VehicleSeats, RotateV and Wheel Rotate with old Hinges are broken

[Scottifly]

• Detailed description of bug; VehicleSeats sometimes no longer work with older wheels using the Hinge Surface joint, or the bug only affects individual Hinges so you may get vehicles that have only 3 out of 4 wheels working.
• Where the bug happens; In game and in Studio.
• When it started happening; First noticed it 3 days ago when the boats in my obby quit driving. It was only certain boats that had 2 propellers on the back driven by Hinge surfaces and VehicleSeats. Other boats that had 2 paddlewheels on each side (like a car’s wheels) still work fine. I don’t get error messages in the Output window.
  -I fixed it in my Boat Obby by changing to HingeConstraints and rescripting the drive scripts, but since Hinges and HingeConstraints act differently it took quite a while to fine-tune the differences.
• Screenshots and videos of the bug; In the video I’m using W, A, S & D but as you can see none of the wheels are turning. I’ve tried increasing Torque since you can see by the red dots at the wheels it’s trying to do something, but no movement of the car.
  robloxapp-20200620-1459111.wmv
• Steps to reproduce the issue (be minimal, specific, consistent!); Happens in a lot of my older games too. Some vehicles don’t drive at all, some drive but individual wheels are locked up, others drive fine. Each vehicle seems to react the same way as its original each time it spawns. Also the AreHingesDetected value reads at 0 although in this case there are 8 Hinges that are attached to the wheels.
  Similar to the report in this post as well: Is this a roblox bug or on my part?
  This is also affecting legacy Motor Surfaces that are set to spin signs or windmills in older places using the Rotate or RotateV Properties. I found it on the dragon I have in the background of the video which is travelling around on a monorail. When the player gets ‘caught’ by a seat in the dragon’s claw the Motors that propel it don’t have enough torque and the dragon stops moving around the track.

If you have had this issue please comment below so the post gets bumped. This will affect many legacy games if it isn’t rectified.

[Scottifly]

As HingeConstraints are not affected by Explosions it makes it more difficult to have a game where you blow vehicles up depending on the design of the cars. If you have a single main chassis Part with the wheels connected to it and you use a rocket launcher or bomb to destroy the car, the wheels stay attached and you have a still functioning vehicle chassis driving around…

[kleptonaut]

Can you send one of the broken car models and/or provide minimal, specific, consistent steps to reproduce the issue?
I just tried building a VehicleSeat car and it worked fine.

[Hajimalago]

Hi all, there was a bug related to some changes in RotateV. I can confirm that this was resolved recently and will be fixed with the next release this week.

[Scottifly]

I think the vehicles I was having the biggest problem with were ones that used a weldscript for attaching the components (the seat wasn’t touching any of the 4 parts the wheels’ Hingesurfaces were attached to) and I was changing the ParamB values to control the wheels with a script that got input from the VehicleSeat Steer and Throttle inputs.
I also noticed a couple of the broken vehicles were moving forward and backward, but not steering properly last night. I increased the Torque setting in the VehicleSeat and it seems to have fixed those issues.