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Rebuilding a 4L60E Transmission with More Toughness

Tough (4L60E) Love

Jim Smart Jun 28, 2017
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Approaching four decades ago, automakers were scrambling for solutions to fuel economy woes, and GM was no exception. Computer-controlled carburetors and the birth of electronic throttle body fuel injection were not enough to slow fuel consumption. In 1982, GM conceived the Turbo-Hydramatic 700-R4 overdrive automatic transmission as a replacement for the time-honored TH350 three-speed automatic.

What made the 700-R4 different than any previous GM automatic was a new approach to shift modulation through a device known as the throttle valve (TV) cable. The TV cable did the work of both the vacuum modulator and kickdown linkage in the TH350/400 and Powerglide transmissions. In true linear fashion, the TV cable was able to modulate shift programming based on throttle position and vehicle speed, and this was a system that worked quite well for a time. It was when technicians and vehicle owners began adjusting throttle valve cables, much of the time improperly, that the 700-R4 became problematic. What’s more, even with precision adjustment, GM was never able to get TV cable shift programming where it needed to be for a perfect balance among driveability, fuel economy, and longevity.

An improperly adjusted TV cable caused irregularities in line pressure and timing to where people were burning up 700-R4 transmissions at quite a clip. And for what it’s worth, Ford had the same problem with the Automatic Overdrive (AOD), which was actually worse than GM’s 700-R4 with its bizarre shift pattern.

In 1990, the 700-R4 was redesignated the 4L60, with “4” meaning four-speed, “L” for longitudinal installation (north/south), and “60” meaning light-to-medium-duty use and 6,000-pounds gross vehicle weight. Although the 700-R4 had a new designation, the same old driveability and shift programing issues persisted. GM powertrain engineers went to work developing a computer-controlled 4L60 known as the 4L60E based on the 700-R4.

The 4L60E arrived for 1993 with precision shift quality like the 700-R4/4L60 had never known before. The 4L60E’s computer-control system consists of a powertrain control module (PCM), which achieves control via a vehicle speed sensor (VSS), throttle position sensor (TPS), and other sensors throughout the system, including from the engine. These sensors provide the necessary feedback to enable the PCM to control shifts based on driver demand. The PCM connects both the engine and the transmission to where both work together in near-perfect harmony.

At a glance, the 4L60 doesn’t look much different than a 700-R4. When the 4L60 crossed over to electronic control to become the 4L60E, it took on a different main case and valvebody to accommodate electronic control. From 1993-’97 the 4L60E was a two-piece affair consisting of a main case and a four-bolt extension housing in passenger car applications. In 1996, the 4L60E went to a removable bolt-on bellhousing and a six-bolt extension housing in some applications.

We recently visited Performance Automatic for a closer look at what they do for 700-R4, 4L60, and 4L60E performance enthusiasts. Tom Cyr of Performance Automatic got into this business because he is passionate about automatic transmission function and racing. Performance Automatic looks at common failure issues with domestic automatic transmissions and comes up with solutions that make them reliable, solid performers. New adaptations are being developed all the time, engineered to make your 700-R4, 4L60, 4L60E, 4L65E, and 4L75E boxes better.

Unless you are a seasoned transmission builder with a lot of experience with the 4L60E series transmissions, it is suggested you never execute transmission rebuilding yourself. Oh sure, you can amass all the right tools and knock one of these guys apart on your home workbench. However, the success rate of a home 4L60E build isn’t exactly high because much of a build is based on experience, how parts fit together, clearances, function, and knowing what to look for in a build. These elements come from experience and knowing what to do with a 4L60E. Performance Automatic’s seasoned professional staff understands your 4L60E woes and how to correct them. Order up a 4L60E for street/strip performance and you can expect Swiss watch precision when it arrives on your doorstep.

We’re unable to show you a step-by-step 4L60E build here because there simply isn’t the space to do so. However, we can show you the Performance Automatic approach to building a brute 4L60E.

Let’s get started.

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1. With its hard parts spread out on the Performance Automatic build bench, the 4L60E doesn’t look much different than the 700-R4, 4L60, 4L65E, or 4L75E. The differences are nearly too minute to see at a glance, which is why we’re here: to take this abused 4L60E and give it greater torque capacity with improvements from Performance Automatic.

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2. Before you is the 1993-’97 4L60E’s main case. This particular 4L60E was significantly trashed with a succession of broken hard parts. Performance Automatic is going build in 400-500 horsepower and greater torque capacity.

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3. One 4L60E weakness is the factory sun reaction shell. It tends to break around the hub, and it doesn’t take much for it to fail. Performance Automatic fits its 4L60E builds with this improved, thicker sun shell (left) with a stronger, welded center hub and a radiused spline area to prevent failure. A heavy-duty Torrington bearing reduces friction in this area upon reassembly, which also reduces heat.

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4. Performance Automatic increases 4L60E torque capacity with a five-pinion front planet (left) and ring gear. With five pinions instead of four (right) we’re spreading torque across more mechanical surface area. Your 4L60E will handle 400-500 horsepower with the five-pinion front planet. That’s 20 percent more torque capacity.

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5. Rear planet torque capacity is increased by 20 percent with a five-pinion planet (left) and ring gear instead of the 4L60E’s vanilla four pinion (right). This will take your 4L60E to 400-500+ horsepower torque capacity and somewhere on the order of 6,500-7,000-pound gross weight. This gives you the capacity of the 4L65E/4L75E.

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6. A larger 3-4 clutch overrun clutch apply piston is employed with an input drum reinforcement sleeve to provide greater hydraulic holding power and stability. Success here also counts on the Teflon-impregnated stator support bushing for stability and smoothness. In short – less friction.

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7. These are forward clutch apply pistons. Performance Automatic strongly suggests the newer piece on the left in stamped steel. Avoid the cast piece on the right, which is prone to failure in performance applications.

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8. The larger Second and Fourth-gear band servo pistons (left) from Performance Automatic give your 4L60E greater band-apply capacity—roughly 18 percent more.

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9. Raybestos forward, overrun, and reverse input clutches and steels (3-4 clutches/drum) go into Performance Automatic 4L60E, 4L65E, and 4L75E builds. You’ll want the full complement of seven clutches.

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10. On the left is the Raybestos ZPak 3-4 clutch pack. They feature exclusive friction materials on these special one-sided clutches, which dissipate heat better.

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11. A trio of 4L60E series input shafts. From left to right: heavy-duty late-model 4L60E input shaft (4L75E), hardened 4L60E input shaft from Performance Automatic, and the stock 4L60E input shaft. This is undoubtedly the easiest modification you can make to your 4L60E, however, there’s more you will need to do to build in toughness.

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12. Performance Automatic is upgrading this 4L60E to the high-volume 13-element (vane) pump for both pressure and volume.

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13. All Performance Automatic builds get fresh seals, bushings, clutches, and other soft parts. Hard parts are inspected and upgraded as warranted.

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14. Easily overlooked but critical to function is this anti-chatter spring. You would be surprised how many 4L60E rebuilders overlook this part. Note the Raybestos high-performance clutches and five-pinion rear planet incorporated into this Performance Automatic 4L60E build.

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15. Clutch drums are resurfaced for better band engagement. Drums that are beyond resurfacing are not used.

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16. The reverse input clutch drum is loaded with Raybestos high-performance clutch frictions. These guys eliminate slippage and unnecessary heat. It is important to remember some clutch slippage is normal. Excessive clutch slippage is what kills transmissions. Heat and excessive clutch material in the fluid shortens transmission life.

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17. One of the greatest innovations from Performance Automatic for the 4L60E has been Teflon sealing rings. Old-school iron sealing rings don’t last, nor seal as well as Teflon. Iron rings tend to break. Where it gets challenging is installing these tougher Teflon rings. Tricky to install, however, they outlast iron.

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18. Check out this five-pinion front planet and ring gear. The main benefit here is increased torque and horsepower capacity. Surrounding the front planet is the Performance Automatic sun shell.

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19. Here’s the five-pinion front planet with the output shaft installed and secured.

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20. This is the 29-element sprag for 700-R4, 4L60, and 4L60E. Like the five-pinion planets mentioned earlier, you’re getting more torque capacity from the 29-element sprag. This sprag was born for the kind of power the LS makes.

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21. Raybestos high-performance frictions provide greater grip and without slippage. Performance Automatic adds frictions where possible, which provides better power transfer and with less heat. Because heat is very destructive to automatic transmissions, you want less of it. Clutch slippage is the greatest generator of heat.

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22. The reverse input drum sporting fresh Raybestos clutches is loaded onto the input drum, which has been fitted with the hardened input shaft from Performance Automatic. This is as durable as it gets for a 400-500-horse capacity street 4L60E. Performance Automatic showed us this clever Teflon sealing ring installation tool, which makes installation easier. If you’re going to build your own 4L60E, this is one of the tools of professionals.

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23. The Raybestos Pro Series band is installed last and tied to the servo and properly adjusted.

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24. The 13-element high-capacity front pump is installed prior to the torque converter installation. When you’re ordering a torque converter, be honest with yourself about stall speed. Where does your engine’s torque curve begin? And, how will your vehicle be used most of the time?

Photos: Jim Smart

Sources

Performance Automatic
Frederick, MD 20879
240-439-4650
www.performanceautomatic.com
Raybestos Powertrain
800-729-7763
raybestospowertrain.com

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