I keep hearing this term "switch pitch 400" what is that? How is that different than a TH400 that I am used too. Ford guy question
A switch pitch 400 is simply a TH400 with a few special parts in it. Primarily it is a torque converter that has vanes that can be set in one of two positions via a solenoid and hydraulics which changes the stall speed. They were initially installed in a lot of big GM cars from 65 through 67 I believe. In the high stall mode, it let the engine idle without "creep" at a stop light, and the low stall mode provided less slippage at highway speeds. In a hot rod with a nasty cammed engine, it gives you the best of both worlds, the ability to have a high stall for launching hard, and low stall for cruising. There are a lot of different ways to control the converter, brake switches, manifold vacuum, manually flipping a switch, etc.
it was used for about 2-3 years had a two speed converter. Variable pitch in Buicks. I had one in a 65 Buick and a 67 Cad. they have a controller on the carb linkage that can be changed to manual control to give you a choice 2000 and 2800 stall speeds what I enjoyed the most is going about 60 and want to pass. stomp on it and it drops a gear changes the vanes in the converter, 4 four barrel kicks in and that big old car jumps. would love to have that transmission in a light hot rod with a gear venders behind and some 4.56 gears in the ass end
That was a Buick transmission with the variable pitch turbine. There was a way to control it on the dash with some pretty easy modification. You should look it up and see what you some up with, but its not same as the GM TH400. Bob
The torque converter is different, it has a variable angle stator in it. The angle is changed hydraulically, and there's an electric solenoid that is used to control the system. Stock converters usually get about 500 rpm more stall in "high stall", but modified converters can have quite a bit more. The converter in my 55 has about 1800 in low stall, and about 3000 high stall. This design was used only in early, non-Chevy TH400s, from 1965-67 There was also a transmission made in the 60s called the ST300, which was mostly like a powerglide, but had the same switch pitch feature as the 400
Interesting. my 1966 olds chassis manual clearly says that it also locks at highway speeds. I've never found ANYTHING to back that up
Yes, they did come in those cars, but they also came in the "B" body LeSabre's as well.......they were called Lesabre 300 and those with TH400 were LeSabre 400......I worked at a Buick store when these cars were new and remember them well. I do not know if Pontiac or Olds used the 300 trans in "B" body cars. Ray
I am using a 1970 Cad 472 and the 400 trans that came with it. It came out of a Fleetwood 60 series. Is it possible I have a switch pitch, and if so how can I tell the difference from a regular TH400 and a switch pitch without taking it apart?
Back in my street racing days, a guy named Boyd had one in his mustard yellow vega. SBC witha single 4 barrel tunnel-ram. He ran on G78's Caldwell tires. When he launched, he would flip the switch off and on to make those tires hook. That was one fast Vega.....
If the transmission is original, it's not switch pitch. The year is on the tag on the side of the trans. You can tell by looking at the stator support (the outer "input" shaft that the torque converter fits over), if it has long splines, it's not switch pitch. If it has short splines (3/8" long) and a long smooth journal, then it's switch pitch. Also there are two wire connectors, but many 400s from the early 70s had two wires, the other was for the 2nd gear switch for the Transmission Controlled Spark system. Pull the pan, if the second wire goes to a pressure switch on the valve body, it's not switch pitch. If it goes to a solenoid on the front pump then it is SP. If there's just one wire, it's not SP. This is a SP stator support
Not just used in Buicks, but also Oldsmobile, Pontiac, and Cadillac, and you can use the switch pitch parts in a TH400 to convert them. Link with a lot of info below..... http://www.442.com/oldsfaq/oftsp.htm
In the early 80s Kenne-Bell sold HP models with several different stall speeds. I used one in my '65 442 w/ a 455, t400 and 12bolt with 411s. Not working the motor hard it went 12 flat @ 117-118 with the convertor locked up. One helluva high gear charge!
Pontiac never used the "switch pitch" feature in their ST300 or ST400. Pontiac always used the fixed angle transmissions.
Yes they did, in 55 the variable pitch Dynaflow was introduced. The variable pitch Dynaflow was used from 55 to 63. The variable pitch idea was also used on Buick and Chevy triple turbine automatics too. Buick thought it might be good to use it on the 300 and 400 turbo hydros, but was dropped for 1968.
Picked up a 425 Buick nailhead out of a 1966 Riviera with the switch pitch th400 for a 56 Buick Special project. Looking forward to connecting that combo to a 9" posi rear end with 3.50 gears and seeing how that old Buick comes out of the hole! Should be a little more spirited than a 322 with a dynaglide.
SBIN, Contact Jim Wiese at tri-shield performance, he has converters with high stall up to around 3000-3500 and low stall close to a stock converter. Fun set-up.
I have a 401 nailhead and 2-4's in my '50 sedan delivery company car. Works great. Installed a push button switch in the hole in the floorboard where the clutch pedal arm used to come through so I can switch it when ever I want.
Misconstude. Thanks for the info That setup sounds very fun 3000-3500k should be a sweet spot in the nailhead torque curve!
I have two switch pitch ST400's for nailheads if anyone is interested. I think they are both 64's. One is from a wildcat and one is from a riv. The kickdown switch (at the carb linkage - that operates the switch pitch) is different from wildcat to riv. Most guys just use a manual dash switch.
Interested if they are switch pitch! 64 did not have switch pitch and were single range ST400s. How many positions does the manual selector have? If 5, then no switch pitch and is single range. Switch pitch transmissions have a two terminal connector just above the pan on driver side. Please check, and if switch pitch please PM with details. Thanks
Two prong plug is service replacement, cannot get single prong, IIRC. Down and dirty way to tell if trans is SP: put 12 volts to each prong; if you hear a click on each, it has two solenoids adn is SP. One click, no go. SP parts (pump, solenoid, converter) can be swopped to Chevy case no problem, you just need all the parts. Only difference in TH400 cases is the bellhousing, nothing else. Cosmo P.S. Use a big cooler.
Years ago when I ordered a SP through Poston Buick I think it came from PAE Enterprises in El Paso. They had about 6 different levels of torque convertor up to 5000 stall. The stock was about 1200/1800
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