'02 3.4 120K: Front End Vibration Diagnosis

Can I diagnose a front-end vibration myself, or do I have to take the car to a "professional"? Alignment seems to be OK, no pulling either way, but on the highway around 70mph I can feel a 'hammering' vibration into the steering wheel. It's a cyclical vibration. At times it seems to go away, then it returns vibrating worse and worse until it disappears again.

The tires are Goodyear Viva II's (Wal-Mart) 225/60 R16's - nothing special, 3.5 years old and 50k miles on them. Wheels are factory steel rims. Everything in the steering through the half-shafts to the wheels (including ball joints, tie-rods, and brake components) are still factory originals.

This could be .. what?:

1.) Bad tire? (out of round?)
2.) Bad wheel bearing? (but no noise that I can hear)
3.) Bad ball joints (don't think so, but I'd have to check)
4.) Bad half-shaft? (they're original and no reason to believe they'd be bad)
5.) Engine mount? (I replaced the intake gaskets one year ago and noticed that the engine could rock forward and back, but was told this was normal).

One thing I should mention is many years ago the wife parked the car on the grass at the park, but didn't see an embedded concrete "ledge" that contained a drain pipe with a huge gulley in front of it. She drove the left front wheel off the ledge into the gulley causing the car's box frame to strike the concrete ledge. This crushed/split the "endcap" portion of the box frame underneath, but left the rest of the box frame unscathed. I've always wondered if this has had any effect on the front end, but I really don't know when the car started vibrating relative to this incident. It's only the 2-3" overhang of the box frame in the front driver corner underneath. Looks pretty ugly being cracked in the middle and crushed kind of upward with black guey stuff smeared all over it, but this "endcap" doesn't seem to have any purpose that I can see...

rotate tires rears to front see if it changes...lost bal wts ,tire bubble ..belt damage....etc...

when you remove tires roll on flat ground to see if they roll without floping over which would indicate a belt/out of round issue..

I DID rotate the tires prior to the last long trip I took (December), and at first it seemed like it was better during that drive, but before the end of the trip I sensed the problem was still there (and maybe even worse, if I remember right). Right now, if I focus my eyes on the steering wheel while the vibration is occurring, the wheel appears to move back and forth (clockwise, counter-clockwise) very tightly and rapidly. I had said this happens at highway speeds, but it's probably most visible at lower speeds (45-55).

I think I'm going to be replacing all four tires before the next trip because they've got 50,000 miles on them and they're looking a little "rubbed off" along the outer edges (tread in the middle doesn't look bad, though). Plus, I've put plugs into a few of these Goodyear Vivas (can't believe how many nails on the road there seem to be around here). Just last night I was plugging the front passenger wheel (again) and saw two other plugs that I had put in previously! And I think this time I'll stay away from Wal-Mart tires and go back to the original factory tire - UniRoyal TigerPaws to see if that makes a difference. Maybe Wal-Mart tires are rejects or 2nds.

I DID rotate the tires prior to the last long trip I took (December), and at first it seemed like it was better during that drive, but before the end of the trip I sensed the problem was still there (and maybe even worse, if I remember right). Right now, if I focus my eyes on the steering wheel while the vibration is occurring, the wheel appears to move back and forth (clockwise, counter-clockwise) very tightly and rapidly. I had said this happens at highway speeds, but it's probably most visible at lower speeds (45-55).

I think I'm going to be replacing all four tires before the next trip because they've got 50,000 miles on them and they're looking a little "rubbed off" along the outer edges (tread in the middle doesn't look bad, though). Plus, I've put plugs into a few of these Goodyear Vivas (can't believe how many nails on the road there seem to be around here). Just last night I was plugging the front passenger wheel (again) and saw two other plugs that I had put in previously! And I think this time I'll stay away from Wal-Mart tires and go back to the original factory tire - UniRoyal TigerPaws to see if that makes a difference. Maybe Wal-Mart tires are rejects or 2nds.


your comment on the outer edges worn on your tires tells me your camber is off,,,this could also mean new stuts/springs....

replace these suspension componets before new tires and alignment...rotate tires every 15,ooomi.....35psi frt,,,30 psi rear...

Yeah, I knew the tire wear pattern meant something, but hadn't looked it up yet. Thanks for the camber suggestion.

I've never replaced struts or springs on any car I've ever owned, so I don't have any idea what that would cost, but I'll check into that. Thanks.

As far as rotation, I was rotating every 6-7k with this set (to see if it made any difference from my previous method of rotating only ONCE - after the front tires had worn about 2/3). 15k rotation is probably about right. That would be about 4 rotations total. I use the criss-cross rotation diagrammed in the Shop Manual where each tire gets rotated through every position on the car. I've heard/read some say you should only go front-to-back, same side. Which is correct? Or does it depend on the tire?

Vibration probably is out of balance/out of round tire, possibly bent rim. Check all. The tire wear sounds more like just low inflation than camber, especially if it's both inner and outter shoulders that are worn. Camber would have to be off by a lot to affect wear. 5 degrees would pull very hard, and imagine 5 degrees across the width of the tire, probably only 1 or 2 32nds side to side. Walmart tires (everything, actually) are lower quality, they tell the manufacturers what they'll pay for something and if the manufacturer can cut corners enough, Walmart sells their stuff. Rotation depends on tire type. Radials should only go front to back... sortta. They need to rotate in the same direction all the time, so if you want to criss-cross you need to flip them around on the rim. Something about the direction of rotation weakens the steel belts and they can blow out if reversed. I don't know about that, just what I've heard. I only run directional tires anyway...

As for tire pressure, the reccomended PSI in the door opening is for the best ride. You'll get better handling, even tire wear, and better gas mileage with higher PSI. I keep mine at the maximum labeled on the sidewall. On my Cavalier's 205/55/16 that's 44 PSI and they wear perfectly square, and that's with considerably more camber than recommended

As far as rotation, I was rotating every 6-7k with this set (to see if it made any difference from my previous method of rotating only ONCE - after the front tires had worn about 2/3). 15k rotation is probably about right. That would be about 4 rotations total. I use the criss-cross rotation diagrammed in the Shop Manual where each tire gets rotated through every position on the car. I've heard/read some say you should only go front-to-back, same side. Which is correct? Or does it depend on the tire?

the owners manual and I agree to use the X criss cross rotation....

I have found the road debris [sand/grit] on the shoulder of the road wears out the tires on the passenger side more so than the drivers side ...keeping the passenger side tires on that side results in more wear to these tires ..

if the outer edge wears out the camber is off also weak stuts/springs will do this and throw the alignment off..

tire shops that align front end for free with a purchase of 4 new tires will F up your ride...these people are not alignment tech's....

Thanks.

One last question: the car doesn't pull to either side, so I don't think I need an alignment. The car has never had an alignment in its life, BTW. But if I were to take it in to a "professional" to have the front end evaluated, should I do so before or after putting the new tires on? Doing it AFTER mounting the new tires makes the most sense to me because if it's just the tires causing the problem, the evaluation may not be necessary. But if it's NOT the tires, having the old tires still on there could yield clues for the front-end guy in isolating where the problem lies. Plus, if the front-end place is also where I buy the tires (certainly a possibility - NOT a chainstore), they could check the rims for trueness. I have no reason to believe the rims are bent, but then again I don't drive this car exclusively, so anything is possible I guess...

Thanks again for your inputs.

Thanks.

One last question: the car doesn't pull to either side, so I don't think I need an alignment. The car has never had an alignment in its life, BTW. But if I were to take it in to a "professional" to have the front end evaluated, should I do so before or after putting the new tires on? Doing it AFTER mounting the new tires makes the most sense to me because if it's just the tires causing the problem, the evaluation may not be necessary. But if it's NOT the tires, having the old tires still on there could yield clues for the front-end guy in isolating where the problem lies. Plus, if the front-end place is also where I buy the tires (certainly a possibility - NOT a chainstore), they could check the rims for trueness. I have no reason to believe the rims are bent, but then again I don't drive this car exclusively, so anything is possible I guess...

Thanks again for your inputs.

after the new tires are mounted get the alignment done..
if the camber is incorrect you will get the outer edge only to wear..this may be equaly off due to worn springs/struts...

vehicle height is off when the springs are beat..rear of vehicle much higher than front...this must be corrected before alignment..

I don't have these problems,,,as the springs and other suspension is properly maintained...worn shocks WILL destroy the springs quickly...

I also don't use the wheel weights that are hammered on the rim edges...these fall off as the aluminum and steel react to create a failed secure mount..the stick on weights properly installed on a cleaned surface last longer and will no damage the alloy..rim..

I agree with a lot of the previous posts. Your problem sounds like out of balance and/or out of round tires. I would bet when you replace them, most of your problems will disappear. I would get a free alignment check when you get the new tires to make sure alignment is good and won't prematurely wear out your tires. I would recommend Goodyear LS-2 or Goodyear Eagle ResponeEdge for this car. I've had very good results with Goodyear's premier tires. I also think you should run the tires at 30psi, and for tire rotation cross the rears to the front and fronts straight back as you've been doing and as GM recommends. The manufacturers now recommend criss-crossing the non-directional radials and they know what they're talking about.

I replaced all four tires and the problem is mostly gone (much better, anyway). This time, I stayed away from Wal-Mart and their Goodyear Viva-2's and went with BF Goodrich Advantage T/A's. These tires are rated 98H - which is an upgraded load index and speed rating over the standard tire (97S). They also had a higher treadwear number. I almost went back to the factory tires (Uniroyal TigerPaws) - because I remembered them being pretty good when the car was brand new, but they were 97S's and I found a place selling the BFG's for a few bucks LESS. Paid just under $400 for the set installed (with the rebate).