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64SFrivi

64 Riviera Transmission

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Hello folks,

I had a question I am trying to rebuild my 64 Buick Riviera's transmission. Looking for an master overhaul kit, but when I do most sites sell a TH-400 kit, even though 64 Rivi's came with a ST-400.

What is the difference between a TH-400 vs ST-400 or is there any? I just don't want to buy a kit and find out their are a slight difference. Most places had really bad return policies. If anyone can help would greatly appreciate it.

thanks!

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My understanding is a ST 400 has a switch pitch stator and Th 400 is a fixed stator. and aside from the converter they are the same. Some of us drag racers would buy the buick switch pitch converter and use it in a TH 400 that was in their Pontiac or later Chevy. I have a friend who runs a switch pitch converter in a 68 Pontiac GTO in the Outlaw class---his converter is set up to be switched as a driver operated electric switch.

BTW, ST 400 means SUPER TURBINE 400, and TH 400 means Turbo Hydramatic 400

D.

Edited by helfen (see edit history)

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As I understand it, the 1964 Buick ST400 has some unique items in it, compared to later model year THM400s, other than the switch pitch torque converter and matching front pump. I don't know if these would affect the rebuild kit parts, BUT I seem to recall different fluid filter/strainer set-ups for the earlier trans? One thing might be the valve body gaskets, as the '64 still had the "typical" PNDLR shift quadrant, rather than the later "standardized" PRND21 quadrant.

Seems like the THM400 family started with Buick, Olds, and Cadillac in '64? Chevy didn't start to use it until mid-year '65 with their newly-introduced Caprice models, with the 396/325 V-8. Buick and Olds used Switch-Pitch variations, but I don't seem to recall Cadillac doing that, but they might have. Switch-Pitch was deleted for the '68 model year . . . the Buick brochures noted "decreased operating temperatures" and related increase in longevity due to the change (or something to that effect), whereas the earlier model year brochures touted its greater torque multiplication and better performance.

From what I found on RockAuto.com, the clutch plates went from about '64-'90. In any event, I suspect that if the kit you get (OEM quality at the minimum!) will cover the '64 models, then it should be fine. But DO compare all of the gaskets and seals with what's in your trans BEFORE you proceed with the rebuild, just to be sure.

Just some thoughts,

NTX5467

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As I understand it, the 1964 Buick ST400 has some unique items in it, compared to later model year THM400s, other than the switch pitch torque converter and matching front pump. I don't know if these would affect the rebuild kit parts, BUT I seem to recall different fluid filter/strainer set-ups for the earlier trans? One thing might be the valve body gaskets, as the '64 still had the "typical" PNDLR shift quadrant, rather than the later "standardized" PRND21 quadrant.

Seems like the THM400 family started with Buick, Olds, and Cadillac in '64? Chevy didn't start to use it until mid-year '65 with their newly-introduced Caprice models, with the 396/325 V-8. Buick and Olds used Switch-Pitch variations, but I don't seem to recall Cadillac doing that, but they might have. Switch-Pitch was deleted for the '68 model year . . . the Buick brochures noted "decreased operating temperatures" and related increase in longevity due to the change (or something to that effect), whereas the earlier model year brochures touted its greater torque multiplication and better performance.

Just some thoughts,

NTX5467

My understanding is Olds and Pontiac got it at the same time (1965) and they are not switch pitch. If you say that the Buick has the old shift quadrant with R at the bottom then certainly the valve body would be different. For 1964 only Cadillac certain models, and Buick get the T-400. There is a difference as you juggled my memory at that would be the number of bolts for the ft pump. BTW the only switch pitch for Olds and Pontiac is the ST 300 Buick gets that one two.

D.

D.

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Oldsmobile used switch-pitch converters in Turbo 400s and 2-speed Jetaways 65-67. They have a unique throttle linkage and switch that is the bane of restorers as the housings are potmetal and tend to get brittle with age. If the switch breaks, not only do you not have switch-pitch and electrical downshift control, you likely have no throttle linkage. If the switch is not adjusted correctly, it will make a switch-pitch Oldsmobile behave strangely.

Seems like I have seen 64 Buicks with a PRNDL quadrant instead of Dynaflow's PNDLR. It was either 65 or 66 that PRNDL2L1 showed up for Buick and Chevrolet, while Olds and Pontiac retained their signature DSL as they had always had HydraMatics. Cadillac also kept their two-position DRIVE position thru at least 1966 and I believe later.

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ST-400 is just a marketing name. This is a TH-400. The 1964 Buicks and Caddys were the first TH-400 production applications. The 64 Buick version uses a unique case that matches the early Buick bellhousing bolt pattern. I've seen these cases before. The switch-pitch converter and pump can be swapped for non-SP versions; they are bolt-in parts (I've personally converted a non-SP TH-400 to a SP version by swapping these parts and adding the second control solenoid - Kenne-Bell used to sell a kit).

The different filter setup was not unique to the ST-400 configuration - all early TH-400s used this. There are many TH-400 internal variations such as number of clutch plates in specific drums, but the basic internal architecture is the same on all of them. All use a 2.48:1 first gear set, 1.48:1 second, and 1:1 third. There are different output shaft and tailhousing lengths, depending on application. Overhaul parts like seals and gaskets should be common to all, but you may need to get additional clutch plates if your trans requires more than included in the kit. I had this problem with the TH-400 in my 69 H/O.

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As I understand it, the 1964 Buick ST400 has some unique items in it, compared to later model year THM400s, other than the switch pitch torque converter and matching front pump. I don't know if these would affect the rebuild kit parts, BUT I seem to recall different fluid filter/strainer set-ups for the earlier trans? One thing might be the valve body gaskets, as the '64 still had the "typical" PNDLR shift quadrant, rather than the later "standardized" PRND21 quadrant.

Seems like the THM400 family started with Buick, Olds, and Cadillac in '64? Chevy didn't start to use it until mid-year '65 with their newly-introduced Caprice models, with the 396/325 V-8. Buick and Olds used Switch-Pitch variations, but I don't seem to recall Cadillac doing that, but they might have. Switch-Pitch was deleted for the '68 model year . . . the Buick brochures noted "decreased operating temperatures" and related increase in longevity due to the change (or something to that effect), whereas the earlier model year brochures touted its greater torque multiplication and better performance.

From what I found on RockAuto.com, the clutch plates went from about '64-'90. In any event, I suspect that if the kit you get (OEM quality at the minimum!) will cover the '64 models, then it should be fine. But DO compare all of the gaskets and seals with what's in your trans BEFORE you proceed with the rebuild, just to be sure.

Just some thoughts,

NTX5467

hello, if you saw a buick riviera with the R for reverse at the bottom of the shift selector, the riviera was a 1963 model, there was never a turbo hydramatic 400 with the old style gear selection. now it's possible that someone installed a 1963 riviera trans and selector into a 1964 riviera. charles coker, 1953 pontiac tech advisor

1958 roadmaster 4dr hdtp

1965 riviera

1967 electra 225 conv.

1969 electra 225

1971 electra limited

1972 electra 225

2000 park ave ultra

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Seems like I have seen 64 Buicks with a PRNDL quadrant instead of Dynaflow's PNDLR. It was either 65 or 66 that PRNDL2L1 showed up for Buick and Chevrolet, while Olds and Pontiac retained their signature DSL as they had always had HydraMatics. Cadillac also kept their two-position DRIVE position thru at least 1966 and I believe later.

Pontiac never used the "S" position until TH400 in 1965. Prior to that Pontiac used the notch indicator to the left of 'DR' as fourth and the notch to the rt as third on Dual Range Hydramatic, Strato-Flight Hydramatic, Later renamed Super Hydramatic. Strato Flight and Super Hydramatic were Pontiac's name for Hydramatic Division's "Controlled coupling Hydramatic" Olds calls it Jetaway, Cadillac calls it 315 Hydramatic.

Roto Hydramatic in Pontiac's used the same 'DR' configuration, also to the left and on that notch it was third gear or fourth range , to the rt. it was 2nd gear or third range.

Controlled Coupling was used by Pontiac from 1956 (Star Chief only) to 1964 and it was Pontiac's only auto transmission from 1957-1960. Star Chief and Bonneville retained the unit until 1964. From 1961-1964 Catalina, Ventura, and Grand Prix used the Roto Hydramatic. Only the console mounted shift cars1962-1964 used the "S" configuration in it's console shifter. The 'DR' column shifter nomenclature was used by Pontiac from 1952-1964 in three types of Hydramatic.

Pontiac Tempest also used the two speed ST300, but Pontiac's version did not use a variable pitch stator.

D.

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We did a early ST-400 from a Riv years back. Shift quad was like a PG, PRNDL. It was a three speed unit but only two speed selection. Regular T-400 gasket kit took care of every thing but the valve body. It was the only one I've ever seen like it. We reassembled it with out VB gaskets, ran a DA over the seperator plate both sides on a granite block. Worked well on the dyno, customer paid and left and never saw it again. It was a bench job and we never saw the car, but it was a supposed to be a 64 Riv. It was not a variable pitch. The picture posted is a Buick but the pump is a late model 6 bolt type. When dealing with a VP you have to be very careful of pump, forward drum and torque converter configurations. It's easy to get lost doing one of them with out a trans dyno, we have been challenged by them over the years, however they are a neat piece and really wake up a heavy torquey car.

www.autotransdesign.com

Edited by mr hipster (see edit history)

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Shift quadrants were standardized in '65 due to federal safety rules. Either PRND21, or similar. No more Reverse "at the bottom" of the shift quadrant.

I seem to recall Olds using PRNDSL, with "S" = "Super", but still 2nd gear and "L" = "Low", but still 1st gear. Pontiac might have been similar, with others using "L2" = 2nd gear and "L1" = 1st gear.

As Joe noted, the engine output could determine the number of clutch plates in the various clutch packs, even within the same transmission family.

The Ron Sessions book, "How to Work With and Modify the Turbo Hydra-Matic 400 Transmission" has LOTS of information and PICTURES of the various differences in the THM400 from 1964 forward until its first publication in 1987.

The 1964 "D-L" version is termed "Single Range", with the "D-2-1" version being termed "Dual Range". On page 60, the different quadrants are mentioned . . .

"All Turbo Hydra-Matics covered, except for the '64 400, have six gearshift positions."

"The '64 400 is completely different. Although it has three forward speeds, just as do all later 400s, you have no way of selecting intermediate range manually. The quadrant reads, from left to right, P,R,N,D, and L." He proceeds to detail that when the shifter is placed in "L" below 20mph, manual "Low" is selected. If the shifter is placed in "L" above 20mph, then you get "intermediate" or second gear, but if the speed drops below 20mph, an automatic (speed-related) downshift into "L" will occur. In his mention of the 1964 THM400 P-R-N-D-L shift quadrant, there is no mention of it being "Buick, incl. Riviera" or otherwise, just as being unique to the 1964 THM400-equipped vehicles.

Reading a few pages later, in the road test diagnosis, it appears there is some differences, divisional and engine-related combinations, regarding "Part throttle downshift" events. Some definite "ins and outs" in that situation, it appears! As to whether or not the switch-pitch versions had part throttle downshift or just used the changing torque converter stator angle to accomplish something of that nature without a physical transmission gear change. It also appears that not all of the '64 era THM400 Cadillacs were switch-pitch.

In one of the many pictures, there is a comparison to the "single range" 1964 THM 400 valve body and the 1965 and later THM400 valve body. PLUS other pictures relating to other items different between the '64 and '65+ THM400s.

I HIGHLY recommend this book! Not only for reference, but also as a comprehensive "rebuild manual" for all things THM400, 1964 - 1986. Including the THM375 and the THM475 HD Truck variations (mentioning how they are different from the basic 400).

Just some thoughts . . .

NTX5467

Edited by NTX5467 (see edit history)

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Shift quadrants were standardized in '65 due to federal safety rules. Either PRND21, or similar. No more Reverse "at the bottom" of the shift quadrant.

Willis, I have also heard that it had to do with having to have that shift sequence in order to even bid on government fleet contracts. Ergo, HMT disappeared as did Mopar pushbutton shift controls.

Hm. HydraMatic had been using variations of that NDLR sequence since 1940 so it ain't like people weren't used to it. Guess they didn't take into consideration all the mayhem the new shift pattern caused at all the GM Divisions that had been using HydraMatics.

Apparently Oldsmobile replaced a LOT of parking lot fence in 1964 and 1965, when people who had been used to HydraMatic were yanking a 2-speed Jetaway's shifter all the way down to back out of the motor pool parking spaces, finding themselves in Low instead of Reverse, and climbing the chain link fence.

I took driver's ed with a boy whose family had had Cruise-O-Matic equipped Fords for years. He had a lot of trouble with the GM driver's ed cars as he usually ended up with the car in intermediate range- the same position the Ford transmission used for normal Drive position.

The DE instructor (unfamiliar with the Ford shift pattern) laid him out over it several times and threatened to flunk him in driver ed until the kid's dad showed up one morning for 0900 DE class and made the instructor look at his Ford's shift quadrant.

No telling what the instructor would have done if a kid had shown up who was used to older HydraMatics.

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Shift quadrants were standardized in '65 due to federal safety rules. Either PRND21, or similar. No more Reverse "at the bottom" of the shift quadrant.

I seem to recall Olds using PRNDSL, with "S" = "Super", but still 2nd gear and "L" = "Low", but still 1st gear. Pontiac might have been similar, with others using "L2" = 2nd gear and "L1" = 1st gear.

NTX5467

Funny you should mention this, but I will tell you first Pontiac after 1965 did not use the L1, L2. The other interesting thing is my 1976 Olds Omega, which is a generic first gen RWD X car (Nova) has the PRNDSL and the exact Chevy Nova has PRNDL2L1. Pontiac Ventura/Phoenix is the same as the Olds and would assume Opollo/Skylark would be like Olds too.

Forgot to mention the Hurst gate shifter which has 1-2-3 in the manual mode and in 1969 Pontiac makes their own version of the Hurst shifter which on the left side says PRNDSL under the glass and on the rt side opposite the DSL and shifter stalk says 3-2-1 in very tiny numbers barely visible embossed in the wood grain painted silver on the console.

D.

D.

Edited by helfen (see edit history)

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