Balance Problem?

[Brady]

Ok, so I don't even know what to make of this anymore.

 

I bought a used set of Rota Tarmac I's off another member. They're a little curbed up, but straight. I recently had them wrapped in my Blizzak LM-25 with about 7,000 miles on them from last winter. Well, the first balance was awful, but oddly it really seemed like it would vary somewhat, like at times they were really bad, and sometimes there was only a little bit of vibration.

 

Well, I took them back in and I was told that all 4 wheels were out of balance (good job, fellas). So he re-balances all 4, says that one is out of round, but they moved that one to the back and all vibration should be gone. And at first, it seemed like it was (this was Tuesday evening). This morning, on my way to work, for part of my drive the vibration was back, then it nearly went away.

 

This is all at about the same speed (65-75 or so) and it seems to get worse with speed, I haven't tried to run beyond 80 or so, but it gets worse up to 80.

 

With every other car I've had, when I've had a balance problem, the shimmy seemed to center around 65 or 70 and then with more speed would taper off.

 

Could this be indicative of something else? Or is my tire shop incompetent?

[PeterJMC]

If you haven't tried to take it to another shop for a re-balance I would. Maybe their machine is off or the techies don't know how to operate it.

[Brady]

A new shop was the next plan of action. It's a little difficult because all the shops around here seem to close early making it tough to get there after work.

 

I guess what has me scratching my head is that the vibration seems to come and go somewhat even while at the same speed, and that the vibration gets worse up to 80 (haven't run beyond).

 

Now, these wheels/tires are larger than wheels/tires I've had in the past, so am I correct in assuming that would correllate to a higher "shimmy" speed? (i.e. the 70 mph shimmy becomes an 80 mph shimmy)

[pflo]

I've had this problem with my alloys on my Golf for the past eight years. Countless rebalancings never fixed the problem. My most trusted mechanic stated that it's likely that one of the wheels is not perfectly round but they balance fine. I notice it most at around 70 mph but not consistently. I have no idea why it's worse at some times vs. others. I have not had them Roadforced which may be the next logical step.

[PeterJMC]

+1 for getting them Roadforced balanced.

 

I've also seen this twice where there was a significant amount of moisture found inside a tire which was throwing off the balance.

 

If anyone has home air compressors, please make sure you have an air/water seperator installed!!

[Vimy101]

Ok, so I don't even know what to make of this anymore.

 

I bought a used set of Rota Tarmac I's off another member. They're a little curbed up, but straight. I recently had them wrapped in my Blizzak LM-25 with about 7,000 miles on them from last winter. Well, the first balance was awful, but oddly it really seemed like it would vary somewhat, like at times they were really bad, and sometimes there was only a little bit of vibration.

 

Well, I took them back in and I was told that all 4 wheels were out of balance (good job, fellas). So he re-balances all 4, says that one is out of round, but they moved that one to the back and all vibration should be gone. And at first, it seemed like it was (this was Tuesday evening). This morning, on my way to work, for part of my drive the vibration was back, then it nearly went away.

 

This is all at about the same speed (65-75 or so) and it seems to get worse with speed, I haven't tried to run beyond 80 or so, but it gets worse up to 80.

 

With every other car I've had, when I've had a balance problem, the shimmy seemed to center around 65 or 70 and then with more speed would taper off.

 

Could this be indicative of something else? Or is my tire shop incompetent?

 

Could be indicative of a failed tire. It happens.

[PeterJMC]

+1 for getting them Roadforced balanced.

 

I've also seen this twice where there was a significant amount of moisture found inside a tire which was throwing off the balance.

 

If anyone has home air compressors, please make sure you have an air/water seperator installed!!

 

 

Also, I've seen a few gas stations that spew water out of their air hoses... watch out for those too.

[Lothar]

If anyone has home air compressors, please make sure you have an air/water seperator installed!!

 

I must admit that I've never even considered such a problem, but now you've got me thinking... I often use a little cigarette-lighter-powered portable compressor (the little things one might keep in a car trunk for emergencies) to add the occasional PSI or two to my tires. Can that kind of compressor cause water problems?

[Lothar]

I had almost the exact same problem you described, Brady, with my new Blizzak LM-22's that I bought along with a set of dedicated rims and TPMS sensors, at a large well-know tire chain (whose name I won't mention). My steering wheel whould shimmy slightly (just enough to be annoying) at around 70-75mph. At a steady speed in that range (with cruise control set), it would shimmy for a few seconds, then become smooth, and that cycle would repeat every few seconds, at an interestingly constant interval.

 

I had the wheels rebalanced, which didn't fix the problem. Next, they told me that one of the wheels had a slight "hop" to it, and the other was slightly out of true, so they sent them back to the factory for replacement. The replacements were no better, and I still had the exact same shimmy behavior. They then rebalanced the wheels yet again. No difference.

 

Finally they sent me to another one of their shop locations to have a road force balance done. When I came back to pick up the car, the technician was almost shaking his head telling me how the tires were simply out of balance, and that there were different types of weights on all the wheels, and he gave me the impression that the last shop didn't know what they were doing.

 

Anyway, that seemed to fix 95% of the problem, though I do still occasionally notice a negligible shimmy that I can live with. So +1 for the suggestion to go to another shop!

[PeterJMC]

I must admit that I've never even considered such a problem, but now you've got me thinking... I often use a little cigarette-lighter-powered portable compressor (the little things one might keep in a car trunk for emergencies) to add the occasional PSI or two to my tires. Can that kind of compressor cause water problems?

 

The ciggy ones aren't a problem because they usually do not have reserve tanks that would accumulate water. You run into the problem when you have a reserve tank for compressed air. When the air is pushed into the tank it contains moisture in the air and if it doesn't get expelled it will condense and collect at the bottom of the tank.

[Brady]

Yeah, I'll try another shop. There was a guy I got a good vibe from before, so I'll try their shop. I don't fully suspect the tires since they were fine when mounted on stock rims in March.

[Lothar]

You run into the problem when you have a reserve tank for compressed air. When the air is pushed into the tank it contains moisture in the air and if it doesn't get expelled it will condense and collect at the bottom of the tank.

 

I've got one of those tank compressors at work too, but it has a drain plug on the bottom that I always open to drain out any condensate. Is that what you meant by an air/water separator? I always though that the purpose of that thing was to keep the air tank from rusting!

[PeterJMC]

I've got one of those tank compressors at work too, but it has a drain plug on the bottom that I always open to drain out any condensate. Is that what you meant by an air/water separator? I always though that the purpose of that thing was to keep the air tank from rusting!

 

The drain in the tank would be to drain the water that finds it's way into the tank.

 

Air water seperator should be used at the line-in of your air tank. It will seperate the water from the air before it enters the tank. Also, you would generally want one at the line-out so that if water is in the tank it wouldn't find it's way to your tires and air tools.

 

Depending on design it would look something like these....

 

http://tbn0.google.com/images?q=tbn:mzUfA1SqpQp0lM:http://www.bc4x4.com/pr/2003/hypertherm/h-2.jpg or http://tbn0.google.com/images?q=tbn:VMe_h6fm7QugrM:http://news.thomasnet.com/images/large/010/10395.jpg

[Lothar]

Thanks so much for that info, Peterjmc, I'll be sure to make sure that is installed on the compressor tank.

[outahere]

......I bought a used set of Rota Tarmac I's off another member. They're a little curbed up, but straight..........

 

Have you actually checked them for axial and radial run out, using a dial indicator?

 

Subaru specifies a maximum of 1.0 mm run out, for an alloy wheel.

[Brady]

Where would one measure this to?

[Brady]

I guess the new shop really is my next step. Let's address the fact we know for certain. The shop mounted 4 tires on 4 wheels. When I brought it back 2 weeks later (because I couldn't find time to go in or it would have been sooner) the shop acknowledged that all 4 were out of balance.

 

On a separate note, they also put sythetic blend instead of full synthetic. Didn't even ask me to change it. They also got greasy finger prints all up and down my drivers side A pillar and I watched the guy spend 15 minutes trying to clean it, but leaving marks behind. I didn't complain since I figured it wouldn't do much good, and it was a good opportunity for me to do some product testing on interior cleaners.

 

Overall, I almost didn't give them a shot at this re-balance to begin with since I felt they were border-line incompetent. I'll give a different shop a chance before I cast my final judgment.