Having a wheel problem with physics

Unlike the other times, I went over this several times before posting.

I started off by using the Physics car race example\tutorial and modified it untill I got a basic working version of what I wanted. Then I drew some new vehicles. The problem occured after adding them. For some reason, the wheels are moving a little wobbly - especially at the start - and occasionally badly when moving fast. The opponent’s are just a shrunken monster truck that came with it and are doing just fine. I had to shrink them as I wanted my vehicles to be at scale and get rid of zooming the layer.

Also, the smooth camera movement can lag behind.

Sounds like a few issues in one post.

WRT the physics car, do the wheel swobble on the first car you have, just the new one or both? When you say wobbly, is it a back and forth wobble, or uncentred point of rotation wobble? How are you attaching the wobbly wheels - to the centre of the image? If so, is that centre in the middle of the wheel?

For the smooth camera issue, are you using lerp to position the camera? If so, make sure the lerp parameters are camera co-ords followed by target co-ords, and play round with the last value of lerp - increasing it closer to 1 may help.

Like the wheels are an uneven circle, bumpy or off center. The more extreme times are like they are trying to come off. It only happened on the new vehicle and not the ones that came with the tutorial. I triple checked the points, bounding box and events.

After posting, I remembered that I have angular force applied to the wheels to make them spin. Later, I should try removing that and see what happens.


I’ve been fiddling around with it and seems to be the wheel joint “suspension”. Changed it to a revolute joint and recentered the point and good now.

How can I have the wheel joint “suspension” be in a fixed up & down motion to the object it is attached to instead of spinning around like it’s on an elastic?

Have you tried changing the frequency (hz) of the wheel joint?

Are you using a wheel joint? According to the wiki, this sounds exactly like what you’re after. :

Wheel Joint

A very specified joint, when you need wheels, you’ll want this joint, and it’s hard to think of a case different than a vehicle’s wheel where the best joint is the wheel joint.
Made to simulate vehicle wheels, this joint does only that, but does it very well!

You can think of the wheel joint as a revolute plus a prismatic joint:
The revolute joint is used to make the second object (the wheel) rotate, and, as the classic revolute joint, it supports a motor to simulate the vehicle motor, causing the wheel to rotate.
The prismatic joint function is to simulate the vehicle wheel suspension, and, as the classic prismatic joint, you can set the axis angle to define the wheel translation direction. Generally, the axis direction is vertical, but, for example, motorbikes have a front-wheel suspension direction different (and in some cases very far) from vertical.

I started with the wheel joint and it doesn’t behave properly. The prismatic joint/suspension part doesn’t stay moving in a straight line, but causes the wheel to fly way from center when moving. That is what was causing the bumpiness, even after changing the frequency. It doesn’t happen with revolute only joints.

What are the parameters/settings you use for the wheel joints?