Volvo AWD questions

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John

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
 
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
Click to expand...
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
front.
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.
 
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.
Quick!

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
control.

bob noble
Reno, NV, USA
 
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
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
Click to expand...

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
front.
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.
Click to expand...
 
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