Technical Information Pages for the Restoration of the Zündapp KS 750 and BMW R75
Monthly available on our website.
© 2012 h-p hommes
The Zündapp KS 750 back bearing shield.
|The back bearing shield (order no. 1063) of
Zündapp KS 750
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.
Now we need a back bearing
shield with oversize.
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.
provided with thread to press the back bearing shield out of the engine
housing are rather weak particularly the original bearing shields.
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.
For this purpose screw the
extractor without the oblique pressure sleeve on the crankshaft.
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.
always interesting which rumors are planted about spare parts remanufactured
by us. Whether it is out of ignorance or bad faith.
However, such rumors unsettle some Zündapp hobbyists.
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.
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.
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