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Thread: Sway bar / anti roll bar selection

  1. #1
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    Sway bar / anti roll bar selection

    Need some advice from the experts... I thought I had already made a thread on this, but can't find it so it must have just been in my head.

    Swapping out the sway bars on the Jags is a PITA as they are located between the subframes and the body, which means lowering the subframe to change the bar, which means it's a case of do it once and do it right.

    There's not much in the way of sway bars to choose from, and there's not much information available on the different bars either.

    The stock front bar is a 32mm OD, hollow bar, all of the OEM bars are this OD, one can just assume that the different OEM versions are different wall thickness, I doubt different materials are used to varying the stiffness.

    There is only one aftermarket front bar available, and it's a 32mm solid bar. It's been fitted to a few cars and everyone reports good things from the handling, but you would also expect after dropping that much coin on it, they are going to convince themselves it's a good thing no matter what...

    About half a dozen OEM front bars are available, but the thickness / stiffness of them is really unknown, so it's hard to pick an OEM one out of the catalogue to be "better" than what's on the car now.

    Just to give you can example, the 32mm hollow front bar on the XKR is the exact same one that's used on the S-Type R (4-door sedan), as well as the XKR-S which is mean to be more "sporty" yet it uses the exact same front bar. Even more confusing the XKR-S GT "trackday car" uses the front sway bar from the 2.0L petrol 4-banger XF sedan. I cannot imagine that the little 4-banger sedan would have a stiffer front bar than the supercharged V8's, so this is a bit confusing...

    For the rear bar it's even more confusing...

    The standard arrangement is a 17mm OD solid bar. Some cars got a 19mm OD solid bar (like the 4.2L XKR-S, and S-Type R sedan) but the rest appear to be a 17mm OD bar, although there are several different versions at the same diameter, which one of the 17mm ones is stiffer I cannot tell you, although there is one version which was used on the 5.0L XKR-S coupes and XFR-S sedan, which one could assume is the "better" one. What's confusing is that on the 4.2L XKR-S, they put a thicker / stiffer rear bar on it, leaving the front bar as standard. This seems a bit counter-intuitive to me, and i've got the same WTF reply from a few other people I've asked about this. But that's what they did from the factory...

    There is a 20mm OD solid rear bar available in the aftermarket, which is usually sold in a pair with the 32mm OD solid front bar.

    Bear in mind these are big heavy cars, ~1800kg, and a bit nose-heavy as well.

    The "logical" option for me is to go the 32mm solid front bar, and leave the rear stock 17mm solid bar, so it's a bit softer in the rear, relatively speaking.

    Does this make sense?
    Jaguar XJR, Freelander 2 HSE, Jaguar XKR

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    Your logical option does make sense.

    The other thing you could look at is adjustable sway bars, if any are made for your car. If not, you might be able to fabricate some adjustment, either by re drilling, or making a bolt on adjuster. Have you got a picture of the end of the sway bar and connecting link you can post here?

    You can also make a sway bar effectively a bit stiffer by replacing the rubber bushes with poly, and/or use rod ends for the driving links.

  3. #3
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    Thanks

    There is only one aftermarket source for sway bars for these cars, and that's a company in Korea. No adjustable bars available.

    This is the end of the bar on the front;



    Haven't got a pic handy of the rear but it's similar, the last inch or so is flattened out for the bolt to go through.

    Not going poly ever again so that's not an option.
    Jaguar XJR, Freelander 2 HSE, Jaguar XKR

    Quote Originally Posted by Marv View Post
    Look, just because you drive a couple of imported luxo Pommy cars doesn't mean you need to act like an Imperialistic Lapdog and be the last bastion of defence for Straya The Beaut's mid-20th-Century ideals
    Quote Originally Posted by nutttr View Post
    People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

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    It's unfortunate that the end points out the side of the car, rather than backwards, it makes it really tricky to make it any stiffer. Would be simple to make it softer though, by adding to it to move the link mount backwards.

    So I would say get the 32mm solid one, if it's too stiff, add a spacer to the end of it to lengthen it, which would make it softer.

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    Arrogant wankeler Slides's Avatar
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    You have put higher rate springs in already? The bars will have less of an impact as a result.

    Stiffer rear relative on the sports model is probably to make the handling balance more responsive and possibly to balance stiffer front springs. Usually if you throw agressive bars from an aftermarket supplier in it will make the car dance more so you have to make a judgment call on that yourself. If you are happy to have a greater relative rear roll stiffness increase do both.

    If you want to use factory gear get the thicker rear and the heaviest by weight front iff they are dimensionally the same, I don't suppose the catalog lists component weights?

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    The solid bars give a better feel IMO Ill just go and grab the file of hollow vs solid BRB.

    I just went to check whitelines test document on hollow vs solid but they changed the format of their site and it's lost in 1880 documents so probably best ring them for that.
    Last edited by Rdyno; 28-09-17 at 10:28 PM.
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    Quote Originally Posted by Jack Nicholson View Post
    ...the XKR-S GT "trackday car" uses the front sway bar from the 2.0L petrol 4-banger XF sedan. I cannot imagine that the little 4-banger sedan would have a stiffer front bar than the supercharged V8's...
    Does the GT, or any of the others for that matter, have active dampers?
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    Registered User irsa76's Avatar
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    I'm assuming these are the ones you were talking about?
    http://www.xk8-parts.com/2014/09/jag...anti-roll-bar/
    Then there is this mod:
    http://www.coventrywest.com/jaguar-x...r-sway-bar-mod
    Last edited by irsa76; 01-10-17 at 03:12 PM.

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    Quote Originally Posted by Sprinkles View Post
    It's unfortunate that the end points out the side of the car, rather than backwards, it makes it really tricky to make it any stiffer. Would be simple to make it softer though, by adding to it to move the link mount backwards.

    So I would say get the 32mm solid one, if it's too stiff, add a spacer to the end of it to lengthen it, which would make it softer.
    Seems like just putting the 32mm solid one on the front is the idea.

    Quote Originally Posted by Slides View Post
    You have put higher rate springs in already? The bars will have less of an impact as a result.

    Stiffer rear relative on the sports model is probably to make the handling balance more responsive and possibly to balance stiffer front springs. Usually if you throw agressive bars from an aftermarket supplier in it will make the car dance more so you have to make a judgment call on that yourself. If you are happy to have a greater relative rear roll stiffness increase do both.

    If you want to use factory gear get the thicker rear and the heaviest by weight front iff they are dimensionally the same, I don't suppose the catalog lists component weights?
    I have "shipping weights" but the accuracy of these numbers is very questionable....


    Quote Originally Posted by Faux Forg View Post
    Does the GT, or any of the others for that matter, have active dampers?
    Yes all the XKR models have active dampers; XKR, XKR-S, XKR-S GT, there is a difference in the cars pre-2010 which are basically an on-off switched system, the later cars are a continuously variable system. Mine has the on-off type. It appears that the 4.2L XKR-S has a different software in the suspension module to the regular XKR, as i've now got those shocks and springs in mine, i'm looking to flash that software to my suspension module so they are matched.

    Quote Originally Posted by irsa76 View Post
    I'm assuming these are the ones you were talking about?
    http://www.xk8-parts.com/2014/09/jag...anti-roll-bar/
    Then there is this mod:
    http://www.coventrywest.com/jaguar-x...r-sway-bar-mod
    Different model, that's the earlier X100 XK8/XKR, different chassis to the X150 XK/XKR which i've got.

    But it's funny that everyone seems to be on the same bandwagon, stiffer rear swaybar.

    I fitted one to the XJR and to be honest, it seems to be worse, understeers more and yet somehow more tail-happy at the same time...
    Jaguar XJR, Freelander 2 HSE, Jaguar XKR

    Quote Originally Posted by Marv View Post
    Look, just because you drive a couple of imported luxo Pommy cars doesn't mean you need to act like an Imperialistic Lapdog and be the last bastion of defence for Straya The Beaut's mid-20th-Century ideals
    Quote Originally Posted by nutttr View Post
    People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

  10. #10
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    Might be able to fit an 1 1/4" bar, they're pretty cheap in the speedway world. There's usually several variety of arms to fit the splines...that can possibly be made to fit.

    American Tire and Racing, out at Wetherill Park might be able to test the bar too - seem to remember it was around 20ish.

  11. #11
    Registered User dougmo's Avatar
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    Is it possible that the XKR-S GT "trackday car" uses a softer front bar and stiffer rear to change the balance?

    bigger isn't always better

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    Quote Originally Posted by gxxr View Post
    Might be able to fit an 1 1/4" bar, they're pretty cheap in the speedway world. There's usually several variety of arms to fit the splines...that can possibly be made to fit.

    American Tire and Racing, out at Wetherill Park might be able to test the bar too - seem to remember it was around 20ish.
    I didn't know there was someone who could test the stiffness of the bars, that could be interesting, but maybe expensive to collect all the different factory bars to compare results...

    Quote Originally Posted by dougmo View Post
    Is it possible that the XKR-S GT "trackday car" uses a softer front bar and stiffer rear to change the balance?

    bigger isn't always better
    The GT got a unique rear bar not used on any other models, but they are $1200 a pop and a heap of hoops to jump through to source it (because restricted sales, special vehicle).

    One can assume that the GT rear bar is stiffer, which is a bit counter-intuitive to having a softer front bar as part of the package.

    But I guess we'll never know unless someone coughs up the dough for bars and testing...
    Jaguar XJR, Freelander 2 HSE, Jaguar XKR

    Quote Originally Posted by Marv View Post
    Look, just because you drive a couple of imported luxo Pommy cars doesn't mean you need to act like an Imperialistic Lapdog and be the last bastion of defence for Straya The Beaut's mid-20th-Century ideals
    Quote Originally Posted by nutttr View Post
    People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

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