I'm slightly confused solving for no kickdown with a 300 Jetaway. The throttle linkage has the round electrical trans controller. I discovered that my throttle linkage travel distance wasn't enough to engage the WOT position contact. This is due to an engine/carb swap. Okay, so she had to be floored to work anyway that's kind of extreme.

I found B&M makes a universal momentary switch I can rig to hit at 90% throttle (more normal kickdown sweet spot). This should be easy to adapt and eliminate the crude factory gizmo for the kickdown function.

Questions are, if the converter has variable pitch to add torque when selected, is engaging it early from pedal motion a problem or a bonus? The other mystery is, a second trans solenoid is energized at idle and dropped when throttle position moves to mid-range. What is this controlling?

I'm seeing some sort of electrical stall thing going on here. Crazy for 64-67 technology!

 

The factory switch is a combination electrical downshift switch and converter stator angle control switch. The stator angle is what the second solenoid is controlling. So, if you lose the factory switch in favor of the B&M switch, you are going to lose the switch pitch function.

Unless the loss of converter angle control doesn't bother you, I'd stick with the factory job and adjust it properly. If you get rid of the switch pitch control, you need to make sure the stator vanes are set at proper angle otherwise the car will be sluggish either off the line or at high speed acceleration depending on where the vanes are set. You might want to consider a different non-SP torque converter if you go that route.

The variable stator angle technology is actually older than 1964. Buick was experimenting with it at least as early as 1955, and Twin-Turbine and Triple-Turbine DynaFlow evolved into ST300 and ST400.

I'll give it to them. Once they combined DynaFlow's torque converter with HydraMatic's ability to shift, they ended up with a very fine transmission indeed.

 

for starters, your throttle bellcrank/switch assembly could probably use a good cleaning inside, i'm sure the grease has turned into an adhesive/insulator. there is an internal, automatic adjustment inside. i'll be working on a vacuum control method for my s.p. thm400's stator angle, when i get the car back together.

you also may want to look up a fellow by the name of Bruce Roe, he's the switch pitch guru. he also has some improved torque converters that are specially prepared to give the switch pitch improved performance.


bill

 

That's EXACTLY what the switch-pitch converter does. The second solenoid applies hydraulic pressure to the converter, where an internal piston moves the stator vanes to change the stall speed. Low stall is about 1400-1600 RPM, high stall is about 2400 RPM. You can wire the converter solenoid to a toggle switch and control stall speed when you want as an option. I did this on a TH400.

 

Thanks for the replies! Okay to be clear, I'm retaining the factory throttle switch device to control the idle circuit. It controls one of two solenoids in the tranny. It has something to do with pitch control when idling in drive. The kickdown (pitch via torque converter) is controlled by a second solenoid where the factory contact position is WOT. Now I certainly can crack the crude can open again and mod it to engage kickdown sooner but risks damaging it. Yeah, they're hard to find and so is the elusive Bruce Roe box.

I took the monster out with a passenger armed with a momentary switch hooked to the passing gear circuit. Wheeeee! When I laid down some serious pedal the helper tripped the switch. She downshifted or should I say, pitch shifted and off she goes! Releasing the switch gently resumed normal "Drive" RPM. Nice, and it works very well. Kind of a 30% boost, not a hard screaming downshift.

Going with the adjustable B&M switch for kickdown where 90% throttle can be dialed in not WOT I hope to time it with the carb's secondary opening... kind of "Rocket" mode. Sorry.

Good info Joe_P, lots to learn here. If anyone is interested I can write up the means and methods to Jet-Away nirvana and post 'em. Rocketraider, interesting evolution of these beauties.

 

You are correct in that the S/P is activated at idle. This is to give you a little more 'get up'
off idle and will also lesson creep at stop lights etc. It shuts off as you said off idle/semi mid range and then is back on at WOT along with the kick down.
If you decide to go with the factory throttle assembly make sure you use the factory wire that supplies 12v to the switch. It's only energized when the ignition is on. You don't want a constant 12v going to the switch and solenoid all the time.
As Bill said the inside of that switch gets crusty over the years so it's good to clean it out if you're going to use it. I did mine and it works like a charm now. I used to use a toggle switch and also a momentary switch to power it but that can get old at times constantly having to actuate it.

 

Great point TripDeuces. The positive, "Batt" terminal is key-on and has a dedicated fuse. The unit can clean up pretty well. I refurbished the copper and used a smear of electrical grease on all contact surfaces. Just compress a couple board pinch points and silicone over the round seam. I had some black silicone that looks right and helps seal it.

That Bruce Roe vacuum activated box sounds cool. It might perform both idle and passing functions?

 

I don't know if you want electrical grease on there - if it's the stuff I'm thinking about, it insulates, and may interfere with proper operation.

- Eric

 

http://www.hotrodhomepage.com/hrhp/2...iring-diagram/

Here's another idea for wiring it up.

Although this is for a TH400 it's the same connector on the case

 

The clear, non-hardening silicone I have is used on contacts and connectors. Di-electric grease is for rubber and ceramics like spark plug boots. This would be bad.

Wow relays, RPM detection and timers discussed. Thumb button in the shifter ... sweet!