Technical Information Pages for the Rstoration of the BMW R75 and Zündapp KS 750.


Editor:  ERSATZTEIL    DIENST       Hans-Peter HOMMES       41363 Jüchen Kamphausen 156 C/2

Monthly available on our website  

No. 26

The Jack
STORZ 21,   G 4,    BILSTEIN


H - P Hommes

   © 2012 h-p hommes




The Jack.


There are always offers of jacks declared as a jack for Zündapp KS 750 and BMW R75 for sale.

The jacks that are offered as originals for our bikes are:

The Stortz, the G 4 and the BILSTEIN.


What information is available?


1. It is mentioned in the spare parts list.


2. It is displayed on several images and drawings of the operating and maintenance instructions. Here it has always a plate below his foot and it is small and compact.


3. In an original letter from BMW to the Wehrmacht, it is included in a list. Without brand but with the description 190/290. This should be the min. and the max. height of the jack.


4. A few years ago my friend Andreu bought a very original preserved BMW R75 in a Spanish village. In the sidecar were the two jacks, a STORZ and G 4 Are these therefore originals?


5. In my opinion Sido from Holland has the correct jack. The BILSTEIN, 165/355. It is two times extendable and fits precisely under the bike and with its 355 mm it is high enough to lift the sidecar


The left jack:
It has a min. / max. height of 190/290.
It is labeled Stortz 21 GF.
The heights are the same as in the BMW letter and were found in a BMW sidecar. But that's about all. The painting is, even if you can interpret it as Wehrmacht beige in this photo, clearly lacquered silver-color.


The right jack:
It has a min. /max. height of 130/170 mm + 30 mm for wood.
It is labeled G 4
The painting is clearly RAL 7021 dark gray.
Even compared with the pictures in the spare parts catalog it can be recognized that this one is a compact little jack and not a rather slim long as this one.





When using it it shows:

The Stortz 21 jack is with 190 mm height too high to get it under the frame or the engine (170 mm) of Zündapp. It is impossible to put a board below to reduce the earth.


The G 4 jack fits exactly under the frame and the engine. When max. lifting the front wheel is raised so far that it can just be rotated freely. However, it is not enough to take out the wheel.



The G 4 is useful for the engine and the frame. To lift the side car frame a first height of 290 mm would be required. You have to put a lot of wood underneath using the G 4 jack.So it is not the right one for our bikes.


The STORZ with a wooden plate of 30 mm would cope fine with it. But it does not fit under the engine.




165 mm min. height and 355 mm max. height

With steel plate for better earth pressure.

two times extendable

Here everything is perfect.

It just looks like in the spare parts list and can perform all the necessary uplifts on our bikes.
For me there is only one more question: Why does the letter from BMW to the Armed Forces state the measurements 190/290?





We offer:

spare parts + accessories + repair for engine, transmission, etc. of the
Zündapp KS 750 and 600

We offer:

spare parts + accessories + repair for the

BMW R75 and Zündapp


H-P Hommes Ersatzteil-Dienst
Ersatzteile + Instandsetzungen
repairing + restoring


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