Balancing and Mounting Wheels
Updated November 29, 2012
Shaking/ Balance Problems
Problems with balance are due to:
- Wheels / tires out of balance
- Bent wheels; Rims with too much run-out
- Out of round tires / slipped belts
- Worn Suspension Parts
- Runflat problems
An out of round tire is one that has been defectively manufactured in an oval shape. AMG had lots of problems with out of round 16.5" GSA's in the past. The one piece steel wheels had a lot of quality control problems with run-out. Run-out is when the wheel is doesn't run true and wobbles from side to side. There are a lot of bent wheels out there from hard off-roading. There have been a number of problems with the 2 piece runflats coming loose in the wheel causing out of balance problems.
A quick way to check your wheels and tires:
The first thing you need to do is check to see if the problem is the wheel/ tire assembly or worn suspension parts. If you are getting a shake in the front you can rotate / swap your front and rear and see if you still have the shake. Of course if you have problems with front and rear wheels this won't be the answer.
For out-of-round, you need to determine whether it is being caused by the tires and or the wheels, and replace the defective part(s). No amount of balancing or dynamic balancers will fix an out-of-round problem.
To check for out-of-round:
Put the wheel / tire on a tire balancer machine. As it spins, look for Up and down and or side to side movement in the tread face. Large or sudden movement in the tread face, particularly up-and-down, indicates an out-of-round condition. Look at the side of the wheel as it spins. If it is wobbling side to side you have a bent wheel.
Other problems that have come up that cause shake all have to do with worn suspension parts. Idler and pitman arms have always been a problem. A severely worn idler and or pitman arm will cause the truck to violently shake around 40 mph. Worn ball joints and bad shocks will also cause slop in the suspension that can lead to shaking.
Realize that a 16.5 12 bolt military wheel weighs 165 pounds while an aluminum wheel with a Goodyear GSA weighs about 116 pounds. The military wheel has almost 50 pounds more of unsprung weight. This is puts a lot more stress, strain and wear on all of your suspension components. A truck with lighter aluminum wheels will weigh 200 lbs less, handle better and have much less wear on tires, springs, shocks, idler, pitman and ball joints.
Other problems have occurred when the center bearing on the front drive shaft starts to wear. You will start to smell burning rubber like a belt slipping. As the problem gets worse you will start to get a shake under the drivers seat. If the bearing goes while you are moving, the truck will start to violently shake. You have to stop immediately or the drive shaft will start to whip around and destroy everything it comes in contact with.
Hunter's GSP9700 Road Force Measurement® System Solves Problems Balancing Alone Can't Fix
If you are getting new tires or trying to solve a balance problem I recommend seeking out a tire dealer that has one of these machines. Not all places have them probably because they cost 15k. This machine will tell you if you have a bad tire. Don't be surprised if a brand new tire is out of spec.
A regular dynamic wheel balancer spins the wheel and tire and tells you to add weight until it's in balance. It will balance a tire even if the tire is out of round. That's why so many Hummer owners I talk to tell me that they still have vibration after they had all their wheels balanced. The thing that makes the Hunter machine unique is it's ability to measure if the tire / wheel assembly is out of round or wobbles side to side. Hunter says it does this by using a “road roller” to apply up to 1,400 lbs. of pressure against the wheel assembly to test if the assembly is round when rolling. The roller can find problems such as lack of tire uniformity that once could only be detected by industrial tire uniformity graders. I can tell you that I had a brand new tire come up with an error message saying it had excessive road force. Another words the tire was either out of round or it's bead wasn't seated. The Hunter also can measure the wheel's radial and lateral run out which would immediately detect a bent wheel.
This is how the machine did a set of Goodyear MTR's on Cepek Aluminum wheels. First the machine rolls the tire against a friction wheel that seats the bead. Then it runs the tire in both directions and gives you the side to side and up and down run out of the wheel. I was impressed, the Cepek wheels were between 2 and 5 thousandth's true in both directions.
Then the machine said to dismount one of the tires and rotate it on the wheel 90 degrees. Surprisingly, this caused the white dot on the tire to match up with the CTI fitting. A dot means that the factory has marked the lighter side of the tire and it should be matched up with the heavier side of the wheel which is usually the tire valve. The technician should have mounted the tire this way in the first place but he was never taught this. You won't find dots on all tires.
The next tire up on the Hunter was rejected. We tried rotating it on the wheel but it was rejected again. The machine suggested we take the tire and mount it on one of the other wheels and this time it was within spec.
Once the tires were balanced the machine has a graphic that tells you which corner of the truck to mount which wheel based on Hunters Road force measurements. All I can say is that the truck was smooth as silk all the way up to 70 on the way home.
Shown in the picture is a 37.5 x 13.5 x 17 Toyo Open Country MT. These tires are 16 lbs heavier than the MTR's. The total weight of the tire and wheel is 132 pounds. These wheels balanced up really nice. The road force limit is 40. I had one as low as 6 and 3 around 16. One hit the limit at 44. I drove on it for about 50 miles and went back to re balance and it must have seated on the rim because now it's 29 which is well within the limit.
Why did I go back to get the tires re balanced? When I got home I found stick on weights in my driveway. The tech didn't clean off the inside of the rim with solvent before he balanced the tires so the weights fell off. Needless to say I cleaned off the inside of the wheels till they were spotless.
I take the CTI lines off when I balance the tires because it' s easier and more consistent. You will need a 1/4" pipe plug, a schrader valve or a JIC cap to do this depending on the kind of wheel fitting you have. We test balanced one with the cti line still on and resting on the balancers center hub. The wheel needed 8.5 oz as opposed to 3.5 oz. I've found that the imbalance caused by the cti lines is negligible compared to the weight of the tire. The only real extra weight is the the end fitting and part of the line. The heaviest part, the quick disconnect is in the center where it won't have an effect. When I balance without the cti line the wheels have never had any shake on the road. If you really want to be a purest you would balance the wheels with the cti in the exact position it will be when installed on the truck. You would also want the cti guard plate installed, especially the steel factory ones that are on one side of the wheel.
In my opinion there is never a need for wheel balancer products such as Centrimatics. If you have good wheels and tires that are balanced and your suspension is in good repair the truck shouldn't have any vibration.
Hunter Screen Showing in Balance
Hunter Literature Says
The GSP9700 extends far beyond the traditional functions of a wheel balancer by performing a simulated road test on the wheel and tire assembly to diagnose and virtually eliminate vibration and tire-related pull problems.
The GSP9700 incorporates Hunter's exclusive Road Force Measurement® System, which uses a “road roller” to apply up to 1,400 lbs. of pressure against the wheel assembly to test if the assembly is round when rolling. The roller can find problems such as lack of tire uniformity that once could only be detected by industrial tire uniformity graders. With this ability, the GSP9700 can perform the ForceMatching® procedure, which finds the stiff or high area on a tire and the low spot on a rim to be matched together to cancel vibration caused by radial force variation and provide that “new car ride.”
The optional StraightTrak® Lateral Force Measurement feature measures lateral forces in tires that cause pulls and drifts. As each wheel is measured, StraightTrak calculates a tire placement plan to produce the least amount of net lateral force and systematically minimize, offset or eliminate these problems. The versatility of the StraightTrak LFM feature enables a technician to integrate this valuable information into tire mounting and balancing processes, tire rotations and alignment service.
Hunter's optional wheel lift system is fully integrated into the balancer and allows one technician to easily mount and balance wheels up to 175 lbs. The wheel lift helps prevent potential injuries and fatigue from manually lifting wheels into place and assists technicians to properly mount wheels for the most accurate “road test” possible. The lift's functions work in unison with the balancer by automatically lowering as the hood is lowered to start the balance and staying in position to help remove the wheel after a spin.
Hunter Engineering is a world leader in wheel alignment, brake service, wheel service and safety inspection lane equipment. Hunter equipment is approved and used by vehicle manufacturers, automobile and truck dealers, tire dealers and automotive service facilities around the world.
Torquing Wheel Bolts:
Another important factor in wheel maintenance is lug nut torque. Torque is important for 2 reasons. The main one is that you don't want the wheel coming off the truck. The second reason is wheel warpage. My pet peeve has always been tire places running the lug nuts on with an impact wrench so tight that I couldn't get them loose to change a tire.
There must have been a rash of law suits against tire stores. The store I go to really takes torquing the bolts seriously. They have a couple of torque wrenches that are calibrated weekly and communicate wirelessly to a computer that documents each bolt's torque on a customer's car. These Cepek wheels are getting torqued to 115 ft lbs. Then they make you sign off saying that the work was done and that you will being the vehicle back for a retorque after 50 miles.
According to GT/ Cepek; new aluminum wheels have some crush value left in them they should be retorqued at 50, 100 and 200 miles. After that they should hold their torque.
When I mount any kind of aluminum wheel on a steel hub I paint antisieze on the hub. This keeps the 2 dissimilar metals from welding together over time. The picture shows wheel corrosion on the back of an aluminum wheel.
Contrary to my belief the tire store told me not to put antisieze on the lug bolts. Evidently this causes incorrect torque measurements. From what I gather it would be ok to use it if you were going to retorque your wheel bolts 3 or more times after the wheels were mounted.