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Thread: New tyres fitted, now brakes judder

  1. #41
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    Quote Originally Posted by Stagnite View Post
    I am glad you have sorted your problem, BUT, discs won't suddenly acquire run out during a tyre change. Unless the discs were loose and dirt was allowed to get between the hub and disc face. Or, your tyre fitters snaffled your discs and swapped them over for a pair with run out!
    Sorry to be so cynical, but something is not quite right here.
    I share your cynicism. Perhaps dirt was allowed to get behind during the tyre fitting and "warped" the discs. Could that result in the 20% run-out the Jaguar dealer measured, and that a good clean of the hub would have solved the issue?

    Either way, I'm glad that new discs, properly fitted with the hub cleaned properly before fitment (I specifically asked for that be done) have solved the problem.

    I see that I kept referring to them as "disks" above. I blame too much time working with computers!

    Cheers,
    Steve

  2. #42
    Senior Member Neilr's Avatar
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    Quote Originally Posted by bass2rez View Post
    My car is a 5.0. It may be that I misunderstood what the garage were telling me, as I mention above.
    All the 5.0 S/C cars with cast iron discs have the "BRAKE UPGRADE PROGRAM" - the 380mm/376mm discs with ATE calipers. The original discs appear to be from ATE too. Pads are usually Jurid at the front and ATE at the back.

    Is runout usually measured in %?
    Whatever

    As discs age/are used, they corrode becoming unevenly rough, have varying amounts of pad material on the disc faces, etc. They stop working smoothly. A refresh is never a bad thing. Mine has new brakes all round and it brakes really smoothly without any vibrations. Hope they stay like that for some time!
    S-Type 3.0 Manual MY2001 in Pacific Blue with Cashmere Leather Sport Seats, Sunroof, Melbourne Alloys, Premium Sound plus some other stuff ... 55k miles.
    XKR 5.0 Speed Pack MY2011 in Polaris White with Ivory/Charcoal Leather, Nevis Alloys and R-Performance Interior plus some other stuff ... 17k miles.
    Hyundai Tucson 1.6T AWD MY2016 in White Sand. Basic, comfortable and surprisingly fast and competent ... 12k miles.
    FIAT Coupe MY1997 in Steel Grey with Tan Leather ... 55k miles.

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  4. #43
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    Quote Originally Posted by Neilr View Post
    All the 5.0 S/C cars with cast iron discs have the "BRAKE UPGRADE PROGRAM" - the 380mm/376mm discs with ATE calipers. The original discs appear to be from ATE too. Pads are usually Jurid at the front and ATE at the back.
    I did not know that. It makes me wonder what makes it an upgrade, if all the 5.0 S/C cars have it. Does having red calipers mean anything, or do all 5.0 S/C cars have those too?


    Quote Originally Posted by Neilr View Post

    Is runout usually measured in %?
    Whatever
    That's how the Jaguar mechanic described the issue to me. I did wonder about the merit of that statement. 20% of what? The diameter of the disc? That would make the run-out about 76mm, no wonder it juddered! Perhaps it is more likely to be 20% of the disc thickness, that would make the run-out 5.6mm, assuming 28mm discs.

    I hope mine stay vibration-free for some time too. I'm not holding the car on the brakes at all, so will hopefully avoid warping the discs.

    Cheers,
    Steve

  5. #44
    Senior Member Neilr's Avatar
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    Quote Originally Posted by bass2rez View Post
    I did not know that. It makes me wonder what makes it an upgrade, if all the 5.0 S/C cars have it. Does having red calipers mean anything, or do all 5.0 S/C cars have those too?
    It is an upgrade on the non-S/C cars

    The name is not important but knowing that one has the bigger brakes makes it easier to order the correct parts.

    Grey calipers were originally standars and you had to pay for red. The Speedpack cars were probably the first 5.0 cars that came with red as standard.

    Quote Originally Posted by bass2rez View Post
    That's how the Jaguar mechanic described the issue to me. I did wonder about the merit of that statement. 20% of what? The diameter of the disc? That would make the run-out about 76mm, no wonder it juddered! Perhaps it is more likely to be 20% of the disc thickness, that would make the run-out 5.6mm, assuming 28mm discs.

    I hope mine stay vibration-free for some time too. I'm not holding the car on the brakes at all, so will hopefully avoid warping the discs
    Run-out is usually measured in fractions of an inch. You don't need much to feel a problem. However, modern ventilated discs are pretty hefty things and are difficult to physically warp with normal road use. Only brakes on rally cars, etc at the end of a hard stage are hot enough to do damage, that is why they try to keep moving, spreading the heat from the pad around the disc. Foot on or off the brake makes little difference as the pad is still pretty much sitting on the disc. How else do they corrode together if left wet?
    S-Type 3.0 Manual MY2001 in Pacific Blue with Cashmere Leather Sport Seats, Sunroof, Melbourne Alloys, Premium Sound plus some other stuff ... 55k miles.
    XKR 5.0 Speed Pack MY2011 in Polaris White with Ivory/Charcoal Leather, Nevis Alloys and R-Performance Interior plus some other stuff ... 17k miles.
    Hyundai Tucson 1.6T AWD MY2016 in White Sand. Basic, comfortable and surprisingly fast and competent ... 12k miles.
    FIAT Coupe MY1997 in Steel Grey with Tan Leather ... 55k miles.

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