so after mulling it over i think i now understand. When off the line or at red light and i floor the car, the switch pitch kicks in thus giving me a better take off, because the engine and trans are locked together at higher speeds as the linkage slowly creeps further out (butterflies opened) the switch pitch kicks in again, giving more efficiency is this correct?
High stall is like "slipping" a clutch in a manual transmission. It allows the engine to rev-up faster and get into it's power-band quicker which equals better acceleration.:Smarty: :TU: :bglasses:
Nope. At "high stall", the converter allows the engine to rev to a higher rpm as the car begins to accelerate. This is useful for accel from a dead stop, but the amount of additional slippage produces a lot more trans heat and lack of efficiency at a steady cruise. At "low stall", the coupling is more efficient with less heat generated, but the engine's torque is utilized at a much lower rpm. Great for a steady speed cruise once you're up to speed, though. Regardless of the stall speed, there is always some slippage in a torque converter by design. It's easier to understand when you think about that while the trans is in gear, your engine is still able to run while the car is stopped. If not for that slippage, the engine could not turn with the car stopped. Nowadays auto transmissions don't utilize the variable pitch feature. A certain amount of slippage is built in by design as a compromise between too much slippage for daily driving, and not enough for accel from a stoplight. One advantage of the "lock up" converters that you read about is that when cruising at speed, they really do physically lock the engine speed to transmission input speed, thus no slippage whatsoever. The lockup converters use a small friction disc inside the torque converter that's not much different that what you'd see in a manual transmission application. I think the "lockup" converters started showing up in the very late '70's if not a bit later depending on the OEM. Devon
i just removed my engine and my trans is a th400 for sure. the trans is currently supported by a jack can i lower it to the ground to that i can clean the top of the trans? Will this mess up linkage or the shifting links? thanks. I need the jack for other stuff.
anyone? i dont know how id search for this? i just removed my engine and my trans is a th400 for sure. the trans is currently supported by a jack can i lower it to the ground to that i can clean the top of the trans? Will this mess up linkage or the shifting links? thanks. I need the jack for other stuff.
NO, not without disconnecting linkage and driveshaft as well as tranny cooler lines. how about using a jack stand under the transmission?
too late im a F*&&*^ idiot and didnt prop the trans up when i was removing the engine so it came down pretty solid. i think the linkage got thrown off. Im looking on how to re adjust it or take it to a shop because of my stupid ass... im pissed. suggestions?
You really need to buy a chassis service manual to show you how all the linkage adjustments are done. If it's bad you could have bent a linkage rod. How far did the the trasmission drop? If you didn't remove the bolts attaching the rear mount to the crossmember you may have also torn the rubber in the rear mount. They're an oddball design with staggered bolts, different from the late TH350 and TH400 mounts. Devon
i do have a chasis manula. and read through it. i think im going to have a pro take on the tranny. f$#$!!
u sure about having a th400 transmission? I thought the switch pitch types were sp400 (or st400) and not th400. You should have a two pin connector, for switch pitch and kickdown switches to energize. Early 70's th400's had two pin connector but were NOT switch pitch types, one connector pin was kickdown, and the other connector pin was for TCV (transmission controlled vacuum). This merely told a solenoid up on the engine when to allow vacuum advanced timing.
I thought that all late model TH-400s (non SP TC) used a vacuum module to kick-down the trans when needed, so no kick-down linkage or position switches are needed. Am I wrong... again?ou:
No, you mean vacuum modulator. That doesn't kick down the transmission. On the ST300, ST400, THM400, the kickdown is electrically actuated. 12 volts is passed to the transmission connection by either a linkage mounted, or gas pedal mounted switch. The THM350 uses a cable to signal downshift. The valve body gets input from 3 sources. Vacuum modulator, governor, and kickdown. They tell the valve body, engine load, road speed, and throttle position. Based on those 3 inputs, the valve body adjusts shift points and line pressure.
Luckily the guys that are re building my engine are going to "hook" up my tranmission for a good price. thank god for reliable and honest mechanics. Just dropped off the block, and i cant wait!!!
i agree. hopefully they are using a new tranny so you wont have to worry about that. depending on how far it fell and what got hit the hardest, i would be concerned for the case and especially the tc and bushing. nows the time for a 200 4r if money isnt a problem and you arnt worried about being origonal. randy:beer
I just wired mine to a switch on the dash because after locating it on the throttle linkage, I found it was cracked in half and am still trying to understand when to use the switch and what setting to leave it on. For example, in a perfectly level parking lot (without holding the brake) if the switch is on the car doesn't move. If I turn the switch off, the car begins to pull itself to about 5mph. Which setting should I be cruising in, on or off? Which setting will get the best accelleration, on or off? Thanks Jesse
use the switch in the on position for snappy performance driving and in the off position for cruising and mileage. with the switch on at a stop light the car won't creep as much and will require less brake pedal pressure to hold it still
so off the line ON Driving around town / freeway OFF? 66Lesabre, im just learning myself, still trying to get my head around trannys...
