SHIFTING FORWARD

SHIFTING FORWARD

A STRONG CASE FOR THE GM 200-4R IN PERFORMANCE STREET MACHINES

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By Terry Cole

There was a time when performance car builders didn’t give a second thought to what transmission was going to be used to transmit power from the engine to the rear wheels. In fact, if you go back far enough, there wasn’t even a choice. A manual gearbox was the only thing available, and shifting became a staple of a performance machine. Catch phrases such as, “banging gears,” “double-clutch,” and “power shift,” were mainstays on the boulevard and quarter-mile track.

 

copyPerformance aftermarket icon Art Carr has been in the transmission business for more than six decades. The trannys he produces from his California Performance Transmission shop in Huntington Beach have been used in virtually every type of application – from wicked street machines to full-on race vehicles for every form of off-road competition.

Performance aftermarket icon Art Carr has been in the transmission business for more than six decades. The trannys he produces from his California Performance Transmission shop in Huntington Beach have been used in virtually every type of application – from wicked street machines to full-on race vehicles for every form of off-road competition.

When the factory muscle car era was ushered in during the late 1950s, virtually all the high-power rides came standard with a manual transmission – usually a “three-on-the-tree” – thus the reference to “standard” when referring to the car’s gearbox. The next wave of cool names like “Rock Crusher,” “Top Loader,” and “Super T-10,” rolled off the lips of enthusiasts as the trend in high-power machines led enthusiasts to the dealerships in the 1960s when big-inch engines upped the power ante and four-speeds replaced the column-shifted three-speeds. Enthusiasts used these transmission names proudly while pointing out what was in their rides. To order anything else was considered an affront to performance and a “lazy-man’s option.”

copyA large percentage of the transmissions produced by Carr’s expert staff find their way into modified street machines and muscle cars. Recently, Chevymax.com visited the California Performance Transmission digs to watch as a beautifully restified ’67 Chevelle SS had its Turbo 400 swapped out for a custom-built 2004R.

A large percentage of the transmissions produced by Carr’s expert staff find their way into modified street machines and muscle cars. Recently, Chevymax.com visited the California Performance Transmission digs to watch as a beautifully restified ’67 Chevelle SS had its Turbo 400 swapped out for a custom-built 2004R.

Of course, over time the automatic transmission chipped away at the manually shifted world and became a viable alternative for those serious about getting to the finish line – or next stoplight — first. Not only did the automatic transmission, bearing monikers such as “Powerglide,” TorqueFlite,” “C-6,” and “Turbo Hydramatic” do the work of upshifting for the driver, but minimalized the wear-and-tear associated with clutches, pressure plates and throw-out bearings. Not to mention that automatics were easier on suspension components and could be dialed in for better launching off the starting line. A good torque converter with the appropriate stall speed was the key to getting the car to work best.

 

copyWhile a perfect fit behind the Chevy 396-cid big-block powerplant, the factory installed TH 400 is limited when it comes to improving drivability and reliability of the gas-guzzling Rat motor. This example had an aftermarket larger-capacity oil pan installed.

While a perfect fit behind the Chevy 396-cid big-block powerplant, the factory installed TH 400 is limited when it comes to improving drivability and reliability of the gas-guzzling Rat motor. This example had an aftermarket larger-capacity oil pan installed.

 

copyThe removal process started at the back of the car with the removal of the U-joint straps connecting the driveshaft to the rearend.

The removal process started at the back of the car with the removal of the U-joint straps connecting the driveshaft to the rearend.

After the downturn in performance brought on by the global “Fuel Crisis” era, manual gearboxes were in small demand in American cars, despite their known advantage in fuel economy over their automatic sibling. The general public simply lost its desire to shift manually and some mainstay machines, like Corvettes and Camaros, which traditionally had manual transmissions, found Powerglides and TH 350s in the tranny tunnel instead.

 

copyWith the four bolts holding the straps in place out, the shaft was removed from the 12-bolt’s yoke and ready for removal. Due to a new tight-fitting dual exhaust system, the driveshaft had to wait until the transmission was dropped down before being taken out of the car.

With the four bolts holding the straps in place out, the shaft was removed from the 12-bolt’s yoke and ready for removal. Due to a new tight-fitting dual exhaust system, the driveshaft had to wait until the transmission was dropped down before being taken out of the car.

That leads us to the second coming of performance and the advent of computer-controlled machines. While not dead, the manual gearbox gave way in the performance world to the automatic overdrive transmission. In the early 1980s, with fuel-injected engines taking the automotive world by storm, General Motors released a lineup of overdrive, four-speed automatics that were up to the task of harnessing the tremendous torque being produced by the fuel-injected power plants. Most well known from that era is perhaps the GM 700R4, a big, bulky and electronic-laden transmission that was found in everything from Corvettes to SUVs. These transmissions were an instant hit with custom car builders and enthusiasts and found their way into everything from street rods to tow vehicles. The overdrive fourth gear allowed the owner to run a lower rearend ratio for quicker performance and the 700’s gear ratio spread meant more efficient use of an engine’s power band.

 

 

copyUnbolting the transmission from the engine is pretty straightforward. Using the correct tools helps the job move along quicker, but patience is still a necessary element. Here an extension is used to get to some of the harder to reach fasteners.

Unbolting the transmission from the engine is pretty straightforward. Using the correct tools helps the job move along quicker, but patience is still a necessary element. Here an extension is used to get to some of the harder to reach fasteners.

 

copyHere the original cable linkage and bracket for the factory console-mounted shifter is removed from the side of the transmission oil pan. Since the 2004R is an overdrive transmission, the linkage must be upgraded in order to be used with the stock factory shifter. A special kit from Shiftworks handles the job with new hardware and the correct cable.

Here the original cable linkage and bracket for the factory console-mounted shifter is removed from the side of the transmission oil pan. Since the 2004R is an overdrive transmission, the linkage must be upgraded in order to be used with the stock factory shifter. A special kit from Shiftworks handles the job with new hardware and the correct cable.

 

copyOnce the bolts holding the transmission to the engine are removed, the next step was to loosen the three bolts holding the torque converter to the flywheel (flexplate). Once more, having the right tools makes the job that much easier and efficient. Busted knuckles are no fun when standing beneath the car. In this case, the technicians used a specialty ring gear wrench to rotate the flywheel, which allowed easier access to the three bolts.

Once the bolts holding the transmission to the engine are removed, the next step was to loosen the three bolts holding the torque converter to the flywheel (flexplate). Once more, having the right tools makes the job that much easier and efficient. Busted knuckles are no fun when standing beneath the car. In this case, the technicians used a specialty ring gear wrench to rotate the flywheel, which allowed easier access to the three bolts.

 

copyThe transmission fluid lines from the TH400 will be reused with the new 2004R. Loosening them with the correct flare wrench helps to minimize any stripped nuts holding the flared ends in the case. Of course, having a drain pan in place helps keep the tranny fluid off the floor.

The transmission fluid lines from the TH400 will be reused with the new 2004R. Loosening them with the correct flare wrench helps to minimize any stripped nuts holding the flared ends in the case. Of course, having a drain pan in place helps keep the tranny fluid off the floor.

But the 700R4 had a few things working against it. First and foremost, it was expensive initially, and often cost-prohibitive to repair and/or modify. Plus it was an electronic-controlled unit, making its adaption into a vintage muscle car more complicated in those early years of electronics. It was big and bulky and weighed considerably more than a Powerglide or TH 350.

 

 

copyOnce the two mount bolts are out, the heavy TH 400 transmission can be jacked up and the crossmember removed.

Once the two mount bolts are out, the heavy TH 400 transmission can be jacked up and the crossmember removed.

 

copyTwo bolts and nuts on each end of the crossmember fasten it to the side rails of the frame. Once removed a little maneuvering back and forth will allow the crossmember to drop down and out of the way.

Two bolts and nuts on each end of the crossmember fasten it to the side rails of the frame. Once removed a little maneuvering back and forth will allow the crossmember to drop down and out of the way.

 

copyOnce the crossmember is removed, the transmission jack is lowered and the strapped-on TH400 comes out from behind the big block with relative ease. Note that the dipstick tube is still in place. Prior to dropping it down, the vacuum line attaching the 400’s shift modulator to the intake manifold was removed. The 2004R uses a T.V throttle cable instead of a vacuum modulator for shift control, so the port on the manifold will have to be capped to prevent a vacuum leak.

Once the crossmember is removed, the transmission jack is lowered and the strapped-on TH400 comes out from behind the big block with relative ease. Note that the dipstick tube is still in place. Prior to dropping it down, the vacuum line attaching the 400’s shift modulator to the intake manifold was removed. The 2004R uses a T.V throttle cable instead of a vacuum modulator for shift control, so the port on the manifold will have to be capped to prevent a vacuum leak.

For those who searched out alternatives there is one transmission that has transcended the generations to be more popular today than ever. The GM 2004R was released a year before its bigger brother and immediately found a cult following among diehard performance enthusiasts and racers who embraced its simplicity and smaller footprint. These attributes made it a perfect replacement for the old TH lineup of 350s and 400s and a no-brainer to replace the antiquated Powerglides.

 

copyWith the transmission removed and out of the way, the driveshaft was lowered and taken out. In most cases, the original driveshaft will be reused since the small length difference between the transmissions is made up for with a new yoke.

With the transmission removed and out of the way, the driveshaft was lowered and taken out. In most cases, the original driveshaft will be reused since the small length difference between the transmissions is made up for with a new yoke.

copyBefore installation, each transmission is custom assembled using top-of-the-line parts and each is dynamometer tested to make sure it shifts correctly and on target and is void of any leakage. The 4-speed overdrive automatic is available in four different versions to suit a particular power range all the way up to 1000 horsepower. Also installed was a high-performance non-lockup torque converter with a 2400-rpm stall speed.

Before installation, each transmission is custom assembled using top-of-the-line parts and each is dynamometer tested to make sure it shifts correctly and on target and is void of any leakage. The 4-speed overdrive automatic is available in four different versions to suit a particular power range all the way up to 1000 horsepower. Also installed was a high-performance non-lockup torque converter with a 2400-rpm stall speed.

 

 

 

 

 

 

 

 

 

 

 

 

copyHere’s the California Performance Transmission 2004R on the lift ready for the converter and then to be plugged into the Chevelle. Installation is simply the reverse of the removal process used on the TH400, with the exception of the linkage assembly and the vacuum line.

Here’s the California Performance Transmission 2004R on the lift ready for the converter and then to be plugged into the Chevelle. Installation is simply the reverse of the removal process used on the TH400, with the exception of the linkage assembly and the vacuum line.

Quietly, GM knew they had a workhorse in the 2004R as they slipped it into a new generation of muscle cars other than the Camaro and Corvette. The Buick Grand National, with its potent turbocharged V6 was the perfect proving ground for the 200. The Buick had tons of power, and was a heavy, rear-wheel-drive mid-size coupe in need of a strong gearbox, but one that would withstand the torque from the turbocharged engine and still maintain a level of economy to allow it to pass the strict fuel efficiency requirements of the federal government. And, its smaller footprint made it the perfect choice.

copyCarr uses a special shifter upgrade kit from Shiftworks, which allows the stock shifter to be used with the extra gear. Included are all the mounting brackets and hardware for the cable and a new pattern detent gate for the “Horseshoe” shifter. The high quality kit also comes with a new visual marker showing the now-familiar “D” with a circle around it, denoting overdrive.

Carr uses a special shifter upgrade kit from Shiftworks, which allows the stock shifter to be used with the extra gear. Included are all the mounting brackets and hardware for the cable and a new pattern detent gate for the “Horseshoe” shifter. The high quality kit also comes with a new visual marker showing the now-familiar “D” with a circle around it, denoting overdrive.

 

copyInstalling the Shiftworks upgrade is straightforward, and with detailed instructions should be a piece of cake for any hands-on enthusiast.

Installing the Shiftworks upgrade is straightforward, and with detailed instructions should be a piece of cake for any hands-on enthusiast.

 

copyThe Shiftworks kit includes a new, correctly bent transmission shifter arm. That was the first part installed after the 2004R was in place. Note the stud for the end of the new cable.

The Shiftworks kit includes a new, correctly bent transmission shifter arm. That was the first part installed after the 2004R was in place. Note the stud for the end of the new cable.

Today, the acceptance and use of the 2004R in the performance world is secure. And one of the reasons for its stellar reputation among muscle-car enthusiasts, racers and street-rod builders is due to the research and development by California Performance Transmissions and its owner Art Carr. A longtime staple in the performance and racing world, and Hot Rod Hall Of Fame member, Carr has refined and perfected the 2004R to the point where it is a direct bolt-in replacement for many classic muscle cars whose owners are looking for modern drivability and increased fuel economy without any sacrifice in performance. For more than six decades, Carr has been building performance transmissions and the modifications he has incorporated into the 2004R are designed to exceed the capabilities of any big-power muscle car or street rod.

 

copyThe cable bracket simply bolts to the transmission oil pan rail by removing a couple fasteners and locating it in place. Care was taken to make sure that the bolts were tight enough.

The cable bracket simply bolts to the transmission oil pan rail by removing a couple fasteners and locating it in place. Care was taken to make sure that the bolts were tight enough.

 

copyHere’s what the new cable looks like when mounted correctly in its bracket and the pivot end attached to the shift lever. A special clip is used to keep the cable firmly in place in the bracket.

Here’s what the new cable looks like when mounted correctly in its bracket and the pivot end attached to the shift lever. A special clip is used to keep the cable firmly in place in the bracket.

 

copyThe pivot pin where the end of the cable attaches must be adjusted correctly so that the cable moves the shift lever throughout its entire range – from Park to Reverse to Nuetral and the four forward gears.

The pivot pin where the end of the cable attaches must be adjusted correctly so that the cable moves the shift lever throughout its entire range – from Park to Reverse to Nuetral and the four forward gears.

With four different versions available, this venerable transmission can be tailored to fit every budget or horsepower rating. And with dimensions almost identical to the time-proven TH 350 three-speed automatic, major modifications to the body’s tunnel and/or firewall are unnecessary and, in most applications, the stock crossmember is retained.

 

CARR24

copyNote the absence of a vacuum modulator as seen on the old TH400. As mentioned earlier, the 2004R uses a T.V. cable that is attached to the carburetor linkage to control shift points. Its elimination means that the vacuum line that was attached to the intake manifold is removed and the fitting must be plugged. Note the quality brass fittings for the transmission cooler lines.

Note the absence of a vacuum modulator as seen on the old TH400. As mentioned earlier, the 2004R uses a T.V. cable that is attached to the carburetor linkage to control shift points. Its elimination means that the vacuum line that was attached to the intake manifold (below) is removed and the fitting must be plugged. Note the quality brass fittings for the transmission cooler lines.

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To get a first-hand perspective on just how easy this swap is, we took a drive over to Carr’s Huntington Beach, California facility where they had a customer’s beautiful big-block-powered ’66 Chevelle SS on the lift ready to undergo the swap from the TH 400 to the new 2004R and its accompanying 2500-stall-speed converter.

 

copyHere’s the business end of the T.V. cable that is routed up to the carburetor.

Here’s the business end of the T.V. cable that is routed up to the carburetor.

 

copyThe bracket for the T.V. cable (and if used, a throttle cable) is mounted to the rear carburetor stud.

The bracket for the T.V. cable (and if used, a throttle cable) is mounted to the rear carburetor stud.

 

copyA special bracket is attached to the carb’s throttle linkage. Note the washer used to correctly position the top of the bracket. The throttle link rod is attached here.

A special bracket is attached to the carb’s throttle linkage. Note the washer used to correctly position the top of the bracket. The throttle link rod is attached here.

 

copyOnce mounted in the bracket, the T.V. cable attaches to the bottom of the special carb linkage and has an adjustable brass stop to allow for the correct position of the cable.

Once mounted in the bracket, the T.V. cable attaches to the bottom of the special carb linkage and has an adjustable brass stop to allow for the correct position of the cable.

This particular Chevelle had been fully restored, but with a few subtle updates sitting hidden beneath its skin it was outfitted for today’s world of traffic conditions and economic environment and at the same time provide the driver with the blast-from-the-past power of a big-block motor beneath the hood. The original TH 400 was still residing in the tunnel behind the Fat Rat; while the new 2004R was on the transmission stand ready to be put in place.

 

copyCooling the transmission fluid of the factory TH400 was the job of the car’s radiator. Keeping the transmission fluid from overheating is an important part of maximizing performance, so Carr’s team installs a dedicated Setrab transmission cooler to handle the job. The Sweedish-made coolers are world-renowned for keeping fluid temps down and are top choice of many race teams and OEMs.

Cooling the transmission fluid of the factory TH400 was the job of the car’s radiator. Keeping the transmission fluid from overheating is an important part of maximizing performance, so Carr’s team installs a dedicated Setrab transmission cooler to handle the job. The Sweedish-made coolers are world-renowned for keeping fluid temps down and are top choice of many race teams and OEMs.

Taking out the old trans was straightforward, with no removal of the custom dual exhaust necessary. Once the bolts were removed from the torque converter and bellhousing, it was simply a matter of disconnecting the stock shifter cable, removing the driveshaft’s rear U-joint straps and the crossmember fasteners to the tranny mount and frame. The crossmember came out easily when the trans was lifted up off its rear mount about an inch or so. The driveshaft, due to the exhaust pipes running close together just beneath it was removed once the transmission was lowered.

 

copyThe top-notch coolers can be used with AN-fittings and steel braded hose, as well as push on connections for the more common rubber hose. In this application, Team Carr used the original steel lines and spliced in the new cooler with rubber hoses that simply pushed on to brass fittings on the cooler.

The top-notch coolers can be used with AN-fittings and steel braded hose, as well as push on connections for the more common rubber hose. In this application, Team Carr used the original steel lines and spliced in the new cooler with rubber hoses that simply pushed on to brass fittings on the cooler.

Once out, the old TH 400 was rolled off to the corner of the shop and the 2004R was lifted into place. Installation was basic and simply a reversal of the process used for removing the old trans. Only other procedures required were a straightforward installation of a Shiftworks adapter so that the original shifter can be retained (and work with the four forward gears), a new shorter driveshaft yoke was installed on the driveshaft and a high-efficiency transmission oil cooler was incorportated inline with the original radiator unit, for added cooling of the fluid.

 

COOLER3

copyRemoving the grille was necessary as the cooler was mounted vertically up high in the core support just in front of the radiator.

Removing the grille was necessary as the cooler was mounted vertically up high in the core support just in front of the radiator.

The oil cooler was positioned in front of the radiator off to the passenger side behind the grille. Fitting it required careful positioning of the unit and custom brackets so as not to damage the fins on both the radiator and cooler. The fluid lines were brought in from underneath and routed away from the lower radiator hose and any interference with the fan or harmonic balancer. The clean install with no kinks in any of the hoses was achieved by carefully routing the rubber hoses as short as possible, while staying clear of any potential obstacles.

 

copySpecial care was taken to not damage any of the cooling fins on either the cooler or the radiator, as it was at close tolerance fit. A piece of cardboard was put in place in front of the radiator during initial fitment.

Special care was taken to not damage any of the cooling fins on either the cooler or the radiator, as it was at close tolerance fit. A piece of cardboard was put in place in front of the radiator during initial fitment.

Once the 2004R and remote trans cooler were in place, buttoning up the swap was a snap, with the TV cable attached to the carb throttle linkage and the Shiftworks adapter positioned inside the factory shift mechanism. Both of these procedures require some attention to detail, but are pretty straightforward with clear instructions. The Shiftworks adapter required taking the top of the console off to expose the shifter handle mechanism. Once in place, the new detent plate coordinates with the 2004R’s shift cable to ratchet through all four forward gears as well as positions for reverse, neutral and park. Basically, it just adds one stop for the overdrive. Included in the update is a factory looking shift indicator panel reflecting the addition of a 4th gear.

 

COOLER6

copyWith the hoses in place, the cooler was positioned just below the top of the radiator support and secured with custom brackets at the top…

With the hoses in place, the cooler was positioned just below the top of the radiator support and secured with custom brackets at the top…

 

copy…and bottom

…and bottom

Attaching the TV cable, which will provide throttle position shifting and passing gear, is a basic install onto the throttle plate of the carburetor. The cable provides a link that is simply attached to an existing hole in the plate, while the cable bracket is attached to the left-rear carb hold-down stud.

 

copyOnce in place, the hoses are routed securely behind the bumper and in through the frame.

Once in place, the hoses are routed securely behind the bumper and in through the frame.

 

copyWith the overall dimensions being very similar to the TH400, the only modification necessary to the driveshaft was to install a new front yoke. Here the old U-joints are taken out and the yoke is removed.

With the overall dimensions being very similar to the TH400, the only modification necessary to the driveshaft was to install a new front yoke. Here the old U-joints are taken out and the yoke is removed.

 

copyDetermining which U-joint to use can be confusing, especially in a 50-year-old car such as this Chevelle SS. Over time the original driveshaft had been changed, so pinpointing the right units to use took a little time.

Determining which U-joint to use can be confusing, especially in a 50-year-old car such as this Chevelle SS. Over time the original driveshaft had been changed, so pinpointing the right units to use took a little time.

 

copyOnce the correct yoke and U-joints were in place, it was simply a matter of installing the driveshaft back under the car and bolting it up to the 12-bolt. Then it was off for a test ride, and getting the feel of having an extra gear.

Once the correct yoke and U-joints were in place, it was simply a matter of installing the driveshaft back under the car and bolting it up to the 12-bolt. Then it was off for a test ride, and getting the feel of having an extra gear.

While the transformation of this ’66 Chevelle SS 396 was pretty straightforward, with quality parts and ease of installation, the true value in this performance upgrade is the increase in drivability and economy. The latter, of course, not the primary concern when taking a muscle car with a big block for a spin to the local drive-in. But all things considered, it is nice to know that a gallon of gas will go a little farther when hitting the highway for the trip back home.

 

SOURCE:

CALIFORNIA PERFORMANCE TRANSMISSION

5502 Engineer Drive, Dept. CMX

Huntington Beach, California 92649

800.278.2277

 

 

 

TOUGH INTERNALS MAKE THE DIFFERENCE

copyEach transmission goes through a extensive rebuild process, and depending to what degree of performance is required, many parts are upgraded to heavy duty ones. Once the assembly is complete, the transmissions find their way onto the dyno for a thorough run-through. Shift points are calibrated, line pressure is checked and of course, oil leaks are looked for. this is a final step a custom-built transmission goes through prior to being shipped, or professionally installed.

Each transmission goes through a extensive rebuild process, and depending to what degree of performance is required, many parts are upgraded to heavy duty ones. Once the assembly is complete, the transmissions find their way onto the dyno for a thorough run-through. Shift points are calibrated, line pressure is checked and of course, oil leaks are looked for. this is a final step a custom-built transmission goes through prior to being shipped, or professionally installed.

 

The GM 2004R is not the first modern four-speed overdrive automatic to gain acceptance among the GM aftermarket street machine crowd. That title most likely is awarded to the venerable 700R4, which adorned the transmission tunnels of Corvettes and F-bodies during the rebirth of performance in the mid-1980s. The 700 offered street machine and street rod owners the availability of an extra forward gear, and one that featured an overdrive ratio, thus allowing enthusiasts to run a lower (higher numerically) final drive rearend ratio and still enjoy a fair amount of fuel economy.

 

But using the 700R4 was no easy task in terms of expense and adaptation. They were costly in the beginning years. But even the initial cost wasn’t the only concern when they were employed in high-powered applications. The most notable drawback was the weal input shaft and drum assembly of the 700. Made from aluminum, this posed a problem for vehicles with more than 500 horsepower under the hood. The power rating being even less if it was a heavy machine.

 

The strength issue was only one strike against the 700. Compared with the 200, which made use of better materials for the input and drum, other drawbacks include an overly steep 3.06 first-gear ratio, compared with the 200’s less-aggressive 2.74:1 number. This was especially important since most performance machines had an abundance of torque from their V8 engines. With a more friendly first gear, coupled with the other three ratios (1.57, 1.1 and 0.67) being closer, meant there was less of an rpm drop between shifts, which would mean that the engine was staying in its power range throughout the entire shifting process. While this may not amount to much with street-only machines, it was a definite improvement at the track. Another caveat of the 700 that applies more to spirited driving than just basic transportation mode is that the 700 would not go into overdrive under full-throttle acceleration. The 2004R has no such limitation and can handle the torque of that Rat motor from first through fourth at wide-open-throttle!

 

As mentioned, California Performance Transmission offers varying degrees of performance levels with its 200-4R gearbox. Whether your car’s engine is a relative sedate 400-horsepower or a brute with more than 1000 ponies on tap, Art Carr and his team of experts can assemble a transmission dedicated to your specific application. Differences, like most other upgrades in engine combination and suspension systems, depend entirely on what the overall intention is for the part. Aside from the basic refinement to areas like the second-gear shift band, stator support and factory clutch pack, Carr can build the 2004R with stealthy parts like an input shaft fully machined from 300m steel, featuring longer splines for a more secure engagement into the shift drum. Valve bodies can be custom tailored for virtually any type of shifting requirement. Not a fan of factory-style lockup torque converters, Carr replaces the original lockup valve in the oil pump and replaces it with a steel valve machined to alter the hydraulic fluid circuits to match more closely with a non-lockup converter.

 

Another area given a lot of attention and tuning depending on horsepower capability is the internal line pressure. OE specs using the stock pressure regulator, boost valve and spring read as follows: 60-psi in Park and Neutral; 110-psi in Reverse; 120-psi in First; 130-psi in Second; and 60-psi in both Third and Overdrive. To increase these pressures to better handle higher horsepower levels, Carr will custom fit replacement components that effectively double the line pressure up to 300-psi for the first two gears. Talk about grip and hold capability, the 2004R will hold back slippage whether power comes from a torque monger big-block Rat motor or a high-winding, high-horsepower small-block.

 

With different components and configurations on hand, the 200-4R conversion will effectively make any high-performance street or track machine much more efficient, whether it’s in terms of better economy while cruising the freeway or better use of the engine’s power and torque while going all-out to the finish line.

 

 

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