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

 

Editor:   ERSATZTEIL- DIENST   Hans-Peter HOMMES       D-41748   VIERSEN   Tiefenstraße 10       Tel. 02162 - 8100933

Monthly available on our website.            www.wehrmachtsgespann.de
 

No.
102

Subject
Back bearing shield
Zündapp KS 750

Editor

H-P  HOMMES

Date

© 2012 h-p hommes

 

The Zündapp KS 750 back bearing shield.

 

The back bearing shield (order no. 1063) of the Zündapp KS 750


It has to be perfectly inserted in the back of the housing. This back bearing shield carries together with the front roller bearing the entire emerging forces of the crankshaft, the connecting rods and the pistons.

A loose-fitting back bearing shield causes the loosening of the screws, results in leakage and damage of the engine housing.

When the hole for the back bearing shield in the housing is already damaged, then the housing must be centered on a boring machine and newly machined.
Thereafter, however, the original shield does not fit anymore.

Now we need a back bearing shield with oversize.
You can buy it from us - order no. 1063-1

 

When the back bearing shield is pulled out of the engine, then it is recommended to pull the bearing shield out together with the crankshaft.

 

Caution:

'The holes provided with thread to press the back bearing shield out of the engine housing are rather weak particularly the original bearing shields.
When pressing it out this way the bearing shield is very often broken.

 

It makes more sense to use the extractor (order no. 1044) for the follower guide to be able to pull the crankshaft together with the bearing shield out of the housing.
The follower guide and the crankshaft have the same thread.

For this purpose screw the extractor without the oblique pressure sleeve on the crankshaft.
Put a square steel with a 12 mm hole above the housing and insert it in the tension screw of the extractor and now tighten the nut firmly. In doing so the crankshaft and the bearing shield pull themselves out of the engine housing.

 

 

 

And make sure that the screw contact surfaces of end shield replica are smooth and not only have a simple rough casting.

The same is also practiced in some other replica cylinders.

No nut can build up reasonable pressure in this case.

But some work steps in the production can be saved.

That is then a cheaper production, but no a good value for money one.

 

 

It's always interesting which rumors are planted about spare parts remanufactured by us. Whether it is out of ignorance or bad faith.
Without understanding anything about it some people are putting it down.

However, such rumors unsettle some Zündapp hobbyists.

 

Example:
Rumor: The Hommes bearing shield is missing an essential oil bore hole and the rear ball bearing is no longer lubricated properly.

 

However, it is correct that this oil bore hole – by the way it is not boring but a 1 mm wide milling in the clip ring nut - would pump too much oil between the ball bearing and the seal down to the oil passage when using a gear oil pump. The result would be a leak to the flywheel seal.

Already 25 years ago, during the development of sleeve bearing shell system, we recognized that, when fitting the original bearing shield, an oil loss often occurred on the flywheel

To close this little slot is almost impossible, and I think that most KS fans do not know that there is such a milling in the bearing shield.


Take an original bearing shield.

With your finger close the small ejection hole through which the oil is sprayed onto the crankshaft. Now blow through the large lateral inflow hole and you will find out that - although the only assumed outlet is closed tightly with the finger - no air pressure builds up and the injected air escapes somewhere.

The milling in the clip ring nut is almost invisible.

Therefore, today we only mount new bearing shields for engines with gear oil pump which do not have this milling.

There's nothing wrong, but it is a deliberate positive change in the design.


Through the increased output of the gear oil pump
sufficient oil always gets to the rear ball bearing anyhow.

 

 

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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