This is buried in various threads across Z4 forums, but I feel it deserves its own attention. The going rate for a bmw soft top motor and pump is $650 at the time I'm typing this, but there is a Ford alternative that works just as well. I recently relocated my motor and pump to the trunk using the Mustang part as follows, and it works great and is faster at raising and lowering than stock:
I just finished up my roof top motor relocation this weekend as well, I utilized the Ford Mustang motor/pump assembly too.
I'm attaching pictures of the pump assembly I used in case it helps other people out. I received the assembly with some of the wiring attached, including a disconnect so I reused that as well.
Some basic info on the pump I used:
- Purchased for $180 off ebay.
- It was listed being for 2008-2014 Ford Mustang.
- Made by Hoerbiger (same as the Z4).
- Pump assembly showed part numbers S109024 and HB80069-002P.
- Electric motor shows part numbers 3M5042, 1090069, and HB80006-019C.
- The fluid reservoir is about 2x the size of the BMW one, but they're interchangeable so I put the BMW reservoir on the Ford pump.
- For wiring, Mustang red to BMW green/grey and Mustang yellow to BMW blue/grey.
- The banjo bolts on the mustang pump are the same size as the BMW, however the inlet/outlets are on the opposite side. Meaning the holes in the bolts are on the bottom when screwed in instead of the top. I'm not sure if this matters but I reused the BMW bolts just in case.
- The pump outlets were labeled 11/13 on one and 12/14. This runs backwards from BMW's setup (at least for my 2003)! I initially plumbed it per the numbering on the pump and it ran in reverse, the open button closed and vice versa. So I had to switch the hydraulic lines so the 11/13 were attached to the pump at 12/14 position, and the bmw lines 12/14 were at the 11/13 position on the pump. Once done, it runs correctly.