This article was written, researched, and documented by Mark 108VanGuy. Enjoy!

This thread covers the Freaky OverDrive (OD) install on his sweet 66 Display and some general OD information. I have been running this same OD in my daily driver, the 69 WedgieVan, for a couple years or so. I made some improvements on this install over the OD in the 69. FreakyTikiTV (Bill) got hooked on these ODs after driving the WedgieVan with me to Branson in 2017. He wanted one for his van so last year Freaky bought a 3 speed SM318 with the R10Q overdrive on ebay. It was just like mine and cost about $1,000 plus shipping.

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The SM 318 shown above is the typical 3 speed manual transmission that is very common in our vans. This one has no rings on the input shaft indicating the higher ratio (lower numerically) for 1st and 2nd gear. One like this but without the OD was the most common option for our later 1st gen and most 2nd gen vans.

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The front half is the regular 3 speed transmission and the rear part is the OD.

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When it arrived, we noticed a cracked input shaft bearing retainer.These bearing retainers are readily available but do come in several sizes. I advise avoiding the off shore manufactured units. IMO, itís best to stick with the OE type. Search by the GM part # cast into it.

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The off-shore manufactured units wonít have the GM #.With the bearing retainer removed, you can check the condition of the input shaft bearing. These looked ok so we scraped the old gasket, installed a new one and applied sealer. Four bolts and done.

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The seven bolts on the side cover were removed so we could take a look inside. All looked well so anew gasket was installed and then button that up also.

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We tested the solenoid by applying 12 volts as shown. Scratch the surface hard just to be sure. If it works, itíll make a satisfying click. That saved him ~$350. for a new solenoid.

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If you buy a loose solenoid, make sure itís the right one and it has been tested.Notice the R10Q designation.

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The shaft length can vary. Other models look similar but will not work.

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After that initial check, the Freaky OD pretty much just sat around all this time until we decided this spring to get this project in gear. Bill trailered the FreakyVan to Sacramento and we were off and running. This month we completed the install in his sweet 66 display

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The OD unit that works well for our vans has a casting that includes ďR10Q-1. It takes the place of the extension housing found on non-OD transmissions. When the R10Q is installed on the SM318, the overall length is the same as the original non-OD equipped transmission. This allows use of the stock driveshaft. The OD unit does not have the cast hanging center mount found on our original transmissions so you need another way to mount the transmission. There are aftermarket cross member type mounts available. They cost anywhere from $60 to over $300 at Speedway Motors, Jegs and other vendors. These work well but can get in the way if you have existing dual exhaust or have plans for installation of other items in that area. I made a hanging mount for the OD that uses the stock transmission mount location under the floor. I like the idea of conserving space for any later project. It tucks in there nice and tight. It can also be removed without pulling the transmission. Iíve made several versions but this is the one I made for Freaky.

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Hereís a pic of the transmission upside down. The bracket wraps around the OD and uses a stock GM rubber mount on the bottom. (Napa BK-6201024)

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This is a pic before paint. There are two cutouts, one for the rear fill hole on the passenger side and one for the lever housing on the driverís side. This was my first OD install in a 1st gen and I had to make a small Sawzall cut to make it fit well. I plan to make another version of this bracket that better fits both the 1st and 2nd gen vans with no modifications. Sorry about cutting the park brake lever extension Bill. It was so much easier than pulling the transmission or remaking the bracket.

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This is the piece I had to cut. Itís the back end of the pivot for the park brake lever. Didnít like that piece sticking out anyway, thing damn near scalped me a couple times.

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So out comes VanGuyís favorite tool. Well, you know, plug in tool. That doesnít sound right either, anyway...

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Park brake operation is not affected with this mod. When designing this bracket, I wanted to allow removing the bracket without pulling the transmission, so I made a little extra clearance on the sides. The next version will tighten up the gap on either side of the bracket and probably have another bend in it to clear the park brake mechanism. That way the hanging mount will work without any cutting.

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Transmission installed, making progress! (But still waiting on spring bushings. DANG IT!)

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I forgot to mention the clutch job. Everything was pretty straightforward except that the driveline had a piece busted off of the yoke and the flywheel teeth were damaged in three separate places around the ring gear. On the bench here is all the parts for the clutch along with a stereo system that should be hanging in the shop instead of clogging up the workbench!

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Not sure what caused this. The guy at the driveline shop took one look at it and said the driveline was too short. He said that he could fix me up for a couple hundred bucks.

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Hmmm, I dunno. Yeah, rain check on that one. Iíll check into it some and get back to you, seeya.

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I compared the length of several other driveshafts that I had and also asked a few members to measure their shaft. (Donít say it Gregg!) It took some splainin but after clarifying my request to my fellow VCVanners, I found out the driveshaft was the same. I installed a different yoke on the existing shaft along with new U Joints. I never did find the other piece of that driveshaft yoke but to tell the truth, I didnít look too hard. Maybe its floating around in the old transmission? Iíll make a note of it on the tag I hang on the old transmission and deal with it later. That non- OD transmission is not going back into this VCVan anyway. No time to fish for broken yoke parts when Iíve got plenty more to do to get this Freaky thing roadable.

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This was what each of those three sections of flywheel looked like. The machine shop installed a new ring and resurfaced the flywheel. Altogether that cost $100. Iím liking that machine shop so I dropped off some engine parts and said ďfix it pleaseĒ. Yet another project. More on that in another post.

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The bell housing was looking pretty grody so I cleaned it up.

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Then I blasted and painted it ďcast aluminumĒ color. There, thatís better. It looks good except for those paint runs. I hope it all works ok!

After the OD is installed, you need at least two items for it to work. Wiring to the solenoid and a cable to engage the control lever. The wiring circuit I used on the WedgieVan is pretty simple. A 16-gauge tinned marine wire from a positive battery source to a 15 amp thermal circuit breaker powers up a 30 amp rated weatherproof relay mounted on the passenger side doghouse. A 15-amp SPST switch under the driverís seat actuates the relay which sends power to the solenoid. The cable pull is mounted right next to the choke cable on that mound near the park brake. This setup has served me well for the last few years. When I first installed this first one, I was unsure of the whole OD thing so I mounted the switch under the driverís seat to shorten the wire run and avoid another hole in the dash area. (So now I have another hole under the seat!) The setup was supposed to be ďtemporaryĒ but since It has been in there for a few years now, Iím guessing Iíll have to redesignate it as ďsemi-permanentĒ.

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This is the wiring harness that came originally with the OD, at least most all of it. At the top of the pic you can see the transmission part of the harness. It includes a couple of wires to the solenoid and one wire to the governor, then to a 3-pin connector. On the left you see the kick-down switch and the relay is below that. There is some literature available on the web about the wiring circuit used on these OD units but I did not think it was very clear and after some study, I now believe the way they used to wire it will just not work for my purposes.

From the pic, you can see most of the components of the original OD wiring harness which included a kick-down switch mounted near the accelerator pedal and an ignition cutout circuit at the distributor. The way it was supposed to work was when you were in OD at highway speeds -and wanted to pass someone, you just hit the accelerator to the floor and the OD would cut out. This was done by the kick down switch interrupting the solenoid power. At the same time, the ignition was cut (short to ground) for just a brief time to allow the torque on the transmission to be relieved. This allowed the OD to disengage. Not a bad setup but I havenít yet found (or looked very hard) for a suitable kickdown switch that would fit well with our accelerator linkage. Maybe we could use another brake light switch as a kick down trigger. Mount it under the van near the original brake light switch or a microswitch mounted near the carburetor. Iíll save that additional project for another day.

Without that kick down cut out circuit, youíd have to switch off the OD manually if you wanted to disengage OD to pass or climb a hill. The ignition cutout circuit was also fine back in the days of breaker point style ignition systems but doesnít work too well with HEI. Temporarily cutting power to the HEI would take another relay or at least interrupting the power to the existing HEI relay (if you are using one). Anyway, the version installed in the FreakyVan has no kick down switch or ignition cut out circuit. Maybe later.

The WedgieVan did not use the governor feature that comes on the OD. Iíll definitely add that in the future. The governor prevents OD engagement below ~28 mph. This was because too much torque can be applied to the OD planetary gear set in the lower gears. This is a weak point of this transmission style. The small planetary gears and their needle bearings can easily be destroyed with the torque of a V8 engine (especially a big block) under full load. Because of this, these ODs were not known to be heavy-duty. They are best suited for light throttle cruise conditions where they should give a good long service life, particularly with a six cylinder. The later model Borg Warner R11 ODs had 4 planetary gears instead of 3 to try and address this issue. An operational governor is like a safety feature to help save your planets. (We all want to save the planet(s), ya?) You can make a harness that can trigger the OD with the switch and cable but if your governor is wired in and working, thereís no OD operation below ~28 mph. The WedgieVan does not use the governor so itís possible to have OD in each forward gear, (almost like a six speed ) BTW, this 28 mph speed for governor operation is just a guess based on the literature and will vary with installation of different sized tires and rims. From my experience, OD in first gear is a waste. Itís hard even to tell much of a difference between OD on or off in 1st gear. So 1st gear OD is not advised, both for OD safety and performance. OD in 2nd gear can make a more noticeable difference in engine speed. Just avoid full throttle if you have a high torque engine and youíll be OK. One nice feature about OD in 2nd gear is when youíre driving around town. For example: you are driving in 2nd gear with OD engaged above say 40 mph when you decelerate to take a turn approaching an intersection. Speed drops below ~28 mph, which disengages the OD. You round the turn and accelerate in 2nd gear no OD. Speed climbs above ~28 mph, you let off the accelerator which reengages the OD. Now youíre in 2nd gear OD with no shift lever or clutch pedal required. Hit the accelerator and you can cruise at 45 mph or so depending on your total drivetrain gear ratio. Itís like a semi-automatic. In summary, the governor creates a path to ground when at speed. For the FreakyVan, I wired the relay actuation circuit through the governor.


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A redundant ground loop circuit was included in the wiring harness and runs from the governor housing to a ľĒ bolt I welded on the frame near the battery. The hot side of the relay actuation circuit is wired through the unfused ignition connection at the original fuse panel. A 3-amp fuse protects the relay actuation circuit. (See PIC 2121 below) That is another feature I did not include on the WedgieVan. Just to be clear, there are two circuit protection devices on the Freaky version. The 3-amp ATC fuse near the switch and the 20-amp thermal circuit breaker near the relay.

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This is another ground lug that I welded in. Later, Iíll connect this lug to the ground wire attached to the back of the bell housing, shown here

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The wiring harness was made with 16 gauge tinned marine rated wire for extra corrosion resistance. Uninsulated ring connectors were all crimped, soldered and then double shrink tube sealed with the good 3M, 3-1 ratio shrink tube that exudes glue when set. A three pin GM Weather Pac connector was used at the bellhousing and secured in place with a GM style connector retainer. This connector separates the transmission harness from the rest of the wiring associated with the OD. The connector will allow the OD harness to remain with the transmission when removed in the future, just like the original. The engine side harness was secured to the clips at the top of the dog house near the seal. It seemed like an appropriate location since this is where the factory routed the existing engine harness. The wires were encased in a 3/8Ē asphalt impregnated cloth wire loom.


This is the electrical parts list I used:



  • 3 pin Weather Pack Connector (came in a larger kit)
  • Hella Weatherproof Relay #007794301 ($8.04)
  • Hella Weatherproof Relay Socket #H84709001 ($12.44)
  • NTE 20 Amp Thermal Circuit Breaker #R58-20A ($7.20)
  • Morris SPST 20 amp Switch #70070 ($10.83)


All parts purchased on Amazon. Total w/o tax $38.51. The wire, loom, solder, shrink tube and ring terminals I already had on hand.

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Selecting the switch location on the FreakyVan was easy since there was an unused switch under the dash already. It was located just left of the steering column and normally hidden from view. Back in the day, it was probably used as an ignition kill switch but had long since been disconnected and abandoned in place. The cable mount fit pretty well just under the dash, also to the left of the column. I wanted it tucked in pretty tight to the dash with just enough room to get your fingers behind it.

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Driverís view.Gotta fix that door stop/check swing too.


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A view from a little lower and pointing under the dash. This pic shows the unfused ignition circuit used to actuate the relay. The blue wire, switch and fuse is my work, not the white wire. Like most VCVs, thereís a lot of wiring work yet to be done.The cable selected was a good grade marine cable. Itís not the spiral wound choke style cable. It is expensive but pulls really smooth. Too bad it doesnít say OVERDRIVE on the handle. Thatís another project for later, I guess. The cable run was made through an existing hole in the firewall where the OE speedometer cable is routed.Like with any cable, you try to make the bends as gentle as possible and keep it clear of anything potentially damaging. Here I routed it through the engine crossmember keeping it in place with zip ties and then securing it with a 90-degree cable restraint to one of the bellhousing rock shield bolts. This keeps it away from the exhaust pipe and the road.

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This cable had to be shortened because when I started the cable install, I wasnít sure of where the handle would end up or the total cable length. After some careful measurements, I cut the cable end taking great pains to not cut the inner cable. I then sealed the end with some colored shrink tube.

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Dorman #03336

We found the correct cable connection combination to mate up to the OD lever. We had to buy a combination pack at OíReillyís Auto Parts that had the one piece we needed. We still had to enlarge the hole for the cable, grind down the retaining screws and narrow the bronze insert for the lever.

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The lube that I recommend is this Liqui Moly mineral Gear Oil, GL4. Which is also available on amazon for $14.52. per liter. Buy two just to be sure. The Borg Warner literature also recommends SAE 40 motor oil or in very hot weather SAE 50 motor can be used. Synthetic lube is not recommended according to the Borg Warner OD literature and other sources. Other types of lube like GL-5 hypoid gear lube which is normally used for rear axles is also specifically not recommended. This is due to potential long-term damage to the bronze bushings from some of the additives used (and other reasons). During initial fill, the rear OD section should be filled first and then the front. Fill them until it runs out. After this initial fill, only the front plug needs to be checked during normal servicing. It should take about a liter.

Sorry about the ďaboutĒ but I used a partial container to start the Freaky fill. With a properly operating OD, your engine RPM will drop by about 30%. Your long-distance highway speed driving fuel economy should be noticeably improved. With a 25-gallon tank, 3.08 rear axle, 215/75r 15 tires and my stock 250 CID, my range was over 500 miles on one tank of fuel. In practice, I never ran the tank that low but itís sure nice to have that kind of potential range. My highway only fuel economy was consistently over 21 mpg when driving from Tacoma, Washington to Sacramento, California. I repeated these fuel economy results several times.

Several other members have expressed interest in this conversion so Iím happy to help with any advice. Iím not planning on any ďworkingĒ road trips in the near future so the most I can do to help is just advise. Besides providing advice, I am selling the transmission mount and harness. Iím offering the current version of my OD hanger mount for $150 plus shipping. The current version of the wiring harness is $175 plus shipping. Parts trades are always welcome.108VanGuyÖ