

the R10 OD unit lever is short and precise. it rotates if i recall 90 degrees. it only moves a little lever that pushes an internal rod and hence not a lot of effort to move. i recall that it's "all in" right at the end of it's travel. i think it's slightly spring loaded so if you crawl under and manually enable OD you might go voer a bump and have it fall out of OD.

but you could do that -- rotate the lever manually the other direction and drive the car. assuming it's otherwise working, it will freewheel until the governor kicks in (28 mph). but it might be easier to just replace/repair the cable and test that way.

the OD is funny -- i found it immediately easy to understand and drive effectively, but very difficult to explain in words how to use it! if you keep in mind it's a somewhat independent box tacked onto the rear of the transmission, it helps. the relay logic is funny but well done.

i love my T5 and will never go back to that craptacular T96 -- but i really enjoyed, loved really, the 3-speed with overdrive. it's a different way of driving. it's NOT MODERN. lots of people stick power steering, tilt wheels, power brakes, AC, foolishness like sound insulation and stereos in their old cars, but i like the raw machine, unmediated by plastic comfort. (i do like my 2004 Scion xB for the "modern" marvel it is. A/C is ummm nice :-)

a T96 with R10 overdrive is more or less an anti-theft device. once i had a fancy restaurant valet brag they'd driven every kind of car there is, and they got totally fouled up and stalled the little American with it's one-finger one-inch clutch and too many shift levers.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2019 at 5:22am
Like TomJ says, hard to tell, but....
To me it looks like the blue circle is around the shifter itself. You had said the linkage rods were removed. Looks to me like the lever without a rod is the 2-3 shift lever on the shifter with no rod attached. The 1-R lever (to the passenger side) looks like it might have the shift rod attached to it. The OD lever on the Twin-Stick is very short under the car and will be to the inside (passenger side) of the shifter. The lever comes about to the bottom of the shifter bracket. The factory shifter mounts to the floor of the car, not to the transmission itself. If you have both sticks it's not likely and aftermarket shifter though, no one makes one with two sticks.

It's possible that it's locked out now. Easy to check! Accelerate then let off the gas. Does the car slow down like you would expect it to do -- the engine slows the car? Then the OD is locked out. If the car isn't running, see if you can rotate the rear wheels while the car is in gear. If you can't OD is locked out. You may have to hold one rear tire still and rotate the other to get the driveshaft to turn since it's likely an open differential and not a Twin-Grip (limited slip or "posi" unit). The OD unit has a free-wheeling clutch that won't hold the car back when you take your foot off the gas. This is to prevent the OD from over revving the engine going down a hill. If you need engine braking (like driving on steep mountain back roads or towing heavy loads) you lock OD out. That limits top speed also, but in those conditions you're not likely to be going very fast, and you can engage OD if you need to.

If the OD unit is "blown" you won't get free-wheeling with the lever in either position. When not shifted properly (usually when the solenoid is straight wired to power rather than through the OD relay and other controls) a strain can be put on the planetary gears. One of the shafts eventually breaks and that planetary jams inside the drum gear attached to the output shaft. Since the car is under power when this happens it jams in tight. The good news is you're not stranded, the bad news is the only way to fix it is to replace the planetary gear set AND the drum gear/output shaft. Those are hard to find as replacement parts, so you end up getting another OD unit for parts. The planetary set from ANY Borg Warner OD unit will work regardless of make. The output shaft interchanges on most, but there could be a spline difference. AFAIK all the units were bought from BW and the output shafts are the same as long as it's an R-10 unit. There is an R-11 that was used behind V-8s. It has a heavier duty planetary set (four gears instead of three). I don't know if the drum gear/output shaft is the same as the R-10 or larger on the R-11 V-8 unit.

Once you determine if your OD unit is working or blown we'll get to the controls. Most of the time the issue is dirty contacts in the various controls or loose/missing wires. Easy enough to clean contacts and connections and reattach wires. Sometimes one of the control switches are bad enough to need replacing... that can be a problem, but there are usually work arounds or modern replacements. We'll get to that as needed...


Edited by farna - Jun/13/2019 at 5:41am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote al1630 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2019 at 9:13pm
If I drive the car with the lever in the position it's in in the photo, the car shifts through all the gears normally, but if I move it 90 degrees as suggested, driving in 1st and 3rd is fine, but in 2nd, if you let off the throttle, the car acts like it's stumbling. The relay and solenoid also don't make a click noise like the manual says they should.

Looking at the bottom of the OD stick from under the car, the cable is completely missing, not even a part of it is left on there.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jun/13/2019 at 11:06pm
well the lack of a cable *might* affect the lever's ability to engage/disable OD!

the OD relay logic can be hard to diagnose; it's not you. i blew up a muffler once; mashed the go-pedal to close the OD kickdown switch, which shorts the spark coil through the contacts in the solenoid; for whatever reason the solenoid stuck/took too long, the exhaust filled up with air/fuel, solenoid operates spark restored, >KABLAM< blew the end out of a new muffler.

you can test it all without driving if you jumper the governor as i mentioned.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2019 at 12:27pm
Now we're getting somewhere!!

Obviously there are some electrical issues. Since it stumbles when you let off the gas with OD engaged, I bet the relay isn't working. Start with checking the fuse on the relay. The next thing to check is the circuit breaker. I don't know exactly where it's located. Follow the brown wire that connects to the end of the fuse back toward the ignition switch. Not sure if the circuit breaker is on the firewall or under the dash. Will look sort of like a flasher unit but with two screw terminals. Make sure you have power on both terminals with the switch on. One comes from the switch, the other to the OD relay. If power isn't on both the circuit breaker is bad, of course. You should have power on the terminal that connects to the switch. These don't have a fuse panel, individual breakers or fuses in only a few circuits. If no power on either, the wire between the switch and breaker is bad or disconnected. If this all works pull the solenoid out and check it at the battery. Take the two mount bolts out and twist the solenoid counter clockwise, then pull out. Ground the case and touch a hot +12V wire to the terminal marked "4" (had an orange wire on it). The solenoid shaft should push out. Note that the solenoid can work on the bench and not have enough power to operate the OD pawl, but this is a start. Next take the two small nuts off the end of the solenoid. The back of the case will then pull off. You will find a set of contact points inside. Use an emery board or small piece of sandpaper and clean those contacts like you would ignition points. Those are used in the kick-down circuit. May as well clean them while you have the solenoid out. Take the rubber boot off the governor and take the top off of it. Another set of contact points that need to be cleaned! Replace the top after cleaning and making sure the spring on the points is working. Replace the solenoid and check operation again. All the switches and relays have contact points that can corrode over time. You might be able to pry the cases off the OD light relay and the OD relay and clean the points. I don't think you can do that to the vacuum switch. The vac switch is normally open, closes with engine running. Should be easy enough to find a generic replacement. https://www.summitracing.com/parts/sww-77343-04/overview/

PM me an e-mail address and I'll send you the TS wiring diagram and the page from the 63 American TSM with the electrical checks. That is if you don't have a TSM. If you do the info is on page 12 and 13 in the Overdrive section.

You CAN "straight wire" the solenoid to check OD operation. Just run a wire from the battery to a toggle switch under the dash, then to the solenoid. Run up to 2nd gear, flip the switch, then let off the gas. It should shift into OD. Now here is the DANGER of doing it this way!! To kick-down out of OD you MUST use the clutch! Press in clutch then flip off switch, wait half a second or so, then let out clutch. You should be back in 2nd gear. If you don't use the clutch to unload the trans (from engine power) you can blow the OD unit as I've mentioned before. The kick-down circuit unloads the trans by grounding out the coil for a half second or so, more or less turning the engine off then back on quickly.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote al1630 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2019 at 4:52pm
I followed the instructions in my TSM to test the relay and those seemed to show that the relay and solenoid are working. There is also voltage on both sides of the fuse and circuit breaker. I also cleaned up the points in the governor, although they weren't very dirty. Do the on the car tests mean the solenoid is OK, or should I still pull it out? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote al1630 Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2019 at 10:43pm
Ok, overdrive seems to be working now. I took the car out on the highway this evening and got it up to about 45mph. If I let off the gas, there was a shifting sound and the engine was quieter when I got back on the throttle. The kickdown button seemed to work as well, and the car shifted out of OD when I pushed it. Now I need to replace the cable from the stick to the lockout lever on the OD unit. How is it attached and routed down there?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jun/14/2019 at 11:22pm
i bet the  ignition-coil-contacts inside the big solenoid scraped clean and are now working. if they get wacky again ('dead spot' in 2nd etc) you can disconnect the wire to the coil -- then to engage OD, you'd push the button and simply let your foot off the throttle for a second (if conditions are right you can hear it >KLUNK< into OD).

if it was just a dirty electrical contact it could very well just start working.

enjoy your overdrive!


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