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Discussion Starter · #1 ·
At freeway speeds I notice vibration (not major but noticable) that seems to come and go. I have new tires and balance, and just had an alignment from a reputable and knowledgable shop. The steering gear is adjusted properly (just checked) and so are the wheel bearings.

What would the symptoms be if the drive shaft were not balanced.....or could the rubber bushing in the torque tube cause this problem if it is worn or dried out....??

at times its rock steady and at times the whole car seems to have a vibration.
 

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Bosco, check the tach and speedo when the vibes start and then when the vibes start again check the tach and speedo for a reference reading. It could be the road or any number of things, like you said, drive shaft, engine/tranny mounts, bad wheel balance, anything that rotates. Also check the tach at the RPM and use the gears to change the speed, that can eliminate an engine problem.

Ron
 

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New control arm bushings?

Vickie
 

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Discussion Starter · #5 ·
I probably should add......it has a new engine, clutch, motor and trans. mounts.,shocks and steering rack bushings......plus the front end was checked out (for worn out parts) prior to being aligned.

Thanks for the responses....
 

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Well, that kinda limits the source of the vibes to the wheels and or bearings and everything back of the tranny. So I would check the speedo and see what speed the vibes occur and if you can get it on a lift and run it to that speed and have a good mech try to find the source of the vibes. If it is the front wheel bearings, that won't help but it is a way of trouble shooting by process of elimination.

Ron
 

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Make sure that the drive shaft bolts are tightened down. I've seen them come loose just after putting it in, then a retighten fixes the vibration. Although this was on my ford ranger.
 

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Discussion Starter · #10 ·
Today I got down underneath and checked things out again and I noticed that there was some play (up and down) where the drive shaft attaches at the torque tube donut. I slid some fuel injection hose up and around the donut (inside the housing) and it took out most of the slop. On the freeway I still notice a little steering wheel shimmy but he body vibration seems to have subsided. I'm wondering how long those pieces of fuel line will last in there. So far I like the result.
 

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Vibration coming and going

I just ran across your posting. Realize you may have already solved the problem but thought I would give an opinion anyway. Vibration that comes and goes at a steady highway speed is nearly always caused by tire balance. A small amount of unbalance in two or more tires will cause this problem. It is caused by the the unbalance of two tires coming in and out of phase. No two tires are exactly the same diameter so they will turn at slightly different RPM's. Peiodically depending on the difference in diameter, cornering etc. The heavy spot in one tire will get in phase with the heavy spot in the other tire. i.e. both heavy spots coming to the top of their rotation at the same time. This will cause the effect of the unbalance, (vibration) to double in magnitude. A few seconds later when the tires have gone into 180 degrees out of phase, (i.e. the heavy spot from one tire is at the top when the other is at the bottom), they cancel each other out, resulting in no vibration. To vibration engineers this is caused a "beat effect". The time in seconds between the incidents of high vibration is called the beat period. This time could theoretically be calculated from the relative difference in diameter of the two tires.
Drive the car at a steady speed on a straight section of road. If this is the cause of your problem the vibration will come and go at regular intervals, usually a few seconds apart. The closer the tires are to having exactly the same diameter, the longer the time between events and the longer you will feel the vibration.

Unfortunately Opel frontends are very sensitive to tire balance due to relatively high flexibility. Often this problem can not be completely eliminated through tire balance alone. On occasion, very worn shock absorbers will magnify the problem.

Let me know how you come out on this.
Doug
 

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Discussion Starter · #12 ·
Thanks for the post.......I think thats probably what it is. I also have a 77 Datsun 280Z in very good condition that does the same thing. Sometimes it's completely smooth and steady then it gets a slight shimmy. I've learned to live with it on that car so will do the same on the Opel.
 

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The way it used to be

Back in the old days, ( when the dinasoars roamed the earth as my kids say), we used to balance tires on the car. We used a vibration pickup mounted under the frame and a strobe light to determine where to place the weights. The car was jacked up and the rear tires were run up to speed, one at a time, and balanced. This corrected for brake drum unbalance and also allowed the mechanic to fine tune the balancing to the individual car. The front tires were balanced in the same way; however, they were brought up to speed with an external spinner. ( 220 volt motor operating a small tire which was pressed against the front tire until the desired speed was reached.) Often mechanics would fine tune the process by opening a door and then watching for movement at the outer most corner of the door. This is still the optimum way to balance tires; however, you'll be hard pressed to find anyone who has the equipment and knowledge to do this today. The last shop that did it this way in our town quit three years ago when there external spinner burnt up. By the way high speed, multi-million dollar equipment in industry is still balanced this way today. In modern times skill has been replaced by computerized, idiot proof electronic balancers, that treat every car and tire the same. 17" tires are spun at the same speed as 13" and of course there's no way to compensate for rotor, hub, drum, etc. unbalance.
Doug
 
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