Low Frequency Vibration During Acceleration

[BulletBarry]

I’m a newbie here and have searched the forum for vibration during acceleration. I found some threads suggesting what the potential problem could be, but would appreciate additional input.

During acceleration from about 15-to-20 mph on up in my 2001 SR5 Sport 2WD Automatic 3.4L, I feel a low frequency vibration in the seat and shift lever, but not the steering wheel (as I recall).The frequency is kind of like when you flutter your tongue. It only happens during acceleration, not at constant speed or when decelerating. The vibration does not vary with speed of the vehicle or engine, or with which gear I am in.

Thank you in advance for any suggestions as to the cause of the problem.

 

[Qyota]

Welcome to the forum! A few things to check are the U-joints, wheel bearings, and torque convertor. Not easy to check the TC, so perhaps you'll need to take it to a transmission shop. How's the transmission fluid look? Ever been changed?

 

[BulletBarry]

Qyota, I'm pretty sure it is not the wheel bearings since there is no change in the noise when steering side to side. Transmission fluid was changed at 37K miles, mileage is now almost 120K. Fluid level is good and fluid looks clean.

One change to my original post; the frequency of the vibration does increase with vehicle speed, but not engine speed and is not dependant on the gear it is in. And I do feel the vibration in the steering wheel (not rotational though), as I do in the whole truck.

I looked at the U-joints and do not see any obvious problem, but I'm not sure I would. I am suspicious that one or both U-joints are the problem.

 

[quicksilvr]

Qyota, I'm pretty sure it is not the wheel bearings since there is no change in the noise when steering side to side. Transmission fluid was changed at 37K miles, mileage is now almost 120K. Fluid level is good and fluid looks clean.

One change to my original post; the frequency of the vibration does increase with vehicle speed, but not engine speed and is not dependant on the gear it is in. And I do feel the vibration in the steering wheel (not rotational though), as I do in the whole truck.

I looked at the U-joints and do not see any obvious problem, but I'm sure I would. I am suspicious that one or both U-joints are the problem.

I would guess U-joints as well. Being 2wd, you don't have the option to grease anything, so you are left with simple replacement. Do you have a little press? It's not a hard job if you have a press.

Otherwise, hopefully you have a good shop that you use. U-joint replacement isn't hard, but I see people overpay for it all the time because they don't know how hard it is, so shops will charge like $500 for unsuspecting customers.

 

[BulletBarry]

I've called a few shops that were recommended and I'm starting to get comfortable with the info they're giving me, but one guy says that only the rear U-joint can be replaced without replacing the whole drive shaft. He says the front U-joint is part of the drive shaft itself. Does anyone know if that is true on this model (2001 2WD SR5 Auto trans)?

And thanks for the helpful info so far.

 

[Qyota]

If you feel it in the steering, it could be a badly feathered or cupped tire (or multiple tires). What condition are the tires in?

 

[BulletBarry]

Qyota, the tires are brand new, Bridgestone Dueler H/L Alenzas -- put on three days ago, and felt silky smooth until the vibration upon acceleration began two days ago. I only feel it in the steering because the whole truck shakes. I feel it more in the shifter, armrest, etc.

 

[quicksilvr]

Wait....you put new tires on 3 days ago, and 2 days ago the vibration started?

Could be a very bad coincidence...or not. You might take it back to the shop that put the tires on and tell them that right after the tires were installed you got some bad vibrations. They should at least look at it for free if they're a decent shop.

 

[GX4SEVEND]

I have the exact same vibration and have even posted about it on here before. However, both the runners I've had this happen on we're after I lifted it AND put new tires on it. Oh, and also after the spidertrax spacers. Both mine were 4wd though.

Hopefully someone can figure this out. I gave up and just deal with it

 

[BulletBarry]

I took the 4Runner to a recommended shop today and went for a drive with the technician. Within a half a mile he diagnosed it as a worn out U-joint. With the car up on the lift after returning, we saw that the front U-joint had partially disintegrated. No obvious sign of failure on the rear U-joint. It appears that both can be replaced, so that's what I'm having done. I plan to report tomorrow if the problem has gone away.

 

[quicksilvr]

Hopefully those new joints get you rolling smooth again. It's strange that it started right after the new tires.

 

[BulletBarry]

quicksilvr, it is strange, but tomorrow when I pick it up we will know the answer. Inspection from beneath did not show any other problem. I will post the result tomorrow.

 

[Qyota]

That'd be awesome if that's all it was. I hope my first guess was right!

 

[mikebontoft]

I am also interested to hear what you find out. My second gen has been starting to do this depending on load (sometimes) but it's throughout the whole body. I had it on a lift and inspected and greased the U-joints but had no luck. Next step for me is to make sure my tires are balanced again.

One other thing. Do you have a lift or anything like that? I noted that my driveline angle probably doesn't cancel itself out, meaning that under a load I could experience vibrations like this.

 

[BulletBarry]

mikebonft, my 4Runner is box stock 2WD. The shop called at 5:30 today and said it is fixed -- said they test drove and there is no vibration. I will confirm tomorrow after I pick it up.

My symptoms were -- whole body shaking at speeds above about 15 mph, frequency increasing with vehicle speed, but not relaed to engine speed.

Full update tomorrow.

 

[BulletBarry]

I picked up my 4Runner today and all is well. It drives smoothly. The only problem was the front U-joint. I had them both replaced so I don't have to do this again anytime soon. The tecnician said that the front U-joints normally fail before the rear one does. BTW, mileage was just under 120K when the problem arose.

Thanks to everybodythat had input on this problem.

 

[mikebontoft]

good to hear its fixed. sounds like my problem as well. Gotta eliminate the obvious first though.

 

[BlackCat914]

Just replaced my rear U-joint for similar issues. 132k here.

 

[BulletBarry]

BlackCat914, did the rear U-joint fail first or have you previously replaced the front one?

 

[BlackCat914]

BlackCat914, did the rear U-joint fail first or have you previously replaced the front one?

I also work on cars for a living, and in my experience, it's almost always the rear joint that fails first. I didn't want to clutter your thread with argumentative BS, so I didn't mention anything. To the best of my knowledge, the others are still original.

My vibration didn't come in until 50+mph though, but it did "chirp" at slow speeds.