"front end" vibration stumper
08-07-2002, 04:39 PM
#1
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"front end" vibration stumper
the vibration is felt strongly through the steering wheel. i think i can almost see the front fenders hopping up and down, but not sure. it only happens right around 65 mph and goes away if i speed up or slow down.
however, the vibration is NOT constant, and so is probably not a wheel balancing problem. i had the wheels balanced and they are well in spec, but the vibration is still there, and was unaffected by the balancing. also, the tires have only about 4,000 miles on them and are R rated. they are 8" wide at the front; 10 at the rear. [it did the same thing with the previous tires].
here's how it feels: imagine counting slowly from one to ten. everytime you say a number, the steering wheel quickly shakes from side to side a few times, for about a second. then it is smoothe. then a few quick vibrations; then smooth, etc. it will do this as long as i stay about 65 mph.
any thoughts?? is it a likely culprit? bearings; ball joints; control arm bushings etc; unbalanced drive shaft?? it does seem to come from the front, and may be a little worse if i hit a bump.
i have had this problem as long as i have had the car, but it is getting worse. i would appreciate any thoughts at all, and i know it is hard to work with this from a short written description.
however, the vibration is NOT constant, and so is probably not a wheel balancing problem. i had the wheels balanced and they are well in spec, but the vibration is still there, and was unaffected by the balancing. also, the tires have only about 4,000 miles on them and are R rated. they are 8" wide at the front; 10 at the rear. [it did the same thing with the previous tires].
here's how it feels: imagine counting slowly from one to ten. everytime you say a number, the steering wheel quickly shakes from side to side a few times, for about a second. then it is smoothe. then a few quick vibrations; then smooth, etc. it will do this as long as i stay about 65 mph.
any thoughts?? is it a likely culprit? bearings; ball joints; control arm bushings etc; unbalanced drive shaft?? it does seem to come from the front, and may be a little worse if i hit a bump.
i have had this problem as long as i have had the car, but it is getting worse. i would appreciate any thoughts at all, and i know it is hard to work with this from a short written description.
08-07-2002, 05:05 PM
#2
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Re: "front end" vibration stumper (64BB)
Find a shop with a Hunter 9700 and have the wheel/tires checked for runout/radial force variation. Look at:
http://www.gsp9700.com
Also check that the inner fender skirts are solidly bonded. They considerably stiffen the front end bodywork, and if any of the bonds are broken, any vibration can cause the front fenders and hood to shake.
The "R" in a radial tire size designation means "radial", not a speed rating. The speed rating, if any, will be in the service description following the size, which consists of a two or three digit code for the load index and a letter for the speed rating.
If this occurred with other tires the problem could be runnout in the wheels or an improper hub hole or bolt circle that does not properly center the wheel on the hub.
Duke
[Modified by SWCDuke, 1:11 PM 8/7/2002]
http://www.gsp9700.com
Also check that the inner fender skirts are solidly bonded. They considerably stiffen the front end bodywork, and if any of the bonds are broken, any vibration can cause the front fenders and hood to shake.
The "R" in a radial tire size designation means "radial", not a speed rating. The speed rating, if any, will be in the service description following the size, which consists of a two or three digit code for the load index and a letter for the speed rating.
If this occurred with other tires the problem could be runnout in the wheels or an improper hub hole or bolt circle that does not properly center the wheel on the hub.
Duke
[Modified by SWCDuke, 1:11 PM 8/7/2002]
08-07-2002, 05:17 PM
#3
Drifting
Re: "front end" vibration stumper (64BB)
You should try to determine if the vibration is road speed-sensitive or engine speed-sensitive.
Do that by noting the rpm at 65mph when the problem occurs, then drive the car at/around that rpm in another gear to see if you can reproduce the vibration (engine speed sensitive if vibration occurs at this different road speed). Also try shifting to neutral at the top end of the vibration speed range to see if that immediately makes the vibration go away (it's engine speed or torque sensitive if vibration immediately stops, wheels & tires, differential, or swing axles are suspect if vibration stays).
If above tests show vibration only occurs when under power at 65mph, given your assertion that it seems a little worse when you hit a bump, I'd suspect U-joints (either driveshaft or swing axles), and also the front differential mount. An engine-driven accessory (loose belt, bad bearing, or out-of-balance) is another possibility if the vibration is only engine-speed sensitive.
Unfortunately, the cyclic nature of your vibration means there could be two causes at work... but I'd bet on U-joints, probably swing-axles. You might also try disconnecting the driveshaft and turning it 1/2 turn and reconnecting it.
Look for evidence of vibration during deceleration, another indicator of failing U-joints.
Make sure the front wheel bearings are snugged down properly.
[Modified by waynec, 1:20 PM 8/7/2002]
Do that by noting the rpm at 65mph when the problem occurs, then drive the car at/around that rpm in another gear to see if you can reproduce the vibration (engine speed sensitive if vibration occurs at this different road speed). Also try shifting to neutral at the top end of the vibration speed range to see if that immediately makes the vibration go away (it's engine speed or torque sensitive if vibration immediately stops, wheels & tires, differential, or swing axles are suspect if vibration stays).
If above tests show vibration only occurs when under power at 65mph, given your assertion that it seems a little worse when you hit a bump, I'd suspect U-joints (either driveshaft or swing axles), and also the front differential mount. An engine-driven accessory (loose belt, bad bearing, or out-of-balance) is another possibility if the vibration is only engine-speed sensitive.
Unfortunately, the cyclic nature of your vibration means there could be two causes at work... but I'd bet on U-joints, probably swing-axles. You might also try disconnecting the driveshaft and turning it 1/2 turn and reconnecting it.
Look for evidence of vibration during deceleration, another indicator of failing U-joints.
Make sure the front wheel bearings are snugged down properly.
[Modified by waynec, 1:20 PM 8/7/2002]
08-07-2002, 05:45 PM
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Re: "front end" vibration stumper (waynec)
duke and waynec, thanks for the help. you've given me lots to go on, especially since you are dealing with my verbal description of the problem without the benefit of a test ride yourselves.
i look forward to any ideas from anyone with this one because it really has me stumped.
thank you all
i look forward to any ideas from anyone with this one because it really has me stumped.
thank you all
08-07-2002, 06:42 PM
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Re: "front end" vibration stumper (64BB)
Had a similar problem and it turned out to be a bent Rally Wheel. It would balance OK. When they put it on a spin balance machine, you could see the runout. Put that wheel on the back....."straight" wheel on the front, and my problem went away. Chuck
08-07-2002, 11:28 PM
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Re: "front end" vibration stumper (Chuck Gongloff)
64BB,
I also have had a set of wheels cause this type of cylic vibration. Turns out that the manufacturer of the wheels did not make the center holes concentric with the outer rim surface. When your typical tire shop balances the wheel/tire assembly, they pilot on this center hole. If you can find a shop that has a "balances on the car" balancer, he may be able to help you, but these guys are almost impossible to find these days. Other way to balance this type of problem is to find a balancer that pilots on the 5 mounting holes.
Note that the above was "my" problem, but a lot of items as Duke and Waynec stated can actually be yours. If you can try a different set of rims/tires, perhaps you can eliminate another item to check.
Good luck,
Plasticman
I also have had a set of wheels cause this type of cylic vibration. Turns out that the manufacturer of the wheels did not make the center holes concentric with the outer rim surface. When your typical tire shop balances the wheel/tire assembly, they pilot on this center hole. If you can find a shop that has a "balances on the car" balancer, he may be able to help you, but these guys are almost impossible to find these days. Other way to balance this type of problem is to find a balancer that pilots on the 5 mounting holes.
Note that the above was "my" problem, but a lot of items as Duke and Waynec stated can actually be yours. If you can try a different set of rims/tires, perhaps you can eliminate another item to check.
Good luck,
Plasticman
