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Lexus RX AWD vs FWD Questions



  • jdw48jdw48 Posts: 4
    I have a 07 350 I just purchased, and have a rattling noise in the left side sunroof area, do you know what they did to fix it. it's out of warranty (miles)
  • I got the same problem on my RX350, rattling noise on coming from the left side of the sunroof. Anybody ????? its driving me nuts.
  • Has anyone figured out how to fix this Rattle problem, i have taken this car apart trying to find it. HELP
  • jacks2jacks2 Posts: 45
    edited December 2010
    Drove 40+ miles through heavy snow this week keeping speed at or below 20 mph without any noticeable slippage or loss of control.

    Initially ETC Snow control and AWD lock mode failed to engage nonetheless I was able to drive through an un-plowed area in bumper high snow without the benefit of those features.

    I felt my 2010 AWD RX ( 19" Bridgestone MS tires) handled as well or better than my 2007 AWD RX did.

    A visible AWD medallion would be helpful when passing a chain control checkpoint.

  • wwestwwest Posts: 10,706
    Your post reads as if you have the earlier RX350 F/awd system WITHOUT the ability to manually "lock" the rear drive in at low speeds.

    In any case I would NEVER drive any F/awd system, and most certainly NOT the early RX350 version, without at least the rear tire chains when the "chains required" sign is up.

    But then it's your life at risk, not "mine", mostly.
  • wwestwwest Posts: 10,706
    "..ETC Snow control and AWD lock mode failed to engage.."

    What were your indications of this, how did you know...?

    To my knowledge ETC only modifies the shift pattern and the DBW gas pedal response rate/"gain". I also understand that the manual F/AWD lock mode only works at lower speeds, below 20(?) mph.
  • wwestwwest Posts: 10,706
    Has it occurred to you, or any RX owner for that matter, that Lexus does not label the RX as "AWD" since there might be some serious liability in FALSELY making that claim..??

    The RX series has not been even a "true" F/awd system since the beginning of the '01 model year. The revision in 2010 represents a VAST improvement but still NO CIGAR.

    No RX should be trusted to perform dynamically, on an adverse condition roadbed, as would an actual F/awd or even a R/awd system, let alone a TRULY capable RWD/4WD vehicle.
  • jacks2jacks2 Posts: 45
    When first starting and attempting to engage ETC and lock mode no indication appeared on the instrument panel. After several minutes of driving control switches worked and displayed on the panel.

    "Lock mode" did cut off above 20 mph, my 2007 AWD did not have a lock mode.

    Do you have an RX or have you personally operated one under adverse driving conditions?

    This is my second RX, other than crappy paint that chips much too easily I like this vehicle.

    Thanks for responding to my post, have a happy new year.

  • jacks2jacks2 Posts: 45

    "I would NEVER drive any F/awd system, and most certainly NOT the early RX350 version, without at least the rear tire chains when the "chains required" sign is up. "

    Why the rear? The manual recommends chains on the front wheels.
  • wwestwwest Posts: 10,706
    "lock mode" is only available with the newer F/awd system, the one that has an electromechanical clutch housed in the front of the rear diff'l. The lock mode indicator may not go off but the actual rear drive engagement goes off at higher speeds.

    My first RX purchase was a 2000 and then the next year I traded "up" (or so I thought at the time) to get the TC, VSC, and HID headlight options. The '00 had a more functional F/awd system but as it happened that was at least partially the reason for all the premature transaxle failures for the 99-00 RX300.

    So as of 2001 the rear LSD option was dropped and the VC fluid formulation was changed to forever remain "flaccid". The VC was really of no matter anyway since TC activation will never allow it to come into "play". That basically why the VC was dropped entirely during teh RX330 model run. The RX300, 330 and early 350's or basically ONE-WHEEL drive vehicles, 3 simple "open" diff'ls, front, center, and rear. TC, Traction Control, is used to "simulate" F/awd functionality but only reactively, AFTER wheelspin/slip is detected.

    My '01 F/awd RX300, now at ~80,000 miles (2 ATF drain/refills) has survived no less than 10 winters, wintertime trips to MT, Ski trips, etc. We have about 3 inches of hard frozen, crusty, snow and ice on the ground here at this very moment.
  • wwestwwest Posts: 10,706
    Your manual also States that higher traction at the front vs the rear is to be avoided as that configuation has a HIGH potential for loss of direction control. I. E. new tires should ONLY go on the rear if only buying two.

    Prior to ABS tire chains ONLY on the front of a FWD or F/awd vehicle was extremely hazardous. Hard braking on a slippery surface, especially downhill, and the front would "anchor" oftentimes with the result of the rear of the car taking the lead, jack-knifing, if you will.

    Obiviously ABS serves to abate that problem to a great extent But then we have the issue of inadvertent engine compression braking sometimes resulting in the same outcome. Many newer vehicles have a new feature, "inverse" ABS, automatically up-rev the engine if/when there is an indication that engine compression braking has/is resulting in front wheelslip/skid.

    So, I use "drag" chains first and then add the front tire chains only when more "drive" traction is required.

    Oh, you will need to add wheel spacers at the rear in order to use rear tire chains since otherwise the clearance between the suspension and tire tread is to tire.

    I have 1.5" wheel spacers all around and upgrated to 17X8 wheels and +1 tires. Wider stance against rollover, more tread on the ground, less suspension softness.
  • jdw48jdw48 Posts: 4
    i just got my 07 RX350 back from an independent shop. the Rattle came from the plastic covers on the forward rails. Also when you open up your sunroof on each side their is a black plastic rail for cosmetics only, but that could rattle. Also on the gas tank their is a shield that could rattle as well, just cut the shield back about 3 inches.
    i hope one of these will fix your problems.
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