TH400 Switch Pitch Drama
July 14th, 2023, 10:15 PM
#1
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Join Date: Jun 2023
Location: Texas
Posts: 110
TH400 Switch Pitch Drama
So, i have a relatively new to me 67, 442 that needed some trans work. Figured a simple TH400 trans rebuild, a heli-coil on a stripped pan bolt, and a buggered up detent switch that needed fixed. Long story short, the trans shop i picked by referral, said i would only save 200 bucks if i carried in the trans myself as opposed to letting them do the whole job if i brought the car in. The car is in really good shape top to bottom so i figured, eh, they will go the extra mile to take good care. They promised to keep it indoors as Texas weather this time of year means hail. I told them from them in the beginning it was a TH400 Switch Pitch, knowing very little about switch pitch, so would need an old schooler that knew how to do it. At that point i did not fully understand the inner workings of a switch pitch. They said no problem.
When i got the call to pick up the car, in 100 degree weather, i happily went to pick it up after 2 weeks and the drive home was NOT encouraging. I heard exhaust leaks, the trans was shifting weird, to say the least, and the engine temp was rising. The temp issue was resolved with a new fan clutch. But the shop had left both exhaust flanges barely hand tight, the pan drain plug was leaking badly, the starter wires need rerouted and a factory heat shield on said wires was broken, and the undercarriage paint was badly dinged up. Fingerprints and smudges all over the car. I was more than a little pissed.
I figured i could deal with all the minutiae myself but was very concerned about the bad trans performance. Turns out the switch pitch and kickdown wires were crossed at the transmission. I dont have the fixed trans detent plug that takes the guessing out. If someone knows a part number for the plug to the detent, that both wires are fixed into at the trans let me know. So, i simply tested for power at both wires with the ignition on. Based on my readings on this sight i knew the switch pitch connector had 12v with key on, not running. Also based on this site input i knew the top most connector, horizontal, on detent at trans was the switch pitch and the vertical bottom connector was the kickdown. I switched the two connections and voila, everything worked perfectly. Once i understood the switch pitch and how it worked i was very impressed with it's functionality. The test drive was brilliant!
So what did i learn? I guess i cannot trust anyone to work on my car but myself. The trans builder knew his stuff but the "installers" were......, well, crap. I am OK farming out specialty tasks like trans or engine rebuilds but the basics of installation i will be handling myself going forward.
When i got the call to pick up the car, in 100 degree weather, i happily went to pick it up after 2 weeks and the drive home was NOT encouraging. I heard exhaust leaks, the trans was shifting weird, to say the least, and the engine temp was rising. The temp issue was resolved with a new fan clutch. But the shop had left both exhaust flanges barely hand tight, the pan drain plug was leaking badly, the starter wires need rerouted and a factory heat shield on said wires was broken, and the undercarriage paint was badly dinged up. Fingerprints and smudges all over the car. I was more than a little pissed.
I figured i could deal with all the minutiae myself but was very concerned about the bad trans performance. Turns out the switch pitch and kickdown wires were crossed at the transmission. I dont have the fixed trans detent plug that takes the guessing out. If someone knows a part number for the plug to the detent, that both wires are fixed into at the trans let me know. So, i simply tested for power at both wires with the ignition on. Based on my readings on this sight i knew the switch pitch connector had 12v with key on, not running. Also based on this site input i knew the top most connector, horizontal, on detent at trans was the switch pitch and the vertical bottom connector was the kickdown. I switched the two connections and voila, everything worked perfectly. Once i understood the switch pitch and how it worked i was very impressed with it's functionality. The test drive was brilliant!
So what did i learn? I guess i cannot trust anyone to work on my car but myself. The trans builder knew his stuff but the "installers" were......, well, crap. I am OK farming out specialty tasks like trans or engine rebuilds but the basics of installation i will be handling myself going forward.
July 14th, 2023, 10:31 PM
#2
Banned
Join Date: Oct 2012
Posts: 6,267
Great post. This point was just brought a week or two ago. The amount of people that understand know and respect old cars these days is becoming fewer and fewer. Yes you pretty much have to do all you can yourself.
When I bought my 70 442 I knew a transmission builder. He built me switch pitch 400. I controlled it with a second bright light switch. I loved it. I controlled coming out of the hole with high revs if I wanted or I could keep the rev's lower and chirp the tires shifting into second. It was a great performance improvement in my car back then.
When I bought my 70 442 I knew a transmission builder. He built me switch pitch 400. I controlled it with a second bright light switch. I loved it. I controlled coming out of the hole with high revs if I wanted or I could keep the rev's lower and chirp the tires shifting into second. It was a great performance improvement in my car back then.
July 15th, 2023, 08:30 PM
#4
Registered User
Join Date: May 2014
Location: Swanton, Ohio
Posts: 161
Most people don't really understand the TH400 Switch Pitch. Depending on how you set it up you can basically have a 6 speed transmission. I have 1 that I used to run in the early 80's in a 65 442. The really interesting note is according the the factory part books that a closed Oldsmobile Dealership gave me off the part counter covering everything Oldsmobile from 1953 to about 1973. The torque converter for a 1966 442 W-30 TH400 Switch Pitch is the same torque converter as a 1965 442 Jetaway.
When I was running the transmission I controlled the switch pitch with 1 of the Hurst shifter t handle that has the push button. With the 455 that I was running the high stall was 2800 rpm and the low stall was 1800 rpm. Our next trip to California is to get the transmission, part counter books, the original parts for the W-30, the 66 tri-power setup, W-31 intake. Most importantly the rest of my tools.
When I was running the transmission I controlled the switch pitch with 1 of the Hurst shifter t handle that has the push button. With the 455 that I was running the high stall was 2800 rpm and the low stall was 1800 rpm. Our next trip to California is to get the transmission, part counter books, the original parts for the W-30, the 66 tri-power setup, W-31 intake. Most importantly the rest of my tools.
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