Vibration from Hell

[Hound Dog]

Hey Fellas,

First post. I own a new-to-me 2000 4runner (180k miles, auto trans, no accidents) and also a 1980 FJ40 Land Cruiser. The FJ40 runs great but the 4runner has a death vibration from hell when I step on the brakes between 45-55mph. It's even worse when braking down hill.

The vibration seems to be emanating from within the truck and causes the entire dashboard to shake violently. The vibration is not necessarily in the brake pedal or the steering wheel. The entire truck just shudders. The vibration subsides under 40mph and over 60mph when braking. 45-55mph while braking is the danger zone with severe shaking of the dashboard.

I took the truck to the Toyota dealer and they were stumped. The brake rotors are brand new, we're tested with a dial caliper, and found to be almost perfectly flat (0.001 or something). There is no side-to-side play in the wheels indicating the tie rod ends are good. There is no top-to-bottom play in the wheels indicating the bearings are good.

The Toyota tech with 30 yrs experience was stumped and they reluctantly recommended replacing the power steering rack because when two people turn the wheels, the rack moves from side to side several millimeters. There is also indications of a fluid leak inside the left inner tie rod boot.

The dealership quoted me $1200 for the job but admitted they didn't have a firm diagnosis and that they would just be throwing parts at the problem and it may not fix it.

Before I spend a lot of money on an undiagnosed problem, I thought I'd ask here on the 4runner forum.

Has anyone here experienced this or have an idea of what the problem could be?

Thanks!

 

[shootmymime]

Rear pads and drums.

 

[Hound Dog]

Forgot to mention I got the truck up to speed and pulled the e-brake while at about 50mph, no vibration at all, indicating the rear drums are true. The truck is smooth as silk with no vibrations until I touch the brakes.

 

[Konkordmusk]

I would check control arm bushings, uppers and lowers, and I would also replace the power steering rack bushings. You can get polyurethane bushings which are a small upgrade for cheap, and eliminate them as being an issue. But have a peek at the control arm bushings for sure, or ask a mechanic to do so.

 

[nissanh]

You need to replace the front rotors together with OEM brake pads. I cannot think of another vibration that can come when you hit the brake.
You can do the front brakes. two rotors may be $60 shipped and TOYOTA brake pads $60ish.

When you check the rotors at COLD (like you did at the dealer), all is good, but when at breaking the temperature of the rotor rapidly goes up and expands leading to wrapping the rotor at cracks that cannot be seen by the naked eye.

The TOYOTA tech at that dealership have no experience in brakes for sure.

 

[bolt]

nissanh's suggestion above is seconded' and endorsed, he and i agree. I'd also suggest perhaps the DEALER mentioned is testing your ability to be royally hosed. Consider, you state "you touch the brakes" and your silken ride is compromised horrifically, this more than suggests warped rotors despite the dealers assessment of the rotors, slightly warped front brakes do do this! If you are advised well here and you save hundreds of dollars from us strangers perhaps let everyone know, nissanh and I may be blowhards, or maybe not. Good luck with that!

 

[tyr0981]

Yeah buddy, it has to be rotors, that's all that would cause that.

My Power steering rack was damaged in an accident with a curb and not paying attention, had nearly an inch of free-play in each side, all that happened to my rig was severe outside edge tire wear. on a side note, DO NOT use OEM rotors / pads, theirs some good cross-drilled rotors with ceramic pads on Amazon that have lasted me years....

Amazon.com: Power Stop K1233 Front Ceramic Brake Pad and Cross Drilled/Slotted Combo Rotor One-Click Brake Kit: Automotive

these are still working great for me ~3 years later no warping or fading.

 

[SilverRidgeRunner1]

I had this problem about a month ago when rotor finally heat up they uncover a vibration that is very violent in nature when the metal expanded. During my diag determined that rack and pinion bushing amplified the vibration a lot. When I replaced the bushing the problem wasn't as bad but still there, proceeded to rotor replacement issue was gone. Also during this process, I learned I'm not very impressed with wagner pads anymore and went with OEM, kinda felt there was some relation between the two.

 

[Hound Dog]

Problem solved.

The original brake rotors were warped. I replaced them with brand new rotors and they were warped right out of the box. I had the original rotors resurfaced and the machinist didn't do it right and they were still warped. I had another shop resurface the original rotors a second time and now the vibration is gone.

Lesson learned:

1) Don't trust new brake rotors from Autozone/Advance Auto. They can be warped right out of the box. In some cases they're fine but in other cases they're not. Definitely check the run out with a dial indicator even when they're brand new.

2) Don't trust machinists (NAPA) to do a perfect job every time. They can and do make mistakes.

The new rotors had a runout of 0.002" which is supposedly within spec and even that caused a severe vibration. I believe these 4runners have very sensitive front ends.