I found this on HMN - enjoy: http://www.hemmings.com/mus/stories/2004/12/01/hmn_feature13.html FEATURE ARTICLE from Hemmings Muscle Machines TURBO 400 TRANSMISSIONS Hemmings Muscle Machines - DECEMBER 1, 2004 - BY JIM O'CLAIR A very interesting automatic transmission to consider, when replacing that tired old transmission or even upgrading an older unit like the Powerglide, is the Turbo Hydra-Matic 400. As automatics go, it is considered the heavy-duty version of the Turbo Hydra-Matic 350; they are similar in many characteristics. They are, for the most part, interchangeable on the same vehicles; however, you would normally find the TH400 in larger engine applications because they are able to function more reliably at higher engine rpms. They also use about 8 more engine horsepower to power them, a TH350 typically uses about 36hp, as opposed to the TH400 using about 44hp. Used extensively by all GM divisions in the Sixties and Seventies, the TH400 was also commonly used by Jeep, Avanti and Checker for applications that required a sturdy automatic transmission. GM continued to use this unit in Chevrolet and GMC trucks into the Nineties. Overseas manufacturers used these transmissions extensively as well, for use in their higher-performance powertrains. One of the most appealing aspects of the TH400 is availability. TH400s were made in a couple of different versions, so knowing the year of the transmission is important to facilitate your being able to swap it into your car easily. The first-generation units were only used in Buick, Olds, and Cadillac, and incorporated a variable-pitch torque converter. This converter could change its stall speed during use, based on an electrical impulse from a switch on the carburetor or accelerator pedal sent to a two-prong switch in the side of the transmission. This variable-pitch version of the TH400 was only used from 1965 to mid-1967. Later units had a fixed-pitch converter and had a one-prong switch, the two-prong "pitch switch" was not used. Another way to identify the early variable-pitch units is by the transmission pan. The earlier pans were identical in shape to the later pans, and all used the same 13-bolt hole pattern; however, the variable-pitch transmissions had four indentations in the pan (one large oval-shaped indentation as well as three small "dimples" around it). The late-1967 and up transmissions used a pan with only two small "dimples" in it. If the pan is not on the transmission, the early filter had an intake pipe attached to it and could be washed and re-used. The later filter was flatter with no intake pipe, and was a throwaway unit. All TH400s used a large black can-type vacuum modulator located on the side of the transmission by the dipstick tube. When you find a transmission for a car newer than 1968, the vehicle's original VIN number will be stamped on the casing. So that would be yet another way to ensure the transmission is not a variable-pitch unit. Shifting ratios were as follows: 1st 2.48:1 2nd 1.48:1 3rd 1.00:1 Reverse 2.08:1 You can find a donor TH400 in one of these vehicles: o 1981-1982 Avanti II o 1964-1981 Buick full-size and mid-size models with big-block V-8 o 1964-1981 Cadillac rear-wheel drive (also in 1982 to 1988 limousines) o 1965-1977 Chevrolet full-size and mid-size models with big-block V-8 o 1969-1977 Corvettes o 1966-1991 Chevrolet and GMC pickups o 1975-1982 Checker o 1965-1977 Oldsmobile full-size and mid-size models with big-block V-8 o 1965-1979 Jeep o 1965-1977 Pontiac full-size and mid-size models with big-block V-8 In imported cars: o 1977-1990 Ferrari 400i o 1968-1990 Bentley and Rolls-Royce o 1977-1985 Daimler Double Six o 1977-1990 Jaguar XJS and XJ12 o 1973-1990 Holden cars If one of these units can be found, it would be a good idea to grab the driveshaft, flywheel, starter, crossmember, neutral switch and shift cable and brackets, as well. You will probably need the front yoke and cable brackets from the donor car at the very least. Turbo 400s use three different tailshaft lengths as well; the most preferred units for a GM swap would have a 4-inch tailshaft. The TH400 was strong enough to be used on 4WD vehicles as well, showing up as original equipment on 1976-1979 Jeep CJ series trucks. These were mated to an AMC engine at the front, and to a Borg-Warner Quadra-Trac transfer case at the rear. The earlier full-size Jeeps, which were equipped with the Buick 350 engine, had the conventional Buick, Cadillac, Oldsmobile and Pontiac bolt pattern on the bellhousing for their TH400s. GM used the TH400 in 4WD applications into the Nineties. For newer GM products, the bolt pattern only makes a difference between Chevy and everything else. Replacing a Powerglide, TH200-4R or TH350 transmission with a TH400 in GM cars is relatively straightforward. The crossmember needs to be moved back in order for the mounting pad on the TH400 to align. Most GM mid-size and full-size cars already have the frame drilled for this, because the cars could be ordered with either transmission. If a new crossmember is desired, they are still available from GM, part number 3912573. The rubber mounts are different, so this would have to be changed, as well (GM number 22188496 is the newest version). The output spline on the TH400 is finer than the 27-spline shaft in the Powerglide, TH200-4R and the TH350, so a new 32-spline yoke would be needed for the driveshaft. GM still sells the correct yoke, part number 14075214. Depending on the application for the TH400, you will to have the driveshaft shortened, as well. Only the TH200-4R driveshaft is similar in length. Here are some GM transmissions dimensions. Overall lengths are less tailshaft: o Powerglide: 16 5/16 inches long, 27-spline output-mounting pad 20 9/16 inches back (on tailshaft) o TH350: 21 5/8 inches long, 27-spline output, mounting pad is 20 3/8 inches back o TH200-4R: 28 1/4 inches, 27-spline output, mounting pad is 27 inches back o TH400: 24 5/16 inches long, 32-spline output, mounting pad is 27 inches back (4-inch tailshaft); 28 inches back (9-inch tailshaft); 27 5/8 inches back (13-inch tailshaft) o TH700-R4: 23 3/8 inches long, 27-spline output, mounting pad is 23 inches back Driveshafts using a smaller U-joint than the one used for the replacement yoke can be modified with the purchase of an adapter U-joint. Spicer (part number 5-3022X), Borg-Warner (part number 114-9HP) and Precision (part number 372) make an aftermarket U-joint, as do other suppliers that incorporate both yoke dimensions and cap sizes. Floor shifters would be interchangeable between these transmissions, too, with the purchase of a changeover kit that would contain a new shift-cable bracket and the shift indicator lens. The TH400 neutral switch would have to be used, as well. Transmission cooler lines will need to be lengthened or replaced with the longer TH400 lines. The bolt pattern on the torque converter may not be the same as your original bolt pattern was, but most GM and aftermarket flex plates are now drilled for both the TH400 and the TH350 bolt patterns. Changes to the speedometer driven gear need to be addressed if your speedometer is inaccurate. Adding two teeth to the number already on the gear will lower your speedometer reading by 5 percent. A chart of GM part numbers for TH400 and TH350 speedometer gears will be posted on our www.hemmings.com website for subscribers to access. TH400 driven gears can have anywhere from 34 teeth to about 45 teeth. When considering using this transmission in older classic cars or non-GM cars, it would be easiest to find one with the Chevrolet bellhousing bolt pattern. This is because engine-to-transmission adapter kits to attach the Chevy bolt pattern are available for: o Buick nailhead V-8 o Ford FE and small-block o Ford 429, 460 and flathead o Lincoln 337-cu.in. flathead o Studebaker V-8 o Mopar big- and small-block V-8s o 1954-1959 Mopar Hemi and Polysphere V-8 o Early Cadillac 346-cu.in. and 1955-1964 V-8 o Pontiac and Buick straight-eight o Buick 215-cu.in. aluminum V-8 o Pontiac V-8, 287 to 389 cubic inches o Chevrolet and GMC stovebolt straight-six o Lincoln, Mercury and Edsel V-8, 317 to 462 cubic inches o Chrysler flathead six and Slant Six o Hudson straight-six and -eight The adapter kits would contain a bolt pattern adapter, flex plate and starter, if necessary, to complete the engine-side changeover. For installation of the TH400 into non-GM cars, aftermarket crossmembers are available from many suppliers. Using the above-mentioned TH400 output yoke will be necessary to adapt the transmission to your existing driveshaft. Adapters are also available for installation of a TH400 into many 4WD vehicles. The added strength of the TH400 over the TH350 makes this transmission a popular choice with off-road enthusiasts. Jeep, Ford small-block and Buick V-6 adapters are available to convert your 4WD to the TH400. Used TH400s are available for between $200 and $500, depending on their mileage. Many companies offer rebuilts, which sell in the $600 to $900 range, but cores are usually required. Neutral switches sell new for around $50. Shifter changeover kits go for $40 to $100 (if a shift cable is also needed). Yokes are in the same price range. New crossmembers sell for $50 to $125, and an aftermarket new mount usually sells for less than $10, unless you want the $20 urethane mount instead of rubber. Engine adapter kits for non-GM cars can fetch $400 to $600. Every little thing adds up, so make sure you have everything you can get out of your donor car, and save yourself a trip back to it later. Even with the purchase of some of these additional parts, you should still be able to install a TH400 in your street rod or collector car for less than $1,000. If you find the right donor car with all the needed parts, you could do this swap for much less. Considering the TH400 transmission when installing a new big-block or high-horsepower small-block is a natural. Because it has added strength over the TH350 or the Chrysler 727, and because it uses less horsepower than the Ford C-6, it can offer better reliability and a smoother ride, both in town and on the highway, for larger-displacement or modified engines. This article originally appeared in the DECEMBER 1, 2004 issue of Hemmings Muscle Machines.
More, from: http://www.trishieldperf.com/transmissions.htm Some thoughts on transmissions. Back in the early 60's before the bean-counters started running the engineering departments of GM's Hydramatic division, the engineers designed us a transmission that could live behind just about any engine you care to put in your car. The Turbo 400 series. Originally named the "Super Turbine 400" for our Buicks. All GM transmissions with a "400" designation, are functionally identical, save for the Variable Pitch 65-67 units, and the single range valve body '64 unit. Differences are only in bell housing patterns, emission control switches, and internal parts materials. Of course, there are a number of valve body and governor calibrations out there, but generally speaking, virtually any Turbo 400 can be modified to fit your application. If your looking for a TH400 to build, it is our opinion that the 65-70 version is the best candidate, as it only requires the addition of a center support spacer ring, which is an easy retrofit. To identify what year a 400 is, look on the Passenger side of the case, and you will find a metal tag. Even if the paint is missing or illegible, you will find the two digit year, two letter trans code, and Julian build date of the trans, stamped on the bottom of that tag. We believe in the TH-400 at TSP, and build and use it exclusively. From a mild street cruiser, to an 800 HP race car, it's tough to beat, for value, reliability, and performance. It is our strong opinion that if you desire a overdrive transmission, you best alternative, when you consider cost, durability and performance is to use a TH400, in conjunction with one of the aftermarket overdrive units on the market now. We use the GearVendors unit here, and installation in a G or A body is nowhere near the big deal that is often portrayed. Stay tuned for pictures of the actual installation in the future. A few words on the Variable Pitch option. This is often know as a "switch pitch", which is a term that was popularized by Kenne-Bell, back in the seventies. GM engineers called it a "Variable" pitch, as the origin of the name relates to the "variable" angle of the torque converter's stator blades. This transmission is preferred for street cars, that see the drag strip once or twice a year. Mainly drag raced vehicles, will benefit from the proper fixed pitch converter, over a VP unit. This is fact that was proved many years ago, regardless of the "hype" you might hear. If you think otherwise, then how can this question be answered: IF a VP trans was the "Ultimate trans for a race car" then why did none of the major manufacturers reproduce it?? Surely, with the millions of TH400's in use, by enthusiasts and racers, they could have realized a tremendous profit, regardless of the investment it would require. There are two reasons for this: Consistency- Regardless of what type of control system is used, the converter's stator return, from high to low stall, is rather time inconsistent. That's not good, if your trying to "run the number". Converter weight- 11,12, and 13" converters are heavy. A good 8, 9 or 10" converter is considerably lighter, which allows the engine it rev faster, which in turn, makes the car faster. Simple as that. That being said, don't get us wrong. We love the VP setup for a street car. So much so, we developed the only furnace brazed, high quality torque converters on the market now. It adds a "neat" dimension to your project, and allows the advantages of a higher stall converter, without the excessive heat buildup, and slippage. IT is used for just that in some of the cars we do here. Not because we would encourage you to build a car, with cam timing that REQUIRES it. Even our Level 2 engine can be driven around in low stall, in traffic, with no fear of stalling, once everything is warmed up and "normalized". A quick word on shift quality is in order here. Generally transmission builders consider a "good shift" to be one that is easy to describe. The engine slows down, and the vehicle speeds up. That's it... And there is not much else to talk about. The shift happens very quickly, and is almost imperceptible, to the driver, under light throttle conditions. With adequate power and gearing, heavier throttle shifts will result in a "chirp" or more, but this is really a function of the speed of the gear ratio change, rather than anything to do with the transmission itself. To put it another way, the engine power, with the ratio change in the transmission, causes the tires to lose traction, as they try to increase the speed of the vehicle. Often times, and incorrectly, enthusiasts feel that if they have a trans that chirps the tires ever time it shifts, they have a "good shifting" trans. Most transmission professionals would beg to differ. What they have is a unit that someone has incorrectly manipulated either the line pressures in the trans, or the hydraulic control system, which was carefully designed, to allow a wide variety of calibrations, for different applications. Throwing half the check balls of the valve body over your shoulder, and reaming out the spacer plate, and making the accumulators in the trans non-functional, are not the proper way to modify a transmission. It's the easy, cheap way. Often times, you end up with a unit that is in 3rd gear by 15 mph, and shifts abruptly, regardless of torque input. The TH400 has a throttle modulation system in it, and we prefer to work with that system, instead of defeating it. And this takes much more knowledge and experience, vs. doing it "the easy way".
Even more from: http://www.442.com/oldsfaq/oftsp.htm Switch Pitch Trans Detail Identification Many GM full size cars (Buick, Olds, Pontiac, and Cadillac) and intermediate cars with the V-8 used a Variable Stator TH-400 transmission from 1965 thru 1967. The 2-speed Jetaway trans used behind the V-8 [not the L6] in the 1965-67 models also utilized a switch pitch torque converter. For a transmission built during these three years, you can identify the transmission as having the switch pitch parts by the electrical connector on the side of the trans case. A run-of-the-mill TH-400 will have a single spade terminal protruding from the case (to activate the kickdown solenoid valve). A switch pitch (aka variable vane) trans will have two terminals (one for kickdown, one for vane angle). Now, trans made/used outside of 1965-1967 might have two terminals, one for the kickdown, and one for the TCS solenoid (prevents vacuum advance except in high gear). The TCS is wired to a pressure switch connected to the accumulator piston area, that allows full vacuum to the distributor only when the car is in third gear when the engine is cold. There probably is two wires coming from the thermostatic vacuum switch on the front of the manifold. The other indicator for the switch-pitch converter would be the switch on the throttle linkage which kicks in the high-stall speed at idle and at WOT (and, I believe, on those years it also controls the kickdown). So, a single terminal is proof that the trans is not a switch pitch unit. Also if one is certain that the trans is a 1967 or earlier unit (didn't these have the horseshoe-shaped indentation in the tranny pan due to the early-design filter?), then the two-terminal connector indicates switch-pitch. Later (is it 70-up?) TH-400s with two terminals indicate TCS. [ Thanks to Joe Padavano, Bob Barry, Mike Rothe for this information. ] General Information How & Why the Switch Pitch Works The name switch pitch comes from the vanes (stator blades) in the torque converter being able to change their angle (pitch) in order to reduce friction (force) and get the vehicle moving. This is similar to somebody trying to start pedaling a ten speed in 10th gear versus 1st or 2nd gear. You pedal fast for the output you get, but you are able to move. These trannys have both an internal kickdown solenoid and an internal variable pitch torque converter, activated by an similar solenoid. If the tranny side electric terminal shows 2 spades, it may still have the variable pitch converter. A very neat item BTW. Unfortunately, most cars had the switch pitch feature tossed by a rebuilder. The 66-67 cars use a control switch which is part of the throttle linkage mounted on the firewall. For variable pitch trannys there will be four spade connectors on the switch. One for 12V, one for the kickdown and two for idle and full throtle switch-pitch converter operation. The switch pitch allows a higer stall speed at idle (to assist old ladies who don't like creep while at the stoplight) and full throttle (when the torque multiplication of the higher stall is helpful). This feature was only available from 65-67 on Olds, Buick and Caddy trans. Oil pressure within the trans holds the stator blades in the converter at a low angle for more efficient coupling. With a high angle, the stator blades offer a greater oil redirection, increased torque multiplication, increased engine speed, maximum performance, and less tendency to creep at idle. This higher angle is achieved by bleeding off the pressure that held the low angle, by applying a 12V signal to the stator control solenoid, located on the back of the pump. This electrical signal is fed into the trans thru the connector on the left side, along with the power for the kickdown solenoid. The two form a "T", with the stator control terminal being the top of the T and the kickdown being the upright. Stator |-- Detent To summarize: Apply 12V ==> hi angle, high performance No signal ==> low angle, better economy The converter changed stall speeds from 1800 rpm to 2600-2800 rpm. A 12" converter was used in the TH-400, and an 11" converter in the Jetaway. You can interchange the converters. You will also see a switch on the throttle linkage near the carb where the throttle position will dictate the change in the two stall speeds via an electrical solenoid located inside the transmission. In the 1965 Oldsmobile Chassis Service Manual, it is stated that switches on the throttle linkage supply the signal for high angle at idle, and at throttle openings greater than 40 degrees. With this setup, the TH-400 offers a 1st gear multiplication ratio of 2.5 via the gears, and 2 via the converter, for an overall 1st gear ratio of 5.0:1. Second and 3rd gears are 1.5:1 and 1.0:1, and are also subject to additional torque multiplication from the torque converter. Reverse gear ratio is 2.0 mechanical * 2 from the converter, for an overall ratio of 4.0:1. I'd suggest looking at a 66 or 67 Olds factory shop manual. It will explain all. Where to find a Switch Pitch trans or converter Many GM large cars (Buick, Olds, Pontiac, Cadillac) and intermediate cars with the V-8 used a Variable Stator trans 1965 thru 1967 (they might have been used in 1964 as well). All such TH-400's & Jetaways share the same bellhouse bolt pattern except Chevy. Unfortunately, most TH-400's were in big cars, and are the long-shaft version, with a tailshaft about a foot long. Luckily, these transes are "easily" [to a trans repairman] converted to an A-body-friendly short shaft trans by simply swapping the output shaft & rear housing, which can even be donated from a Chevy short-shaft trans. BE AWARE: These early big-car versions of the TH-400 often have no provision for a speedometer drive, as the cars used the left front wheel to drive the speedo. So, you might need to round up three transes to make one short shaft switch pitch TH-400: The '65-'67 SP for the converter & workings, a later BOP TH-400 for the correct bellhouse pattern case with speedo drive accomodation, and a short shaft (even a Chevy type will do) to supply the short output shaft & tail housing. Due to a one-year-only, hard to find filter configuration, the 1965 TH-400's are slightly less desirable than later versions, though they will certainly work just as well. The "early" hard to find filter was actually used through 1967. The 2-speed Jetaway trans used behind the V-8 [not the L6] in the 1965-67 models also utilized an SP torque converter- these may make good and fairly plentiful converter donors. The matching fit has not been checked yet, but chances are very good that they will interchange. Previous version of this guide indicated that Jetaways up to 1969? might have had the variable pitch system- however, according to the 1968 Chassis Manual, that feature was no longer available on the Oldsmobile TH-400 or the Jetaway after 1967. How To Identify a SP trans or Converter by Examination The trans is very easy. Look for TWO electrical terminals in the LH side connector. This is not a *guarantee* that the trans is SP, as later units used a wire from the trans to help control spark advance. However, if there are 2 electrical feeds, and the year of the trans is '65 thru '67 [see tag on RH side], then it almost surely indicates an SP trans. To be certain, simply examine the trans input shaft. You will see a smaller 1.0" fine-splined shaft protruding furthest. This is the same for both types. You want to examine the larger 1.5" or so coarsely splined protrusion that surrounds the 1" shaft. The difference here is obvious. This is the key: the SP trans has a *short* splined section, 1.40" diameter by dial calipers, about *1/2"* long, behind which is a *very smooth* section of shaft, slightly *larger* in diameter [1.43" by calipers], and about 1-1/4" long, with a 0.160" oil feed hole in the bottom. Behind that, the shaft necks down to about 1.270" diameter for some 3/4" and after that enters the trans. In contrast, the standard constant-angle stator transmissions have similar shaped splines on that larger input shaft, but these splines are much longer, about 1-1/8" along the shaft, and behind the splines, the shaft is SMALLER in diameter [1.270" or so] and NOT finely machined. Another way to identify a switch pitch TH-400 is by the pan. You will see three dimples and a shoe heel impression. The shoe heel impression is where the filter picks up fluid and the pickup is shaped just like a shoe heel. How To Identify a SP Converter by Examination In making this guide, an SP converter from a 1965 "OA" code Switch Pitch trans, and "normal" converters from an early 1970's TH350 & one from, though not necessarily original to, a 1968 "OW" TH-400 non-SP trans were examined. On the back side of both TH-400 converters, near the shaft that goes into the trans, about 2" from the converter's snout, were seven plug welds about 1/2" diameter. The TH350 converter did not have these welds. A previous version of this guide indicated these welds might be a clue as to whether the converter is SP or not, but it now looks like more of an indication as to whether the converter is TH-400 vs. TH350 caliber. The best SP ID tip involves looking down into the converter. You should remove most of the oil from it in order to see the details. This is easily done by vacuum pump or siphoning with a small hose [1/4" or so] overnight. Matching the trans shaft, of course, farthest down in will be the splined hole for the 1" trans shaft. Above that will be the more coarsely splined section which mates with the trans's larger shaft. KEY: in the SP converter, there will be virtually NO GAP between these two splined sections, with the larger coarsely splined hole, about 1" long [deep?], beginning at a depth of about 3-7/8" down from the edge of the converter snout. With the standard converter, there *is* a gap of about 1" between the smaller fine-splined section and larger coarsely splined section. [Aside: Into this gap, you can guide a stiff 1/4" hose to reach even more oil when siphoning the oil from these units.] While this unit also has a coarsely splined hole depth of about 1", these splines start about 2-7/8" down from the edge of the converter snout, some 1" higher than the SP converter. You are now an Expert at identifying SP transes & torque converters while perusuing the piles at the scrap metal dealers. [ Thanks to Chris Witt, Bob Handren, George Nenadovich for this information. ] Torque Multiplication The torque multiplication is 30% greater at stall in high stall than low stall (2.6 fold vs 2.0 fold). It makes it damn near impossible to hook up a healthy big or small block engine even with street gears without some very sticky tires. However the slip at all engine speeds in high stall is much greater and for best results it is best to leave high stall around 2/3 to 3/4 way through 1st gear. The launch is dramatically improved if you can hook up. A car with 2.93 gears will accelerate from a standstill like the same car with 3.42-3.55 gears and a fixed pitch converter matching the stall speed of the lower stall setting of the variable pitch. Therefore you can sort of use it as a poor mans over-drive, gear the car higher and let the converter in high stall make up for the lack of a low first gear. If you switch back to low stall towards the end of 1st gear you'll be able to stay in first gear longer as the rpm's will drop 500 due to the converter tightening up. There is some information in the book How to Work With and Modify The Turbo 400 Transmission by Ron Sessions. 10 Years ago Kenne-Bell sold lots of variable pitch parts plus had lots of free info on them. I'm not sure if he still does or not, he seems to have moved more to the mustang market now. I have always thought (through reading and explanations of how hydraulic dynamics work) that a higher stall converter has torque multiplication over a tighter converter, period. So I don't understand the comment that the high position doesn't involve any multiplication over a lower stall because it's a switch-pitch converter. Seems like a contradiction. As to the time it takes for the switch to take place, the vanes are fighting the fluid and only kept in the high position by the fluid pressure applied through the front pump solenoid valve which controls pitch angle. It changes pretty quickly. The other way may be different. I've played with mine some but it's a while since I did the following. When I tried applying the high pitch from low pitch at WOT it seemed to me the pitch did not change until I let up. In other words application of the fluid pressure by activating the solenoid on the front pump to increase stall didn't happen very quickly under WOT conditions, if at all. No drag race reason I can think of you'd want to do that but as best as I can recall that's what happened. Stall speed on the Jetaway high pitch is 2800-3000 and 2300-2500 on low. The Jetaway converter was stock for the '67 W-30. One inch or so smaller diameter than the TH-400 convertor. Works great. The whole point of the switch pitch design originally was to provide the added torque multiplication for a "passing gear" effect. The pitch which gets "switched" is the angle of the stator vanes in the converter - this same angle determines the torque multiplication. More pitch=>more multiplication. Since you can't get something for nothing, this torque multiplication is at the expense of "slippage". I suspect that what you're seeing is the hydraulic equivalent of a gearing down; in other words, the input to the converter (what is that, the impeller?) must turn faster to flow more oil through the stator and onto the turbine wheel due to the more severe angle of the stator, but this more severe angle provides the multiplication. I'm sure that there's some inefficiency involved, as the angles of the impeller, stator, and turbine blades are probably optimized for a certain rpm and changing one without matching the others will likely result in additional slippage. As for real world driving with a switch pitch, I had one installed in a 71 Cutlass with a built 455. At the track I would launch at high stall and switch to low stall about halfway through first gear. It's been quite a while since I drove the car, but I don't recall any noticeable delay in the time it took to change pitch. Perhaps this is due to the opposite effect from the one Bob H. noted; I was trying to go from _high_ stall to _low_ stall under WOT conditions (including the use of nitrous). If Bob's theory is correct, the WOT conditions would actually contribute to moving the vanes to a low stall position. I should note, though I doubt that it matters, that this was a 69 H/O trans to which I added a switch pitch front pump and converter from Kenne-Bell. I had also rebuilt the tranny using a B&M rebuild kit. [ Thanks to Phil Penketh, Bob Handren, Joe Padavano for this information. ] Retrofitting I just wanted to add that it is possible to convert any TH-400 to a switch-pitch configuration with the appropriate pump, converter, and solenoid. Apparently the passageways are cast into all the valve bodies to allow the system to work. Kenne-Bell used to (and may still) offer just such a kit. GM made switch pitch TH-400s from 1965-67 and also switch pitch Super Turbine TH-300 Jetaway two speeds from 1964-68. The parts to convert a TH-400 to a switch pitch can be acquired from these as the necessary parts are inter-changeable between these models. You need a variable pitch torque converter, the special front pump and the input shaft. Tou also need a oil restricter to place in an oil channel in the case, some wire and a switch. The rest of the internals are identical to a regular TH-400. You may use a kickdown/converter switch at the carb linkage. If not, you may be able to adapt a later kickdown switch to your gas pedal or linkage, as the later cars had. When the downshift switch is activated, it sends 12V+ to the solenoid, which kicks down the tranny. [ Thanks to Phil Penketh, Bob Barry, Joe Padavano for this information. ] Torque Convertor A high stall converter does have a bit more RPM loss than a low stall converter. The GM 12" converter which has a stall speed of about 1800 RPM in most applications has about 100 RPM loss when it is fully coupled (i.e., at RPM well above its stall speed). The GM 12" converter which has a 2400 RPM stall speed in most applications (the P7) has about 200 RPM loss when it is fully coupled. The RPM loss is the difference between the crankshaft RPM and the transmission's input shaft RPM. This loss is a direct power loss - multiply the RPM loss by the torque at the input shaft, and you have the power loss. So, a higher stall speed converter puts a little less power to the wheels. Usually, the best way to drive one of these is to start in high stall, then when the road speed is high enough that you won't pull the engine below its power band, switch to the low stall speed. Since it takes the converter a noticeable amount of time to change, you may wish to anticipate the speed and switch it a little early. [ Thanks to Bob Hale for this information. ]
Even EVEN more from: http://www.novak-adapt.com/knowledge/th400.htm The Novak Guide to the<br> </span>GM TH400 Automatic Transmission </h1> <p class="paragraph">The TH400 is an automatic shift, three-speed, longitudinally positioned transmission. It is widely regarded to be a supremely durable and legendary transmission. </p> <p class="paragraph">The TH400 is conservatively rated at 450 ft. lbs. of input torque. Aftermarket building techniques take it well past that figure. </p> <p class="paragraph"><strong>History</strong><br> The Turbo 400 was introduced in 1964 in Buick and Cadillac cars and in Chevrolet and Oldsmobile cars the following year. An innovative variable pitch stator was available in the 1965-1967 cars that could essentially vary the characteristics of the torque converter. </p> <p class="paragraph">The TH400 made its way into heavier duty GM trucks in the 1970's in 2wd and 4wd configurations. The 400 was not just a GM exclusive transmission. It is an immensely popular transmission in the automotive industry as well as the aftermarket. They are found in GM's, Jeeps, Jaguars, Rolls-Royces, Ferraris and others. </p> <p class="paragraph">As with other GM transmissions, GM changed the naming scheme of the TH400 in 1990 and it was then referred to as the 3L80 (<strong>3</strong>-speeds, <strong>L</strong>ongitudinally positioned, <strong>80</strong>00 lbs. GVW). An overdrive version of it was introduced as the 4L80-E. This electronically controlled transmission remains in production and wide use in heavy-duty GM and military applications. </p> <p class="paragraph"><strong>Identification</strong><br> The 400 transmission has a main case of cast aluminum alloy with a length of 24-3/8" long. Its aluminum case is essentially smooth. The rear mounting face of the transmission has a hex bolt pattern with ribs running forward longitudinally. The fluid pan shape is irregular (see image, left), being likened unto a distorted Texas pattern. The TH400 is the largest of the common GM auto transmissions, but still surprisingly compact in light of the immense power they can handle. </p> <table width="228" border="0" align="right" cellpadding="5" cellspacing="5" class="borderboxtext_gray"> <tr> <td width="204">The TH400 and Jeeps have quite a history together. This list is of the Jeep powertrains that had this excellent transmission. The TH400 came in 2wd or 4wd Jeeps, coupled either to the popular Model 20 transfer case or the Quadra-Trac, the latter being an option from 1973 to 1979. The early versions had factory block adapters. Later AMC versions had their own case with no adapter. <br> <br> 1965-1967, 230 I6 (Kaiser)<br> 1966-1968, 327 V8 (Buick)<br> 1968-1974, 232 I6 (Kaiser)<br> 1969-1972, 225 V6 (Buick)<br> 1969-1971, 350 V8 (Buick)<br> 1971-1979, 258 I6 (AMC)<br> 1971-1979, 304 V8 (AMC)<br> 1971-1979, 360 V8 (AMC)<br> 1974-1975, 401 V8 (AMC)</td> </tr> </table> <p class="paragraph">There are two significant variations of the TH400. The TH375 was a version of the transmission used from 1972-1976 in smaller displacement cars. It is identified easiest by its "375-THM" designation cast in the underside of the tail housing. The TH475 was an extra-heavy-duty version, and was found in larger trucks from 1971 on. </p> <p>If you are trying to determine the TH400 from another in a vehicle, a fast way to tell is to look at the kick down mechanism. The TH400 uses an electrical slide switch, which is controlled by the throttle linkage. The TH350 uses a mechanical cable kick-down mechanism that is attached to the throttle linkage. </p> <p>An interesting variable pitch stator feature of the Turbo 400 was available in 1965-1967 Buick, Olds and Cadillacs. These are identified by the two-prong plug on the case. While 1970-1974 models also had this plug, it is for the transmission controlled spark system.</p> <table width="200" border="0" align="right" cellpadding="5" cellspacing="5"> <tr> <td><a href=http://www.novak-adapt.com//catalog/kit_124.htm><img src=http://www.novak-adapt.com/images/pics/transmissions/th400_to_model_20.jpg alt="Adapting the TH-400 to the Dana 20 Transfer Case" width="215" height="192" border="0"></a></td> </tr> <tr> <td class="picboxtext">The Turbo 400 as adapted to a Jeep or IH Dana 20 transfer case. </td> </tr> <tr> <td class="picboxtext"> </td> </tr> <tr> <td class="picboxtext"></td> </tr> <tr> A factory Jeep design of the TH400 adapter to the Dana 20 transfer case. OEM adapters are highly prone to breakage. Novak offers a strengthened reproduction of this adapter (#8624113) to replace these broken units, in addition to our superior dual-bearing design #124 adapter kit. </td> </tr> </table> <p><strong>Transfer Case Adaptability<br> </strong>This transmission makes an excellent conversion transmission due to its adaptability into most Jeeps longer than CJ5s. Both 2wd and 4wd versions of the Turbo 400 can be used equally well, and there are no inherent advantages to either one once you have installed our adapter assembly. </p> <p>It is of interest that the 1976-1979 AMC case, while more or less similar from the collar of the case, back, is tilted about four degrees. This was presumably for transfer case clearance purposes. Novak's #134 & #141 adapter designs compensate for this clocking to relevel the adapter and mount assembly. </p> <p>2wd transmissions feature conical shaped tailhousings and an output yoke, which are replaced with a typically shorter 4wd style output shaft (included with our adapter assemblies) of varying lengths and spline counts, depending on the application. The HydraMatic can be adapted to the popular Jeep (and many IH) transfer cases, including the:</p> <ul class="list"> <li> <p>Dana 18, 1941-1971 </p> </li> <li> <p>Dana 20, 1962-1979</p> </li> <li> <p>Dana 300, 1980-1986</p> </li> <li> <p>New Process Jeep 208, 219 & 229</p> </li> <li> <p>New Process 207, 231, 241OR, 242 & 249 </p> </li> </ul> <p>Essentially all factory GM 4wd applications available with an OEM configured TH400 have adapters and transfer cases that are prohibitively long for a Jeep, and transfer cases whose sizes and gearing fall short of desirable for most Jeep applications. </p> <p><strong>Engine Compatibility and Adaptability</strong><br> <em>Chevrolet</em> <br> The front face TH400 is natively compatible with either the Chevy 90 degree “Small Block” & “Big Block” patterned engines (image, left), including the V6, V8, I6 & Iron Duke I4 (the latter mentioned only for accuracy and perhaps some comedy). </p> <p>These differences only affect the front bell of the case, and all Turbo 400 cases are largely similar from that point back.</p> <p><em>Buick / Olsmobile / Pontiac / Cadillac</em><br> Buick engines and TH400's are natively compatible when choosing a Buick V8 or V6 version of the transmission. All Buick, Olds, Pontiac and Cadillac TH400's share the same engine pattern, commonly refered to as the "BOPC" pattern. </p> <p><em>AMC/Mopar Jeep</em> <br> The first Turbo 400s found in Jeeps had a factory adapter plate, while later AMC versions had a dedicated AMC style case. </p> <p> The Chevy 400 can be made compatible with AMC I6 & V8 engines. See our Kit #437AMC for details. This conversion can help make for an improved Jeep powertrain over 727, 999, AW4 and other, lesser transmissions. </p> <p><strong>Summary</strong><br> <span class="paragraph">A fantastically designed and built transmission, the Turbo 400 is broadly popular for Jeep conversions. They are very servicable, buildable and their </span>strength puts them into the top tiers of Jeep sports and performance applications.</p>
It's great stuff and thanks for posting it. A great compilation of info. My 2-speed Jetaway is fading (and the kickdown isn't performing like it used to with the Holley in place... the old stock Quadrajet was completely shot) and I have been torn as to what tranny I will replace it with. Looks like the TH400, perhaps with the Gear Vendors overdrive. It'll all probably happen when I rebuild the 330. Thanks again.
No prob, guys. I put it on here, thinking it would come up in a search one day and someone who could use it would find it. Looks like it's served it's purpose. ~Jason
lots of good information, thanks BTW: Did the article mention that the 64 transmissions used in Buicks and Cads are SINGLE RANGE 3 speeds. Yep only had one DR position and one LO.
I've been scouring the net for info on ST400s and swapping one into my '63 Riviera. Thought I'd add another article I found to this thread: http://www.buickperformance.com/switchpitch.htm
Hell, I'll post it, too! Thanks, nail-head! FYI, http://www.buickperformance.com is no more, and the URL has been bought by Buick themselves. The pictures are at the below link, as it's been archived. From http://web.archive.org/web/20070807215149/http://www.buickperformance.com/switchpitch.htm : Itching for a Switch Pitch Transmission by George Nenadovich and Jim Burek Switch pitch(s.p.) transmissions were availabe from 1965-7 in the full size BOP cars. Even some Cadillacs have the s.p. transmissions. The name switch pitch comes from the vanes in the torque converter being able to change their angle (pitch) in order to reduce friction(force) and get the vehicle moving. This would be similar to somebody trying to start pedaling a ten speed in 10th gear versus 1st or 2nd gear. These transmissions were used in the full size cars since the engines did not make a lot of torque and they were quite heavy. There are s/p TH400 and s/p TH300 transmissions. The s/p 300 were found in 1964-7 and were two speeds. The s/p 300 converters are 12 inch while the s/p 400 are 13 inch. For instance, I pulled a s.p. TH400 and 430 engine from a 1967 Electra 225. When I took the car to the salvage yard, it still weighed in at 3600 lbs. With complete motor and trans, figure close to 5000 lbs. The easiest way to identify the s.p. is by looking at the trans. pan. On the TH400, you will see 3 dimples and a shoe heel impression. The s.p. is also found in the ST300 trans. but are not common. The shoe heel impression is where the filter picks up fluid and the pickup is shaped just like a shoe heel (see photo below). If you need a filter, use WIX 51879 or a cross referenced one. Photo by Gary Fanning Here is a side view of the trans electrical plug. This is from the 67 LeSabre. Notice there are two contacts. The top tang is for the switch pitch....when +12V is on...it changes to high stall and no voltage the converter remains in low stall. Bottom tang is for the downshift which goes thru the switch mounted on the gas pedal retainer. Here is the trans ID tag on the pass. side. The top words are SUPER TURBINE 400 1965 300 LeSabre BU 401 with 3.07 axle BJ 401 Riviera 3.23 axle BR 425 4-bbl 3.07 axle BN 425 3.23 axle BT 425 2 carbs 3.07 axle BQ 425 2 carbs Riviera 3.42 axle BS 1966 340 LeSabre BU 401 V-8 BR 425 GS and Riviera BS 425 all others BT 1967 340 LeSabre 400 BU 400 GS400 BA 430 Wildcat, Electra, and Riviera BT 430 Sport Wagon 400 BW Also note that 65 and 66 will only bolt up to Nailheads. SP400 were only made from 65-67. Also you will need to get a newer tail housing because the SP400 housing will not accept newer drive shaft yolks (larger diameter). Factory info courtesy of member,Steve David. This is one of the welds on the outer perimeter of the s/p conv. Notice all the spot welds around the s/p conv. hub. This is the input shaft of the s/p 400 from the 67 LeSabre. Here is the switch pitch internals. Here is the stator. Here is a pic with the arrow indicating the factory switch for the S/P trans. Here is a pic of the factory pumps used in SP trans. Here is the solenoid that is connected to the backside of the top tang. The converter changed stall speeds from 1800 rpm to 2600-2800 rpm. You can interchange the converters. You will also see a switch on the throttle linkage near the carb where the throttle position will dictate the change in the two stall speeds via an electrical solenoid located inside the trans. Most people will remove the entire harness from the donor car and then use a toggle switch mounted on the dash to activate the s.p. converter. The 1967 Electra 225, I pulled my s.p. from had a short shaft TH400 but most of the time the full size BOP cars will have the longshaft transmissions which is not desirable in the 1968-72 GM A-bodies. The best bet is to remove the entire trans. and then convert a shortshaft TH400 to the s.p. converter. All 1973-77 Pontiac Grand Prix cars have shortshaft TH400 and are quite common. If you know how to change the non-s.p. trans over, you can pull the pump, switch and solenoid out of the longshaft s.p. trans and then install it into the non-s.p. trans. That way you won't have to buy two transmissions from the salvage yard. When changing over a non-s/p to s/p, you must transfer oriface plug behind the pump or the system will not work. If you can't remove the old plug, you can make a new one from the end of the old style glass fuses. Break the glass, clean out the end with a soldering iron to remove the old fuse solder then drill a 0.028" hole in the center of the cap. This hole size is critical. You can also buy a new plug from GM, part 8611710, for $10.50. Aftermarket converters are still available and several companies can make a converter to order. Please see our Buick vendors page for additional info. Some additional info from that 1967 Electra 225 is the 430 had a center sump oil pan since it has an "X" frame. This center sump engine will not work in 1968-72 Skylarks since it will not clear the frame. You will need to find a rear sump BB(big block) from 1970-76 Electras, LeSabres and get the oil pan and pickup tube. The s.p. trans. bolts up just like the non-s.p. trans. If you have any questions, please e-mail. Good Luck! If you have any questions: George [email protected] If you would like a s/p trans built for you, Jim Burek [email protected] Switch Pitch Trans for Older Nailheads by Steve Stabler [email protected] I saw in your article about switch pitches that only the 65/66 400t only fit nailheads. They also made the 64 fit too, but was a 6 month only trans. I found out that in late 65, they made the BOP design, so if you want a good t400, it must be from a 64 late or a 65 late trans only. Otherwise, the 64 has the 64 only case, and the 66 is a bop designed bellhousing. Also, the t400 will fit in the 61-65 late nailheads IF you can find the flexplate from a 64-66 nailhead. All you have to do it grind about 1/16th of an inch from the inside of the flexplate, and it will bolt right up to any year nailhead from 61-66. Especially the 63 and older that had the Dynaflow. I did all this to my 62 buick. I went from 9 mpg to 26 with a 401 bored .040 over, factory 2x4 manifold with 2-4bbl carbs. She ran great and never ran better.
I found this thread and found it very informative. What is the difference between the long and short tailshaft TH400? What are the advantages/disadvantages of them? Thanks alot for any info.
Bookmarked!! Very cool thread, I have always been a big fan of the THM400,,why did I just put a THM350 in my Lincoln? Duh... People just don't make sense...
The plug on the switch pitch TH400 has two connections, one is for kickdown, the other is for switch pitch. From one of the long posts above (right under the picture of the wires plugged into the trans) "The top tang is for the switch pitch" The control switch isn't very picky, it just needs to get power to the trans to make it go into high stall.
Some very good, interesting reading there. So i assume to run a s/p converter, you need one of those specific year transmissions that came equipped from the factory with one? I'm not seasoned with auto's, i'm much more a 4 speed guy, but the s/p set up has always been of interest to me and now that i run a 400 in my truck, it's of even more interest. But, i didn't know if i would need just an s/p conv, or a whole new trans.... Squirrel, you run one of these in your 55 right? Any input on this? Thanks for the info.. Tony
subscribed, this is good info, i have a pontiac 400 but i dont really want to use it because its a power hog and hot rods are funner with 3 pedals
I'm going to be switching manually. So, should I be running power on each pole on a dashmount toggle switch and switch between the 2 positions (on/off) to engage/disengage switch pitch and kickdown?
Some very informative TH400 information. I've always been a big fan of them, but I have some drag racing buddies that really frown on them, preferring the Powerglide naturally, or even the TH350 for freeing up a few horspower. After looking for a pretty long time, I was finally able to purchase a TH475 out of a fire engine and had it built up for my car accordingly. I consider it the "Rockcrusher" of GM automatics! I even cut it for an Ultrabell and consider this my "lifetime" automatic. It's on the short list, along with my Magnesium wheels, of things I never want to sell!
my first th400 came from a junk yard 68 biscayne with a 307, paid $50 with the cross member, a torch a sledge hammer and a couple of hours later it was in my 72 nova, the cross member needed a little adjustment to fit, i have one now in an 80 pickup, can i convert it to a slip yolk from a bolt on yolk?
You need only a single pole, single throw (two terminal) switch for the switch pitch. Connect one side of the switch to a fused, switched power source (like the power that runs the radio, wipers, that sort of thing), and connect the other side of the switch to the trans. When the key is on, and the switch is on, it will go into high stall. When you switch the switch off, it will go to low stall. For kickdown, you REALLY want a proper kickdown switch, a momentary switch that engages as the throttle linkage reaches full throttle. No toggle switch here...either find an OEM switch or one of the aftermarket ones. Tony-- You need the switch pitch parts out of one of those transmissions, but to use them in a Chevy you either need to get an adapter to put a buick or olds trans behind your engine, or find an early (60s or 70s) Chevy case that has the passage cast into it, and put the guts in it. You need to make sure to get the orifice in the case installed or it wont' work.
I'm wiring my own switch at the dash. I'm using a 2 pole switch. does it matter which pole the hot side is on? Should the constant hot run to the top or bottom side of the plug at the tranny? I just stumbled on the switch pitch connection last night. Thanks!!
It should be as simple as unbolting the old one. Same seals and everything. Good luck with the project
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