Workshopmanual Kreidler MP Page 5 - Repairing Cranckshaft

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#1 Bericht door **Maarten** » 25 jan 2005, 21:10

Workshopmanual Kreidler MP mopeds
Page 5. Repairing crankshaft, Removing bearings from the case halves
This pages contain the workshopmanual of the MP automatic 2 speed moped engine,
as used on MP1, MP2, MP3 and the American MP9 and MP19 bikes.

CONTENTS:

Repairing the Crankshaft
If the crankshaft bearings are worn or show excessive play, they must be exchanged. Apply two screwdrivers for forcing the cage with the balls off the inner race (Fig. 54).

Afbeelding

The inner races can be removed from the shaft journal only with a special tool, Pt. No. 09.11.11-26/12. The tool is positioned with the pressure ring in its upper position; then the ring is forced down so that it closes the collet which grips the race in the ball groove. Ensure that only the upper crankshaft web is held during the blows against the ring so that no pressure is exerted upon the crankpin (fig. 55) Do not clamp in a vise for mounting the puller because the hammer blows would cause the shaft to slip out of the vise.

Afbeelding

The inner race is now unseated by vigorously turning the tool pressure screw. Only now it proves advantageous to clamp the small diameter portion of the upper lifting disc in a vise because otherwise you are unable to apply sufficient torque. Clamp the disc somewhat inclined to ensure that only one web is caught end no pressure (or twist) is transferred via the crankpin, since this would bend the crankshaft (Fig. 56).

Afbeelding

Below the bearing races you find the washers for axial crankshaft play compensation. Normally, the position of these spacers requires no change if new bearings are seated because the inner bearing races are made to very close tolerances.
Accordingly, the washers must be marked and kept separate (Fig. 57). If it is found later on that another washer must be added, it must be fitted on the magneto side of the crankshaft.

Afbeelding

Removing Bearings from the case halves
Now only the shaft seals and bearings are left in the case halves. As a matter of principle the halves must be heated when the bearings are to be removed. At 100 degrees C sprayed on water would fizz, however, this is much too low. You need about 150 degrees C, which exist when the oil left on the case starts developing smoke. At that temperature the bearings usually fall out by themselves; however, if necessary, you may gently hit the case ribs with a plastic hammer (do not hit on the sealing surfaces). If a bearing should be unexpectedly tight in its seat, you may use an angular screwdriver for a lever arm. Do not use a wending torch. One accidental movement with the torch may melt the aluminium within seconds (particularly in thin places). Propane gas is risky, too. The least risk offers a hot plate (Fig. 58 ).
Universally applicable tools are readily available on the market for pulling bearings from housing seats; however, their economical employment is only warranted in large repair shops. Even if you use such bearing pullers you must always heat the housing since repeated bearing exchange in cold condition will damage the bearing seat in the housing so that a tight fit is no longer ensured.
When fitting new bearings in the housing parts make sure the bearings are pressed in all the way against the stop in the seat. Shaft seals should be pressed into their seat until they are flush with the edge of the seat bore.

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