Hum at different speeds

[PhillyDizzle]

Hey guys,

my 99 SR5 is making a super weird noise. At 30 mph and 60 mph a weird hum comes from the front of the car. It gradually gets louder as I stay near that speed. I can hear it at other speeds, but it is not nearly as loud as it is at 30 and 60. Changing gears doesn't affect the noise and it seems to linger a little when slowing down. What I mean by that is that slowing down doesn't immediately make it quieter.
Sometimes around 30 mph the noise will even oscillate.

4runner is a 5mt w/ lift and 33s.

Recent maintenance includes rack bushings, rear wheel bearings, rear axle seals, CV boots, rear brake shoes and drums, plugs, wires, and ignition boots.

 

[4'running'26]

Maybe a U-joint?

I'm no expert, not even close, but I had a similar type of hum/vibration at a couple different speeds this past summer when I was traveling out in CA and it ended up being the rear u-joint. Just a thought.

Hopefully someone has a better, more conclusive idea.

Best of luck.

JT

 

[thecole1098]

Could be the c axle needle bearing on the drivers side front diff. Is it a rotational hum or constant?

 

[SpidermanGeek]

I've had a U-Joint hum in mine for a little over 2 years. I'm so afraid that doing anything about will be a can of worms though (so many horrors on here about Driveshaft work turning into a vibration inducing disaster).

...but.. I really should get it replaced before the Driveshaft pops at 60MPH on the highway.

 

[redshift83]

Huh, I have a similar noise at 21-22 mph. I haven't heard it yet at higher speeds though. Couple questions, does the noise vary when you're going around turns? Also, can you feel any associated vibrations with the noise?

 

[Bijan]

Sometimes around 30 mph the noise will even oscillate.

4runner is a 5mt w/ lift and 33s.

Recent maintenance includes rack bushings, rear wheel bearings, rear axle seals, CV boots, rear brake shoes and drums, plugs, wires, and ignition boots.

Oscillate how? Do feel any vibrations in your:
Steering wheel
Seat butt
pedals / floor board

 

[PhillyDizzle]

Thanks for all the help, guys.

Could be the c axle needle bearing on the drivers side front diff. Is it a rotational hum or constant?

It's a constant hum.

Huh, I have a similar noise at 21-22 mph. I haven't heard it yet at higher speeds though. Couple questions, does the noise vary when you're going around turns? Also, can you feel any associated vibrations with the noise?

It isn't affected by turning at all. I can feel it vibrate a little bit, but its a pretty high frequency vibration.

Oscillate how? Do feel any vibrations in your:
Steering wheel
Seat butt
pedals / floor board

I'm not sure how much physics you know, but sometimes when two different sounds have different wavelengths there is constructive and destructive interference. The interference makes the volume of the sound change rhythmically. This is what it sounds like to me. The sound only oscillates on occasion.

I feel the vibration mostly through the floor board, but it resonates in the cabin a lot so it seems like it's coming from everywhere.

 

[mtbtim]

You listed off a lot of recent repairs. Did the noise start right after one of those repairs? If not, I'm suspecting a u-joint. The u-joints going on lifted trucks is more common than a front wheel bearing failing on one of these rigs.

Have you manually inspected the u-joints on your rear driveshaft for obvious play? There's also a chance it's the pinion bearing in the 3rd member. Grab the 3rd member flange and see if you can detect any bearing play.

 

[Bijan]

Thanks for all the help, guys.



It's a constant hum.



It isn't affected by turning at all. I can feel it vibrate a little bit, but its a pretty high frequency vibration.



I'm not sure how much physics you know, but sometimes when two different sounds have different wavelengths there is constructive and destructive interference. The interference makes the volume of the sound change rhythmically. This is what it sounds like to me. The sound only oscillates on occasion.

I feel the vibration mostly through the floor board, but it resonates in the cabin a lot so it seems like it's coming from everywhere.

So it's a high frequency oscillating hum?

Sounds drive line related for sure, but is it in your diff or driveshafts / CVs

Does it go away in 4x4?

 

[kolelt]

Wheel bearing(s)?

 

[PhillyDizzle]

Thanks again for the all the help, fellas. Unfortunately I have finals coming up next week and don't have enough time to do any further diagnosing right now. A friend of mine is a senior auto major (he's actually building a 2JZ long travel 1st gen right now for his senior project) and he's planning to take a look at it for me next Thursday.

You listed off a lot of recent repairs. Did the noise start right after one of those repairs? If not, I'm suspecting a u-joint. The u-joints going on lifted trucks is more common than a front wheel bearing failing on one of these rigs.

Have you manually inspected the u-joints on your rear driveshaft for obvious play? There's also a chance it's the pinion bearing in the 3rd member. Grab the 3rd member flange and see if you can detect any bearing play.

The noise actually started up a couple days after a decent day of wheeling.

So it's a high frequency oscillating hum?

Sounds drive line related for sure, but is it in your diff or driveshafts / CVs

Does it go away in 4x4?

I don't think I can be that specific regarding where exactly the noise sounds like it's coming from. Unfortunately the sound sort of resonates, so it seemingly comes from everywhere.

Wheel bearing(s)?

We'll see I guess, haha.

 

[thezentree]

I don't think I can be that specific regarding where exactly the noise sounds like it's coming from. Unfortunately the sound sort of resonates, so it seemingly comes from everywhere.

I am having a very similar issue to yours, only mine started after installing a lift. I've got a 3 page thread about it, but to make a (very) long story short, the only thing that's dampened that particular vibration is reducing my lift height. It's not gone, but tolerable. I suspect it's my rear pinion angle being on the ragged edge of acceptable.

Maybe the wheeling trip pushed your rear u-joint over the proverbial edge?