Odd Front End Vibration

[fdbyrne]

I need your help. I'm trying to find the cause of a vibration that is very much like an out of balance front tire, but not likely caused by my tires.

It happens during prolonged acceleration like merging onto the freeway. The steering wheel rocks back and forth like an out of balance tire. After I get up to speed and back off of the gas things settle down but not immediately. It takes a couple of seconds. It usually only happens the first time I get on the freeway. If I'm on a road trip, it doesn't happen again as I accelerate up hills or anything like that.

My tires are new and have been balanced multiple times using a Hunter machine with a lug adapter per the Toyota TSB.

I don't have any kind of lift. All of my bearings are new. The driveshaft is new and was balanced before I installed it. My CV shafts are new but they are cheapo aftermarket units.

Since it doesn't happen at all speeds, at all throttle levels, I don't think it's the tires. It seema driveline related to me. My guess is maybe its the cheapo CVs, but I wanted to see what you guys think.

 

[Morphyne]

Sway bar? Sway bar bushing?

 

[fdbyrne]

The sway bar seems to be in fine shape and the ends and bushings are new as well.

I guess I could pull the sway bar off when I get back home and run it without one for a few days to see if that helps.

 

[repo]

There was a TSB for the lexus gx about this "flutter" at certain speeds but I cant find it. It involved taking out the steering rack and draining the fluid, putting a different pretensioner spring in the rack guide and torqing to a specific spec with an SST.

 

[fdbyrne]

Thanks. That's good info.

Is this something common to most of our 4Runners or am I one of an unlucky few?

 

[tom5191]

You said you drive shaft is new, so I'm guess the u joints were new too? Have you greased the u joints recently?

 

[edwardvmassey]

Might want to check the CV axles. I had a similar issue a while back and it turned out my AAP replacement CV was a bad fit and I would get that vibration at higher speeds on the throttle. Worth looking in to.

 

[fdbyrne]

You said you drive shaft is new, so I'm guess the u joints were new too? Have you greased the u joints recently?

Yes. I grease the joints at every oil change.

 

[CAN-03runner]

Have you checked for seized calipers.

 

[fdbyrne]

Have you checked for seized calipers.

Sorry. I should have mentioned that too. I was typing up my original post on my phone.

My entire braking system is new. Rotors, calipers, and pads all the way around.

Thank you for pointing it out. It's a common enough problem that it would be a likely cause in most scenarios.

Also new are my lower control arms including bushings and ball joint. I replaced my upper control arm bushings with poly versions. Both the inner and outer tie rods are new and seem tight.

 

[CAN-03runner]

And then you did an alignment I gather.

Tire pressures are the same?

 

[fdbyrne]

Yes. I got an alignment after all of that and then took it back a month later to make sure it was still in spec.

I added air to the tires about a month ago when it got really cold and the TPS light came on as the tire pressure decreased. They're all right at 34 psi.

I've been thinking this one through for a while and I think that it has to be one of a small handful of things. It could be the cheap CV shafts, crappy tires (BFG Rugged Terrains), rack mounts, or a design flaw that affects many 4Runners and I'm just one of those OCD-type people that it really bothers. Then again, I guess I could be overlooking something.

 

[fdbyrne]

I'm still dealing with this issue so I thought I'd bring the thread back to the top of the list and see if anybody had any additional thoughts.

 

[Bob22222]

Have you checked (closely) your engine and transmission mounts?

 

[fdbyrne]

Good idea.

I've checked them as closely as I know how. They all look fine but I'm not really sure how to test them. With the hood raised I can see the engine from the driver's seat. When I give it gas, the engine doesn't appear to rock around inside the engine compartment.

How else can I check them?

 

[Bob22222]

Doesn't sound like bad mounts. Steering rack nice and snug? What about the u-joint in the steering shaft? Not like likely but maybe worth checking.

 

[Urbanrunner716]

You're not the only one with this problem. Mine acts the exact same way.

 

[fdbyrne]

Doesn't sound like bad mounts. Steering rack nice and snug? What about the u-joint in the steering shaft? Not like likely but maybe worth checking.

I've crawled underneath and had the wife rock the steering wheel back and forth while I looked at the rack bushings for play. There may have been 1mm of deflection which I think is pretty normal for rubber mounts.

I'm starting to think that one of my new, cheapo CV shafts is binding occasionally. I'll have to look into it further here in the next week or so.

 

[fdbyrne]

You're not the only one with this problem. Mine acts the exact same way.

I'm sorry that you are dealing with it too, but I'm glad I'm not crazy.

 

[Urbanrunner716]

I'm sorry that you are dealing with it too, but I'm glad I'm not crazy.

Ya, it sucks but I've learned to just deal with it. Btw I'm still running the factory cvs as far as I know. Post up if you figure out the answer cause it's very annoying.