'08 SRX V8 with Magnetic Ride Control Dive/Squat
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Cadillac SRX First Generation Forum - 2004 - 2009 Discussion, '08 SRX V8 with Magnetic Ride Control Dive/Squat in Cadillac SRX Forums; Hey Guys, A friend has MRC in his SRX. I was driving it today, and was surprised by the brake ...
  1. #1
    jarlque is offline Cadillac Owners Member
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    '08 SRX V8 with Magnetic Ride Control Dive/Squat

    Hey Guys,
    A friend has MRC in his SRX. I was driving it today, and was surprised by the brake dive and acceleration squat in the car. If I torqued the engine to about 1200 RPM and pulsed the brakes (gently), I could get it to dive/squat like a rocking horse. Anyone with one of these babies can tell me if this is normal? I connected my scan tool and could get no codes.

    Thanks Much!

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  3. #2
    jarlque is offline Cadillac Owners Member
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    Re: '08 SRX V8 with Magnetic Ride Control Dive/Squat

    Car has only 35K. Any SRX owners W/O MRC have any comments? We're mystified about this. Can't imagine the SRX is supposed to do this dive/squat with either suspension, but W/O codes, only other thing could be a bunch of bad shocks? On such a low mileage car, doesn't seem possible.
    Thanks!

  4. #3
    JayTF1 is offline Cadillac Owners Fanatic
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    Don't have any experience with the mag suspension, but mine has always impressed me with the braking characteristics especially considering the weight of the vehicle.

    You would think that if the shocks were a problem, the ride would suffer as well. Bouncing etc.

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    glake89 is online now Cadillac Owners Connoisseur
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    Re: '08 SRX V8 with Magnetic Ride Control Dive/Squat

    Are you sure car has MRC? Is F55 listed on label? If so, maybe a PO had installed the alternate replacement system.
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    jarlque is offline Cadillac Owners Member
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    Re: '08 SRX V8 with Magnetic Ride Control Dive/Squat

    JayTF1--Agreed on the possible bouncing ride. I wasn't able to really wring it out, but on typical 30-40 MPH streets, there was no wallowing etc. Ride didn't seem firm, but was damped. Tried swerving the car a little as traffic allowed, and the car rolled...more than I expected, but not sure what's normal. It acts as though the MRC system has a defect and has reverted to "default" behavior. But no codes, no check-engine light or other warnings.

    glake89--Yes, both F55 and FE3 are listed on the VIN printout, and there are cables on each side going to the shock towers. The car is well-kept and in beautiful condition, but he didn't buy it new.

    I know some cars allow some dive to transfer weight to the front wheels for better braking, but the pitching that can be produced by simply hitting the brakes while torquing the engine seems way off base. You can become a spectacle quickly, like being on a rocking horse! I always thought MRC was specifically designed to counteract any forces--cornering, braking, accelerating or otherwise (even uneven road surfaces) by firming up the appropriate shock(s).

    FYI I first noticed the dive immediately when driving down a row of cars in a mall parking lot! Was only going 10 MPH or so, hit the brakes to turn at the end or the row, and sensed significant dive.

    Thanks guys for the interest and replies.

  7. #6
    conedoctor is offline Cadillac Owners Connoisseur
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    Re: '08 SRX V8 with Magnetic Ride Control Dive/Squat

    If you are trying to make the car rock back and forth then you will, does it do it in normal driving?

    If I saw the wheel back and forth I will spin, this does not make the car unstable just means I was doing something on purpose to get the car to spin.

  8. #7
    jarlque is offline Cadillac Owners Member
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    Re: '08 SRX V8 with Magnetic Ride Control Dive/Squat

    conedoctor--Thanks for the info. You're saying that brake dive is normal in typical driving? I guess they set it up to be much softer than I would expect. Agreed on sawing the wheel back and forth that this gets the car to swerve. Main concern is excessive brake dive when hitting brakes in normal driving.

    He's bringing the car in to have it checked, but we wanted an idea of what's normal before dropping it off.

    Thanks again.

  9. #8
    conedoctor is offline Cadillac Owners Connoisseur
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    Re: '08 SRX V8 with Magnetic Ride Control Dive/Squat

    Well dive is unavoidable, and is it diving or is the back coming up?

    The shocks can't control how far the car will move but just how fast it gets there, the springs are holding up the car and are the limiting factor.

    If the car had no squat or dive you would have no grip, this will turn into a long story but if it was stiff to the point of not moving it would suck.

    Now the question is the yaw sensor is not really doing anything here so does MRC limit roll only and not pitch?

    I mean by normal is the guys at GM did not design the car to drive with throttle on and pulse the brakes while driving down the road.

    We have solved the question of if I can left foot brake when I race the SRX

  10. #9
    jarlque is offline Cadillac Owners Member
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    Re: '08 SRX V8 with Magnetic Ride Control Dive/Squat

    Hi conedoctor,

    Thanks for the info. I've attached (if I did it properly) a really interesting White Paper from Cadillac describing the CVRSS system, forerunner of the modern Cadillac chassis control systems. It predates MRC, and describes a lot of other stuff as well...Stabilitrak, ABS, Rear Level Control, Traction Control, and much more. Following is a copy/paste from the description of how the PCM determines dive rate: it computes it! At least, that's how it worked starting in the late 90s:

    "Lift/Dive Input.
    The lift/dive input is sent from the PCM to the CVRSS module (Figure 8-53).
    Suspension lift information is obtained by the PCM from the throttle position, vehicle speed, and
    transaxle gear input signals. The PCM calculates suspension dive information from the rate of
    vehicle speed change when decelerating."

    He brought it to Cadillac today. They drove it and said it needed front struts. Also someone said if the car sits for a long time, the iron particles can "settle out" and the unit will have little damping effect. Since the car only has 35K, I guess it's possible it sat...but I find it hard to believe the particles could settle, especially when you consider what's going on inside a shock absorber! Could they somehow become magnetized and adhere to the shock internals?

    I'll know more about how this pans out in a few days. But it's interesting that they agree there IS a problem, and the car is flapping around way too much. Next question: are the rear shocks shot too?

    On the left foot racing: yeah man!

    Thanks to all for your posts!
    Attached Files

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