Vehicle Suspension Behavior is Reversed

For some reason, some vehicle bases have this problem where the suspension animation is reversed. When you brake, the front of the vehicle lifts up, and when you accelerate, the back of the vehicle lifts up. I've observed this issue with a variety of vehicle bases, from Officer Underwood's Charger to SentryGunMan's 2020 FPIU. The specific vehicle I am having trouble with is Matt's 2011-2015 FPIU base. You can see this issue in this video:

Really unsure why there's a bunch of sirens and crap in the video as I didn't hear any when I was recording it.

I've attempted to modify the handling line, but that has either further broken the vehicle or done absolutely nothing. I had an idea that maybe swapping the names of the suspension object would solve the issue, but this particular vehicle does not have any suspension objects? Maybe this is a reason that would cause the suspension to not work properly - I've not tested if adding suspension objects would resolve the issue, but this issue also occurs on Thero's and SentryGunMan's FPIU models, and those do not have suspension objects either. I will be experimenting with adding the suspension object next to see if that is the root of the issue. EDIT: Nope, detached the suspension polygons from the chassis and named them accordingly, but that did absolutely nothing. Reversed the names as well (front is now back, back is now front) and that did literally nothing either.

Is there anything I need to be doing through zmodeler in order for the vehicle to function properly, or is it something I'm missing with a meta file?

Thanks!

Quote from NopeBye

What exactly did you try modiftying in the handling, too me it looks like it would be an issue with the "VECINERTIAMULTIPLIER" as that is what controls the body roll of a vehicle.

Here is what I found on more about it:

"The way I understand 'vecInertiaMultiplier' to work is that:

x = How your vehicle tilts from side to side (set this low & car will corkscrew easily when jumping)

y = How your vehicle tilts from front to rear (set this low & car will somersault easily when jumping)

z = How the vehicle rotates/turns (ie raising this slightly makes the car slower at turning)"

Original Topic

From that alone I'd try editing the y value and see where that gets you. Thats really the only thing I can think of that would fix it, I don't neccessarily think its anything to do with the model itself.

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That wouldn't really change anything in relation to my issue (believe me, I've tried). I've tried to modify the suspension values (CompDamp, ReboundDamp, UpperLimit, LowerLimit). I've not tried modifying the RollBar or RollCenter values as suggested by GreenAid, so I'll be trying that this morning.

Quote from GreenAid

That just makes the vehicle rotate slower in those axes, the actual value he needs to lower is RollCentre, provided the COM is in the right place, usually values of 0 or 0.1 are good.

I'll try that now, thanks!

Edit: I'm pretty sure the vehicle center of mass is set correctly, so I haven't changed that from the original (x="0.000000" y="-0.130000" z="0.040000"). For both RollCenter values, I've attempted lowering the values (was 0.75 for both), making the values negative, making the values zero, and making the values an extreme negative OR an extreme positive (which didn't fix anything, but made the reversed suspension effect a LOT more noticable). None of these changes actually fixed anything - should I just try a different handling line or is there something else I should change?

Handling line for reference

Quote from GreenAid

RollCentre is like centimetres (or metres) off of the ground, so all those values are too oof for the car, leave it at 0.1 for that car and check it ingame. The rest looks mostly fine, so it should work properly.

It was originally 0.75 for both - I've tried a variety of values, and tested 0.1 for both again in case it worked this time. Changing the values there has no effect on the reversed suspension behavior; it only changes how much the car raises off the ground when accelerating/braking.

Quote from GreenAid

Well I guess the collisions might have something wrong then? Have you converted it yourself? Is anyone else having that issue? Because I can't think of anything else.

I honestly don't know. I didn't convert anything - I just got the base from Insanity, then got the edits from Trooper 18, then changed the front interior to the one from Thero's.

I don't really know what to do at this point. I'll try different handling lines but I don't expect that would fix anything.