Is the smart weight balance really smart?

Discussion in 'SRT Hellcat Wheels and Tires' started by Tire God, Apr 6, 2016.

  1. Tire God

    Tire God Hellcat Member

    Joined:
    Apr 5, 2016
    Messages:
    153
    Likes Received:
    30
    Trophy Points:
    18
    Vehicle:
    Challenger SRT Hellcat
    I was kind of hesitant to post this part of balancing. But after all of the issues you guys are having I broke down and can't take it anymore. One of hunters greatest inventions and features is called "Smart weight". The balancers automatically balance in this mode and can't be turned off for good. But you can disable it with a push of a button for a certain car. First you must understand the balancing theory and the different types of weight placement and what it does and doesn't do. There are two types of wheel and tire imbalance, static and couple. Static is the up and down vibration and couple is the side to side or the "steering wheel shake" you get. Research shows that a tire and wheel that is vibrating can almost always be fixed by only accounting for the static imbalance in an assembly. The static imbalance is always the more prominent problem. That being said, smart weight is a very good thing for many reasons. 1: it optimizes the static imbalance to certain limits where you "should not feel a vibration". 2: it actually moves the weights to a slightly different position and usually only requires weight placement on one side and this saves the shop time and money because less wheel weights are used and it's faster. 3: it keeps uneducated or lazy techs from looking at the screen that says .25 and .50 and saying "eh, good enough".
    BUT...
    Let's assume all of the things that should be done are perfect. The balancer is calibrated properly, the tech used the proper precision cone, the tech performed the centering check to make sure he has used the right cone and the wheel is perfectly centered on the balancer. The tech places the data arms to the correct position to tell the balancer where the weight placement should be. Great.
    Now he strips the weights, spins the assembly, and it says to add 1.00oz to the outside. So he does. The balancer now says "OK" on both sides. Now I will stop you right there. If you look at the smart weight part of the screen, it shows the balance limits that are set by hunter where you should not feel vibrations. And you see the "Ok" for each weight plain. If you turn off smart weight, you will see the wheel is now not balanced but it says .50 on each side but usually 180 degrees apart. This technology is great for MOST VEHICLES. But when you are dealing with high performance cars, I always turn it off and it fixes the problem. When it is actually balanced it will say 0.00 on each side. Not "OK". The point is to make sure the tech turns the smart weight feature off and you should no longer have vibration issues unless it's a radial force variation problem in which you would need a road force balancer to fix that. I have a very long post about that you can read. Don't let anyone balance the wheels using a static center balance (where there is one strip of weights in the center of the wheel) unless you have a crazy fitment with a very negative offset wheel and there is only room for one weight placement. The wheel weights need to be as far away from each other as possible. (Flush with the back lip, and right behind the spoke on the front.) The static balance only measures for up and down movement. Where as a dynamic balance measure both up and down and side to side movement. (Static and couple forces). Smart weight measures both but changes the weight placement to optimize the static imbalance more than the dynamic because that is where most vibration issues are. So you leave the shop and you still have that anoyying shake at 70-80mph. That is exactly what the dynamic balance not being correct causes. And I really hope with the future balancers they still have smart weight but the limits are much tighter as to what is acceptable especially with Hellcats running around haha. I hope I have made the little light bulb go off for thoes of you that service tires, and for thoes of you that stand there and watch them balance them. Just ask for a dynamic balance with smart weight turned off, and make sure the balancer is calibrated prior to your wheels going on it. I don't call it smart weight anymore I call it the "OK" balance. I hope this helps you guys in the future tire servicing.
     
    • Useful Useful x 2
  2. Tire God

    Tire God Hellcat Member

    Joined:
    Apr 5, 2016
    Messages:
    153
    Likes Received:
    30
    Trophy Points:
    18
    Vehicle:
    Challenger SRT Hellcat
    This link explains why it's good, but, the tolerances set by the hunter engineers aren't close enough to perfect for the high performance cars on the road today. The fact that it says .25 on each side when smart weight is turned off in the beginning of the video means that you need to fix that tiny bit of imbalance if your vehicle is extremely sensitive. Or you could let smart weight do its work and add a smaller overall number of weight to a different spot that still meets the "limits". The reason I was hesitant to share this was because I'm afraid people will request it on their 89 camry or 2006 civic. When in fact regular cars it is not nesasary and truly is a waste of lead weights when smart weight is not being used. I use it until I work on a car that has 55 series or lower tires on it. Good rule of thumb.

     
    • Like Like x 1
  3. Aarcuda

    Aarcuda Gold Member

    Joined:
    Oct 22, 2014
    Messages:
    1,428
    Likes Received:
    459
    Trophy Points:
    258
    Location:
    The Boonies
    Vehicle:
    Challenger SRT Hellcat
    love it!!
     
    • Agree Agree x 1

Share This Page