Shimmying: Rotors Or Tires

[kevinh]

My 2005 RX330 has taken to shaking badly when I hit 70 mph and above on highways; also shakes when I first start braking at those speeds. Shaking comes right through the steerinf wheel as well.

I'm not sure if the problem is warped rotors (front? back?), tires out of alignment, or if there a specific RX-type problem anyone is aware of, like bushing slipping.

Tires have 50,000 miles on them, so they need to be replaced anyway. I'm thinking of replacing them with same Michellins as came on care (real pleased with tires so far).

So, I was thinking of getting tires replaced, seeing if that fixes problem. If not, going to presume rotors need to be rebalanced/replaced.

Any thoughts or recommendations?

[dal]

My 2005 RX330 has taken to shaking badly when I hit 70 mph and above on highways; also shakes when I first start braking at those speeds. Shaking comes right through the steerinf wheel as well.

I'm not sure if the problem is warped rotors (front? back?), tires out of alignment, or if there a specific RX-type problem anyone is aware of, like bushing slipping.

Tires have 50,000 miles on them, so they need to be replaced anyway. I'm thinking of replacing them with same Michellins as came on care (real pleased with tires so far).

So, I was thinking of getting tires replaced, seeing if that fixes problem. If not, going to presume rotors need to be rebalanced/replaced.

Any thoughts or recommendations?

If all the mechanical items check out OK visually (rotors, etc.) also consider tire cupping to cause these symptoms - especially the shimmy during braking at highway speeds. I've had two vehicles with this issue - shimmy when braking at high speed - and turned out to be cupped tires. Given you have high mileage tires and are replacing anyway, I would do the tires first, see how it impacts and then check the mechanical stuff.

[lenore]

I would agree, tires first, the rotors would generally only show that kind of problem when actually braking. Also another possibility is that the balancing weights on the tires have come off.

[TunedRX300]

Rotate rear tires to the front and see if the problem goes away. Steering wheel is connect to the front axel. Most likely you won't be able to feel if rear rotors are warped since RX is not a 4 "steering" wheel SUV.

[Rx330driver]

i have the same problem completely and after telling my service advisor every time i go, the problem is still left unsolved. btw 50K on one set of tires is a lot, lol i changed my stock tires at 30K. I just got my car back from a service last week and i noticed the steering wheel is shaking more than usual above 65 mph. THe only thing im worried about is that my gas milage is probably dropped because of this "tire problem"

[Grumpa72]

Have your dealer check the rotor for runout. That is measured with a dial indicator and will tell if the rotor is warped or not. In addition, tires that shimmy a lot may have a broken belt inside the casing. Unfortunately, there isn't any real way to tell until the tire self destructs. If you are planning on getting new tires, swap front to back just to see if it is tires. If so, go get new ones.

Gary

[COZ]

I say, always start with the simple and cheap stuff first. Get the tires balance checked. A number of things happen as tires get older.

First, the balance changes as the rubber wears down which will cause a harmonic shaking at certain speeds. When you put on the brakes that shaking will transfer to the steering wheel. The very first thing I would do is check the balance.

Second, the wheel could have thrown a weight. Check the balance.

Third, if you use gas station air filling stations you could have introduced water into the tires. Gas stations don't usually have good water removal filters on these stations and you can actually pump water vapor and drops into the tire. This will cause the tire balance to change as the tire rotates, it will never balance. A good tire changer will recognize this and the only way to fix it is to remove the tire and wipe out the water.

If the balance checks good then I would proceed to looking at the rotors.

Of coarse, if you get new tires you will start with a freshly balanced set and water free.

[mikern10]

I had the exact same problem where the car would shake over 70mh. What I discovered was a slow leak in one of my tires caused by a very small nail. Once the tire was repaired and the pressure in my tires equalized, the problem went away.