My 96 chevy truck is vibrating any ideas as to what it might be?

1 ANSWERS

1. Arslan Masaud
   

   Hello, Vehicle vibration has become a common and reoccurring complaint with the trucks. I had a very bad vibration in my truck from day one. In my quest to cure this problem I had to battle with all the way through arbitration and I ended up having to fix the vibration myself, because they could not. I will save my war story for another chapter. In my efforts to fix my own truck I have learned a few things that I would like to pass on to those of you having the same problem. I hope to save you some time and frustration. There are many things that can induce a vibration in the truck, but it seems that most of the common vibration problems in the trucks are centered in two areas, balance and wheel/tire defects. There are lots of different things that can cause vibration, but I am only going to focus on the two areas listed above which I feel are the most common in trucks. If your truck vibrates only when you hit the brakes, then you most likely have warped rotors and this page does not apply to you. If your steering wheel oscillates slightly back and forth at highway speeds with no vibration felt in the vehicle then that is most likely an alignment issue and this page does not apply to you. Balance / Haweka Adapter: I have gotten tons of email from people that have had a truck that drove nice and smooth, then the dealer touched it. The stories are usually the same. The dealer talked them into an unneeded re-balance or they just got new tires and their trucks now shake and never did before. They have had it rebalanced, and rebalanced, and rebalanced and it never gets any better. They have lead weights all over the wheel. Think about it two lead weights on opposite sides of the wheel, and they are the same weight. I have seen this time and time again and it just does not make sense at all. How in the world does this happen? Here is the problem. The wheels used on the most of the trucks are lug centric and are not the more common hub centric wheels like on most cars and light trucks. Hub centric wheels are centered on the vehicle hubs using the center hole in the wheel. That is kind of simple. On lug centric wheels the wheels are centered on the vehicle hub using the lug bolt holes and not the center hole. When the wheels are made and machined they are done so using the lug holes to mount the wheels to the machines that make them. The lug holes are the true center of the wheel and not the center hole. So, if the center hole is not in the true center you can understand how mounting the wheel to the balance machine using the center hole is not going to work very well. The wheel needs to be mounted to the balance machine using the lugholes. This is done with a flange plate adapter made by Haweka. The Haweka adapter firmly locks the wheel onto the balance machine in its true center. It holds wheel very solid and prevents movement. Toyota realized they had a problem with balancing these wheels and issued a Technical Service Bulletin (TSB SU002-96) requiring the Haweka adapter when balancing these wheels. The problem is that it seems that few Toyota dealers know about the TSB let alone have the adapter. While on one of my many, many visits to the dealer to get the vibration fixed, I saw one of my tires on their balance machine. I walked over to it and grabbed the tire and shook it. It wobbled all over the place. I asked they guy how he thinks he can balance the tire with it moving around so much, all the truck wheels do that. That my friends, is the very center of the problem. If they cannot get the wheel to hold still on the shaft there is no way they can ever properly balance it. The Haweka adapter does two very basic things. First it mounts the wheel to the balance machine the same way it is mounted to your truck, and second it locks it to the shaft of the balance machine and prevents movement so you get a consistent and proper balance. When you have your tires balanced with the Haweka adapter you will be surprise how little weight the tire will take. I have Michelin LTX (courtesy of Toyota arbitration) and I have one tire with no weight at all and the other three with just one small one. Before the Haweka adapter I had weights all over the wheels installed by the dealer. If you ever get new tires, or decide to have them rebalanced you really should do yourself a favor and make sure the shop has and uses the needed Haweka adapter before you let them touch your truck. It is possible to get a balance without it, but why take the chance and have to go back, and back again. You have the greatest chance of having it balanced right the first time, every time using the adapter. Back to page index Wheel Defects: If the wheels are not round enough they will cause your truck to shake. That was my problem; I had two wheels that were not round enough. Round enough you say? Believe it or not wheels are not perfectly round. They are close, but not perfectly round. Mine were so bad you could jack the truck up and spin the wheels and see with the plain eye that they were not round. This is what was causing my vibration. The wheels are measured in two directions. Using the center of the wheel and going outward is called radial runout. If you look at the wheel on its edge, spin it and see any side-to-side movement that is called lateral runout. There are specifications as to how much of radial and lateral runout is acceptable, but the less the better. There is a point where lateral and radial runout can be felt as a vibration. As far as I can tell this concept is way beyond Toyota to understand. They put 17 new tires on my truck to cure a vibration caused by radial runout in two of the wheels. They kept insisting it was a tire problem, but I knew better because I ran my own tests and proved it was the wheels. I eventually got tired of having Toyota installing new tires on bad wheels and then improperly balancing them on top of that. I replace the two bad wheels and balanced them with the Haweka adapter and the vibration was gone for good. I will discuss later on the easiest way I have found to test your wheels for defects. Back to page index Tire defects: Just like wheels, tires can have excessive radial and lateral runout. Again too much and it will present as a vibration even when they are perfectly balanced. I am sure you can understand how this works just like the wheels and I will not go into it again. There is another defect in tires that can cause a vibration called loaded road force variance. The tires and pass a visual inspection, a radial and lateral runout test, be perfectly balanced, but still cause a vibration. This is due to the internal defects in the tire. All tires have variances in the stiffness of the sidewalls. As the tires roll with a load on them and they roll onto a soft section of the sidewall the truck will settle slightly down toward the road. As it rolls to a stiffer part the truck will be raised up slightly. When the sidewall variances are the same on both sides this causes an up and down motion in the truck. When the sidewall stiffness is different from right and left side when the tire is viewed on edge, then this can induce a side-to-side movement called a lateral variance. If these variances in sidewall stiffness get to be too much you will feel it as a vibration. There are other things that add to this like the way the tire casing is constructed and if it has seems or not, but it all ends up causing the same problem. The problem is how can you measure for this and correct it? Until recently you really could not, but there is hope. There is a new type of balance machine on the market called a road force balancer and Hunter makes it. Back to page index Position Balance: There is a process called position balancing, or OEM match mounting. This process can reduce the overall amount of radial runout from the wheel/tire assembly. This is done by doing a radial runout test on the wheels and then the wheel and tires. Remember wheels and tires are not perfectly round. The idea of position balancing is to find the high spot on the wheel and line it up with the low spot on the tire. This reduces the overall amount of radial runout in the wheel/tire assembly and gives a smoother ride. The process can be time consuming and is not normally done. Back to page index The Easy Fix: Hunter recognized a market for a new type of balance machine and developed the GSP-9700 Road Force Balancer. This machine will automatically do several checks automatically in a very short time that once took a very long time to do manually. In addition it can check tires for internal defects that contribute to loaded road force variations. Force variations only show up when there is a load on the tire. Because of this it is very, very hard to find this problem. The thing that separates the GSP-9700 apart from the rest is that it can put a load on the tire to simulate the load the tire will have driving down the road. It uses a roller that is pressed against the tire as it is turned on the balance shaft and looks for the force variations. With this technique the GSP-9700 can give you the smoothest ride possible out of the wheel/tire assembly. The first thing that is done is the wheel/tire assembly is mounted onto the balance machine using the proper flange plate. The machine then checks the wheel for lateral and radial runout. If this is within acceptable limits it will then press a roller against the tire to simulate it being loaded on the road. It checks for force variations, which is reported in pounds. If the tire passes this test then the machine will then run a test to determine how the tire should be positioned on the wheel to give the overall smoothest ride. It will take into account radial runout of the wheel, tire and the force variations in the tire. The operator marks the wheel and the tire in the spots indicated by the machine. The assembly is removed from the balancer and taken to the tire mounting machine where the tire is rotated on the wheel to match the marks indicated by the balancer. The assembly is then mounted back on the machine and then given a traditional dynamic dual plane balance. Back to page index My Personal Experience: I have a Ford F-150 that had a vibration problem since new. I took it back to the dealer and had them rebalance it with no change in the vibration. I then took it to a friends shop, that is one of the better shops in the area, He has a GSP-9700 and had them do their thing. The initial checks showed that I had two wheel/tire assemblies that had real high road force variations. One was over 80 pounds and one was 60 pounds. The tire with the 80 pound reading was found to be defective and had to be replaced. After the work up all the tires now range from between 25 and 35 pound of force variations. This greatly improved the ride of the truck to a point it was acceptable. It is not perfect. The interesting thing was the operator told me that I would still be able to feel a slight vibration in the truck as anything over the 15-20 pound range can be felt. He told me this before the tires where remounted on the truck. He was right. The only way to make it perfect is to put better tires on the truck. It came stock with Goodyear Wranglers and I hate them. I cannot wait for them to wear out so I can replace them with the Michelin LTX. He said that the LTX is consistently the best truck tire they have seen with the normal force variations at a consistent glass smooth 6 pounds. The Michelin tires on my Maxima finally wore out after over 80,000 miles of use and had them replaced with, of course new Michelins. On the way home from the tire store I noticed a vibration in the car that has never been there. I took it back to the tire shop and had them rebalanced. Not much of a change. I then took it to my friends shop and had them balanced on his GSP-9700 and the car was back to glass smooth. Back to page index Recommendation: The front ends on the 4Runner and Tacoma are super sensitive. If you have something that is just slightly out of whack you will definitely know it on these trucks. If you have a vibration and believe it to be cause be the wheels and/or tires, then you should not waist your time by going to a shop with old technology. If your time is as valuable as mine then you should find a shop with the needed Haweka adapter, a GSP-9700, and a technician that has a clue. The easiest way to find what you need is to go this web site and use their shop locator function to get a list of shops near you that has one. Next call the shops and make sure that they have the Haweka adaptor for your wheels. If they tell you that they do not have it or don?t need it, then hang up and call the next shop. Do not waist your time with them. If they are willing to spend $10,000 on the state of the art road force balancer, and not get a set of Haweka adapters to go with it then they probably are not smart enough to work the machine anyway. When you find a shop that has both items make an appointment and have them do a road force variation work up and see if you need to replace your wheels or tires and then get a good old-fashioned balance. The combination of the GSP-9700 and the Haweka adaptor should cure the most common cause of vibration in the truks. This combination will give you the greatest chance of getting you vibration problem fixed on the first visit as possible. hope it helps

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