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TH-400 Build options and information

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 extensively. From a mild street cruiser, to an 800 HP race car, it's tough to beat, for value, reliability, and performance.


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- 12" and 13" converters are heavy. Our 9.5" 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 welded, high quality torque converters on the market now. We are the exclusive provider of Hi Performance VP converters these days.

 The VP setup adds a "neat" dimension to your project, and allows the advantages of a higher stall converter, without the excessive heat buildup, and slippage. Itis 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".

All our transmissions are built with full metal thrust washers, and complete attention to detail. All steel deep pan equipped transmissions come with a welded in drain plug kit, which is exactly like an oil pan drain plug.  Full satisfaction guaranteed.  We use only the Trans - Go premium shift/durability upgrade kits. Compare our prices to others, who don't use this $100 Kit, and you can see the value.

And we don't paint our transmission cases, black, silver, or any other color. Paint is used to keep metal driveline parts from rusting, and last I checked, aluminum does not rust! The real reason transmission cases are painted, is because it's cheaper to paint, than to bead blast. Don't be fooled.


Level 1

This service includes full disassembly and inspection of the transmission. It is not a full custom rebuild, but rather a re-seal and friction material replacement, with the installation of a Trans go shift kit, adjustable vacuum modulator, and dyno testing the function of the trans. Trans is cleaned using conventional methods, case gets 1 hour in the glass bead cabinet. All internal and external seals replaced. Most trans shops consider this a “rebuild”.

 If you want a good working TH-400, but don’t quite need the torque capacity of our higher performance Level 2 trans. This is a good option, and value, for the typical high performance street cars out there.

1-year warrantee on trans parts/labor


Level  2

This is our full custom rebuild for a street strip car. Includes fully glass bead blasted case, deeper Aluminum oil pan,  Hi performance clutches and steels, HD roller bearings, an adjustable vacuum modulator, and our high rpm governor. Built with the early style intermediate Sprag clutch drum, with a HD sprag assembly. Up to 7 clutches in the  direct pack, and 5 in the intermediate  is optional. Fully blueprinted and detailed. No better 400 can be built at any price. Full three-year warrantee. If you can hurt this one, I will fix it! Fully dyno tested and leak checked.

Use this option if you want the ultimate in Automatic Transmission performance and durability.

Our most popular street/strip trans. This is the culmination of many years of drag racing our company street/strip cars. This is the trans for a High performance application, all of the ones pictured below are Level 2 units.

Level  3  
Our trans brake equipped racing 400.

This is a Level 2 trans with a trans brake installed, and an aluminum deep pan. Six clutches in the forward and direct clutch packs standard. Up to 7 available in the forward/direct clutches and 5 in the intermediate This is the same trans that has been used sucessfully in our winning race cars for the last 15 years!

Race only, no automatic shift features. Reverse shift pattern.



Pricing and options

Level 1 Turbo 400  An excellent stock type rebuild, with shift and durablity upgrades, options available. TSP-400-1 $895.00

Level 2 Turbo 400  Our best seller- a good value on a first class TH 400 TSP-400-2 $995.00

Level 3 Turbo 400- Trans Brake equipped race transmission TSP-400-3 $1395.00

Add sprag clutch drum and HD sprag to Level 1 ( ‘71/later trans) add $175.00
Add deep steel w/drain plug pan to Level 1 add $75.00
Substitute alum pan for steel deep pan in Level 2 add $75.00
Level 2 clutch upgrade  - Direct - 7 clutches/nitrided steels add $169.00
Level 2 clutch upgrade - Intermediate clutch - 5 clutches and nitrided steels add $149.00
Variable Pitch Transmission upgrade (not including converter) add $295.00
2.75 low gear set add $475.00
All transmissions are exchange priced- to purchase outright add $175.00  

Give us a call today, we will help you sort thru the maze of options to get the right trans for your project!


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