When did Buick start to use the ST400? 1965-68? Some say that they used the ordinary TH400 in 1969/70. Trying to learn..
1964 was the 1st. yr. in Full Size Buck's only along with Cadillac. '65-'67 there were a switch pitch in Buick, Cadillac & some Olds. '68 - end of production was NOT a switch-pitch, but could be converted. Tom T.
Hey Tom, When (if ever) did GM quit building the THM 400? I saw them in the 6.2 Diesel military Hummers years after their production for passenger cars had ceased. I remember talking to some military maintenance personnel around 2006 who said that the Hummers that the military owned used the non-turbo, mechanically-injected Diesel, non-computer THM 400 setup because it was immune to EMP damage. The absence of the turbo was because the Hummers were often used in very sandy, dusty environments, and turbos don't like dirt. The 6.2 Diesels were overworked in this application, but a rebuild every 25,000 miles or so was a hell of a lot cheaper then having to leave the whole vehicle behind when some super-delicate or electronic marvel gave up the ghost. I agree.
All the more reason to keep the points setup in my Sporty Tom and others .. so was ther ST designation only applicable to SwitchPitch trans ?
TH-400 is GM's "official name" of the model. 1964-1968 ST "Super Turbine" is Buick's "name", and it was applied to the ST-300 and the ST-400. In the Buick line, ST, TH and THM are the same with regard to the 400 and ST-400 and TH-400 and THM-400 are "interchangeable terms" for the Buick 3 speed during its run. The Switch Pitch versions of the 400 were in 1965-1967. (IIRC)
mid 11 second timeslipsRe: St400 Absolutely not. I ran the switch pitch behind my current engine for 3 years on the street and the track. I have 20 mid 11 second time slips. That transmission was still shifting great when I swapped it for a fixed pitch 400. The only difference between a switch pitch and a fixed pitch 400 is the front pump, input shaft, electronics, and the converter of course. The valve body calibrations are also specific to the switch pitch. http://www.buickperformanceclub.com/SPTrans.htm http://www.buickperformanceclub.com/switchpitch.htm http://www.v8buick.com/showthread.php?143723-VP-converter-Trans-visual-ID-guide
Re: mid 11 second timeslipsRe: St400 B&M shift kit and modified 12" ST-300 converter from Jim Weise (TSP). Before that, I had a stock 13" converter. Just as tough as any other THM400.
Nothing fragile about the switch pitch 400 Turbo, the one in my 53 came out of a wrecked 67 Buick Gran Sport went through years of bracket racing, starting in 1970. Never broke and had one rebuild. Bob H.
The above is an excellent answer. Beyond that, the engineering term from Buick for the Switch Pitch (a term popularized by Kenne-Bell in 70's) was Variable Pitch, or VP for short. You will see this in both the engineering books as well as the service manuals. It's why you will hear me often refer to a VP-400, which I have never seen used by Buick or GM, and often has folks look at me like I have two heads.. but you get used to that after a while. :grin: I used the term "VP Converter" to differentiate my converters from the others that were on the market in the late 90's, when I started doing them. As far as durablity, an ST/T/THM/VP 400 is all the same trans, with identical parts, save for the front pump. The converters are very durable, I have only ever seen 2 of my units fail.. both failed the front bearing, and both were in full size cars with a lot of power, and driven very hard. We had kicked around the idea of retro-fitting a HD front bearing to solve that issue, but with the advent of the small diameter fixed pitch converters, the need for the VP is nowhere near what it used to be. It's now possible to have a fixed pitch converter that drives like a 1800 stall 12" at light throttle, yet stalls to 32-3500 at full throttle. This was not the case back when 3000 stall converters were made from 11 and 12 inch shells. And the ST-300 VP converters, which I use as a core for my VP converters, are getting harder and harder to find, considering the newest one from the assembly line is now 50 years old.. But I still do a handful each year. JW
Jim, I have a 67 skylark with a 300 and a st300 in it that is going to be scrapped next year sometime. Do I need to consider scrounging the converter out of that for you? Tom
Chatarina, the guys here providing responses are as knowledgeable as any Buick guys on the planet. "ST" didn't make it a switch pitch.
Yes, please do... deliver it to the shop and I will have a C-note for you.. that deal is always good, for folks that happen to be passing thru. Otherwise I send out a converter box with a plug, with a return tag, and a $75 check. You take the check, throw the converter in the box with the plug on it, and stick on the new label, and find a UPS guy to give it to. Always looking for those 65-7 ST 300 converter cores. JW
What's wrong with the '64 st300 converter cores? IIRC those were switch pitch as well. If not why would my '64 Skylark have the switch pitch kick down linkage on the engine? Derek
You would simply have to ID the converter, there is a sticky in the trans section. That linkage switch was not unique to the VP cars.. it was also used as a simple detent switch on some models, but I am not 100% sure on the 64 300... 65-7 on the 400 for sure. JW
Pretty sure the '64 st300 is a S/P, it has the accordion switch on the carb with the 2 prong(IIRC) plug in the trans. Derek
