Front end vibration 63mph+. through steering column
#1
10-16-2016, 10:47 PM
Front end vibration 63mph+. through steering column
Hi.
Replacing the front sway bar bushings on my 97SC2 finally got my car to a state where it could be aligned and track properly on the road.
In addition, probably 3 different overlapping vibrations have disappeared since the replacement of various suspension components to get to where it is today.
There now remains one very clearly definable vibration I'd like to address.
The car drives smooth as silk up to 60 mph.
At almost exactly 63 mph, there is a sizeable resonance somewhere in the front end being transmitted up through the steering column to the steering wheel
It dissipates a little but remains as I increase in speed to about 70mph.
It is then pretty much steadily there and doesn't really increase in amplitude as I go faster.
It seems worse with significant engine loading (maintaining 65 going up a long hill on the interstate) vs flat vs downhill, although downhill with accel pushed down also accentuates it at the right speed. So maybe it's just worse w increasing engine loading.
It also increases when I turn the wheel slightly to the left or the right.
This immediately brings up the thought of wheel bearings (254K originals), but I have no standard symptoms of wheel bearing issues like the growling or airplane noise at any speed including the range mentioned above.
Both LCAs (w integral ball joints) are new AC Delco w in the last year, so those bushings should not be an issue.
L upper strut mount and bearing replaced 6 mo ago due to a strange noise coming from bearing.
R front strut piston will NOT turn when fully assembled, even with brand new Saturn strut mount at top. The heads of the upward facing mounting posts on the underside of the strut mount collide with what is underneath, and even though the bearing is fine, the strut rotates easily when not installed, and the strut behavior is normal in the vertical direction, The strut will not rotate when turning.
The result is that the spring, along with the whole assembly, rotate as one when I turn the wheel, with the spring squealing against the rubber underside ot the mount. It is surprisingly not difficult to drive this way but it is noisy and somewhat embarrassing.
CV's are original boots intact (254K)
All tie rods original except outer R tie rod nut (254K)
Struts KYB GR2 70K on them
Wheels balanced
Camber, toe AND caster in tolerance
Wheel bearings original (254k)
Hubs original
No play at wheels with car on lift
--------------------------------------
So does any of this ring a bell as to where to look next?
Suspensions are not my strongest suit but apparently will become stronger via this troubleshooting session.
I understand a 19 year old car is not going to run like new. But resonances like this signal to me that something is literally mechanically "out of balance" or worn and should be addressed as they are likely accelerating wear on something.
PS: I have not personally checked to see if the wheels are true; I would think they would have been a beeeach to balance if one of the rims was bent.
Replacing the front sway bar bushings on my 97SC2 finally got my car to a state where it could be aligned and track properly on the road.
In addition, probably 3 different overlapping vibrations have disappeared since the replacement of various suspension components to get to where it is today.
There now remains one very clearly definable vibration I'd like to address.
The car drives smooth as silk up to 60 mph.
At almost exactly 63 mph, there is a sizeable resonance somewhere in the front end being transmitted up through the steering column to the steering wheel
It dissipates a little but remains as I increase in speed to about 70mph.
It is then pretty much steadily there and doesn't really increase in amplitude as I go faster.
It seems worse with significant engine loading (maintaining 65 going up a long hill on the interstate) vs flat vs downhill, although downhill with accel pushed down also accentuates it at the right speed. So maybe it's just worse w increasing engine loading.
It also increases when I turn the wheel slightly to the left or the right.
This immediately brings up the thought of wheel bearings (254K originals), but I have no standard symptoms of wheel bearing issues like the growling or airplane noise at any speed including the range mentioned above.
Both LCAs (w integral ball joints) are new AC Delco w in the last year, so those bushings should not be an issue.
L upper strut mount and bearing replaced 6 mo ago due to a strange noise coming from bearing.
R front strut piston will NOT turn when fully assembled, even with brand new Saturn strut mount at top. The heads of the upward facing mounting posts on the underside of the strut mount collide with what is underneath, and even though the bearing is fine, the strut rotates easily when not installed, and the strut behavior is normal in the vertical direction, The strut will not rotate when turning.
The result is that the spring, along with the whole assembly, rotate as one when I turn the wheel, with the spring squealing against the rubber underside ot the mount. It is surprisingly not difficult to drive this way but it is noisy and somewhat embarrassing.
CV's are original boots intact (254K)
All tie rods original except outer R tie rod nut (254K)
Struts KYB GR2 70K on them
Wheels balanced
Camber, toe AND caster in tolerance
Wheel bearings original (254k)
Hubs original
No play at wheels with car on lift
--------------------------------------
So does any of this ring a bell as to where to look next?
Suspensions are not my strongest suit but apparently will become stronger via this troubleshooting session.
I understand a 19 year old car is not going to run like new. But resonances like this signal to me that something is literally mechanically "out of balance" or worn and should be addressed as they are likely accelerating wear on something.
PS: I have not personally checked to see if the wheels are true; I would think they would have been a beeeach to balance if one of the rims was bent.
#2
10-17-2016, 08:02 AM
The first thing I'd suggest is moving the front tires to the back and see if happens again, derf. You could have a belt separation going on in a tire. That's the quickest and easiest thing I can think of to check first. I don't much think it's a bearing, but I'm not really a mechanic, so don't take my word for it. If the tire rotation doesn't solve it, have a REPUTABLE front end shop check the drive axles. A cv joint could be starting to go bad. Have you tried the 10:00-6:00 and 3:00-9:00 tests to rule out ball joint and tie rod play? If you're not familiar with what I'm referring to, email, pm or try to call me and I'll explain it. You can text me too, if you wanna.
Last edited by Rubehayseed; 10-17-2016 at 08:05 AM.
#3
10-17-2016, 11:17 AM
I suspect a front tire is not quite round. You can balance an egg but it will still bounce when rolled. We fight this at work with the 25 F-550 we have. They bend wheels and sometimes the paint/powder coat gets uneven between the duals and the hubs. The tire/wheel combos weigh a lot so when they bounce the whole truck shakes.
#4
10-18-2016, 01:22 AM
Tried full rotation before the last balancing. No change in symptoms or severity.
I will try to get it up on a lift --- or front. then back, and spin each wheel with a rod held fixed difference from the tread surface and see if the separation changes. I would do the same for the sidewall to check for misshapeness.
I may also try putting properly inflated saturn spares on the front (I have access to the 95's spare), though I do not enjoy the concept of a 70mph road test on 20 yr old spares. I will check for deformities and most of all dry rot before putting them on the car. They both still hold air.
If the oem wheels and/or the tires are directly causing the problem, then the resonance should disappear (assuming the spares are true)
If the oem wheels and/or the tires are NOT DIRECTLY causing the issue, I would expect
1) a resonance but a a higher speed since the mass on the half axles will be less than that of the oem setup (assuming the half axles are part of the problem)
OR
2) a resonance at about the same speed, indicating I'm barking up a nearby but wrong tree.
I will try to get it up on a lift --- or front. then back, and spin each wheel with a rod held fixed difference from the tread surface and see if the separation changes. I would do the same for the sidewall to check for misshapeness.
I may also try putting properly inflated saturn spares on the front (I have access to the 95's spare), though I do not enjoy the concept of a 70mph road test on 20 yr old spares. I will check for deformities and most of all dry rot before putting them on the car. They both still hold air.
If the oem wheels and/or the tires are directly causing the problem, then the resonance should disappear (assuming the spares are true)
If the oem wheels and/or the tires are NOT DIRECTLY causing the issue, I would expect
1) a resonance but a a higher speed since the mass on the half axles will be less than that of the oem setup (assuming the half axles are part of the problem)
OR
2) a resonance at about the same speed, indicating I'm barking up a nearby but wrong tree.
#5
10-18-2016, 02:04 AM
just did some reading up on how to differentiate between bent wheels and out of round tires.
Time to go look at the wheels, then the tires.
$1 my rims are all equally bent to hell. That vehicle has been through alot in it's lifetime......
Time to go look at the wheels, then the tires.
$1 my rims are all equally bent to hell. That vehicle has been through alot in it's lifetime......
#7
10-18-2016, 11:00 PM
What I found out today:
1) Equal and significant pressure loss all from all 4 tires.
2) I am a bozo for not noticing the sag in the fronts sooner.
3) I fear my aluminum wheels have become porous. Either that or
a)the balancer deflated them all for balancing and didn't put them back to pressure
OR
b) the alignment dude deflated them during alignment
both of which are idiotic explanations that would have made each task more work..or maybe there is something I don't know
(I can believe that tire pressure will slightly affect camber, but i doubt changing all the wheels to the same pressure would accomplish a camber shift)
(I guess I can understand how a bent rim might have a resonance (subharmonic) that interferes with balancing so hey let air out to move the resonance out of the way)
Sorry, especially paranoid tonight
Here is an article I just found on addressing the porosity. I would think there must be a brush on sealant with which you just coat the entire inside surface of the wheel. Te key, of course, would to get an even layer so that the wheel + tire can still be balanced. or and adhesive product wrap. Of course I can understand the mess if an adhesive film came loose in there
------------------------
How To Tell When a Wheel, Not a Tire, is Leaking
By Mike Allen (Popular Mechanics)
Oct 30, 2009
Q: One tire on my Yukon has a slow leak. Or so I thought, until I just replaced the tire because I got tired of filling it every week. Now the new tire leaks. The guy at the gas station wants to put some of that green, slimy goo in the tire to fix it, but I want him to replace the new tire with one that doesn't leak.
A: Did either of you two think that maybe the tire isn't leaking? Most cars have alloy rims nowadays. And unlike steel rims, a fair number of these wheels leak air. It's not a bead-seat surface leak, where air can creep out between the rim and rubber, but a leak through porosities in the cast-aluminum alloy.
GM has a published repair procedure for this problem: Inflate the tire to 40 psi or so, and immerse the whole thing in a conventional dunk tank. Mark the rim with a grease pencil where the bubbles form. Then pull the rim out of the water, and demount the tire from the rim. Scuff lightly with 80-grit sandpaper. Dry off and clean the area corresponding to the leak on the inside of the rim with carb cleaner or mineral spirits, and cover it with a thin layer of silicone gasket sealer. (Don't use silicone tub caulk, which outgases acetic acid as it cures; it will corrode the metal wheel and may damage any tire-pressure monitoring-system sender.) Allow it to cure a few hours, then remount and rebalance the tire.
That's GM's take.
1) Equal and significant pressure loss all from all 4 tires.
2) I am a bozo for not noticing the sag in the fronts sooner.
3) I fear my aluminum wheels have become porous. Either that or
a)the balancer deflated them all for balancing and didn't put them back to pressure
OR
b) the alignment dude deflated them during alignment
both of which are idiotic explanations that would have made each task more work..or maybe there is something I don't know
(I can believe that tire pressure will slightly affect camber, but i doubt changing all the wheels to the same pressure would accomplish a camber shift)
(I guess I can understand how a bent rim might have a resonance (subharmonic) that interferes with balancing so hey let air out to move the resonance out of the way)
Sorry, especially paranoid tonight
Here is an article I just found on addressing the porosity. I would think there must be a brush on sealant with which you just coat the entire inside surface of the wheel. Te key, of course, would to get an even layer so that the wheel + tire can still be balanced. or and adhesive product wrap. Of course I can understand the mess if an adhesive film came loose in there
------------------------
How To Tell When a Wheel, Not a Tire, is Leaking
By Mike Allen (Popular Mechanics)
Oct 30, 2009
Q: One tire on my Yukon has a slow leak. Or so I thought, until I just replaced the tire because I got tired of filling it every week. Now the new tire leaks. The guy at the gas station wants to put some of that green, slimy goo in the tire to fix it, but I want him to replace the new tire with one that doesn't leak.
A: Did either of you two think that maybe the tire isn't leaking? Most cars have alloy rims nowadays. And unlike steel rims, a fair number of these wheels leak air. It's not a bead-seat surface leak, where air can creep out between the rim and rubber, but a leak through porosities in the cast-aluminum alloy.
GM has a published repair procedure for this problem: Inflate the tire to 40 psi or so, and immerse the whole thing in a conventional dunk tank. Mark the rim with a grease pencil where the bubbles form. Then pull the rim out of the water, and demount the tire from the rim. Scuff lightly with 80-grit sandpaper. Dry off and clean the area corresponding to the leak on the inside of the rim with carb cleaner or mineral spirits, and cover it with a thin layer of silicone gasket sealer. (Don't use silicone tub caulk, which outgases acetic acid as it cures; it will corrode the metal wheel and may damage any tire-pressure monitoring-system sender.) Allow it to cure a few hours, then remount and rebalance the tire.
That's GM's take.
#8
10-18-2016, 11:50 PM
I have an old set of slot mags with a set of mud brute tires for playing ink the mud. One of the wheels leaks through the wheel itself. I had a tube installed and now there are no leaks. I hate tubes.
#9
10-19-2016, 02:28 AM
Derf
I have had more than my share of tread separation. A not uncommon problem out here where heat and UV cause all kinds of tire rot. The easiest way I have found to check for tread separation is to take something akin to a T-shirt cloth (one layer) between my hand and the surface of the tire and rub around the tire surface either by moving my hand, or if jacked up, holding my hand still and spinning the tire. It is amazing the level of sensitivity that piece of cloth brings to your hand. But if you can feel the vibration in the steering wheel, it is not a parasitic figment of imagination, something serious is out of balance. I changed two front wheel bearings, same bearing different cars and one of them was on my 94 The book says they are non re-place able, the book lies. I have a front strut and associated parts in my parts stash if you run across something you need from it. I forget which side it is from but it is the whole strut and steering knuckle. It was a junk yard freebie once so I grabbed it. I have never had an "aluminum" wheel leak from porosity, but I guess truth is stranger than fiction.
I have had more than my share of tread separation. A not uncommon problem out here where heat and UV cause all kinds of tire rot. The easiest way I have found to check for tread separation is to take something akin to a T-shirt cloth (one layer) between my hand and the surface of the tire and rub around the tire surface either by moving my hand, or if jacked up, holding my hand still and spinning the tire. It is amazing the level of sensitivity that piece of cloth brings to your hand. But if you can feel the vibration in the steering wheel, it is not a parasitic figment of imagination, something serious is out of balance. I changed two front wheel bearings, same bearing different cars and one of them was on my 94 The book says they are non re-place able, the book lies. I have a front strut and associated parts in my parts stash if you run across something you need from it. I forget which side it is from but it is the whole strut and steering knuckle. It was a junk yard freebie once so I grabbed it. I have never had an "aluminum" wheel leak from porosity, but I guess truth is stranger than fiction.