Vehicle randomly goes straight while turning

[Pentagon005875]

TLDR: My bus randomly goes straight when turning

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You can write your topic however you want, but you need to answer these questions:

1. What do you want to achieve? Keep it simple and clear!

• I want it so that when the bus is turning, it follows its intended turning radius. Given a wheelbase of 27 studs and turning at 45 degrees, the turning radius should also be 27 studs or around that. I want it to stay on its intended turning path.

2. What is the issue? Include screenshots / videos if possible!

• it doesnt turn strictly on its turning path. It randomly moves straight instead of turning, as if it ignores the front wheels’s turning angle and the back wheels just push the bus forward. This of course results to the bus going out of the turning path. In gameplay, this results to insufficient turning while a player turns, which results to crashing into unintended paths. When i turn to a tight turn, i might crash to a building instead if the bus randomly stop turning while im turning.

4. What solutions have you tried so far? Did you look for solutions on the Creator Hub?

• ive asked help with AIs, DevForum, and heres what ive tried so far:

1. I reduced friction of the backwheels. I want to copy real life buses where they have double wheels at the back. So to represent this, i doubled the width of the back wheels. Even by reducing friction at the back due to the doubled width, it doesnt work too.

2. Applying ackermann principle. Apparently i did some research and two front wheels should not lazily turn at the same angle. During a turn, in a right turn for example, the right front wheels have smaller turning radius and the left front wheels have larger turning radius. The required turning angle for the left and right front wheels can be calculated by some trigonometry maths according to ackermann principle. It seems to not work either.

3. Doing 44 / 46 degrees turning instead of 45. I tried this in hopes that maybe a perfect 45 degrees can cause confusion to roblox. This seems to have no effect / doesnt solve the problem either.

4. Increasing the road / floor friction - doesnt work too

5. (proportionately) increasing friction / friction weight of both front and back wheels - doesnt work

6. equalizing spring stiffness for both front and back wheels. Maybe you know, a stronger stiffness of spring might unfairly increase the friction of one wheels, I tried to make it equal for all, no effect either.

What i havent tried so far is trying to change the bus weight cuz im afraid it might complicate the problem further. However i can assure you I equalized the center of mass fairly for both front and back wheels by making all parts in the bus massless, and just setting one sacrifice part that has the weight, situated to front and back wheels at equal center distance.

Thank you:) been working on this problem for like over a month now.![Bus|690x305]

Please see video :

• the blue circle represents estimated turning radius. The bus should turn around that.
• the yellow squares represents a quarter 27x27 of the turning radius.

Bus turning problem

[thesnailcrusher (Forknife_whereweeatn)]

What script handles the turning? Is it just the default Roblox car system (driveseat and all)? And if so, check if there’s any parts that could collide with the bus

[Pentagon005875]

I forgot to mention in the post, I use hingeconstraint for the turning :

angular responsiveness = 200
angular acceleration = 4
angular max torque = either a large number or inf both doesnt work

All parts surrounding the wheels had already been set to noncollide and the problem still persists

[Pentagon005875]

I figured out that the solution was NOT increasing, but its actually decreasing the friction to the default 0.3 or even turn off custom physics properties. Apparently increasing friction seems to not increase wheel traction, but increase the wheel friction as if it was a non-rotating object.