Bus suspension shake

The whole bus has massless. There is a part Mass in the center of the bus, which sets the whole mass. But for some reason it doesn’t help, or I’m doing something wrong. The wheels cannot touch anything in theory, they are assigned collision groups that cannot collide with the bus in any way.
The wheels have a standard weight. I tried adding Density to them, but it didn’t help.
WHEELS HAVE CYLINDRICAL PART. The wheels are made using a cylinder. Without suspension, the bus rides very smoothly and nothing shakes.

VIDEO - Bug demo - YouTube

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You should try to tweak spring constraint properties and see if anything helps. Also you should not have double wheels deal with physics, instead you should have a physical wheel and a visual double wheel.

I just removed the second wheels from the back, it didn’t change anything, so the problem is definitely not in them, since they also don’t interact with each other in any way, they have a collision removed among themselves

It seems like it, but it’s also good practice to have one cylinder instead of 2 for a double wheel since otherwise the game engine will have to deal with more constraints and collisions.

Is it possible for you to share chassis only? so that I can try out for myself.

Here is few suggestions:

  1. Duplicate your model and remove the visuals only, and then attempt to diagnose the problem.
  2. Are sizes of all of the wheels the same?
  3. Is surface that you’re driving on smooth?
  4. Did you try to lower all of the values, since I know that Roblox’s game engine sometimes acts weird when dealing with large numbers?
  5. Is the mass part perfectly centered?

Lower all the spring’s stiffness, I personally set it to 4500 and it didn’t shake anymore. As I mentioned in my first reply.

And as of fixing the suspension height, you can set all of the spring’s MinLength property to 1.75 or something higher.

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the suspension is not quite as soft as it should be, too rigid, and when setting softer values, the shaking returns

Alright, how about this configuration?

MaxLength: 3
MinLength: 1.75
FreeLength: 2.5
Stiffness: 80000
Damping: 5000

It shouldn’t shake at low speed. The only thing I can think of is just adjusting the Stiffness and Damping.

for some reason, I have a feeling that something is pressing on the front wheels, because with the same MaxLength, the front wheels fall below the rear ones, but I can’t figure out what exactly is pressing


This is not the ideal solution… i was able to fix your bus very quickly by raising the actual size of your Mass part, so that instead of it weighing about 1600 it was about 4500… and i centered the part too… it rode fine after that.

Edit: same result achieved changing the density from the 32 to about 85 (which gets it to the same weight as above).

can you send me rbxl file please?

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Sorry i just read this… i literally just went into the Mass part, went down to the custom physical properties and changed density to 85. Let me know if you still need the file, but its just one small change.

I tried to do as you said, and I got a bus with a low suspension, and as soon as I lift it, the shaking starts again)
Below is a demonstration of the perfect suspension with gravity 80, as for me it is the perfect balance for a transport simulator.With gravity 196, of course I get the same suspension, but the shaking spoils everything. if there is still a solution to make exactly the same suspension without shaking at a speed of 1-20 km/h, then of course I will switch back to gravity 196

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Well why don’t you add a vector force to only affect the gravity of only the bus??

-I suggest you look into vector force it is really beneficial for any anti-gravity thing resource you want to make with it. :