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| Vibration at speed https://slantsix.org/forum/viewtopic.php?t=41665 |
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| Author: | wjajr [ Sun Aug 29, 2010 3:17 pm ] |
| Post subject: | Vibration at speed |
Today I took a the Dart for a 200 mile spin to a car show. Because of our crummy low speed limits here in Maine, I have not driven the Dart for any distance over 60 mph since I got it 2.5 years ago. Now we live near to I 95, and can use that rode to access different shows, etc. I find there is a rather prominent vibration at 60 to 75 mph on the smooth interstate when I got to drive a few miles on it today. When the car is shifted into neutral at 60 to 75 mph speeds, the engine idles down, but the vibration continues. I suspect it may be tires, but the drive shaft or transmission could also be causing this as well. Short of changing tires, or rebalancing them, how could one winnow out what is causing this type of vibration? Bill |
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| Author: | emsvitil [ Sun Aug 29, 2010 4:12 pm ] |
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Rotate the tires If the rear tires are the problem, and you move them up front you should feel the vibration in the steering wheel. |
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| Author: | wjajr [ Sun Aug 29, 2010 5:01 pm ] |
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Good idea, I can do that. |
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| Author: | Volare4life [ Sun Aug 29, 2010 6:13 pm ] |
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and if its tires, you may just need a rebalance, could lost a wheel weight somewhere along the line, -Mike |
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| Author: | wjajr [ Mon Aug 30, 2010 5:20 am ] |
| Post subject: | |
Has anyone experienced vibration from installing rear U joint 180 degrees from it previous mounting in the yoke? |
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| Author: | rustyfords [ Mon Aug 30, 2010 12:17 pm ] |
| Post subject: | |
It's hard to say without riding in the car, but I'd generally start with tires. I've revived a number of old cars over the years....a few of them with radials that sat for longer than 6 months. And, when this is the situation, the tires will develop a semi-permanent, or permanent flat spot that is only apparent at speed. Back in the day, when bias-plys were still widely sold, many of the tire shops had tire shaving/truing machines that would actually shave a small amount of rubber off of the tires to make them perfectly round. This would almost always smooth out a vibrating ride. I haven't seen one of those machines since I had the bias-plys shaved on my 54 Chevy pickup when I was in high school in the early 80's though. The downside was that you would loose some tread and some tire life, but it sure would smooth out a vibrating ride if it was related to the tires. I also recently bought a Honda minivan that I was told needed CV joints because of the vibration. I was a bit dubious about the need for CV joints because of the relatively low mileage on the car and when I put new tires on it all the way around, it rode like glass and the vibration went away. I could go on and on with the anecdotal stories, but the one that really comes to mind is the little Ford Escort that my wife and I had when we got married. I could only afford the cheapest of tires at the time and it wasn't long before the vibration in these cheap radials was simply horrible. I thought something was seriously wrong with the car until I replaced the tires with some higher quality tires. The ride was instantly perfect again (well....ok....as perfect as the ride can be in an Escort) and stayed that way until I sold the car. Cheap radials will often develop a vibration after they've been on the car for a while and even higher quality tires will sometimes develop a vibration if something else is needing replacement, like shocks. Once a "groove" or memory is worn into the tire, it's very hard if not impossible to fix it like you could back in the day with the shaving machines. Finally....my 76 Valiant is sporting some pretty old radials that are contributing to some vibration. They do however, have a ton of good tread left on them and are not overly cracked due to the car having sat inside for years. Fortunately my commute to work is only 20 minutes on a 40mph country road, so I plan on running some of the rubber off of these tires before I replace them. Until I replace them, I avoid the interstate. |
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| Author: | Aggressive Ted [ Mon Aug 30, 2010 12:43 pm ] |
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Bill, No, on the U-joint question. Hopefully your yoke is true and not bent. My son sheared a yoke one year at the drags when his truck pulled a wheelie. What brand and size tires/profile are you running now? |
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| Author: | Doc [ Mon Aug 30, 2010 12:52 pm ] |
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Another "do-it-yourself" check you can do on a drum brake car, is to jack-up the front of the car and see if either of the front wheel assemblies "settle" into the same position every time. If the assembly is perfectly balanced, the wheel will stop in a different, random" location, every time it stops. Many times, the assembly "settles" and stops at the same position, the low point being heavy. (mark the low point, give the assembly a slow rotation and see if it stops back at the same spot... often you will see the assembly "seek-out" the same position or heavy point) If you see this, look closely for any weight(s) added to the wheels and / or brake drums. Sometimes, the "heavy side" condition can be corrected if you reposition the wheel on the brake drum. Next test, get some extra wheel balancing weights and add them to the light side of the assembly. (I spray paint those weights so I can keep track of the ones I've added) Test drive the vehicle to see if there has been improvement. Also... much like the old tire "truing" machine, there use to be "on car" wheel balancing equipment, that would spin the entire wheel / brake drum assembly, then tell you where to add weight... but it's been a long time since I have seen any of that equipment. DD |
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| Author: | Sam Powell [ Mon Aug 30, 2010 3:11 pm ] |
| Post subject: | |
Bill, The best tire balancing available for standard walk-in customers is done on a Hunter Ground Force balancing machine. Anyone who tells you they can do as well an a standard spin balancer is blowing smoke, or has never experienced the difference. It is pretty expensive, but well worth the difference. Do a Google search, and you will find dealers who have one. Then there is operator skill, which comes into play. If you really want the best reference, call Rudy at Tire Rack, and tell him you want to get your tires balanced on a Hunter Ground Force machine. He will likely refer you to someone good. Tell him you are a picky customer. I suggest Rudy because he is the contact I have used to get tires and balancing on my Miata, and those cares are very prone to tire balance problems because they are so light, and the suspension parts are so light. All serious Miata owners patronize companies that use a Hunter Ground Force wheel balancer. Now, on to the vibration. The drive shaft vibration will be about 3 times as fast as the wheels, but usually is present at most speeds over 40 MPH if it is indeed the drive shaft. And, for some reason, drive shaft vibration is usually more intense when you take it out of gear and let it coast. AT least that has been my experience. AT this point I would focus on the tires. Good luck. Sam |
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| Author: | wjajr [ Mon Aug 30, 2010 6:39 pm ] |
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Rustyford, I think the last Bias-Ply tires I purchased was around 1974, god those things were dreadful. This car has done its share of sitting around. I have experienced the feeling of new tires after using up a few sets of these high mileage tires that are all the rage these days. I now try to get something that last no longer than 50,000 miles, There is something about driving on half warn out tires for 60,00 miles on Maine’s pot hole & frost heave riddled roads. General they never make the full distance before braking a cord. Ted, I don’t think my U joint is molested, it is the large type, connected to a 8 ¾ rear end. But, they are going to get a shot of grease tomorrow. Doc, I have Kesley- Hayes disks up front. The steering wheel dose not transmit any of the vibration, it’s felt mostly in the seat of the pants. So, I’m thinking drive train, or rear tires. Currently I have a matched set of BF Goodrich Radial T/A 205 70 R 14 with a quarter of an inch of tread. Also listed next to the size is the following: 93S M&S. Using “The Tire Rack’s†ID guide, 93 is load rating, and S is speed rating, and M&S is Mud & Snow. There is no DOT number as used since 2000, just E4 028586 So these tires are 1990’s vintage, and most likely are now junk even though they look like new, with ¼ inch of tread left, and causing this annoying vibration.. In the mean time I’ll keep it under 60 mph, or below vibratory speed which ever comes first. My old house is under contract once again, hopefully be gone mid October, so new tires are on the short list, as well as a Firm Feel steering box. Doug, I remember those on the hub wheel balancing machines, they did a great job if the guy using it knew what he was doing. Balancing a tire & wheel mounted on its hub corrects for all unsprung rotating mass which I always though yielded a better result. Also I haven’t seen one of those things since the early seventies. Thanks for your impute guys, Bill |
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| Author: | Doc [ Tue Aug 31, 2010 8:56 am ] |
| Post subject: | |
Quote: ... Doc, I have Kesley- Hayes disks up front. The steering wheel dose not transmit any of the vibration, it’s felt mostly in the seat of the pants. So, I’m thinking drive train, or rear tires. ...
Yes, DB equipped vehicles have more drag on the assembly so you have to get the pads out of the way in order to run the test.Thanks for your input guys, Bill If you think the vibration is from an out-of balance drive shaft, you can add temporary weight to the shaft in order to check. I use the stick-on led mag wheel balancing material and then cover it with a screw type hose clamp. I usually start by adding more weight to the location where I see current weight, then test drive to see if things improve. If it gets worse, move the added weight 180 degrees and retest. DD |
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