Volvo AWD questions

Discussion in 'General Motoring' started by John, Nov 19, 2003.

  1. John

    John Guest

    I have a 2001 XC AWD with the older viscous coupling, So far it has worked
    well, but it's always bothered me that it can't tolerate more than 3mm
    difference between tire diameters, can't be towed on two wheels, and would
    be very expensive to repair out of warranty. Does the Haldex system in the
    2004 S60 AWD suffer from any of these issues, and is it considered a better
    system generally? Thank you very much for your help. --- John
    John, Nov 19, 2003
  2. I just recently [last week] picked up an S60 R, with the model year 2004
    version of AWD. The owner's manual does say that flatbed towing is
    preferred, but doesn't prohibit towing with two wheels on the ground, the
    rear as I remember. There are no warnings in the manual about slight
    differences in tread depth among the tires, although I recall that it does
    say that all 4 tires should be of the same type. My prior sedan was a VW
    Passat with 4Motion, which is an AWD system featuring a Torsen center
    differential: purely mechanical system, and the power split can go from
    50/50 to as much as 66/34 front bias or 34/66 rear bias. Exactly the same
    system that Audi was calling Quattro in MY 2001. Audi dealers were
    recommending replacing all 4 tires if any tire needed replacement; the VW
    manual said nothing special about tire selection and replacement. A local
    tire dealer told me that replacement of all 4 tires was desirable if tread
    variation among the tires exceeded 3/32 of an inch. My garage queen is a
    Honda S2000 with a Torsen rear differential, and Honda recommends that the
    temporary spare NEVER be used on the rear, to avoid diameter differences -
    if you get a rear flat you must swap front to rear and put the spare on the
    My plan for the S60 R AWD is to carefully monitor and rotate the
    original equipment tires, and replace them when there is a lot of wear, or
    if one tire is much different than its mates. The car did come with a big
    warning sticker which said that its high performance tires may not last as
    much as 20,000 miles, and that they are not suitable for driving in snow.
    My understanding is that the cost of the 235/40 x 18 Pirellis is about $225
    plus a pint of blood each, so I will administer lots of TLC and check the
    pressures quite often.
    AWD systems can be very expensive to repair, i.e., many thousands of $$,
    and I am sure the Haldex system is no exception. For now, it is extremely
    transparent in usage, and I am thankful for the 48 month, 50,000 mile
    warranty. Any lesser warranty and I might have been scared away.
    Joe and Ruth Levy, Nov 19, 2003
  3. John

    Bob Noble Guest

    Hi, John - - -

    My wife drives our 98 V70XC. I drive our 02 S60AWD. The older AWD has
    the viscous coupling and the newer the Haldex system.

    The simplest description of the two is that the older is a "coupling"
    that is always connecting front and rear wheels, while the Haldex system
    is a "clutch" that is brought into action within milliseconds where
    there is a difference in rotation, front to rear, that the computer
    perceives to represent slippage. At this point the Haldex clutch is
    fully engaged within about 1/6 of a revolution of the rear wheels.

    The difference in systems is obvious - the older being mechanical, the
    newer controlled electronically. While both of our cars have called the
    systems into operation, neither has "commented" at the time, just
    getting the job done without complaint. The reasons for change by Volvo
    would likely represent cost (a local Volvo independent told me that the
    rear propellor shaft, with coupling, was over US$2,500 several years
    ago) and the fact that the Haldex is designed for external, electronic

    bob noble
    Reno, NV, USA
    Bob Noble, Nov 21, 2003
  4. The Haldex system can cope with differently worn tires without problems,
    but you should alway use tires with the same dimension.
    If you have differently worn tires, you will get optimum performance (as
    well as optimum safety) putting the worn tires at the front. Rotating
    the tires in order to keep them equally worn will be fine as well.

    The car can be towed on two wheels - preferably with ignition off.

    The Haldex coupling is a very superior system compared to the old visco.
    Both traction and handling is improved significantly.

    Staffan Nilsson, Dec 12, 2003
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