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What would cause this???

Posted by static1701 (My Page) on
Thu, May 12, 05 at 7:50

I have a '94 Cavalier that I just had new tires installed on. When I get up to about 70mph, I get a vibration. It seems to get better at 80mph.(Try driving slower on 696 in MI, you will get run over)I know that the wheels are balanced, I watched the shop balance them. The rear shocks have been replaced.
I also have a '92 sunbird with the same problem, I had the wheels re-balanced on it but it did not make any difference. The sunbird does it much worst then the cavalier. What else causes this problem, it seems to be comming from the rear of the cars.

Static


Follow-Up Postings:

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RE: What would cause this???

I had this same problem with a 1981 Citation. The problem wasn't dangerous, just annoying at certain speeds, and new tires never seemed to help. I even had the tires removed from the rims and the tire shop couldn't find anything unusual. I finally took it to a tire shop that knew what they were doing and they got the tires balanced properly. I found out later from talking to a friend, that these balancing machines have settings that are usually set to a coarse setting which would be OK for most tires. Smaller size tires like the 13 inch on the Citation, seem to require a finer adjustment to balance them out.

GG


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RE: What would cause this???

All the suspension components must be in good shape. This includes all of the bushings - a softer rubber is used to combat noise and vibrations - but this will NOT last as long as before..
IMO, the best way to balance tires is on the car - the old spin(dynamic) balance..
Off the car is only a partial balance..
Very interesting what Gooseberry has to say , I have never used these new, computerized , fast, fast, fast machines..
And I don't know about using the on the car spin balancer with front drive - here we always used the bubble unit, tricky to use at times..


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RE: What would cause this???

My moms car had 55mph shakes, slower or about 65 was fine. Was ball joints.


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RE: What would cause this???

Both of the cars have high miles, 223 for the Cavalier and 276 for the Sunbird. The Cavalier had work done on it before I bought it, and it lookes like the front end suspension parts have all been replaced. Everything is tight and the bushing look new. On the sunbird, I know that the front end needs work. I just replaced the shocks. The thing about it is that it drove just fine until about a month ago. I had it up to 110
on the freeway and it was smooth, I usually drive between 70-85 mph back and forth from work so I would like to get them to be smooth at those speeds. I did notice when they balanced the tires, the machine was not going very fast. I am going to call them up and ask them about the balancing.
Would wheel bearings cause this? I can grab the tire while the car is on a jack and I don't feel any play.

Static


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Shops answer

I spoke to someone at Discount tire, and he said to bring the car back and they would re-balance them. I asked him about what speeds they are balanced for and he said the balance machine is computerized and they should be good through all speed ranges. I asked him if any other parts on my car would cause the problem at 70mph then go away at 80mph and he said he did not thing anything besides the tires wheels would cause that.

One thing I thought of, after they put the tires back on my car, they put the plastic wheel covers back on. Could the wheel covers cause this problem? They are just the cheap plastic kind with a metal snap ring to hold them on.

Static


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RE: What would cause this???

That Citation had this problem since new. It wasn't really a problem until around 65. It was just something that was there, nothing I couldn't live with. When I finally did get a good balance, the car had over 250K and never had any suspension parts replaced during the life of it except for one wheel bearing at about 90K.

Wheel bearings aren't likely to be a cause of wheel vibration. Bad bearings in in FWD cars will usually show up as a low growl or hum, and even then, there won't be much play in the bearing assembly before you decide you need to replace it.

I don't think wheel covers would be anything to suspect as a cause. There isn't that much weight to them, that they could likely create an out of balance condition.

You mentioned Discount Tire. That sounds like the place I took it to that finally cured my problem. I was impressed with that place since it was the first tire shop that I ever recall seeing a torque wrench used for final tightening. Good luck.

GG


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RE: What would cause this???

If the tires were over inflated during mounting, parts of the belt could be damaged or broken. No amount of balancing can fix this. What happens is that the tire changes shape over some speed, for example, 55 mph and either goes out of balance or out of round. I had one once that vibrated at 55 mph, then smoothed out again over 65 mph. 'Twas a dangerous tire.

It took about 5000 mile of driving for the damage to show. The center of the tread wore out before the edges, yet to the eye, the tire was flat across the tread. The tread depth at center was much less than at the edges. The tire carcas had stretched where the belts were broken.

Most tires have a maximum inflation pressure on the sidewall. This is not the service pressure, it is the maximum pressure allowable at anytime including mounting.

Could this be your problem?

ps. You mentioned taking this tire over 100 mph. Be very careful. Did you check its speed rating before doing this?


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RE: What would cause this???

Good point about the speed rating of the tires. Most of the newer cars are speed limited by the computer to the speed rating of the factory-installed tires, but these cars are older and may not be.

The first thing I'd do is swap the tires back to front to see if the noise moves. That way you can tell for sure if it's the tires.

Front-drive cars are notorious for having odd wear on the rear tires. If they are cupped badly, you can actually feel it by running your hand along the tire. As the tire turns, those uneven areas are going to make it vibrate. Leaving them on the front for a while can often smooth them out some, but this is sometimes not a desirable option because a vibration is more objectionable and has more chance of causing handling or other problems if it's on the front wheels rather than the back.


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Fixed!!!

Well, I got the problems fixed. I took the Cavalier back to Discount tire and they found the drivers front was off by half an ounce and the passanger rear was off by a quarter ounce. I did not drive it on the expressway yet. I took the Sunbird in and they found that the drivers rear tire was bad on the inside edges, he said something about it being "cupped" Cowboyind, you had it figured. He told me no amount of balancing was going to fix it. I bought 2 new tires for the front and had the old fronts put on the rear. I drove it to work and it was smooth all the way up to 90mph. What a difference it made, like driving a different car.

I do know about the speed rating, and no my tires are not Z rated. I don't drive at 100 for any lenght of time. My understanding is that if I did, the tire would come apart because it could not handle the heat generated at that speed. Our expressways around here usually go from 75-85mph most of the time and I have never had a problem. Today it seemed that people really wanted to move. People in the fast lane were doing 90+

I would like to thank everyone that shared some ideas about this, I could not understand way the car would be so bad after just having them balanced a few weeks ago.

I watched the guys balance my tires and they have the machine that reads zero's when the tire is balanced. They used pre torq sticks and a torq wrench to put the wheels back on. Many times I have had a hard time getting lug nuts off after having service. I was pleased with the service.

Static


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RE: What would cause this???

It is good to hear of a place that practices quality craftsmanship ,such as Discount Tires.

I do know that an improper balance attempt, without throughly inspecting the tires ( via the on the car spin balance) can be an exercise in futility..
Also, some bubble balance machines simply do not work very well, or can be too tricky to be effective.

BTW,static, what in the world are "pre-torque sticks" ??

Check the specs on the tire, then relate this to your owners manual.
S = 112
T = 118
H = 130
on and on
Z = 149 plus
this is from the '96 Saab 900 manual, but IMO, people now drive too damned fast, and I believe that most are not qualified to do this...
I could be wrong.


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RE: What would cause this???

E W,

I was wondering the same about the sticks. I think these are what he was referring to as "pre-torque sticks; a tool that fits on an impact wrench anvil that limits the torque from a wrench that may have max torque beyond what you want to tighten to.

Why bother to use one when you can screw up the customer's car enough that he needs to come back for more repairs?

GG

Here is a link that might be useful: torque sticks


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RE: What would cause this???

I bought a torque stick off Ebay. I use it in conjunction with a Harbor Freight electric impact wrench for rotating tires.

I also leave it in the car when I take it in for service with instructions to my mechanic to use it when re-installing the wheels. He has no problem with that; after all, I'm paying the bill.


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RE: What would cause this???

223000 and 276000 miles?Some knock GM and others knock Cavaliers.Seems there doing something right in Lordstown Ohio.Home of the Cavalier and Sunbird.


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RE: What would cause this???

I would never use a customer's tool- for anything, I have my own and know how to use them ! With the CP 1/2" impact I can dial back the torque to 50 and less ft lbs - not really that accurate, plus the air pressure is constantly changing.
I have also tried a version of a "torque stick", nothing more than a 6" extension - this helps reduce the power quite a bit..It is possible to have pretty exact tightening by using these two "adjustments", but only on fasteners that are engineered to be not so sensitive.

The Saab lugs nuts of the 60s were really rugged, but that came to an abrupt end in the 70s.
Damned bean counters again !
It is simply a matter of caring and having the time to care..The dealers and car manufacturers can help a lot more in this area..
At the end, however, only the good torque wrench will be accurate enough..
And these "precision torque sticks" do seem to be an excellent idea...


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RE: What would cause this???

Gooseberry,,

"Why bother to use one when you can screw up the customer's car enough that he needs to come back for more repairs?"

I hope your trying to be funny, frankly I fail to see the humor.

"FEW PEOPLE HAVE A JOB WHERE THEY HAVE TO BE AS PRECISE IN EVERYTHING THEY DO AS WHAT AN AUTO TECHNICIAN DOES"

Very few people have a job that has as many traps as auto repair does, so sure things go wrong. That's all part of being human. Integrity is about admitting mistakes and dealing with them. One of the ways of dealing with past mistakes has been the use of torque sticks, and then torquing the bolts to specs by hand. Many shops will use a 80 ft/lb torque stick, and then retorque to whatever the spec is. The thing to realize though is corrosion between the nuts and the wheel, as well as the wheel and hub may make break away torque be much higher a few months later. So it's not uncommon for a "properlly torqued" wheel nut to be quite difficult to remove with a standard tire iron. Thats why I carry a breaker bar and a correctly sized socket and use it instead of a tire iron if I have to. Likewise my 22 year old daughter that weighs 110lbs soaking wet not only has a breaker bar and socket, but a cheater pipe that fits onto the breaker bar to allow her to use her weight to break the nuts loose if she ever gets a flat.


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RE: What would cause this???

I agree with you John.

Having said that, I'm taking my Durango back to Firestone today where I purchased tires last year. My impact wrench won't budge a single one of the lug nuts since, and I know they put them on way too tight. I aways torque them to 90-100 ft lbs which is the low end of the spec for this vehicle and never had a problem. Going back to ask them nicely to loosen and re-torque. I'm also going to nicely suggest that if they break them, they bought them since someone there was the last one to have a wrench on them. Sound reasonable?

I don't like complaining but I don't think I should have to waste my time and $$$ replacing 24 studs and decorative lug nuts because a tire installer didn't want to take an extra minute to use a torque wrench.


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RE: What would cause this???

"Going back to ask them nicely to loosen and re-torque. I'm also going to nicely suggest that if they break them, they bought them since someone there was the last one to have a wrench on them. Sound reasonable?"

Reasonable yes to a degree, but if you really had to could you prove it? I mean proove that no-one had any of the wheels off at some time in the last year?

Most impact guns can be rated as high as 600ft/lb torque, but the truth is the wheel nuts would stretch and break long before that torque is ever achieved. While they could have in fact overtorqued them, and whether they did or not they will in all likelyhood break them loose for you and retorque them. There is a point where it would be perfectly reasonable for them to tell you they cannot and would not assume responsibility for the lugs and studs. Many of these allow wheels corrode between the nut and the wheel and bind the nut to the wheel with much more force than was used to tighten the nut. A properly torqued nut at 100ft/lbs may six months later require 300ft/lbs of torque to break it loose! In fact I have had some where the nuts simply would not stand up to the effort required to remove them and ultimately had to resort to drilling the stud out of the lugnut to get the wheel off. The blame for this wasn't the shop that put the wheels on last. It's the materials used and the fact that the wheels are almost never taken off the car by the owner!


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RE: What would cause this???

Static1701, glad you got that problem fixed. Tires do make a world of difference in the way a car rides and drives.


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Drove the Cavalier today

Hello,

I drove the Cavalier to work this morning, and it rides great again. Now that I know what a difference the tires make, I will never let them get worn to the point of the car riding bad again.

Static


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RE: What would cause this???

If anyone was wondering how they work, since they do appear to be nothing more than an extension: The torque stick is engineered to flex/twist when the proper torque has been reached, so the impact wrench cannot tighten the bolt any further.


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