object speed detection (for collision)

ive been making a car latly for rping in city envirements and the way im working on making the car depending on your speed when you hit into any solid object (other than avatars/land) it will couse a message to be sent to the rest of the car trigering the actian of parts

the problem right now i cant seam to fix is you can tap into something and it will couse the action to hapen but when i flip the (< > around it wont trigger it will littaly eather trigger at very little touch or wont trigger at all

key sound = "";
integer crash;
default
{
    state_entry()
    {
        //llCollisionFilter("wall", NULL_KEY, TRUE);
        llMessageLinked(LINK_SET, 0, "repair", NULL_KEY);
        llListen(0,"",llGetOwner(),"");
    }
    listen( integer channel, string name, key id, string message )
    {
        if(message == ".crashstart")
        {
            llMessageLinked(LINK_SET, 0, "crash", NULL_KEY);
        }
        if(message == ".crashrepair")
        {
            llMessageLinked(LINK_SET, 0, "repair", NULL_KEY);
        }
    }
    //collision_end(integer x)
    collision(integer x)
    {
        if(llDetectedType(0) & AGENT) 
        {
        }
        else if(crash == FALSE)
        {
            if(llVecDist(llGetPos(),llDetectedPos(0)) > 5)
            {
                llTriggerSound(sound,1);
                llMessageLinked(LINK_SET, 0, "crash", NULL_KEY);
                crash = TRUE;
            }
        }
        if(crash == TRUE)
        {
            llSetStatus(STATUS_PHYSICS,FALSE);
        }
    }
    land_collision(vector y)
    {
    }
}

You can try:

vector velocity = llGetVel();
float speed = llVecMag(velocity);

vector otherObjectVelocity = llDetectedVel(n);
float otherObjectSpeed = llVecMag(otherObjectVelocity);

But I'm not sure how much the velocity will have already been affected by the physical collision at the time that the 'collision_start' event is triggered. You may instead/also need a frequent timer to remember velocity so you can use the last recorded one to deal with the results of the collision.

im gong alittle stupid right now but how would i incorperate that into my script for i need to create a list to rember the last valocitys?

Do you need a history of velocities, or just the most recent?

float TIMER_PERIOD = 0.1;

velocity lastVelocity = ZERO_VECTOR;

default
{
    state_entry()
    {
        llSetTimerEvent(TIMER_PERIOD);
    }

    timer()
    {
        lastVelocity = llGetVel();
    }

    collision_start(integer nDetected)
    {
        float speed = llVecMag(lastVelocity);
        // ...
    }
}

dosent seam to work but compiles and lsleditor dosent trow out any errors eather here is what i got

key sound = "";
float TIMER_PERIOD = 1;
vector lastVelocity;
integer crash;

default
{
    state_entry()
    {
        llSetTimerEvent(TIMER_PERIOD);
        crash = FALSE;
    }

    timer()
    {
        lastVelocity = llGetVel();
    }

    collision_start(integer nDetected)
    {
        float speed = llVecMag(lastVelocity);
        {
            if(llDetectedType(0) & AGENT) 
            {
            }
            else if(crash = FALSE)
            {
                if(speed < 1)
                {
                    llTriggerSound(sound,1);
                    llMessageLinked(LINK_SET, 0, "crash", NULL_KEY);
                    crash = TRUE;
                }
            }
            if(crash == TRUE)
            {
                llSetStatus(STATUS_PHYSICS,FALSE);
            }
        }
    }
    land_collision(vector y)
    {
    }
}