BMW/AUDI/VW Using the ZF5HP19 Style Transmission Slips in Reverse or Flared 2-3 Up-shift when Hot
From time to time a vehicle may come in using the ZF5HP19 type transmission with a complaint of slipping in reverse and/or a flared 2-3 up-shift when hot. In some cases the problem is not resolved after a rebuild.
This transmission is used in a BMW, an Audi or a VW and although there are differences in design between them, the transmission is basically the same. The valve body is fairly large making it easy to inspect for sticking valves and to clean with mineral spirit without disassembling it.
Since pulling each and every valve out of the valve body can be a time consuming process and in most cases unnecessary, to simply clean and inspect is often times the common approach. But what should be included in this cleaning and inspection process is the removal and replacement of the O rings on the D and F clutch accumulator piston caps.
The D accumulator piston is used to cushion the reverse engagement and the F assists in the 2-3 shift feel. When these O rings get hard or flatten out, the pressure sent to these pistons leak past the cap causing the reverse and/or 2-3 shift complaint when hot. To replace these O rings is simple and quick resolving the complaint at hand.
