Wheel/Gas Pedal Shake @ 70 MPH with pulsating hum (varies with RPM)

2003 Hyundai Accent. I will try to give a good description of the issue. Wheel was shaking (or was noticeable) at about 60 mph. Lessened after that but still bad. I had my tires changed and balanced as well as an alignment. My rear right toe is still off a bit. Now, the shaking is noticeable at 68-70 mph and higher. Pedal shakes, wheel shakes. I can feel some vibration all over including the seat, gas pedal and wheel the most. Wheel not jerking, just vibrating mildly. It is not quite as bad as before and does not happen until 68-70, 10 mph higher than before the tire change/balance. I have put my back wheels on the front and it is the exact same condition - this would remove tire and balance as the culprit (?). I also hear an audible hum… kind of a pulsing sound at 50 mph+. This speeds up and slows down with my speed. For instance if I am going 70… I hear it every half second, 50 mph I hear it less often. It is pretty faint, not a thump. It seems to be coming from the front but I can’t pin-point it. I feel no tire play up/down/side/side.

What is the next step here? I’m going to get the rear toe fixed but this shouldn’t be the cause of the pulse/wheel + pedal vibration. Vibration/sound doesn’t happen when I am braking. No rubbing shield behind rotor. Ideas? Thanks.


Here’s a few ideas . . .

Bad wheel bearings are known for making a rumbling noise . . . which might be described as a hum

Bad wheel bearings can be rough . . . and therefore bad . . . WITHOUT showing any detectable wear or looseness

Unevenly worn tires . . . due to alignment or balance problems . . . are notorious for making noise. This could also be described as a hum

it’s possible that 1 or more of your rims are bent

Very closely examine tires. Make sure there’s no damage, tread separation, bubble, bad belt, etc.

The speed-specific nature of the problem does make it sound like a balance problem.
In order to rule out other possibilities, I suggest that you have the tires balanced by a mechanic who uses the Hunter GSP9700 machine, which does what is called Road Force Balancing.

When all else failed with my crappy Continental tires, balancing them with this machine finally did the trick. Here is a link to find a shop that uses this superior equipment:

While it is in the shop for Road Force Balancing, I suggest that you have the rear toe attended to also, before you ruin the rear tires.

Incidentally…Are the tires in question Continental tires?

I would not describe the sound as a rumbling. It is a pulsating hum which changes with speed. Also, I can’t see how this would be a balance/tire issue anymore as I have put the backs on fronts and the issue is exactly replicated. It would at the least change a bit. What I can’t figure out is why this went from a 60mph issue to now a 70mph issue post tire replacement/balance. I will check for bent rims though again, tires back to front and then front to back with the same symptoms would rule out the exact same pedal/wheel shake, but this is just what I’ve read. Also keeping wheel bearings in mind. Thanks for the ideas so far.

My vote is for wheel bearings. I’ve seen wheel bearings that had a pulsating hum at higher speeds. They can create a beat frequency in combination with a tire tread hum which could explain why the trigger speed changed with different tires. This is exactly happened on an Oldsmobile I once owned.

I think MY 2¢ has the answer.

However, beware of bad tire balancers. I once bought a new set of tires from a tire chain, and one was out of balance, obvious vibration, etc. A second try was no better… they were blaming it on the wheel. Gave up on them and took it elsewhere, where they had no trouble balancing it. Pep Boys, of all places.

After a drive, feel your front wheels to make sure one is not warmer than the other.

If the wheels and tires are perfectly round, properly balanced and all rotating in the same plane and the bearings, suspension, and steering components are within their wear limits and working correctly then it won’t vibrate. So the problem has to be among those items.

I’d guess the most likely problem is with a tire or rim. Have you tried swapping the tires around to different positions on the car? That might provide a clue. If I had this problem, after jacking up all four sides and doing a push-pull-twist-spin inspection on each wheel, if that all looked good, that would be what I’d do next.

Yes, as stated above I have already put the tires front to back and back to front - all resulting in this exact same pulsating hum and wheel/pedal shake with an overall car vibration. The hum varies with car speed. At 70 mph, the hum occurs every half second to .75 seconds if I was guessing for instances, so it is not a constant hum. It’s a pulsing, medium-deep hum (not a thumping) that is from the front but hard to detect left or right side.

After listening to it more, I’d say the sound is more of a pulsating rubbing sound that is intermitent, speeding up as the car goes faster. It becomes audible to my ears at approx. 50 mph. The vibration in the wheel/pedal and really all over is noticeable lower than I thought - even as low as 30mph. It is very minimal at this speed but after 65 is when you can tell something is very wrong. Going to try and isolate the sound today.

Could be quite a few things, but my first guess is a problematic tire. Tires are made in molds from laminates with the patterns of each layer configured in precise orientations, and sometimes that all doesn’t go exactly right during the manufacture of the tire. I think you are on the right track to try to isolate where the sound is coming from, then you can swap tires to see if it follows the swap. Some shops have a listening gadget for problems like this, where they can put microphones at various places around the car and go for a drive, switching which microphone they are listening to.

chassis ears

Pretty cheap . . . less than $200 for the kit, I believe

I used mine a few months ago, to locate a noise over bumps. Turns out it was sway bar links

here’s the clinchers . . .

The truck was an F450, a massive beast

It’s impossible to jounce the truck and reproduce the noise, in the work bay. Maybe King Kong could do it, but I can’t

I initially suspected the sway bar links, but they were TIGHT. No kind of slop whatsoever, when I was checking them by hand and with a sizable pry bar

I set up my leads and the selector box, hooked up the headphones and grabbed a colleague. He drove, while I switched channels. In less than 1 minute of driving, I knew the sway bar links were bad

I suppose I could have guessed without using the chassis ears, but that’s not diagnosis

After installing the fresh sway bar links, I drove the truck again, on the same roads. No more noises. Night and day difference. it’s also important to verify the repair. And that’s where some guys fail

Various possibilities come to mind, including:

  • A bad tire, maybe with a damaged belt?
  • A worn CV joint, triggering half-shaft vibration.
  • Incorrectly balanced tires(s).

See if you still experience the problem by staying in 4th, manual trans axle or turning overdrive off auto trans. Could be an overdrive problem.

I have put the car in neutral and as well as turned OD off.

George, I appreciate your thoughts, but as I’ve stated several times in this thread I have already changed my tire placement up to try and eliminate bad tires/balance/rims as the culprit. The problem is exactly the same with my back tires on the front and vice versa. I can “feel” the vibration in the wheel/pedal. It feels pretty shitty. It is something to do with the front based on how it feels. Going to try and isolate the sound now, but it is hard as it doesn’t become audible to my ears until 50 or so.

If you are certain it is coming from a front tire, then you are right, by swapping front/back, you’ve eliminated the tires as a possibility. So now you’re looking from among

  1. transmission/differential problem
  2. inner cv joints
  3. drive shafts
  4. outer cv joints
  5. hubs
  6. bearings

What I’d do next if I had this problem i-- provided this can be done safely – is drive it just ove the speed where it vibrates, then put it in neutral and let it coast back down through the vibration speed. If the vibration ceases at that speed when coasting, I’d guess the problem is more likely 1-4; if the vibration continues even when coasting, then I’d guess 5 and 6 are more likely. If I had to guess now, I’d say 2, one or both of the inner CV joints.

George, I mentioned above I have already shifted to neutral around 70 mph and let it coast down, the noise does not skip a beat - continues on the same was as if I was in drive. I have also turned the OD off my trans and while I won’t drive at 70 with it off, around 55 mph the car is already starting to shake with that speed dependent rubbing sound coming from the front. The wheel was still shaking prior to this rubbing sound so I have to view it that MAYBE they aren’t connected, but it is probably an escalation of the original shaking symptom and linked. The wheel/pedal vibration is my main concern as it feels terrible to drive. Thanks for your insights.

Bad tires.

Based on what you’ve determined OP, I’d focus on the front hubs, bearings, and anything attached to the hub ass’ys like ball joints, control arm bushings, sway bar bushings, etc.

Okay, so I found something but I am not sure it is anything. I jacked both front tires up. On the right side, I have up and down movement in the tire - and it is the strut. Without load on the tire, the rubber pieces at the top (spring pad/bushing?) does not rest in the concave holder. If there was a load place on it, the rubber would sit in this area fine, but I am not sure if this is broken. The rubber in the strut mount is not cracked or worn. The LEFT front strut in the same area does not drop down at all when load is taken off of it. It remains seated in it’s case. What is correct here?