Shake rattle n roll

[rpounds]

I would like anyone's opinion on wheel balancing procedures. In this day and age, everything is done on a computerized machine. Back at the old garage, when I was a kid, my dad had a spin balancer that balanced tires on the car. Dad always swore it was the best way, because all of the rotating components were then balanced. Makes sense. Problem is, nobody seems to do this anymore.

My 'vette starts to get a pretty wicked vibration (a very obvious tire balance vibration) at about 90 MPH and just gets worse as the speedometer climbs. At 110, I get a little scared and back off. The tires have been balanced the 'new fashioned' way. There are fairly new KYB shocks. The mechanical components are in perfect shape. What I need is a more precise balance. I would like to be able to take her up to 130 or more, but not until we get rid of the tire balance problem.

Question: What is everyone out there doing with theirs? What speed have you acquired and what were the results?

Any suggestions would be appreciated. However, I hope that along with opinions, there is some imperical data to substantiate the claim.

TIA

Ron:grinsanta

 

[69MyWay]

I will chime in without an once of imperical data.

However, I have fought the wicked tire shake on many a car. I have found that the Corvette is very prone to vibration problems. The tire balance is the most obvious.

I think when you have a tire tech that really cares about what he/she is doing your will have a great result. For example, while they are balancing they should always be looking for a bent rim and bring it to your attention by comparing to other rims that appear to be straight.

Second, if the machine is asking for a large number of weights on any one side, a really good tech will break the tire down and spin it on the rim, and even go as far as to swap it out with the other tires and rims to get a combo that requires the least amount of weight. This is very critical when you have custom rims that you don't want big clip on weights cluttering up the look of the wheel, so you are asking them to use adhesive weights only on the inside bead of the rim. This is very difficult to get right as they are denied the use of putting weights on the inside and outside to balance it out.

Third, there are more bad tires out there than you would imagine. A bent, broken, slipped belt in a tire will cause you a world of vibrations that no amount of balancing can solve or even detect while balancing the tire.

Then, you come down to the fact that the half shaft u-joints are often installed wrong. That is I have seen plenty of them where they were not pressed all the way center and the cars had vibrations and shakes, noises as a result.

If the wheel bearings are getting loose, or there are other weak suspension components, at speed one wheel can start moving (kind of like the shopping cart at the supermarket that almost always has one wheel that is flipping around out of control). So, I don't think there is any trick to it. Good solid suspension, good tight and proper installed ujoints, healthy tires, and a tire tech that knows how to use the machine and will take enough pride in his/her work to get it right and you are cruising like glass.

 

[Ken]

I have found that the Corvette is very prone to vibration problems.

Chris, I assume that you're talking about Sharks, eh? I've never encountered any kind of suspension-related vibration problems in my C4, althought I haven't had it any faster than 125 mph. It was steady as could be at that speed.

_ken

 

[69MyWay]

Both really,

In 88 when I had my 85 model the tire stores were just starting to really get use to the larger rims. Up until then 15" was about as big as they ever dealt with. I needed tires almost right away and had a heck of a time finding a tire store that was up to the task. Now a days, 16" is pretty standard on everything.

We fought some bad vibes in Nikki's 90. Turned out the front rim was bent. We sent it out to california where it was originally chrome plated and had it reworked. That along with a good balance and it is smooth.

I did a lot of suspension work on my buddies 77. When all else failed I found the ujoints installed wrong on the half shafts, and that finally fixed the vibes.

I also had a bad front ball joint on the 85 in the early 90's that caused a vibration at certain speeds over 65. So, as I said before plenty of factors play into getting it right.

 

[Bullitt]

Very Good, Chris

As you point out, many factors can play into the balance of the car, concerning the tires. My sister experienced this problem of wobble, a few months ago. After bugging the tech a bit, he showed me where the tire had seperated on itself, a slipped belt basically. These tires were in the middle of thier lifespan and were nowhere near death concerning the tread wear. Luckily, the tire was still under warranty and was replaced for free. There's nothing that could've signaled this happening, it was just a bad tire. I don't think that the manufacturer matters either, so I had no problem putting on the same make tire. So Ron, check everything out starting with the tire and work from there. It 's amazing how some things can adversly affect handling performance, but will only show up under speed and careful analysis. --Bullitt

 

[Eric]

Chris is dead on about the good balancing technicians. When I had the new Firehawks mounted on the Vette rims a few months back the gentleman that did it was probably in his late 50's. He looked at the wheels and said "these are vette rims, what do you have them on?" I told him they were off of the car they left the factory with, a 71 vette (I didn't have the car w/ me). He started reminiscing about people back in the day putting those 8" ralleys on everything before mags got cheap. Back to the point, he asked if I minded if he took a little extra time to get it perfect since they were for a vette and I of course obliged. He did just what Chris said, he ran each wheel without a tire first to check for warps. Once he got the tires on, if the machine came up with what he thought was too much weight in one spot he used smaller weights and spread them out until zeros lighted up on the machine. Some of the younger guys at the shop were laughing at him for taking so long but I was amazed - this guy new exactly what he was doing. On one wheel, he even broke the thread and spun the tire halfway around the rim to get a better balance. Needless to say, I was impressed, so much that I tipped the guy and bought him lunch. The next week I took the Z24 in to get Firehawks mounted and I made sure he was the one doing it. Needless to say, neither car has even the slightest vibration .