ZF6HP26 Transmission Overhaul Gasket and Seal Kit

This is the full soft-seal overhaul set for the ZF 6HP26 six-speed automatic, and it also covers the 6HP28. It replaces ZF kit T18300A, which is the combination of T18302A, T183080A and T183081A. Inside are the case and pump gaskets, the lip seals, the O-ring assortment and the sealing ring set the unit needs when it comes apart - no clutches or steels, this is the sealing package.

Applications are the rear-drive ZF cars: BMW 3, 5, 6 and 7 Series, X3, X5 and X6 including the 550i and 750i, plus Jaguar and Land Rover units running 6HP26 and 6HP28. Reference OE number 1068298051.

The 6HP26 is the transmission behind the well-known Mechatronic sleeve and adapter-plate leak. ATF wicks up the wiring sleeve, the pan gasket weeps, and the internal clutch piston seals harden until apply pressure drops and you get a delayed or slipping shift. Anyone opening one of these to address a leak or a valve body problem needs the whole sealing package, not a single seal, because the rubber in a 100,000-plus mile 6HP26 is uniformly hard.

On the bench: this unit is sensitive to sealing ring fitment, so size every Teflon ring with a resizer before the drum goes in - a ring that is even slightly proud will shave on assembly and cross-leak. Replace the pan gasket and the Mechatronic sleeve seal at the same time rather than chasing the leak twice. ZF calls for Lifeguard 6 fluid; set the fill level at the correct temperature window using the standpipe, since these have no dipstick and both overfill and underfill cause shift complaints.