Hello all, I'm new to the HAMB. I don't really have a HAMB-friendly hot rod/custom - yet - but I can pull a lot of information from you guys (and already have). I'm currently building my first project car. My question for you all is, what do I need in the way of solenoids/switches to make the engine and trans combo work? It's a '74 Cad 472 and a '67 ST400. Thanks!
You'll need to leave all the nonsense out and rephrase the question sticking to things that are ALMOST on topic around here.
there are two terminals on the side of the transmission. One is for kickdown, the other is for switch pitch. I think switch pitch is the top one..if you get it wrong, just switch them. Kickdown wants to get 12v when the throttle is wide open, so the trans kicks down. Switch pitch wants to get 12v when you want the converter to go into high stall, and no voltage when you want low stall. I find that it works best if it gets high stall when the vehicle speed is low, like under 10 mph. Or when you are going down the dragstrip. A toggle switch works. You could also wire it to the brake light switch, or to a switch on the throttle linkage, to give it SP when either your foot is off the gas, or when the pedal is down half way, or pretty much any other combo you want. If you run a toggle switch and drive it for a while, you might be able to figure it out.
Donor car either has the kickdown switch on the gas pedal linkage inside or linked to the carb. I think the 500 in my ot truck has the same switch on the manifold. Or had at least. Photo nabbed off the net.
My 472 has that exact same kickdown switch, but the plastic tab that connects it to the carb linkage is all busted up. I might just find one to replace it.
The Cadillac was originally set up like this. It was designed with grandma in mind Jim's explanation is quite simple With a toggle switch, you take the place of timers and vacuum canisters and dashpots and the multi pole throttle switch. Electric Kick down for passing gear / +12 volts to Trans at full throttle. There are plenty of sources for the switch that mount under dash near the gas pedal.
OK I have been running a 71-73 472 in my sedan for 14 years now. I never hooked any of this up. It kicks down fine. Guess my only complaint is that it upshifts too quick if accelerating slowly. Any thoughts? Sent from my A521L using The H.A.M.B. mobile app
Very unlikely that you have a switch pitch Trans, Kick down works mechanically without electricity but adding the electric kick down is the difference between a small hammer and a sledge hammer. Vacuume modulator would be the first place I looked for up shifts to fast. High vacuume is low engine load so it will shift fast, low vacuume is high engine load so it will hold the gears longer. There are different modulators that respond to different vacuume signals as well as adjustable ones. There's a bunch more shift quality stuff but it's all inside the Trans. The stock caddy stuff is going to act like its in a Cadillac luxury car for debutants and grandparents, you have to tell it to act like a hot rod by changing stuff.
And the shift characteristics of the transmission, were originally tailored for the vehicle it was installed in. So a Caddy trans was set up to give good shift feel with the long highway gears, and if you put it in front of some steeper rear end gears, it will shift early and soft. The replacement modulators all seem to be the same one, and it's adjustable. See if there's a little slot screw adjustment in the vacuum hole in it, and if you screw it in, it will add more spring tension, so the vacuum will have to work harder to pull it out, and it should shift a bit later and firmer. You can add a shift kit, also. A bit more on the effect of having the electric kickdown solenoid connected...it will hold the transmission in a lower gear longer, at full throttle. The vacuum modulator will usually only hold it to around 3000-4000 rpm, while the kickdown will hold it to 4500 or so. I had a Vette years ago with the TH400, and it was set up to shift at red line (5500 rpm) just by holding the throttle down and engaging the kickdown. Most of them are set up to shift around 4500. You can also play with the governor, but that's another subject.
Thanks for the info. It does have an adjustable modulator. I just haven't really messed with it. I'll give that a try and see what happens. Sent from my A521L using The H.A.M.B. mobile app
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