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Joined 1 year ago
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Cake day: October 19th, 2023

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  • Body on frame car is very old (80’s).

    Since then cars are unibody which means the frame part is integrated and spread across the body and floor parts.

    Manufacturers have moved on to subframes. A strong U or boxshaped tube rail to fasten powertrain mounts, steering, suspension arm and all moving parts onto. They then bolt the subframe to the unibody with dampers and bushings to reduce NVH into the cabin.

    For soundproofing, most windshields now have 2 panes with glue sandwiched between the 2, the pillars are filled with foam, door panels and the floor have strategically placed thick sheets of sound dampening,

    As for smoothness, lots of cars have different suspension to do the job. The standard is the multi-link suspension( many control arm with different range of rotation and angles that together keep the wheel flat on the surface if you accelerate, Brake, corner) having as many arms as possible helps the ride stay smooth and quiet.



  • Thanks for clearing this out.

    I figured there would still be enough documentation through previous engine generations (J series V6 engines have been built and upgraded since 1996) to have the main issues and main limits figured out for their purpose (fuel efficient urban driving and urban/crossover levels of towing capacity). Basically it would be fully optimised by then and only be tweaked around knowing anything else pushes the failure rate.


  • While this is true, some parts are so simple and have been designed/updated with so much experience and feedback, the defect can only be because of Quality control or Bad design.

    Like if shopping around get them the material that is so cheap it is not the same, if the parts weren’t treated or finished like designed, if the tolerances are the issue or some other problems you would think should not be an after decades of engineering in engines.

    I would appreciate more infos on if manufacturers have something like design rules that would say any rod bearing for cranks of X diameter,x oil grade made to spin to x RPM and up to X operating temperature needs to have X fitment and X metal treatment to avoid this issue.