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I have my overdrive hooked up to relay, governor, and solenoid, but a toggle instead of the kickdown switch. I usually leave the toggle on all the time and just let the overdrive kick in after 30 mph by lifting off the gas to lower the rpms. I think I heard Jay Leno say to just flip the toggle on over 28-30 for a better response. Can anyone verify this. I don't want to mess up my coveted overdrive. Thanks

Install a kick down switch in the manner that the factory intended and you won't have any problems.
Fred

The factory kickdown switch is a little (OK, a lot) hard to find, but a 3-pole industrial quality micro switch can be substituted for it with a little creative bracketing. The function of the kickdown is to momentarily interrupt the solenoid power and shut off the ignition circuit to unload the driveline so the solenoid spring can retract and put the powertrain back into direct drive. The kickdown makes that transition quick and effortless, like using the kickdown on an automatic transmission.
Jerry

At the moment, I have two SPDT switches mounted side-by-side for a kickdown switch. They were all I could find at the time; the original switches being nearly impossible to obtain. I have a Carter YF, so as Hotrod Lincoln said, some creative bracketing was required.

I ordered these DPDT switches from Amazon last month, but haven't had a chance to install them yet:

DPDT Roller Lever Switches

They are more robust than the current switches, and will be a better solution.

-Kevin

Based on my speedometer, the overdrive is enabled at 30mph, and disabled at 25mph.

I am a supporter of letting the automatic overdrive work automatically as designed. There is sufficient protection in the governor/solenoid/relay system to ensure proper operation, and the kickdown feels just like an automatic transmission.

-Kevin

I seem to recall that there might be a problem with the kickdown switch and the HEI being incompatible.

Side note: I read that only cars had the kickdown switch.

The overdrive units are SO VERY easy to wire up right I fail to see the need for toggle switches. When the governor is activated at @30mph it passes current through to the solenoid and breaks the connection at @25mph on the way down. The in floor kick down switches are getting scarce but all one needs is a starter like push button switch where one side goes to the (-) side of the coil and the other wire goes to a good ground. If one wants to keep the switch out of the water and muck of the toe board location then ANY place along the accelerator linkage can be used as long as it is adjusted correctly. Picture of a 57 with the kick down switch on a bracket held by the carburetor top screws and a tab tacked to the throttle arm of the carb to work the switch. Looks like the owner didn't have a good selection of 10-32 screws and the wiring didn't win a prize at the craftsmans fair but it worked good. We V8'd and A/T'd the truck so I guess it's all in a scrap pile now.

[img]https://i.postimg.cc/F7RpPwVC/relocated-kick-down-sw-001.jpg[/img]

Evan, there's a little more to that kickdown switch than meets the eye- - - -it's not just a simple ground. It's still pretty simple to duplicate the factory circuit with a non-OEM switch, however.
Jerry

No kickdown switch on my setup.

All stock overdrive applications used a KD switch, Chevy cars & trucks, Hudson's, Ford's, Rambler's, Studebaker's, Mopar's ,etc.
Ford style switches are reproduced and are on ebay for about $30. (or you can pay about $150 for a NOS GM switch) They all work the same. You can also get a suitable switch from Rock Auto for about $5. Look up 84 Chevy Malibu/ElCamino brake light switch. It's a 4 contact switch and they work fine.

Early Ford KD switches mounted under the floor, later ones mounted on the firewall. GM KD switches had a bracket located on or near the carburetor.

Fred

I'm going this route: It seems the best solution so far is to put a relay into the battery wire that powers the electronic ignition, that way you can safely interrupt the battery power going to the electronic ignition (before it gets there) so the overdrive can shift and you will not damage the module in your electronic ignition. This way should also not generate any voltage within the electronic ignition because everything is happening BEFORE the electronic ignition. Randy Rundle

I have the HEI ignition setup from Langdon's. I have the kickdown switch ground the negative side of the coil, just like the original configuration...works great. I figured that was the way to go, but I called and talked to Tom to verify before I wired it up. It's my electronic training kicking in, i'm sure...but I hate interrupting power to a circuit while it's under load.

If you have an HEI where the coil is inside the distributor itself, then you'll probably be compelled to cut power to the HEI.

-Kevin

That's fantastic news because I have Langdon's HEI too! I think I will keep the toggle on the dash as a lockout switch. I checked out the wiring diagram and it looks straight forward enough, even for me! I have a modern relay so do you know which posts match up with the original? Made my day Kevin-Thanks!

My pickup has a crate motor from Jasper Engines, and a Carter YF carb, so whatever was original has long since departed. The previous owner had installed an overdrive relay, but no kickdown capability at all. It was a pain to drive that way.

If you would send me a photo or part # of the relay you have, I will try to conjure up a wiring diagram for you.

-Kevin

DPDT relay. I used the last diagram in Deve's overdrive wiring page. It doesn't specifically say the toggle takes the place of the kickdown switch, but it does seem to suggest it. http://devestechnet.com/Figures/bwwiring.pdf

I've seen this elsewhere; I think he's overcomplicated things a bit. That last diagram is a good guide.

-Kevin

I can direct you to someone that has replacement parts and rebuilt overdrive units available when that system fails.
Fred

Why would the system fail Fred?

Mostly due to operator error. Using toggle switches or any configuration other than stock makes it a one person driver.
By forgetting to disengage the solenoid and starting off with it engaged puts an undue load on the overdrive components.
Think about moving a two ton truck from a dead stop with three one inch pinion gears. That's the size of the pinions that make up the planetary. The same situation applies to the teeth on the sun gear & control plate.
Also, when shifting into reverse the overdrive is disengaged in normal operations. If it is possible for it to become engaged in reverse
it will destroy a whole bunch of expensive components.
I see the referenced diagram uses the governor but quite frankly I don't see the need for 2 power sources to complicate something that is relatively simple.
A guy called me a while back and he had installed an OD with the aforementioned wiring configuration. He could not get it to work correctly.
I offered a couple of suggestions to see if I could help him but I'm not sure if he ever got it to work.
Fred

I believe the governor does not engage the overdrive until the 27-30 mph is achieved. I leave the toggle on from start and lift off the gas when I'm at about 35 mph. The engine usually has to decrease to 1000 rpm for the overdrive to engage. I have not had any problems, but I would like to know if the toggle on the diagram acts as a kickdown and can it be flipped when the governor is within it's range without damage.

*The DPDT relay in
my circuit substitutes for the special kickdown switch.

The downside of this setup is I have to let up on the accelerator for 6-7 seconds (1000 rpm) to let the overdrive kick in. Can anyone can tell me how to hook up the relay to interrupt power to the ignition coil for a quicker response.

The engine should not have to slow down that much. Is your circuit wired like the OEM wiring diagram? Normal OD engagement shouldn't take more than one second or so.
Jerry

No I used the DPDT relay instead of the kickdown switch. I guess I'll have to succumb to the pressure of reality and put the switch in. Will any 4 post kickdown switch work Jerry?

I like to use a "Micro Switch" brand DPDT switch with a roller contact arm. It's much more rugged than some of the other switches people try to use. You still need the relay, but it also needs to follow the OEM wiring diagram to function properly. The kickdown switch and the relay just replace the OEM parts that are scarce and expensive with more modern components. I use 60 amp Bosch-type relays, mostly because the wires in the connector plug are heavier and the connector is less likely to get damaged. One function of the kickdown switch is that it kills the ignition circuit momentarily to get a quick unload on the driveline, at least during the downshift part of the engage/disengage cycle. The driveline needs to be completely unloaded at least momentarily to allow the solenoid to engage/disengage, sort of like shifting a 2-speed rear end.
Jerry

I think the complete unloading is what takes the 6-7 seconds in my setup. There is no momentary interruption of the circuit. Back to the drawing board.

I really don't want to put in a kickdown switch on the floor, as I always have to open it up to access the engine, coe. Is there a dash switch In could use instead and stiii get the benefit of the engine unloading? My Langdon HEI has an external coul. So as I understand I can hook a switch to that somehow to pause the current. My head hurts.

Kickdown switches normally mount at the carburetor. If you're going to insist on not doing it the way the Borg-Warner engineers chose, just push the clutch in while the OD is trying to engage to unload the driveline- - - - -treat the OD like another gear in the transmission.
Jerry

A hundred and fifteen thousand miles using a push/pull on/off switch. I think your blocker ring lacks enough friction to engage the pawl.

You can also drop the overdrive out by turning the ign switch off and on rapidly.

Slow engagement could also be caused by a sticky solenoid, or one that's in the process of shorting out the magnetic coil. The way it's supposed to work is that the solenoid pre-loads a spring, and as soon as the driveline unloads by letting off the throttle, the locking plunger snaps into place. It sounds like the magnetism is weak, or the plunger is sticky. You might need to remove the solenoid and bench test it.
Jerry