What kind of crankshaft can not be straightened

  • Good evening,
    I have another question. How do I correctly place the crankshaft in the left bearing? So I have the left half of the engine in front of me. Snap ring in. Determine the distance to the sealing surface of the engine half and insert the corresponding shims. Heat the bearing seat with the hot air gun, the bearing from the freezer falls in by itself. Washer on, shaft seal on it. Then I carefully heated the bearing (didn't want to kill the sealing ring right away). The crankshaft came from the freezer. Set on and it didn't slip. Beat up ???
    I'm a little afraid of that. The way the crankshaft is constructed, I clap the two weights together on one side when I hit the shaft from behind. And from the other side I can either hit the snap ring with a suitable piece of pipe or the inner ring of the ball bearing. But both of these fail, right?
    How do I get the crankshaft elegantly into the left bearing? Must also keep the minimum distance to the crankcase wall (at least 0.25 mm) ...
    Best wishes

    S50 B 2, year 1976, 3 gears, M 53/22 KF

  • What kind of engine do you have? On the left side of the M541 there are no Simmerrings and no shims either.
    Edit: I meant retaining rings or something similar: wink:

  • The left crankshaft bearing is used very last.
    If the right side is mounted with the crankshaft, continue as follows.

    => heat the left motor housing to 100 degrees
    => in the meantime, coat the right housing thinly with sealant (e.g. Curil T) and apply the seal
    => put the hot heater in the left KW bearing and only heat the inner ring (not the outer ring or the whole bearing!)
    => Remove the housing from the heating plate, quickly insert the left KW oil seal into the left engine housing
    => quickly coat the left housing sealing surface thinly with sealant
    => Thread in the still warm left housing (in the kick starter shaft, clutch shaft, output shaft and selector shaft of the selector fork), put it on, slide it onto the shafts and quickly tighten the 10 screws in a predetermined order.
    => then insert the oil guide disc
    => then push the left KW bearing with its warm inner ring over the crankshaft journal using a hollow mandrel (or a suitable tube with the diameter of the bearing outer ring) and insert it into the (still warm) KW bearing seat. Use a rubber mallet and only light blows.
    => then assemble all the rest.

    Get out of the EU! - Bring the D-Mark! - Right away !

  • But now I'm totally amazed, can't I distinguish left from right here? For me this is the left half of the engine:


  • Sorry, I forgot: it's an S50, 3 gear.

    seggi: that's the left half for me too.

    And now I'm also a little insecure. Even the blue original repair manual says that you start on the left and only end on the right. Or am I completely wrong now?

    Foolish talkers: thanks for the detailed instructions. Was it because of the insufficiently heated inner ring of the bearing that I couldn't get it together? Or, to put it another way: does the crankshaft simply have to be attached to it if it is running properly. I mean now completely without violence? So that I can get an idea of ​​what is normal and what is not.
    And I confess that I completely did not understand your instructions. You use the Simmering first. It happens from the right side, in other words in the crankcase. Then the crankshaft comes in and then you want to insert the bearing from the other side. How am I supposed to check the specified minimum distance between the crankcase wall and the crank web? And can it not happen if I slide the bearing in from the left side that I then slide the oil seal out on the other side and then have no chance of getting it back in?

    S50 B 2, year 1976, 3 gears, M 53/22 KF

  • I've only always repaired the S51 engines, never had one of your design apart, unfortunately I can't help you with that. But to rule out misunderstandings, you can type your vehicle in detail in your profile.
    But the KW can actually cope with axial blows, but you should use a rubber or plastic hammer. Since the connection between the bearing inner ring and the KW are designed as a press fit, the KW should be easy to assemble with oil or grease. I've never had any problems with that.
    However, you can briefly heat the inner ring with a gas soldering pen on a small flame, the Simmerring can cope with that. It doesn't stay cold when driving. I also have the repair manual, if you don't have a patio heater, you can use a screw or bolt of the appropriate diameter (if necessary grind to size), but don't insert it too far.

  • Stop everything !, command back and the whole department will return!
    I actually somehow confused right and left last night. Well, at least you both kind of noticed. That's probably what happens when you work too much in the evening instead of doing good to your girlfriend.
    Of course I meant that right Crankshaft bearing that is used very last.

    => First of all, the snap ring of the KW bearing is inserted into the left Housing half inserted
    => then the width of the left KW bearing, the housing (depth from left KW housing wall to the snap ring) and the crankshaft (crank arm to the end of the bearing seat of the left KW pin) and, if necessary, washers placed next to the snap ring so that the crankshaft at the end of the Assembly also sits exactly in the middle. So calculate everything and of course that too right Take the housing half, the crankshaft width and the thickness of the engine center seal into account in the overall calculation.
    => Then the left The housing half is heated to about 100 degrees on the heating plate (not warmer !!!) and then the left KW bearings are used, giving only light blows to the bearing outer ring
    => left Insert the oil seal
    => then the hot patio heater comes from Left in the inner ring of the left KW warehouse
    => then take the crankshaft out of the cooling compartment and quickly put it in the hot one left Insert the bearing inner ring from the right. If necessary, hit it lightly with a rubber hammer, but it actually slips by itself because of the temperature difference and the expansion ratio. If light blows are necessary, then if possible only hit the point on the crank web where the crank pin is located.
    => then right Heat the motor housing on the heating plate to about 100 degrees
    => meanwhile left Apply a thin layer of sealant (e.g. Curil T) to the housing and apply the engine center seal
    => the hot patio heater in the right Insert the KW bearing and only heat the inner ring (not the outer ring or the entire bearing!)
    => right Remove the housing part from the heating plate quickly right KW-Simmering ins right Insert the motor housing
    => quickly die right Apply a thin layer of sealant to the housing sealing surface
    => the still warm one right Thread the housing (into the kick starter shaft, clutch shaft, output shaft and selector shaft of the selector fork), place it on and push it onto the shafts. Possibly lightly with a rubber mallet
    => then insert the oil guide disc on the right
    => then that right Crankshaft bearings by means of a hollow mandrel (or a suitable tube with a diameter just below the KW bearing outer ring) with its warm inner ring over the right crankshaft journal and into the (still warm) KW bearing seat of the right Insert the housing => use a rubber mallet and only hit lightly and gently
    => then tighten the 10 housing screws crosswise in the specified order
    => then to compensate for play the washers on right Include bearings (use caliper) => the KW clearance should be 0.2 - 0.3 mm.
    => then mount the sealing cap with seal and sealant.
    => when the engine is cold, retighten all housing screws.

    To ask?

    Just ask, you should learn something.

    Get out of the EU! - Bring the Deutsche Mark! - Right away !

  • Thanks for your contributions!

    @ Dummies: Aha, I'm reassured that this can happen again to experienced people ... Now the instructions read a lot better. And I will probably come back to “Any questions?” In the course of this operation. So the next thing to do is to turn a patio heater; will make the process a lot easier. It continues on Monday. I'm with my girlfriend right now and do something good for her

    seggi: I put my bike in my profile.
    In my current experience, I can't recommend hitting the crankshaft even a bit. Did it when she didn't really want to go to the camp. So only light hits with a rubber mallet. Clamped in the lathe again today, and lo and behold - imbalance in the shaft Dial gauge on and very carefully straightened again. Now it still has an unbalance of 2/100 mm. But I hope that is within the realms of possibility.

    S50 B 2, year 1976, 3 gears, M 53/22 KF

  • I can't imagine that the imbalance was caused by careful assembly with a rubber mallet. After all, the KW is made of tool steel, and it takes more than rubber. Have you installed a new KW or the old one?
    With the S51 motors, you can at least warm up the bearing inner rings properly without having to worry about an oil seal.

  • Got a new crankshaft. But is it really new? Rather regenerated. With the old one, the needle bearing already had a lot of play. Unfortunately, I only checked the new one for imbalance after I tried to use it. But I can't imagine that it came out of the shop like this. Well, with a patio heater it should go without any blows, I hope.
    While browsing and reading I already noticed that I was laughing at a somewhat "service-unfriendly" engine. But I really wanted to have a 3-speed Simson again, because I had one before. Sentimental

    S50 B 2, year 1976, 3 gears, M 53/22 KF

  • The M541 is also available as a 3-speed gear, which would then be called the M531.