700R4 vs 722.6: Differences and Which One to Choose

700R4 vs 722.6: Differences and Which One to Choose

700R4 vs 722.6: Differences and Which One to Choose

These two automatics almost never sit in the same vehicle, but they end up on the same shortlist more often than you would think. A GM 700R4 (later renamed 4L60) is the cheap, cable-shifted four-speed overdrive that hot rodders and truck owners have leaned on since 1982. A Mercedes 722.6 (sold to Chrysler, Dodge and Jeep as the NAG1) is the electronically controlled five-speed that shows up in everything from an E-Class to a Wrangler. If you are picking a transmission for a swap, or you have one of each in the driveway and are deciding which one is worth rebuilding, the differences that matter are gearing, control method, torque rating, and what fails first.

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The short answer

Choose the 700R4 if you want a mechanically controlled overdrive that runs without a computer, bolts to a GM bellhousing, and can be rebuilt on a bench with hand tools. Choose the 722.6 if you want five speeds, a much higher factory torque rating, and modern shift quality, and you are willing to live with electronic control and a valve body that is a wear item.

Gearing: four wide ratios vs five closer ones

Sonnax notes that the GM 4L60 (700R4) family carries the steepest first gear ratio of any four-speed automatic at 3.06, with second at 1.63, direct third, and an overdrive fourth. That 3.06-to-1.63 step is a big RPM drop, which Sonnax describes as dropping performance engines out of their power band; it is exactly why their 2.84 ratio input carrier kit (77284-K) exists to re-space the box to a closer 2.84/1.55.

The 722.6 splits the same speed range five ways. Per the 5G-Tronic reference, the higher-torque variants (W5A400, W5A580, W5A900) run 3.588, 2.186, 1.405, 1.000 and 0.831, while the lighter-duty W5A280/300/330 units use a wider 3.932, 2.408, 1.486, 1.000, 0.830 set. Sonnax adds that in the US NAG1 family, the W5A330 has the widest gear ratio while the others share the same ratio set.

Practical read: the 722.6 has a deeper first gear than the 700R4 and a taller top gear, plus an extra ratio in the middle where the 700R4 has a hole. If you are chasing cruise RPM and drivability, the five-speed wins on paper. If you are chasing simplicity, the four-speed wins everywhere else.

Control method: TV cable vs shift-by-wire

This is the real dividing line. Sonnax describes the 700R4 as having a cast iron valve body controlled by throttle cable and a mechanical governor that determines shift points, versus the later 4L60-E's aluminum valve body with computer-controlled solenoids. That is why Sonnax lists the 700R4 as a compact unit that is "usually simple to install without a computer."

It is also why the TV cable is the single most important adjustment on a 700R4. Get it wrong and line pressure never rises with throttle, and the unit burns clutches quickly. Sonnax sells a TV Cable Corrector Kit (AS1-01K) for exactly this reason. If you are running one, read our walkthrough on 700R4 TV cable setup before you drive the vehicle.

The 722.6 is the opposite philosophy: an electronically shifted unit with a control module and conductor plate living inside the transmission, and a multi-disc torque converter clutch that locks up typically in gears 3, 4 and 5. There is no cable to adjust. There is also nothing to fall back on when the electronics get wet, which is a documented weak point.

Strength and torque ratings

The 722.6 is rated by name. Sonnax explains that in the W5A series the last three digits are the maximum input torque in Newton meters; US NAG1 units include the W5A580, W5A380, W5A330 and W5J400, and the J400 identifies a Jeep application. A W5A580 is therefore rated around 580 N·m, roughly 428 lb-ft, at the input. The 5G-Tronic reference lists the family spanning 280 through 900 N·m depending on variant, with the top version handling up to 1,000 N·m.

GM never published the 700R4 that way. Sonnax's own build guide puts a practical ceiling on it instead: with the right internal upgrades, the 700R4 is "still very capable in many applications up to about 750HP." That number assumes a built unit with a heavy duty input housing, better servos, and a boosted pump — not a stock core.

What fails first on each

700R4. Failures cluster around line pressure and the 3-4 clutch pack. Sonnax's recommended upgrade list for a durable build reads like a failure list: pump line pressure booster kit, reverse boost valve kit, TCC apply valve kit, heavy duty reaction shaft kit, heavy duty overrun clutch hub, SmartShell reaction shell kit, and 2nd/4th gear Super Hold servo kits. Note the input shaft change: Sonnax's Smart-Tech input housing kit fits '85-later units with the 298mm converter and 30-spline input shaft, and '82-'84 units with a 27-spline shaft need the converter and stator shaft updated to the '85-later design.

722.6. The valve body is the wear item. Sonnax's 722.6 technical write-up identifies the specific mechanism: the outer bore of the working pressure regulator valve wears and lets pMod solenoid signal oil leak past the boost end of the valve, so working pressure stops rising with engine load. The driver feels engine RPM flare on the 2-3 or 4-5 upshift, or a neutral flare on the 5-4 or 3-2 downshift, and Sonnax notes that on high-mileage cars a 2-3 flare commonly pushed the vehicle into limp mode. The 1-2/4-5, 2-3 and 3-4 overlap sleeves sit in the same pMod circuit and wear on the I.D. while leaking at the O.D., which further reduces pressure at the working pressure valve. Gearboxlist adds that the control unit inside the transmission is vulnerable to water intrusion and that a failed radiator can push coolant into the fluid.

The fix: which parts you actually buy

722.6 overhaul transmission rebuild kit with gaskets, seals and sealing rings
722.6 overhaul kit — the gasket, seal and sealing ring set that goes back in on every 722.6 teardown.

For a 700R4 that is slipping or flaring, the parts that go back in are frictions, steels, gaskets and seals, a filter, and — because the TV system is the root cause so often — a shift correction kit and a fresh servo. Our 700R4 Master Rebuild Kit with frictions, steels, gaskets, seals, filter, shift kit and servo bundles that set so you are not chasing pieces mid-build.

For a 722.6 with flare or limp-mode complaints, plan on pulling the valve body and vacuum testing the working pressure regulator bore and the overlap sleeves before you order anything internal. Whatever the verdict, the unit does not go back together without a full seal and sealing-ring set: the 722.6 overhaul rebuild kit covers that. Both models live in our transmission rebuild kits collection.

Replace while you are in there

  • Both: filter, pan gasket, all case and pump seals, cooler lines flushed, and a cooler if the fluid came out burnt.
  • 700R4: TV cable and TV cable geometry checked, 2nd and 4th gear servos, 3-4 clutch pack, pump line pressure components, and the reaction shell.
  • 722.6: valve body inspection with a vacuum test, internal control unit and case connector area checked for fluid or moisture intrusion, torque converter replaced if the fluid carried debris, and radiator condition verified before refill.

Cost and effort

The 700R4 is the cheaper project by a wide margin. It is a bench rebuild with common tools, no scan tool required to make it shift, and no programming afterward. Figure a long weekend for an experienced DIYer, plus a day of TV cable and road-test tuning.

The 722.6 is not harder to disassemble, but it is harder to finish. Diagnosis needs a scan tool that can read the transmission module, the valve body work is precision bore repair rather than parts swapping, and fluid is not universal. Sonnax notes that Sprinter, Crossfire and Mercedes units require a specific fluid because of calibration issues, while other Chrysler applications use ATF+4 — so confirm the fill spec for your exact chassis before you buy a case of anything. Gearboxlist lists total capacity in the 7.0 to 9.5 liter range depending on version, with a partial change taking 5.0 to 7.5 liters.

FAQ

Can I swap a 722.6 in place of a 700R4? Not as a bolt-in. Different bellhousing pattern, different mount and output geometry, and the 722.6 needs its control module and vehicle wiring to shift at all. A GM-family overdrive swap is far simpler — see our 700R4 vs 4L60E comparison if you are staying in the GM camp, or the 4L80E vs 722.6 breakdown for the heavy-duty side of the same question.

Is a 700R4 the same as a 4L60? Yes. Sonnax states the 700R4 is the exact same transmission as the GM 4L60; the name changed in 1989, about eight years after the unit was introduced, and 1993 was the last year for most models before the electronic 4L60-E took over.

How do I tell a German 722.6 from a Chrysler-built NAG1? Sonnax gives a simple tell: a pin stamp on the driver's side, or a pin stamp plus a bar code tag, means it was built in Germany. A bar code tag only means it was built by Chrysler.

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