mattylex77

hello everyone, i have had my LS for a bit over a year now and i have visited this site religiously as a means to as cheaply as possible rehabilitate my car. Today i decided to finally make a profile and post on here to potentially add to the literature because i am completely bewildered and believe i have something unheard of on my hands.
my car just turned 130k, i drive it daily. I was getting loud front end clunking, brake pedal and steering wheel vibration when braking at high speeds. THen i decided to replace all four lower control arm bushing with the roca replacements. they work beautifully, no more of any of these symptoms, totally blissful.
Now the issue that has taken its place is that the steering wheel shakes at high speeds, not when braking, BUT ONLY WHEN THE AC IS ON??????!!!!! And it is VIOLENT, as if the wheel is moving 1 or 2 inches side to side per oscillation. If i turn the ac off it takes a couple minutes and the shaking stops... although there is still a minor shake, but with the ac on its like my nak volume dial is connected to my steering wheel and i turn it all the way to the right.
So as an offering to the forum i will be posting a fix i discovered the other day for my rattling headliner (in the headliner rattle thread of course) that has not yet been posted on here, hope it helps someone out there.
anyway thanks in advance for your thoughts people!

RA40

iTrader: (6)

Welcome your first post on Club Lexus.

My thoughts on the shaking issue:

My main thought is there are still worn suspension parts that need attention. The strut bars and checking the rack bushings. The LS is quite sensitive to wheel balance and this can be compounded with worn bushings that allow wide tolerances. Wheel balance, re-check alignment, and wheel bearings. Pretty much anything bushing related is a candidate for replacement at this stage.

The clutch on the A/C compressor is exhibiting runout and or it may be cycling on-off erratically. This is causing pulsation in the drive belt that will spin the PS pump. How is the PS fluid? The PS pump may also be having issues of its own.

dveneman

Yes , what RA said.
Before I replaced my strut bushings, applying brakes would shake the wheel badly so that I had planned to turn the rotors right after tires and strut bushings.
After strut bushings, I can barely feel any runout from the rotors.
AC on? No idea how that might effect wheel shake..
Welcome to the CL Forum!!

timmy0tool

iTrader: (7)

welcome!

how is your transmission mount? it is a very common vibration culprit and having the AC on only adds to the problem. i would change your transmission mount (~$60 for the part). the motor mounts could be worn as well but may not be necessary. they are not cheap either at ~$100 per side.

sha4000

iTrader: (1)

Does it shake with the A/C on when the car is in park or idling at a light? Have you checked your motor mounts? I googled it and lots of ppl said to make sure the alt is good.

Yamae

The serpentine belt is driving both the P/S pump and the A/C compressor. I suggest you to check any abnormal behavior of it when the engine rpm reaches at a certain point or a range. Are bolts that hold equipments driven by the belt tight enough?

The other day, one of my friends Celsior had an unusual vibration when running. It was caused by loose bolts that hold hydraulic pump for the cooling fan.

kevvo

If the car is stationary with the aircon running and you rev the engine to, say, 2500 RPM or the revs at which the vibrations kick in at 55 mph, does the vibrating occur then?

mattylex77

Thankyou for your input everyone. My ps is very stiff at all times and is especially hard to turn during parking maneuvers. I have a leak somewhere bc my ps began whining. I added fluid and the problem went away. No ATF on the gArage floor and I have no white smoke and my idle up functions( upon turning the wheel idle elevates 200 rpm). Did a ps fluid flush, discovered that the pump screen had been burnt to a crisp so I threw it away, apparently unnecessary. Interestingly enough my mechanic found a bolt near my ps pump that was just floating in there. Maybe I should figure out where that goes lol. Is there a maintenance item for the ac I could look at doing to prevent the runout?

mattylex77

also revved the engine in park w ac on to 4000 rpm, smooth as can be, so vehicle speed is a factor...