Master overhaul set for the Mercedes 722.3 four-speed automatic with friction discs, steel plates, gaskets, seals and o-rings in one kit.
The 722.3 is the heavy-duty version of Mercedes-Benz's four-speed automatic, the box behind the V8s in the 1992-1993 400E, 500E and 500SEL and the 1994-1995 S420 and S500, and the one Porsche bolted to the 928. If one of these cars now flares between gears, slips in third or fourth when you lean on it, or shows dark, burnt fluid on the dipstick, the clutch packs inside are worn and this master rebuild kit is what a bench overhaul calls for. It carries the friction discs, steel plates, gaskets, seals, o-rings and sealing rings in one box, cross-referenced to rebuild sets T06400A, T06402A, T064080A and T064081A.
Mercedes coded this unit W4A 040, meaning a four-speed automatic rated for 40 kp-m of input torque, about 392 N-m or 289 lb-ft. That is double the rating of the smaller 722.4, which is why the big V8 and turbodiesel cars used it. There is no lock-up clutch in the converter. Shift timing and shift feel come from hydraulics: a governor, a throttle linkage, and a vacuum modulator that tells the valve body how hard the engine is working, with electric solenoids only for kickdown and, on some models, a 2-3 upshift delay. Because nothing electronic manages slip, worn plates are felt directly as flare and soft shifts. The master kit renews every wear surface in those packs and reseals every piston, so each apply element gets full pressure again.
Rule out the cheap causes first. A 1994 technical bulletin covering the 722.3, 722.4 and 722.5 explains that the rubber cap on the vacuum modulator is part of the vacuum circuit, not a dust cover. A cracked, missing or loose cap leaks vacuum and gives harsh or erratic shifts. Put a hand vacuum pump on the modulator hose fitting; the cap and modulator should hold at least 14 inches. Check the fluid level hot, the vacuum line, and the throttle linkage adjustment. If the fluid is burnt and the slip remains once those are right, the packs are worn. If you are unsure whether your car has this box or the electronic five-speed that replaced it from 1996, our 722.6 common problems guide covers the later unit, and the 722.6 rebuild cost guide shows what a teardown involves on a Mercedes automatic.
As listed: Mercedes-Benz 400E and 500E 4.2L and 5.0L (1992-1993), 500SEL 5.0L (1992-1993), S350 3.4L, S420 4.2L and S500 5.0L (1994-1995), and the Porsche 928 4.5L, 4.7L, 5.0L and 5.4L. The 722.3 changed over its long run; Mercedes revised the ratios in the mid-1980s and clutch counts differ between versions, so count your old frictions against the kit before you rebuild. Early 928s were also built with a different automatic, so read the number on the case. When in doubt, send us the year and VIN. Browse every Mercedes kit and part on our 722 transmission page.
If the tag on your case reads 722.4, the 722.4 master rebuild kit is the correct set, and a 722.5 five-speed takes the 722.5 master rebuild kit.
| Transmission | |
| Kit level | |
| Cross-reference | |
| Mercedes fitment | |
| Porsche fitment | |
| Friction material | |
| Shipping weight | |
| Package size |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, the 1992-1993 400E and 500E are on the listed fitment. Confirm the case reads 722.3 and count your frictions against the kit before teardown, since clutch counts changed during production.
The kit is listed for the 928 4.5L through 5.4L. Early 928s were also built with a different Mercedes-sourced automatic, so read the number on your transmission case or send us the year and VIN.
No. The kit covers frictions, steels, gaskets, seals, o-rings and sealing rings. The torque converter, valve body and hard parts such as drums and gears are inspected and bought separately.
Not always. Harsh or erratic shifts on this family are often a vacuum leak at the modulator cap or line. Test the modulator with a hand vacuum pump first; it should hold at least 14 inches. Slipping and burnt fluid point to the clutch packs.
Use the automatic transmission fluid Mercedes or Porsche specifies for your model and check the level at operating temperature. Do not assume the fluid used in the later 722.6 or 722.9 is correct for this older four-speed.
