Borg Warner Overdrive Governor Interior Views

[pelesl]

I've been working on getting the overdrive unit on my '68 working. After getting a new solenoid from 5th Avenue Auto Parts, I was getting intermittent shifting; most of the time it would not work. I tested bits one at a time. I cleaned the contacts on the relay; nothing. I could make the solenoid actuate directly from the relay consistently, so I knew the relay and all the wires to the solenoid were right. I verified my kickdown switch does not actually "switch", but I could also make the solenoid actuate consistently by grounding the governor wire, so even though the kickdown switch doesn't kickdown, it seems to be fine in its normal state. So I decided to take the governor off and take a look inside.

I was really surprised by its construction (and the excellent condition in which I found its guts) so I figured I'd post my pictures and what I found.

Here's the governor straight out of the overdrive. To remove it, you unscrew it by gripping on to the big hex part. You'll need a skinny wrench or channel locks with skinny jaws to get in there without gripping the round part, which according to the Borg Warner book from 5th Avenue is a big no-no. In retrospect the body looks like a pretty heavy casting so as long as you don't go nuts you could probably grip it (If you deform it the centrifugal action may be deterred, ruining the unit). Mine is covered entirely in clay which is why it looks more like elementary school pottery than anything else. The yellow crimp-on butt joint I added since the wire was badly frayed. You can see that the gear and shaft that sits inside the overdrive unit are in really good shape (the oil is brand new; I exchanged it when I replaced the solenoid). Note the gear actually slides up and down on the shaft about a quarter inch; it's held on by a retaining clip. This is surely just so you can install the whole unit by screwing in the body while allowing this gear to mesh; I'm not quite sure how it looks inside the overdrive unit but I figure the pilot must seat into a bushing when the tranny is going forward since the slight helix on the teeth would give some axial load. When I reinstalled the unit I definitely had to twist it a bit until it "went in" and then I could screw the body onto the overdrive housing. You'll also note the seal which I think could be easily replaced with an O-ring (mine looks tapered but I'm guessing that's just deformity). You don't need to drain the overdrive oil because this thing sits pretty high, so this seal is really just retaining "splash".

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The back side has four slotted screws, and you can see where the wire comes in. Although it looks like a crimp connection, mine seems to also have been soldered. The cloth insulation is long gone which is why I cut most of it off and crimped on a new wire.

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If you remove those four screws you immediately see the switching action on the end plate. Mine looked brand new except for a bit of oil and slight build up where the shaft contacts the dark lever in the center. There's a gasket between the back plate and the body. The "petals" you see are the weights. As shown the governor is obviously not rotating so the petals are "flat". When the governor gets to a certain speed, they form a "cone", forcing the shaft "into" the body (towards the driven gear). Note this internal shaft slides with respect to the external shaft so from the outside you don't see any change.

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More on my next post (3 attachment limit....)

[pelesl]

This is a view of the inside of the endplate. This is the actual switch itself. It's pretty clever: all rotating parts are mechanical; there are no rotating brushes or anything of the sort. The dark lever in the center touches the shaft in the governor (right where the oil drop is there's a dimple on this lever). The switch itself is the copper "horseshoe" and the L shape riveted through the end plate in a sort of "phenolic sandwich". On this side the phenolic is clear and clean but of course on the outside everything looks the same color after being covered in that clay. The hysteresis in the overdrive switching (the fact that it switches on at 28 mph and off at 22 mph) is entirely in the design of the lever, the spring, and the horseshoe (all mechanical). Pretty clever. When you actuate it, it almost feels like there's a magnet in the switch but I think that's just the layout of the bits and the action of the spring. As shown, the governor switch is closed (the solenoid would be on and you'd be in overdrive). In it's natural, non-rotating position, the govern shaft would push the black lever into the recess and open the switch.

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I carefully placed the pilot of the external shaft in the chuck of a hand drill and rested the body on the vice to test the spinning action. Here you see a picture of it stopped; the petals are all on the same plane.

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With the drill it's easy to go "over 28 mph". Here's a picture of it spinning at the point where the petals form a cone. It looks stopped in the picture because of the flash, but you can clearly see the difference. The cone formed by the petals pulls the shaft in via the spokes which lets the dark lever in the cover plate return to its natural position and close the switch.

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In the end I was able to remove all the strands of old wire and solder my new wire directly, so I don't have the butt splice anymore. Although it looked relatively dry inside, it certainly looked like at some point there was a bit of oil in the governor. I don't think it leaked in from the transmission seeing as how it was mainly at the tips of the petals where they tuck under that outer ring and on the dark tip of the internal shaft (and correspondingly on the dark lever). Given the angle this thing sits (end plate tilted towards the ground) I would expect a leak coming in through the driven shaft to leave oil on the body. Judging by the spotty rust I'd say this thing was never full of oil. I put a bit of oil on the gasket with my fingers and reassembled it. Not sure if I should have made a new gasket or if anyone out there knows if this thing was supposed to be lubricated inside in some way. The face of the body where it meets the end plate is pretty rough (I don't think it's machined after the casting) so my guess is that gasket is mainly for dust. I "reinstalled" the clay all around this thing so if my assessment is correct, I should be fine.

After reassembling it I checked for contact between the wire and one of the four screws. Certainly sitting there it made no contact but when I spun it up with the drill fast enough it did. So I'm not sure if I "did" anything here, or if the problem is elsewhere (didn't have the foresight to test first; I just couldn't wait to get it open).

I didn't attempt to disassemble further than this; now I know why no one makes reproductions of these. It's very clever mechanically but that also means that the spring on the switch and the weight of the petals is critical to the behavior of the thing.

[Green23]

Great post! Thanks for posting these pictures and explanation of the B-W governor. I have a B-W OD in my truck and I enjoyed reading this info.