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When quality counts you can count on J.W. Performance Transmissions. Our reputation for quality and innovation is known worldwide. Every J.W. Performance Transmissions products are backed by a product warranty but chances are you won’t need to use it. J.W. Performance Transmissions product return ratio is less than 1%. J.W. Performance Transmissions will celebrate its 32nd year anniversary in 2008. Originally, the company started by simply rebuilding transmissions but today over 250 new products have been introduced to the marketplace with over eight different product lines serving many different markets. While the competition is busy copying our revolutions of two decades ago we are producing the next big turbo-hydro 400 revolution. Our commitment to Quality, Innovation and Customer Service has remained the same over the past 32 years.

TH-400 Trans Brake

Description:

JW’s New Trans-Brake Brings Quicker Launches, Increased Consistency

And Greater Reliability To Racers Using The TH-400

Story & Photos By Jim Hill

          When it comes to race performance, there’s a “holy trinity” of automatic transmissions produced by General Motors and used by their various divisions.  These three most popular transmissions are the Powerglide, a two-speed automatic that first appeared as a cast-iron unit available in 1955 Chevrolets; The Turbo-Hydramatic 350 (TH-350), first offered for the V-8 ’68 Camaro; and The Turbo-Hydramatic 400 (TH-400), for high torque engines such as the big-block Chevy 396-427.  The TH-350 and TH-400 units both offer three forward speeds and have two sets of planetary gears.  All three are known for their basic simplicity and reliability. 
           

          Of the three units the Turbo-Hydramatic 400 is the strongest.  Like the TH-350, the Turbo-400 offers three forward speeds plus reverse, neutral and park, and is especially favored by racers running heavier full-bodied cars, high-torque, big-block engines or those running “power enhancers” such as superchargers, turbochargers or Nitrous-Oxide.  Turbo 400’s are also rules-required for some NHRA and IHRA Super Stock and Stock Eliminator classes in which the 400 was offered as the production transmission for specific big-block engine options.  Those very famous and now rare L-72 C.O.P.O. option, 427-425 HP ’69 Camaros and LS-5/LS-6 454 Chevelles and Corvettes came with the TH-400 as did big-block powered Chevy and GMC trucks.
         

          Because the Turbo 400 is a bigger, beefier version of the GM TH-350, this added strength comes with increased rotating weight and mass of its gears and internal components.  As all good racers know, weight and mass absorbs horsepower produced by the engine, and those stronger, wider gears increase what the engineers refer to as “parasitic loss”, due to greater friction.  Just how much power is sacrificed to a TH-400 over, say, an aftermarket design, two-speed Powerglide varies by application.  Despite this shortcoming, when power and torque exceed the capability of an automatic transmission to resist component failure, the answer is often found in a Turbo 400.  It’s also still reasonably easy to locate a used Turbo 400 transmission core as a starting point, and the cost of a racing rebuild is also still attractive.
           

          To compliment their inherent strength, the Turbo 400 can be readily improved with upgrades, courtesy of the very innovative performance and racing aftermarket.  Improvements such as numerically higher, first-gear sets, improved clutches, steel separators, bands and other components render this already robust transmission even stronger.  When high HP engine output or heavy-car issues are at hand, this added strength is obviously welcome.
           

           The next obvious improvement to the TH-400 has to be the addition of a reliable, electronically activated Trans-Brake, to allow more precise driver launch control and to raise starting line engine RPM.   JW Performance Transmission, the same Florida folks who created the Ultra-Bell replacement bellhousing and “The Wheel”, steel flexplate flywheels for serious drag racing, now offers a brand new, precision manufactured, JW Trans-Brake for Turbo 400’s.
           

         JW’s new Trans-Brake brings the instant engagement capabilities of a Trans-Brake to the proven strength of the TH-400.  This combination of brute strength plus consistent, accurate engagement means more consistent starting line launches, quicker 60’ short times and lower reaction times when correctly matched with the right torque converter stall speed, cam profile and traction availability.  When these items are properly matched the result is more round wins with less breakage, something any serious racer is seeking.
           

           JW’s new TH-400 Trans-Brake is available as Valve Body Part No. 30218-RN, or  Trans-Brake Part No. 30550-BRN.  The JW Trans-Brake is a Reverse-Only manual brake design, and allows you to take greater advantage of the stall speed of the selected torque converter by increasing the engine speed (rpm) at which the car leaves the starting line.
           

           While it’s not the same as a Pro/Stock, sky-high launch, a properly set up, brake-equipped automatic transmission and tuned suspension system offers a tremendous upgrade in performance potential and launch consistency.
           

           A specific advantage to this new Trans-Brake, according to JW President and founder, John Winter, is it operates with lower line pressure while in Park or Neutral, but provides increased line pressure when in 1-2-3.  The new JW design valve body is CNC machined from T-6 aluminum alloy material.  CNC machining is significantly more accurate than the casting processes used by other manufacturers, and allows dimensions in all fluid passages to be tightly controlled.  This machining accuracy translates into improved response, quicker release and quicker, more precise upshifts.
          

          Each JW TH-400 Trans-Brake is carefully assembled by master racing transmission technicians, and then each unit is in-house tested for both performance and reliability on JW’s own transmission dynamometer.  John Winter’s dedication to quality is commendable, but he is quick to explain that it’s the only way he can guarantee a 100% fail-safe unit going to racers.  John’s oversight and insistence on this quality is something he championed when he began JW Performance Transmissions 30+ years ago, and this credo continues throughout the company’s product line.  In drag strip field tests of the new JW TH-400 Trans-Brakes all those who tried the new brakes reported complete satisfaction with the new units, and more importantly, zero failures!  
           

          GM’s Turbo 400 units were installed in several hundred thousand, big-block powered Chevy cars and trucks, but in spite of those OE numbers, Chevy TH-400 units still have the lowest total GM production numbers.  These carried a Chevy bolt pattern bellhousing.  Considerably more TH-400’s were installed in “B-O-P” (Buick-Oldsmobile-Pontiac) vehicles, but these vehicles used a different B-O-P bellhousing bolt pattern. TH-400 Chevy units are more difficult to locate, and of course, are more pricey than B-O-P 400’s.  But, the hot rodder inspired, performance aftermarket now offers a viable solution, a sturdy, reengineered, aftermarket bellhousing that carries the more desirable Chevy bolt pattern.
           

          One such example is JW Performance Transmission’s “Ultra-Bell” unit.  These require careful band saw removal of the stock bellhousing so the 400 transmission case can be used with the aftermarket housing, but this also allows use of the less expensive B-O-P Turbo 400 transmission.  Taking a saw to an aluminum case transmission may make you nervous, but the folks at JW tell us this is merely minor surgery, and the “patient” is well served by this procedure.  After this it’s a fairly straightforward job to adapt a B-O-P unit for easy bolt-on to a Chevy simply by using a JW Ultra-Bell.  This modification also yields a TH-400 unit that is significantly stronger, due to the race-inspired, structurally improved design of the Ultra-Bell housing.  Reducing or eliminating trans case flex insures that internal components remain in place, retain their alignment and reduce more of that pesky parasitic power loss due to side-loading of gears when a stock case does the “hootchy-cootchy” while being torqued by a big-inch, big-torque, big-block engine.  It’s a classic case of a situation where being completely inflexible is a drag racing attribute!
           

          The new JW TH-400 Trans-Brake is a perfect addition to a JW race transmission system.  This includes the new JW Trans-Brake, a JW Ultra-Bell one-piece racing bellhousing, a JW “The Wheel” flywheel and a complete JW built racing transmission for a driveline package that’s not only stronger and more reliable, but quicker and more consistent.  And that’s what drag racers everywhere are seeking!
           

          The new JW TH-400 Trans-Brake Valve Body, Part No. 30218-RN, or Trans-Brake, Part No. 30550-BRN, and other fine JW products are available by calling JW’s performance/racing drivetrain tech help experts at JW Performance Transmissions, 1829 Baldwin Street, Rockledge, FL 32955, (321) 632-6205, or their website at: www.racewithjw.com

Features:

THE FIRST EVER TURBO-HYDRO 400 ALUMINUM AFTERMARKET TRANSMISISON BRAKE AND REVERSE PATTERN VALVE BODY COURTESY OF J.W. PERFORMANCE TRANSMISSIONS.

- Aluminum cast valve body

- CNC precision machined for improved oil passages

- The only transmission brake with two check valves

- In house and field tested

- Available in reverse pattern only (30218RN) and reverse pattern transmission brake ( 30551BR)

- This hot new product is only $173.81 for part number 30218RN and $431.36 for part number 30551BR.

- Backed by a 90-day product warranty

- Available through J.W. Performance Transmissions distributors world wide