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Thread: Wide tyres

  1. #31
    Senior Member 8bit's Avatar
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    Quote Originally Posted by Titus View Post
    Then maybe your system's faulty? The ride (when driving gently) is beautifully smooth - at least as good as any luxury saloon I've travelled in. As I understand it, the system's default mode is rock hard, but the clever electronics can pull it into 'soft and gentle' mode when appropriate - similar to the way the flap valves on the XKR's exhaust back box are normally open ('loud') but can be pulled shut by the special vacuum pump when the electronics calls for 'quiet(er)' mode.

    No doubt people on here who are more clued-up than me can confirm whether this is correct or not.
    Ride quality is subjective though. What might be beautifully smooth to you could well be bone-jarring to Simpo. The CATS system (at least the two-stage system on the 4.2) puts the suspension in the softer mode on startup and will only change to firm mode if the car detects enthusiastic driving inputs for a while. I think what you mean is that if the system fails it defaults back to the firm mode as that's what the shocks are in when they are not energised.

    The difference between modes is fairly subtle, at least it was on my old 4.2, just a small but appreciable extra taut-ness in the suspension when making progress. It's not like you're suddenly finding yourself driving an Audi, or anything...
    Current: 2009 XKR 5.0
    Previous: 2008 XKR 4.2

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  2. #32
    Senior Member simpo3's Avatar
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    Good post, thanks. I doubt I'm going to notice a small change. When I first viewed the car at Chiltern the CATS light (and several others) were on. A week later when I went to collect it they were all off, and have stayed off. I think I just expect a higher level of luxury from a flagship Jaguar costing £50K in 2006. Seat comfort is not patch on the S-Type or BMW 7 either. Padded with stale bread!

    But I said before, the car looks so good that I'll live with the bumps. It's got more nice comments from random people than any other

  3. #33
    Senior Member 8bit's Avatar
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    Perhaps Chiltern just removed the bulbs from the warning lamps I found the seats in my 4.2 pretty comfortable and the ones in my 5.0 even more so. I do have the perfect upgrade for the ride quality for you though sir - eat more pies and drink more beer. Works for me
    Current: 2009 XKR 5.0
    Previous: 2008 XKR 4.2

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  5. #34
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    Quote Originally Posted by Titus View Post
    The ride (when driving gently) is beautifully smooth - at least as good as any luxury saloon I've travelled in.
    The first X150 I ever drove was an XK and I actually found the ride softer than the ride in my then current 4.2 litre X350.
    Current Jag: 2010 5.0 XKR (XKR-S X-Pipe, smaller S/C pulley and Tune ~600bhp - 11.925@120.59, max v=121.89)

    Previous Jags: 2007 4.2 XKR | 2004 4.2 XJ8 | 1998 4.0 XJR | 1996 6.0 XJ12 | 1989 5.3 XJ-S | 1983 5.3 XJ-S | 1980 5.3 XJ-S

  6. #35
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    Quote Originally Posted by 8bit View Post
    I found the seats in my 4.2 pretty comfortable and the ones in my 5.0 even more so.
    I spent a little while in the passenger seat of my '10 XKR recently and found that it was much harder than the drivers seat. Not too unsurprising as it hardly ever gets used but it was noticeably harder.
    Current Jag: 2010 5.0 XKR (XKR-S X-Pipe, smaller S/C pulley and Tune ~600bhp - 11.925@120.59, max v=121.89)

    Previous Jags: 2007 4.2 XKR | 2004 4.2 XJ8 | 1998 4.0 XJR | 1996 6.0 XJ12 | 1989 5.3 XJ-S | 1983 5.3 XJ-S | 1980 5.3 XJ-S

  7. #36
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    Quote Originally Posted by simpo3 View Post
    Apparently the car has CATS, but I don't see how 19" wheels with 35/45 profile tyres can begin to approach the ride of, say, 17" 235/60s just with electronics. Laws of physics and all that!

    Next time it goes in for a service I'll ask, but I think magic carpets are a thing of the past.
    You would definitely know if it had defaulted to "hard". It literally feels like there's no suspension, you wouldn't even get it off the drive

  8. #37
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    Quote Originally Posted by 8bit View Post
    Perhaps Chiltern just removed the bulbs from the warning lamps
    sorry sir, that's not possible. They don't have individual bulbs

  9. #38
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    Quote Originally Posted by 8bit View Post
    Ride quality is subjective though. What might be beautifully smooth to you could well be bone-jarring to Simpo. The CATS system (at least the two-stage system on the 4.2) puts the suspension in the softer mode on startup and will only change to firm mode if the car detects enthusiastic driving inputs for a while. I think what you mean is that if the system fails it defaults back to the firm mode as that's what the shocks are in when they are not energised.

    The difference between modes is fairly subtle, at least it was on my old 4.2, just a small but appreciable extra taut-ness in the suspension when making progress. It's not like you're suddenly finding yourself driving an Audi, or anything...
    That's not quite how CATS works. It doesn't have a hard and soft mode as if it switches from one to the other for a period of time. The damper states (yes, hard and soft) are really quick-reacting things, during a corner, even at low speed, the damper state shifts from one to the other several times a second.

    Obviously when you're pressing on, the dampers will be working harder, but its not the case that the computer thinks "we've got to go hard now".

  10. #39
    Senior Member 8bit's Avatar
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    Quote Originally Posted by 2woody View Post
    You would definitely know if it had defaulted to "hard". It literally feels like there's no suspension, you wouldn't even get it off the drive
    So does it fail into some other state beyond the firm setting it uses when operating normally then? On my 4.2 I could feel when it had gone into firm mode but it was nowhere near as hard as you describe, certainly didn't feel like there was "no suspension".



    Quote Originally Posted by 2woody View Post
    That's not quite how CATS works. It doesn't have a hard and soft mode as if it switches from one to the other for a period of time. The damper states (yes, hard and soft) are really quick-reacting things, during a corner, even at low speed, the damper state shifts from one to the other several times a second.

    Obviously when you're pressing on, the dampers will be working harder, but its not the case that the computer thinks "we've got to go hard now".
    Is that not how it works on the 5.0 cars? I know it's not just a two-stage system on them, it's fully adjustable but I thought I read that the continuous adjustment came in with the later system and the earlier one was a much simpler thing, operating as I described. The 4.2 workshop manual doesn't say much about how and when the system switches modes, just about how it actually achieves that.
    Current: 2009 XKR 5.0
    Previous: 2008 XKR 4.2

    I take photos of cars! Find me on Facebook, Instagram and Flickr.

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