49 Merc 3 Speed Overdrive Parts Identification

[Ehlien]

I'm trying to adapt a floor shifter to my 49 Merc overdrive trans but to do that I have to identify some of the components that are hung on the side of the overdrive and how they function. Specifically there is a lever on the tail section, behind the solenoid on the same side as the shift linkages. Can anyone help me out. I have a parts drawing with numbers but it does not specifically say what they are or how they function. It would be good if I could score access to some more detailed drawings or service manual pages.

Thanks for your help or direction.

[Robz51]

The lever you mention engages and disengaged the freewheeling unit, necessary for your overdrive to function. The overdrive handle under the dash hooks to this lever.

[Ehlien]

Understood..of course .. thanks. .although not sure what the whole process is to engage and disengage.

[expavr]

Originally Posted by Ehlien

Understood..of course .. thanks. .although not sure what the whole process is to engage and disengage.

Attached are links to the Borg Warner O/D transmission that may help shed some light on how they function.
http://www.fordification.com/tech/overdrive.htm
http://www.hotrod.com/how-to/transmi...ner-overdrive/
I have a 49 Merc O/D transmission in my 1940 Tonner. It is set up with a toggle switch rather than the relay and governor combo to engage the solenoid. See the attached Fordbarn link that shows this setup on my truck.
https://www.fordbarn.com/forum/showthread.php?t=156620

[Ehlien]

Excellent stuff!! Thanks much. BY chance to you have any details of how you set up the toggle to replace the relay and governor set up? Thanks again!!

[expavr]

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Originally Posted by Ehlien

Excellent stuff!! Thanks much. BY chance to you have any details of how you set up the toggle to replace the relay and governor set up? Thanks again!!

I ran a 10 gauge wire with a 30 amp in line fuse to the Toggle switch from the "On" side of the truck's On/Off switch. From the toggle I then ran the 10 gauge wire directly to the solenoid. If you decide to go this route make sure you get a toggle switch that will handle 30 amps. When the O/D is set up in this manner you are controlling its function NOT the relay/governor which means that you are sacrificing the automatic engagement function that is a plus if you plan on using it a lot in a daily driving mode. In my case I drive the truck primarily with the O/D locked out engaging it only when the truck speed exceeds 50 MPH such as freeway driving. On the plus side with the toggle you have eliminated the relay and the governor which have become scarce as hen's teeth, especially the 6V ones.

[Ehlien]

Are you running 6V? I'm planning to upgrade to 12V. Not sure how this would effect the solenoid or how I could accommodate for the added voltage.

[Ehlien]

Another question. How effective is the overdrive for you?

[expavr]

The electrical system on the truck is 6V. There is a thread here on the Fordbarn that discusses 6V vs 12V solenoids and their interchangeability. I'm not an expert on such things, but I would think that if your planning to use a 12V system a better fit would be to locate a 12V solenoid. As I understand it they're available. Best to solicit the opinion of others here on the Barn on that score.
Regarding the effectiveness of the O/D the truck has 4.11 gears and 30" tires which along with the O/D allows it to cruise nicely at 65 MPH with the engine turning about 2200 RPM. No worries about sending a rod thru the block while trying to keep up with traffic.

[Ehlien]

Thanks for the very good advice. Enjoy the summer driving season!! My project continues.

[raybee]

I installed a 50 merc overdrive in my 36 p/u with an 8BA. I fabbed up a mount to bolt a HURST Synchro Loc shifter. It sits high but worked out good in my P/U. It takes a lot of trial and error to get the rods right, but well worth it in the end. Ray

[Ehlien]

Originally Posted by Ehlien

Thanks for the very good advice. Enjoy the summer driving season!! My project continues.

another concern will be my rear
end . I'm hooking up to an S10.

[Ehlien]

So more questions after reading the articles you posted. So I'm dropping this trans into. A 47 study pickup that's sitting on an S 10 chassis. The cab is stripped so what components would I need to set it up to keep the governater
rather than going to a separate toggle switch ?

[expavr]

Originally Posted by Ehlien

So more questions after reading the articles you posted. So I'm dropping this trans into. A 47 study pickup that's sitting on an S 10 chassis. The cab is stripped so what components would I need to set it up to keep the governater
rather than going to a separate toggle switch ?

Look at Figure 9 in the attached Borg Warner "Overdrive" file. It shows all the electrical components needed to make the transmission function as originally designed. http://www.studebakerclubs.com/North.../Overdrive.pdf
You may have some of these components such as the governor and the shift rail lockout switch on your transmission. You would be looking for the relay that goes on the firewall and the kickdown switch on the floor. Whether or not you'll be able to use any of these components with a 12V system is a question you'll need to resolve before going too far down the road.

[expavr]

"So more questions after reading the articles you posted. So I'm dropping this trans into. A 47 study pickup that's sitting on an S 10 chassis. "

Regarding your build I think that you might find the HAMB a better source of information. There are many considerations involved in designing and building a safe, functional vehicle and from what I gather you are at step 1 in that process. For example you may find that a better trans solution would be the use of a T5. The 49 Merc O/D will only be useful if connected to a Ford/Merc flathead engine. Is that in your plan? There are folks on the HAMB who "have been there done that" and can offer more specific advice about your project. JMO.

[Ehlien]

My trans is a mate to a 49 Merc flathead both of which are going into the build. I have also been using HAMB and a couple other sites for reference . I looked at moving to a T5 but wanted to keep the Merc drivetrain in tact. I have most of the build thought out at least theoretically but the little details are always a challenge. Currently I'm trying to figure out the details for the trans shifter. Hurst is unable to supply the right mounting bracket anymore for their Indy shifter so looks like some fab work coming up. Today I clear coated my grills and front fender extensions.

[Ehlien]

You are a great source of info!! So yet another question. I read in the articles you posted about free wheeling and forgetting to switch out of OD when to stop if you use a toggle switch etc. It would be a lot simpler to go the toggle switch route. What has been your experience using the switch method vs the stock system of governor and kick down switch etc. What are the keys to operation or things to be aware of? Thanks again.

[expavr]

Two things to be aware of when using the toggle switch: 1. If you're in O/D and start to feel the engine lug you will either need to toggle it off or grab a lower gear or maybe do both in order to stay on the engine's torque curve. In the OEM system you could accomplish the same thing by punching the kick down switch. 2. In order to operate the transmission as a conventional 3 speed with the full benefit of engine compression for braking and to engage reverse you must disengage the O/D unit by pulling the cable out. This is also true for the OEM system. The difference being that I pull the cable out with the vehicle at a full stop. I think this can be done on the OEM system while the vehicle is moving. It involves the interaction between the governor and shift rail lockout system which is bypassed by using the toggle switch. Other than that the trans while in O/D functions the same and you and "your seat of the pants" feeling regarding how your vehicle is performing will dictate what action to take (toggle off or grab a gear). This isn't a steep learning curve. In that regard when you toggle the O/D off you do get some benefit from the engine's braking compression, but not nearly the same as when the O/D is locked out and you're getting full advantage of the engine's compression. For example when coming down a steep grade you'll need to anticipate how much braking effort you want to concede to the brakes alone. Depending on the nature of the grade I'll toggle out of O/D at the crest of the hill and either leave it in 2nd or drop down to 2nd or if it looks like a long steep grade with some curves thrown in stop and lock out the O/D completely. Using an O/D transmission with a toggle mainly involves common sense and some "stick time" with your truck to get the feel of it. Regardless of how you setup the O/D operating system once you get it on the road I think you'll really like it. Good luck with your project. Have you started a thread on the HAMB? A Stude pickup with a Merc flathead engine and transmission on a S10 chassis ---now that's what I call "thinking outside of the box"!!!!

[Ehlien]

I wanted a interesting and unique ride not another common Chevy small block deal. Yes I have been posting on Hamb. Gotta say that going the toggle route would make installation a lot simpler but there do seem to be advantages to the stock system.

[scooder]

Les, regarding OEM overdrive setup. Firstly, with the OEM wether the cable is in or out, reverse can be selected as normal. There is a rod that disengages the overdrive when selecting reverse, does the same job as the cable being pulled out. Now of course on the OEM the overdrive solenoid isn't energized at a stop (or any time below 25 - 28 ish mph) due to the governor.
Engine braking, cable pulled out, as you stated it (the transmission) acts exactly like a conventional 3 speed so you have full engine braking.
Cable pushed in, above governor cut in speed full engine braking should be there, not as much though due to the overdrive ratio. So second gear overdrive will have engine braking similar to conventional third or top gear, third over has engine braking but the engine now thinks you got. Bonneville gears in back, obviously this feels like not much engine braking.
When your speed drops below the governor cut in speed, and the cable is in, the solenoid drops out unlocking the freewheel, result, no engine braking.
This is how it's ment to work, if it don't, something up.
In your setup with the toggle, you should be able to just switch it off and select reverse without touching the cable.
For long grades down hill when your in overdrive, it was suggested that you simply shift to second gear, which with overdrive enabled will be second over and this will/should give you engine braking close to what's available in top gear with conventional 3 speed. If that isn't enough braking and your on wiggly steep down hill stuff, you should really be in direct drive, cable pulled out.
As I say this is how it's supposed to work. The setup in my pickup is OEM style, kickdown and everything. That's what I wanted, around town it will act like a two speed automatic trans, tween second and overdrive second, only needing the clutch when I stop.
Martin.

[expavr]

Martin
On my transmission I'm unable to shift into reverse with the toggle "on" and the solenoid engaged. It must have something to do with the fact that I'm bypassing the governor and the shift rail lock out switch. You've identified another downside to the use of a toggle switch. The next time I have the truck out I intend to try and shift into reverse with the toggle off and the cable left in. I primarily drive the truck with the cable out to take full advantage of engine compression for braking and when I do use the O/D its mainly for higher speed travel. Thanks for pointing that out. Les

[scooder]

Yes Les, toggle off = solenoid off = shift into reverse accomplished.
OEM = governor not powering solenoid = solenoid off = shift into reverse accomplished.
Both of these results are irrespective of cable position.
Again how it should work.
Another thing, make sure your handbrake (E brake) works well. And get into the habit of using it when you park. The freewheel part in the trans has a disadvantage here.
Martin.

[expavr]

Martin
To avoid the free wheeling issue my "toggle" SOP says that when the toggle is off the cable is out. Now that I'm getting older and occasionally suffer from that CRS disease your suggestion about the E Brake is well taken. Thanks.
Les