AL4 DPO Transmission Master Rebuild Kit for Peugeot 307

This is a full master overhaul kit for the AL4 four-speed automatic, also badged DP0/DPO depending on the year and market. It covers the parts you replace on a standard bench rebuild: the friction clutch plates, steel plates, seals, gaskets and O-rings that wear out and cause the AL4's usual complaints. It cross-references OE numbers T15500A, T15502A, T155080B and 155940.

Fitment covers the Citroen SM and the Peugeot range: 307 2.0L (2003-2010), 308 1.6L (2009-2021), 407 2.2L and 2.9L (2006-2009), 607 2.9L (2002-2008), and 5008 1.6L and 2.0L (2019-2022). Check the casting and the OE tag on your unit before ordering - PSA ran several AL4 variants and the friction counts differ between them.

The AL4 typically comes across the bench with a slipping or flaring 2-3 shift, a hard 1-2 bang once the box is hot, or a delayed engagement into drive after it sits overnight. Most of that traces back to glazed frictions and hardened piston seals letting apply pressure bleed off. Tearing it down and replacing the whole friction and seal set at once is the only repair that holds - swapping one pack and reusing old seals just brings the car back a few months later.

Work through it the usual way: pull the valve body and filter, split the case, strip the drums, and measure clutch clearance as you stack each pack rather than assuming the new frictions are the same thickness as what came out. Soak the new frictions in clean ATF before assembly and lube every seal with transmission assembly gel so nothing rolls or cuts on install. Replace the filter and flush the cooler and lines before the box goes back in.