Saturday 26 January 2013

BMW marine gear box by ZF

This one does not exist, so said the ZF factory in 2005, November 10th, when I emailed to tell them I had a used gear box off the D50 BMW/Hatz marine diesel. Model number ZF BW7 Ratio 2.05:1 reversing transmission.

The reply was:

Dear Mr McBride.

I'm sorry to inform you that I don't have this unit listed in the ZF production, neither historically:
ZF never produced this. I can't help you since also my older collegue doesn't remember the brand that was building it.

Best regards.

(how odd?) 

Cleaned and before repainting.

I was trying to get the drawings or service manual, you can imagine my shock to get such a reply!

Ready for a coat of twin pack etch primer, then top coats.

Made in Spain? ZF obviously did make this marine gearbox!

Note the stainless pipe on the left hand side, another projects on the other side and is the sea water raw water cooling for the box. The pipe goes straight through, I think just the cooler water is enough to cool the output shaft bearing down?

This was rebuilt by the BMW agents Prokura here in Cape Town, new bearings right through, its done about 200 hours only since. 

Click on the file, it will enlarge, printed its also readable.

The sellers info is below, the ZF BW-7 reversing marine transmission is still for sale, one day left only and ex USA, from V12 Engineering.

ZF BW7 Ratio 2.05:1 reversing transmission
Shipping weight : 40 lbs. Dim: 17" X 14" X 11"

This transmission was fitted to the BMW D50-1 engine. BMW also used Hurth transmissions. A similiar model ZF BW7 was also fitted to the D50-2.

We understand that Westerbeke also sold some of their engines with this transmission.

In that, parts for these ZF transmissions are very difficult to find. It is best to have a spare.

We purchased this transmission very well. It is very rough on the outside because of poor storage over the years. The ratio on this unit is 2.05:1 in forward. The engine we purchased this transmission with was in similiar condition but also new and never having been installed in a boat

There are more drawings in the Ebay link.

Etch primed then silver gloss top coat.

So it seems the spare one I have in stock is real and ZF did make it!

A full PDF file of the workshop manual can be found here

Does anyone know what direction forward is with this box, does the gear control push forwards to engage forward, if so its in reverse right now?

29 / 01 / 2013 this has just come in from a vendor on Ebay USA.


Good to hear from you. Our young lady, Rhia Schaerig, got to surfing and we found your blog.

Interesting that ZF did not admit to making the transmission. Of course, I think it was made in Spain so that could be the reason.

Roy, are you in the buying mood?

Best regards,

Rich Langtry
V12 Engineering
Tel: + 807-543-3003
- v12engineering