Full master overhaul kit for the GM 4L30E four-speed automatic: frictions, steel plates, gaskets and seals to rebuild BMW, Isuzu, Honda and Cadillac units.
If you own a Honda Passport, Isuzu Rodeo or Trooper, an E36 or E34 BMW six-cylinder, a Z3 or a Cadillac Catera and the automatic has started slipping, flaring or engaging late, odds are you are looking at the GM 4L30E. This master rebuild kit carries the friction plates, steel plates, the gasket and seal set and the sealing rings for a full bench overhaul of that four-speed. The listing cross-references overhaul kit 4L30E TROO5, and it is aimed at the owner or shop that has already decided the unit is coming out and wants one box instead of a dozen part numbers.
The 4L30E is a light-duty rear-drive four-speed that GM built in Strasbourg, France, rated for about 350 Nm of engine torque. It went into a wide spread of European and Japanese vehicles, and it was not built the same way for all of them. Published ratio data shows two gearsets: the BMW and Opel version runs a 2.40 first gear, while the Isuzu Trooper and Rodeo version runs a deeper 2.86 first gear, both sharing a 0.723 overdrive. That is why a master kit is the right way to service one: the soft parts that wear out (clutch frictions, steels, lip seals, lathe-cut piston seals and the teflon and iron sealing rings on the drums and pump) are renewed together, while the hard parts that define your version stay with your case.
Do the electrical checks before you commit to a rebuild. Transmission Digest documented a 1998 Honda Passport 4L30E that shifted hard with a dead gear indicator; the cause was not worn clutches but a mode switch (range sensor) circuit that kept burning out because the harness had chafed through on the bellhousing shield and shorted to ground. A failed mode switch or a shorted signal wire can make a healthy unit shift badly, so check power, ground and each switch circuit first. Then do a hot fluid check and a stall and line-pressure test; our line pressure testing guide covers the gauge hookup, and flare vs slip explains which symptom points at a clutch pack and which points at hydraulics. Pressure that is normal with a pack that still slips means the frictions are done.
The listing covers BMW 318i, 323i, 325i, 328i, 525i, 528i and Z3 from 1991 to 2000, the Cadillac Catera 3.0L 1997-2001, Acura SLX 3.2/3.5L 1996-1999, Honda Passport 2.6/3.2L 1994-2002 and Isuzu Rodeo, Trooper, Amigo, Axiom and VehiCROSS 1991-2004. Not every model year of those vehicles used this unit. Later BMW 3 and 5 Series moved to the GM 5L40-E five-speed, and published 4L30E application lists end the Honda Passport at 2001 and the Trooper at 2002. Read the transmission tag before you order, and if you are not sure, send us the year and VIN and we will check the kit against your case. Every 4L30E part we stock is on the 4L30E master rebuild kit page and the related parts below.
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The listing covers both. The soft parts are shared across the family, but the BMW/Opel and Isuzu versions use different first-gear ratios and some case-side parts differ, so keep your own hard parts together and confirm your tag or send us your year and VIN.
Not always. Check the mode switch (range sensor) circuits and the harness near the bellhousing first. Transmission Digest documented a Passport 4L30E whose hard shifts came from a shorted range-switch wire, not worn clutches.
Per the listing: friction clutch plates, steel plates, the gasket and seal set, and sealing rings. Inspect bushings, the pump, the band and drums during teardown and order those separately if they are worn.
GM specified a Dexron III-type fluid for the 4L30E. Fill, start the engine, cycle the selector and set the final level with the fluid hot per your vehicle's procedure.
Worn pump parts, the filter, any scored bushings, and the cooler if the old unit burned its clutches. Many rebuilders also add a shift kit on trucks that tow.
