Engines get all the glory, but without a stout transmission backing it up even the most exotic mill is nothing more than a noisemaker. And as engines keep putting out more and more power, the transmissions backing them up start to fail on a far too frequent basis. This is especially true of automatics. After all, there’s a lot going on in there and high-performance engines generate high amounts of transmission-killing heat. If all that heat wasn’t bad enough, they’re also subjected to loads of metal-twisting, shaft-snapping torque.
A stock 4L60E transmission is fine behind a stock GM engine, but if you’re reading this magazine then chances are the word “stock” isn’t part of your lexicon. Some guys will spend big bucks getting their LS engine to churn out 600, 700, or even more horsepower and then cheap out on the transmission. You can spot them easily: they’re the ones griping and complaining about breaking yet another “junk” transmission. What did they think was going to happen? Let me repeat, stock transmissions (and that 4L60E with a shift kit really is still stock where it counts) are designed to reside behind relatively stock engines. It’s really that simple.
So, what do you do if you want a transmission that’s going to suck up big power and not let you down? Simple: buy one that’s built to take it. It costs more, but the adage of “buy once, cry once” was coined for a reason.
PerformaBuilt Transmissions is run by car guys and they’ve learned what makes a transmission handle big power and what’s just a waste of cash. Their Stage 2 Pro Race transmission can handle gobs of power while their Invincible Black Edition 4L60E trans can support over 1,000 ponies. That’s a power level where you used to have to move to a heavier 4L80E, but not anymore—and that’s good news for those of us trying to shoehorn a transmission into a tight trans tunnel. As PerformaBuilt’s Alan Pickering told us, “We don’t just rebuild transmissions. Instead, we systematically re-engineer each model to eliminate OEM flaws and turn out transmissions that can achieve the highest levels of performance.”
They also perform extensive testing. “All units are tested at various points during the build process, including a half hour on our custom dyno. We run it through all the shifts, up and down, from cold start through operating temperature. Afterwards, we test each of the solenoids and switches to make sure they’re still in range when hot,” remarked Pickering.
To see what’s involved, we stopped by their shop and watched them craft together one of their sweet Level 3 Black Edition 4L60E transmissions.
01. The starting point for any transmission build is the case. PerformaBuilt uses only good cases that have been thoroughly cleaned and inspected. For this build it’s a 4L60E version.
02. After cleaning, the case is heated. This opens the “pores” of the casting and fuses the paint to the metal. This makes for a much stronger bond and a vastly more durable finish.
03. The new billet output shaft from Sonnax is far stronger than the OEM shaft (top).
04. OEM five-pinion planets and a late-model ring gear are used. The result is a huge strength increase in this area of the transmission since the load is spread over a larger area. Here you can see the four-pinion planetary (right) next to the stronger five-pinion version (left).
05. OEM five-pinion planets and a late-model ring gear are used. The result is a huge strength increase in this area of the transmission since the load is spread over a larger area. Here you can see the four-pinion planetary (right) next to the stronger five-pinion version (left).
06. The sun gear bushing is then replaced with a heavier, wider version. Again, anywhere they can make improvements, they make them.
07. They also cut grooves in the gear (left) to allow for better lubrication to the planetary assembly. This greatly improves what is historically a weak point in the transmission. In fact, most planetary failures can be traced back to a lack of adequate lubrication under load.
08. The OEM sun shell is replaced with a Sonnax Smart Shell (right). The Smart Shell is not only balanced, the lugs that lock into the Reverse input drum are cryogenically hardened for superior strength.
09. The same cryo treatment is given to the base of the Smart Shell where the teeth mesh with the sun gear.
10. The OEM 3-4 frictions are replaced with Raybestos Stage 1 frictions (left) and the number is increased from six to nine to provide substantially more engagement surface. This has been long known to be one of the weaker segments on the 4L60 series of transmissions and this modification makes for a huge improvement in performance and durability.
11. PerformaBuilt replaces the input drum with a Sonnax Smart Tech assembly. This comes complete with a billet input shaft, which allows for the additional frictions as well as thicker steels for better heat dissipation.
12. The OEM type sprag is replaced with a 29-element dual-cage BorgWarner piece; the strongest available.
13. Of note is that the Sonnax Smart Tech drum has a hardened, bolt-on end plate that replaces the weaker OEM combination of a more flexible end plate and a simple snap ring to hold the friction module in place.
14. The wide carbon band they use in their builds, replacing the red band on the left, increases the holding power and engagement strength tremendously; roughly 30 percent.
15. To actuate the band, they use a combination of Sonnax Super Hold servos for Second and Fourth gears. This results in, again, significantly increased engagement strength and holding power for the larger bands. So many aspects of the transmission are modified or replaced because the end product is only as strong as the weakest link.
16. The Reverse/input drum is replaced with a new OEM piece to ensure the best possible, flattest gripping surface for the band.
17. The pump is upgraded to a 13-vane rotor and a Sonnax 0.500-inch boost valve is installed along with a Teflon pump bushing.
18. The pump is upgraded to a 13-vane rotor and a Sonnax 0.500-inch boost valve is installed along with a Teflon pump bushing.
19. Much of what PerformaBuilt does to the valvebody is classified, but they perform a number of modifications and upgrades. There is a Sonnax 2-3 shift valve upgrade, all new solenoids, and a new wiring harness. The rest is hush-hush.
20. Much of what PerformaBuilt does to the valvebody is classified, but they perform a number of modifications and upgrades. There is a Sonnax 2-3 shift valve upgrade, all new solenoids, and a new wiring harness. The rest is hush-hush.
21. Heat is death to a transmission. So, to keep things cooler they run a deep pan with a filter extension. The heavy-gauge cast-aluminum pan allows for an additional two quarts of transmission fluid, which enhances cooling under extreme conditions.
22. See, that’s all it takes to build a 4L60E trans that’s rated to handle over 1,000 horsepower. It’s not just one or two parts that makes PerformaBuilt’s Level 3 Black Edition trans so stout, it’s a recipe of parts put together by guys that have “been there and done that” for a long time.
23. The Stage 3 Black Edition 4L60E (rated to over 1,000 horsepower) pencils out around $4,800 with a one-year warranty (extended warranties available). For those on a tighter budget, and pushing out less power, they offer a Stage 3 (rated up to 800 horsepower) for $2,900, and you can get their Stage 2 (rated up to 700 horsepower) for around $800 less. Note you need to use your original bell and extension housings. If you don’t have ’em off your stock transmission they’re sold separately.