Unsolved Unstable Wheel Speed

You can see that when rotational force is applied to the wheels they do not work properly. The jbeam wheel hubs do not have the same issue which leads me to think the issue is with the wheel rims/tyres.
The speedo is attached to the front right wheel, you can see how it differs from the air speed of the vehicle in the top left.

The wheel code is strongly based on the Sunburst wheels+rims (found in the common zip file), most of the values are copy pasted. The vehicle was based on hub wheels originally, but I converted it over to pressure wheels which is when the issues started.

Code:

"pressureWheels": [
            ["name","hubGroup","group","node1:","node2:","nodeS","nodeArm:","wheelDir"],
            {"disableMeshBreaking":true,"disableHubMeshBreaking":false},
            {"enableTireReinfBeams":false},
            {"enableTireLbeams":true},
            {"enableTireSideReinfBeams":false},
            {"enableTreadReinfBeams":true},
         
            {"enableABS":true}
            {"selfCollision":false}

            //general settings
            {"radius":0.31}, //Radius of the tire nodes
            {"hubRadius":0.23}, //Radius of the rim
            {"wheelOffset":0}, //Offset from the original position(Left/right)
            {"hubWidth":0.195}, //Width of the rim
            {"tireWidth":0.185}, //Width of the tire
            {"numRays":16}, //The amount of nodes to make the circle, more may result in smoother driving, but at the cost of performance, weight & stability(This value must contain an even number between 2-50 ideally between 16-28. numbers below 10 shouldn't be used)
       
         
            //hub options
            {"hubTreadBeamSpring":1101000, "hubTreadBeamDamp":10},
            {"hubPeripheryBeamSpring":1101000, "hubPeripheryBeamDamp":10},
            {"hubSideBeamSpring":1601000, "hubSideBeamDamp":10},
            {"hubNodeWeight":0.42},
            {"hubBeamDeform":55600, "hubBeamStrength":63000},
            {"hubNodeMaterial":"|NM_METAL"},
            {"hubFrictionCoef":0.5},
         
            //tire options
            {"wheelSideBeamSpring":0,"wheelSideBeamDamp":20},
            {"wheelSideBeamSpringExpansion":351000,"wheelSideBeamDampExpansion":20},
            {"wheelSideTransitionZone":0.1,"wheelSideBeamPrecompression":0.99},

            {"wheelReinfBeamSpring":45000,"wheelReinfBeamDamp":70},
            {"wheelReinfBeamPrecompression":0.99},

            {"wheelTreadBeamSpring":201000,"wheelTreadBeamDamp":35},
            {"wheelTreadBeamPrecompression":0.99},

            {"wheelTreadReinfBeamSpring":61000,"wheelTreadReinfBeamDamp":35},
            {"wheelTreadReinfBeamPrecompression":0.99},

            {"wheelPeripheryBeamSpring":161000,"wheelPeripheryBeamDamp":20},
            {"wheelPeripheryBeamPrecompression":0.98},

            //general tire values
            {"nodeWeight":0.13},
            {"nodeMaterial":"|NM_RUBBER","hasTire":true},
            {"frictionCoef":1.15},
            {"triangleCollision":false},
            {"pressurePSI":26},
            {"maxPressurePSI":1500},
            {"dragCoef":10},
         
            //deform values
            {"wheelSideBeamDeform":14000,"wheelSideBeamStrength":16000},
            {"wheelReinfBeamDeform":101000,"wheelReinfBeamStrength":1001000},
            {"wheelTreadBeamDeform":14000,"wheelTreadBeamStrength":16000},
            {"wheelTreadReinfBeamDeform":14000,"wheelTreadReinfBeamStrength":16000},
            {"wheelPeripheryBeamDeform":101000,"wheelPeripheryBeamStrength":1001000},
     
            //pressure options
            //{"pressurePSI":26}, //Tire pressure in PSI, higher tends to slide more
            //{"reinforcementPressurePSI":30},
            //{"pressureSpring":761000},
            //{"reinforcementPressureSpring":110000},
            //{"pressureDamp":60},
            //{"reinforcementPressureDamp":60},
         
            {"selfCollision":false}
            {"collision":true}
         
            {"propulsed":1}
            //{"brakeTorque":800},
            {"brakeTorque":1800},
            {"parkingTorque":0},
         
         
            {"group":"WheelFR"},
            {"axleBeams":["axle_FR",]}
            ["FR", "WheelFR", "tire_FR", "fr2", "fr1", 9999,  "fr6", 1, {"speedo" : true}],
            {"group":""}
         
            {"group":"WheelFL"},
            {"axleBeams":["axle_FL",]}
            ["FL", "WheelFL", "tire_FL", "fl2", "fl1", 9999,  "fl6", -1],
            {"group":""}
         
            {"propulsed":1}
            //{"brakeTorque":600},
            {"brakeTorque":1000},
            {"parkingTorque":3000},
         
            {"group":"WheelRR"},
            {"axleBeams":["rr1","rr3",]}
            ["RR", "WheelRR", "tire_RR", "rr2", "rr1", 9999,  "rr6", 1],
            {"group":""}
         
            {"group":"WheelRL"},
            {"axleBeams":["rl1","rl3",]}
            ["RL", "WheelRL", "tire_RL", "rl2", "rl1", 9999,  "rl6", -1],
            {"group":""}
     
             
        ],

Thanks for any help

 

Im not sure i understand your issue. In the first video everything looks fine as far as i can tell, what is the issue here? In the second video you have the parking brake enabled intentionally? or is that the issue?

 

If you look at the speedo, you can see that it is not accelerating steadily, it is bouncing all over the place, while the cars air speed is not. This would lead me to believe that the wheel is behaving in an unstable manor. Since the speedo is attached to the front right wheel.

The point of the second video was to show that the same effect is present even when braking as well as accelerating.

 

Edit: after watching the first video again it does seam a bit spazzy even if it was slipping. Check my third suggestion

Try very very slowly accelerating on the gird map pure map, and compare the speeds then.

Its also possible that your wheels are very close to being unstable, which is causing them to shake/jitter a bit and messing with the speedometer reading. In which case adjusting the spring values of the wheels would help

 

I'm having this exact same problem, with custom wheels. Not sure if yours are custom or not

But, I don't think it's the wheels themselves.

I actually believe it's caused by some kind of transmission clutch problem (in my case anyways) because the wheels are perfectly stable when not using the engine, i.e. braking, coasting, and sitting.

Still looking for a cure...

However, I notice that the transmission clutch has a little sag in it- like a torque converter.

Try messing around with the clutch and maybe one of us will find a solution.

 

I'm pretty sure this is being caused by the "clutchTorque" being much higher than the engine's torque. This coupled with a low ratio 1st gear causes that weird jumpy-ness.

 

I tried changing the clutch to 100 and it was still happening (along side a lot of clutch slip). I also tried securing the wheel hubs in place better with extra (temporary) beams directly to the main chassis, that also did not fix anything. I have dropped the wheel and hub spring values from 1101000 to 901000 which had no effect.

Here is a slow motion video showing the same issue. The airspeed is shown in the top left of the screen.


The Engine Torque keeps jumping between positive and negative values, which is potentially causing these issues. Gonna look into that a little more.

 

Yep, exact same issue here.

 

It would actually seem that all of the engines can produce unlimited Torque, and are only limited by the clutch.

However the Torque curve graph is accurate and states the maximum torque at 270Nm, while engine debug shows the maximum Torque as whatever the clutch can provide.

EDIT: This seems to be the case with all cars in game actually. According to the engine debug app all cars can produce as much Torque as the clutch can allow?

 

I think I found a potential solution. It's not the wheels, but rather the suspension attaching to the wheels.

If you beamSpring value is anywhere above 30 million, it should become unstable no matter what you do. Just something with pressureWheels I guess.

However, a high wheel torque output makes things worse.

Hope this helps

 

This is interesting, I have similar problems with the CRD Monster Truck. I'm yet to find a proper solution.

I'll check my clutchTorque values.

 

I don't have a single Beam that is above 12 million in the entire vehicle. However the only beams with a value that high are the suspension arms.

 

What's the weight of your wheel hubs?

 

6kg per node, with 6 nodes per wheel hub. So 36kg per hub.
The bit of the chassis that the suspension arm attaches onto is 7kg per node.

 

Ah, see my wheel hubs are 35kg per node. Try lowering the values of your hub to suspension attaching beams, see if that works. Just a quick test.

Edit:
Oh, wait. You meant your hubs. I meant the wheel nodes themselves, often called "Spindles."

 

I changed it from 12million to 1.2million, no change.

I did find that adding TorqueCoupling and TorqueArm values to the wheels helped a bit.

 

I just set them to the frame Solved my problem.

Edit:
Oh, and did you by any chance use a locked differential?

 

Its front wheel drive with an open diff. However I find the issue still occurs with 4 wheel drive with both locked and open diffs.

 

Hm. This is a tough case.

 

Yeah, It wouldn't be such an issue if it didn't result in the car going into reverse under very heavy braking. The ABS seems to be struggling to figure out what is happening because the wheel motion is not smooth.