High Performance Big Block Cadillacs
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Author Topic: Turbo-Hydramatic 400  (Read 28818 times)
~JM~
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« Reply #15 on: December 03, 2007, 03:03:12 PM »

15


* Stampies TH400 Info 7.jpg (49.99 KB, 825x638 - viewed 622 times.)
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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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« Reply #16 on: December 03, 2007, 03:05:42 PM »

Pageboys Shift Kit for the TH400

Here is my own poor man's shift kit for the TH400. Referring to the spacer plate diagram, hole A and the check ball near it control the 1 - 2 shift. On a 1 - 2 up shift, the check ball is closed, forcing fluid through the restriction hole slowing the shift. On a 2 - 1 downshift, the check ball opens bypassing the restriction hole and allowing an immediate downshift. Hole B controls the 2 - 3 up shift; there is no check ball used with it. Fluid is forced through the restriction hole, slowing the up shift. Hole C and the check ball nearest it control the 3 - 2 downshift. On a 2 - 3 up shift, the check ball is open so that only hole B controls the up shift. On a 3 - 2 downshift the check ball closes and fluid is forced through restriction hole C, slowing the downshift. The idea was to give the engine a little time to rev up before second gear engages. These holes will be various sizes in different cars, depending on how softly the General thought a car should shift. For starters, open up holes A and B by .020 over their original size, and go for a test drive. This will give an idea of how much the shifts will be firmed up. These holes can be opened up to any size you want, but consider about 3/16 to be a practical maximum, because at the size, the holes will not offer any more restriction to fluid flow. Also, removing check ball A would have the same effect as drilling out the restriction hole, as without the check ball there, fluid will bypass the hole all the time. Check ball C can removed no matter what, bypassing restriction hole C all the time. The engine simply doesn't need any extra time to rev up. Some later transmissions don't have a hole under check ball C, and it's already completely nonfunctional. If this is the case, then remove the check ball and drill out hole C to 3/16. Most TH400s have 6 check balls in them to start with, but after these mods you might put back in only 5 or 4 check balls. This way when you lose one in your gravel driveway, you will have an extra or two that can be used. After drilling out a hole in the spacer plate, use a drill bit by hand about double the size of the hole to de-burr the hole on both sides of the plate. The diagram shows where the check balls go. In the area where there are two check balls with the word OR in between them, the check ball can go in either place as the spacer plate is installed. It goes into the same passage in the transmission case. If the holes get drilled out to 3/16, this firmness level is all that can be done with the spacer plate. And this really does quite a bit. My car can more than chirp the tires at each shift under hard throttle.

I would also recommend removing the spring from underneath the 2 - 3 accumulator piston. Even the factory didn't install this spring in some high performance cars. This firms up the 2 - 3 shift. Sometimes the accumulator piston can be flipped upside down in the valve body without the spring there, firming up the 2 - 3 shift a little more. And sometimes it can't. If it can't, put it in right side up and don't lose any sleep over it. Further details and pictures for this and other shift improving modifications can be found in Ron Sessions' book. But the kind of information given above I have never seen in print anywhere. I figured it out for myself the hard way. Now we'll see how the size of this diagram turns out.



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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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« Reply #17 on: December 03, 2007, 03:06:52 PM »

 Grin


* Page Boys Shift Kit For The TH400 Valve Body.jpg (126.9 KB, 800x704 - viewed 757 times.)
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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
~JM~
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Posts: 1854


« Reply #18 on: March 10, 2008, 05:25:42 PM »

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.

http://www.hemmings.com/mus/stories/2004/12/01/hmn_feature13.html
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PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
steelybill
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« Reply #19 on: March 04, 2010, 10:22:42 PM »

 

 Thanks for posting all that info JM.  I sort of wish I would have researched more before I rebuilt mine.  The one I'm using isn't from a Caddy I think. It has one less clutch.  I did use a Transgo 1-2 shift kit, so maybe it will survive.  It's not bolted in yet, so if it bugs me too much, I'll take it apart enough to do a bit more to it.
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Schurkey
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« Reply #20 on: January 21, 2014, 03:43:38 PM »

Turbo 400 Transmissions

Hemmings Muscle Machines - DECEMBER 1, 2004 - BY JIM O'CLAIR

 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.
Suspect info.  The TH350 has essentially no interchangeable parts with the 400 other than the governor, modulator, and torque converter.  The internal workings are very different.  I'd like to know who did the research, and what the protocol was, to determine how much HP the 350 and 400 "use".

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.
The '64 valve body was SIGNIFICANTLY different from the '65-onward valve body.  The '64 valve body is more closely related to the TH425 front-drive transmission.

NOT all '65, 66, 67 TH400 had the switch-pitch torque converters.  Switch-pitch was typically only used on Olds and Buick big-block engines, and Cadillac.  Switch-pitch was never installed in a Chevrolet or Pontiac TH400.

Remember that the TH400, like all the other GM automatics, had hundreds of variations relating to valve body and governor (shift timing and quality) along with variations in number of clutches (torque capacity).  A TH400 behind a small-block in a taxi had fewer clutches and lower torque capacity than one installed behind a "performance" big-block, or one pulling a limousine around town.

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.
There are two designs for the pans, aside from "deep" pans for added fluid capacity.  The early "box" filter required the early pan, and the late "flat" filter requires the late pan.  An early-style pan does NOT indicate a switch-pitch transmission, although all switch-pitch transmissions were built with the early pan.
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~JM~
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Posts: 1854


« Reply #21 on: January 23, 2014, 09:39:39 AM »

Schurkey,

Thank you for the clarification. I tried to present the most accurate information that I could find.

Good luck
~JM~
Logged

PS. You don't have enough cam. Grin

...Summit has a kit for $99.... Shocked
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