I took a transmission to my transmission guy today to have it freshened up. As the title says, we know nothing about this transmission. It came out of a 69 GS that we bought from some rednecks in North Carolina. It has a 430 engine that didn't run, but will be soon. We thought we would freshen up the transmission. When my transmission guy looked at it he said holy bad word! This is a switch pitch Transmission! He said they are very rare. The most the car has ever moved under our ownership is forward and reverse into the garage. We have the torque converter that came with it. It's my sons car and he was planning on buying a Jim Weise torque converter because we thought it was a regular 400. Now what do we do? I will take any and all opinions .
If you want the Switch Pitch function, keep it. If you want to go another route, higher stall converter for example, sell/trade it. There are folks that desire the switch pitch.
I heard that. The transmission guy said these are highly desirable. Just didn't know if that's what we wanted. I think we figured out the guy probably bought the combo. The 430 engine with the switch pitch transmission
Tomorrow I have to research it. I know there's a thread on here all about them, and I don't want to look like a DA
Here are a couple rather dated articles on switch pitch 400's. For research purposes, if nothing else. http://www.bdub.net/tranny/TwoTimer-CarCraft-11-77-text.pdf#search="switch pitch conversion parts" http://www.bdub.net/tranny/SwitchPitch-StreetRodder-5-77-text.pdf
You need to have the micro switch on your linkage to make it work. I guess you could control it manually for better launch. The best source for that transmission is the 65 tp 67 LeSabre, they put them behind 300s and 340s. They may have used them in 64 but I hear the 64 400s weren't that good.
There were NO switch pitch TH400's in '64. It can't be a bad trans. as long as it not unnessicarly abused. The one in my '64 Riv. has 300K on it & I've owned it since '64. Did a LOT of drag racing with it over the years. The latest was when I was testing my Rocker Arms. I have pics. & video of the L/F off the ground quite a few times. Not a lot mind you BUT at 4400pds. even an inch is a lot. Tom T.
I ran a switch pitch for many years. Ran 11.50's with it. What you need to do is have a way to control it. Bruce Roe sells a control box for it. Worked great on the street for me. https://www.v8buick.com/index.php?threads/vp-converter-trans-visual-id-guide.143723/ https://www.v8buick.com/index.php?threads/controlling-a-switch-pitch.356444/#post-3054026 https://www.v8buick.com/index.php?t...es-electronic-controller.190075/#post-1663402
Hands down the 9.5 Jim. Loved the novelty of the switch pitch, and explaining it to guys at cruise meets who had absolutely no idea what I was talking about. There were more than a few of them who flat out did not believe me. I remember one guy was a transmission mechanic at Banner Transmissions (right across the street from Long Islands biggest cruise meet, Bellmore). He flat out told me he had never heard of the SP, and thought I was mistaken. At the time, I had a copy of Ron Sessions' THM400 book. I pulled it out of the trunk and turned it to page 53, and told him to read the short section on the SP. Then I went to get an ice cream and came back to see him smiling and shaking his head. Then I started the car, put it in gear, and flipped the manual control switch and told him to watch the tachometer. He was a believer after that. I actually ran my best ET with the switch pitch one day at Cecil County. I wired the switch pitch to run hi stall for the entire pass. The result was an 11.54 @ 115 MPH. I lost a little MPH, but ran the best ET. That was with the 1000DP. That day was a Banner Cecil Day with mine shaft air. I actually ran in the 11.60's with the Q-jet. The SP ran great on the street once I got Bruce Roe's control box and had him tweak it for me. The hi stall on the 12" converter was actually a bit loose for me, and I couldn't adjust the brake timer below 3.2 seconds delay. Had Bruce modify the circuitry so that it would go directly to lo stall after I released the brake. The box had a vacuum switch that gave me high stall below 5" of vacuum. That really made a huge difference in stall control, it basically operated the same as Buick intended. The 9.5 is the best of both worlds. It literally feels like a stock converter until you lean on it. Then it goes right to the sweet spot. I can boil the tires from a roll without going to WOT, just stab it. Works well with the Gear Vendors, and I can even get a hydraulic kick down from 3rd over to 2nd over on the highway if I have enough room in front of me. I haven't been able to really test the converter at the track on a good air day. The one time I had it at Cecil, it was hot, and the DA was 1500-2000'. I also had a pesky ATF leak from the speedo gear seal that cut my racing short. The converter felt great on launch, and I matched my best 60' of 1.62 with the SP. There was also a very big difference with the 1000DP and the 9.5. The gas was so sensitive, I almost hit a metal trash can at Cecil after I swapped carburetors.
I ran into the same issue. I have a 1967 GS400. The previous owner told me the trans was upgraded to a TH400. The original engine was gone as well. I dropped in a 430, tried to mate it to the trans with the 400 torque converter he gave me and nope, wouldn't fully seat. I drop the trans and try it outside and nope still. I look at the partial VIN and trans tag and it says it's from 1974 , what gives? Dad dropped it off at a shop this AM and I get a call saying they can't get the converter on as well and to come take a look. It's a Switch Pitch inside a 74 Heavy duty TH400 Case. Now I called the original owner and he said he had bought the converter for th400 thinking it was a th400 and tossed the Switch pitch one... Jim, I need one now haha this car has been fighting me, I had no idea it was a switch pitch.
There is nothing wrong with converting a 70s TH400 to a switch pitch, the only case difference is an oil passage with a restrictor. I have done a few, and there are advantages like a better valve body, center support protection ring, and a common filter. But the torque converter and pump assembly are a set, these parts cannot be mixed between switch pitch or not. I have observed a switch pitch having advantages in performance, economy, and smoothness over a stock TH400. But for pure performance, a lot of other things get ignored, and a switch pitch is usually not the optimum possible. Bruce Roe
I haven't been on here for a while, but I do like all the comments. My son and I have decided to go with this transmission. I know it's not the greatest performance transmission compared to a turbo 400 with a nice stall converter, but it's sitting here in our laps and it is all rebuilt and probably will run pretty good. Eventually, when the engine gets out of the machine shop we will let you know. It is amazing the knowledge on this Buick forum!!!