Built the Bugatti Chiron and initially everything worked. With the shifter in "drive" the wheels turned and the pistons moved, in neutral the wheels moved but the pistons didn’t. The reverse gear also moved the pistons. The paddles worked and changed the gearing. But now the wheels still move together, but the pistons don't move.

  • Hi Kelvin and welcome to Bricks.SE! Thank you for the detailed description of the issue, I hope you'll receive assistance here. Meanwhile, please check out the help center pages and take the tour to learn more about this community and how things work here.
    – zovits
    Feb 14 at 11:42
  • 3
    The obvious thing to clarify would be what happened between the "used to work" and "now it doesn't work" states. Was the model dropped, modified, completed, just sitting on a shelf, etc? Or to diagnose the issue yourself, you might try to follow the motion of the wheels along the drivetrain to see if the problem can be constrained to the wheels, transmission, engine or the connections between them.
    – zovits
    Feb 14 at 11:51
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    The model hasnot been dropped or modified. When working the paddles changed the gears and the pistons faster or slower, depending on the gear shift. I have tried to follow the wheels alon the drive train and as a far as i can see they are connected up correctly. I can see the the gear leaver moving the gray selector but I am not sure that the blue and red gears are moving correct. I can see the white gear moving correctly, whether it is in D, N or R. It seems that the connection to engine drive shaft is not working? Feb 14 at 12:52

1 Answer 1


Based on the comments (the rotation of the wheels is confirmedly transferred via the DNR selector and the transmission), it seems likely (and is basically the only possibility left) that the connection between the transmission and the engine is at fault. To check this, take a look at the black axle connector signified by the uppermost white arrow at this step:

Step 465 ("The Marriage") of the Chiron assembly process

If it came loose, there might not be a mechanical link that would transfer motion to the pistons.

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