Dadillac Posted January 19, 2005 Report Share Posted January 19, 2005 My '02 Seville SLS has the infamous shimmy, between 60-75 mph. I have just had my tires road force balanced on a Hunter 9700 machine, without too much success. My car has 54,000 miles on it, and rides great otherwise. My question, is about my stock struts. Is it possible, that the struts are starting to fail, with 50+ k miles on it? If the strut, at resting height, develops a "dead" spot, in that area of the travel, wouldn't it cause a slight wheel hopping situation? That particular area in the struts travel, is the most used spot. Is it, that that area could wear out, but the rest of the travel still be working okay? if so, wouldn't it alos be safe to say, that hitting a slight dip or bump in the road, could cause, what feels like a vibration/shimmy, because the strut is worn in that spot? The reason this qestion comes up, is because, sometimes, when the vibration/shimmy is present, if the suspension travels even further, it stops momentarily. It then will return, once the car has settled back to ride height. I am no genius when it comes to struts, and do not fully understand, how they work. I know what they do, but not how the innards work. I am thinking that new struts may help, but, would like some feedback from folks who have good knowledge about struts. Thanks in advance. Don "Modern warriors saddle iron horses of chrome." Link to comment Share on other sites More sharing options...
Marika Posted January 19, 2005 Report Share Posted January 19, 2005 You might want to read this topic, especially the article that I copied/pasted from a newspaper. http://caddyinfo.ipbhost.com/index.php?showtopic=4732 If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans. Link to comment Share on other sites More sharing options...
KHE Posted January 19, 2005 Report Share Posted January 19, 2005 I would start looking at either outer tie rod ends or ball joints. When they are worn, they will cause a shimmy. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Hud Posted January 19, 2005 Report Share Posted January 19, 2005 A friend of mine had what sounds like a similar problem with his Cadillac. He got rid of it by replacing the Good Year tires on his. Link to comment Share on other sites More sharing options...
Scotty Posted January 19, 2005 Report Share Posted January 19, 2005 Lots of discussion has been had here recently regarding struts. You case is a little different, while I will be the first to say that YES at 46,000 miles my struts were shot, at that time my car was seven years old. Your car is relatively new in my opinion with 56,000 miles, so from a mileage standpoint yes you could be feeling the beginning of struts not controlling/dampening bumps, but from the age of your car, I am surprised.... However, you are complaining about a shimmy, not necessarily a bump induced feeling that continues after you hit say an expansion joint, bump, etc. The strut controls/dampens the up and down motion created by a bump, since you have eliminated (we hope) the out of round tire potential, that would cause a harmonic bouncing tire, a bad strut is unlikely. That said, I would eliminate everything else first, you balanced your tires with the road force balance method and I think that would show an out of round tire, but I would make sure by using a known good tire at each corner. I would check each for wheel damage, proper torque, bent lugs, run-out, and bad lug nut seats. Also check for bad parts as Kevin suggests tie rods, ball joints, bushings, etc. The best thing you could do is get the car in the air and push and pull the wheels around the clock looking for ANY play. We have had a few people go NUTS trying to find shimmy problems and it ended up being the lugs, all of them being bent in the same direction... After reading this from HUNTER, I doubt you have an out of round tire: What is Road Force Measurement? couresy of Hunter Engineering Road Force Measurement Road Force MeasurementT is new to the automotive service industry. This new measurement identifies tire and wheel uniformity, which has been measured for years in assembly plants and manufacturing facilities. Road Force can be used to solve uniformity related tire and wheel vibrations. Tire/wheel assembly uniformity can only be measured under load. The load roller on the GSP9700 performs a computer simulated "road test". It measures the tire/wheel assembly to determine how "round" the assembly is when rolling under a load. If a tire were not exposed to the road surface, then balance would be more than sufficient. However, not all tires roll round under a load. For example, an egg-shaped tire/wheel assembly can be balanced about its axis, but an egg-shaped tire-wheel loaded against a surface would not give a smooth ride. To understand the effects of radial force variation on vibration, a model of a tire can be used. The sidewall and footprint can be understood as a collection of springs between the rim and the tire contact patch. If the "springs" are not of uniform stiffness, a varied force is exerted on the axle and causes it to move up and down as the tire rotates and flexes. This movement creates a vibration in the vehicle unrelated to balance. The GSP9700 load roller applies a force of up to 1400 pounds against the rotating tire/wheel assembly as it performs the Road Force MeasurementT. The GSP9700 measures loaded radial runout of the tire/wheel assembly within 0.002". It plots data points as the component is rotated and calculates the radial first harmonic of the tire/wheel assembly and the first harmonic of wheel runout. The peak-to-peak value (Total Indicated Runout) and second, third and fourth harmonics of Road Force are also calculated and used for diagnostics. These measurements are all displayed on other screens. The measurements of loaded radial runout are converted to Road Force Measurement in pounds, kilograms or Newtons using the following equation: (Loaded Radial Runout) x (Tire Spring Rate) = Road Force Measurement Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life. Link to comment Share on other sites More sharing options...
Dadillac Posted January 19, 2005 Author Report Share Posted January 19, 2005 Thanks for the input from all. I am assuming that the vibration that I am getting, is not too different, from the other Seville's on the road. I have every intention of checking out the front end components, when the weather warms up. But, i was concerned with the struts. I am just wondering, in a nutshell, if a strut can go bad, in a portion of it's travel, or will it go bad, through it's entire travel? Since I bought this car, when it had 50,000 miles on it, I am unsure, as to how it has been treated. I live in central NJ, and our roads are crap. What is even worse, is if the previous owner, lived in Staten Island NY, which is just across the river from me. So, I do not know if the struts have been taxed, or not. If anyone knows, if a strut, can be worn out, in the first portion of travel, and then be okay, through the rest of the travel, please chime in. I am guessing that this isn't possible, but want to know for sure. Thanks again Don "Modern warriors saddle iron horses of chrome." Link to comment Share on other sites More sharing options...
STYES Posted January 20, 2005 Report Share Posted January 20, 2005 It's the tires. If you do not change them, you will develop other suspension related problems. Link to comment Share on other sites More sharing options...
acklac7 Posted January 20, 2005 Report Share Posted January 20, 2005 Whats wrong with Good years? why do they cause suspension problems? A.J. Link to comment Share on other sites More sharing options...
Dadillac Posted January 20, 2005 Author Report Share Posted January 20, 2005 Yes, I would like to know what is wrong with Good Years also. There are millions of them on the highway, without a problem. I have had many GY tires on my cars, and trucks, and did not experience any ill affects. My current tires are GY Assurrance triple treads, and they have 4,500 miles on them. So it is not like my tires have 54,500 miles, and need to be changed. I continually hear how GY's are crappy tires (tread seperation, not round, etc), but how come our Caddy's, are the only vehicles, that get bad GY's? I suspect a very sensitive suspension system, that cannot handle a normal amount of movement. I would wager alot of money, if I put my tires on my wifes Infiniti, her car would ride perfect. The problem has to lie in the suspension, not the tires. Just my opinion by the way. Don "Modern warriors saddle iron horses of chrome." Link to comment Share on other sites More sharing options...
Hud Posted January 21, 2005 Report Share Posted January 21, 2005 Once you have experienced a vibration you can't seem to get rid of, no matter how many times and what type of balance you do, and you then get rid of the Good Year's and the vibration is gone, then you are a believer. Link to comment Share on other sites More sharing options...
yenko Posted January 21, 2005 Report Share Posted January 21, 2005 Do you only notice this is a certain model of goodyears or is it goodyear tires in general? It doesnt make much sense to me! IMPORT CRUSHER Link to comment Share on other sites More sharing options...
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