Broken rear suspension spring. Do I need to replace both sides?

[abscate]

Replace one and if the ride height is close, say within 1/2 inch, then don't replace the other.

I would like to hear the unified theory of how ride height will influence AWD performance.

[precopster]

The other one won't follow. These are random metallurgical faults. Even left/right ride height is the determining factor for whether to replace both or not.

If the ride height isn't even one of the CV axles will be stressed and in an extended position and other one will be compressed. Uneven wear in rear outer CV cages would occur and probably nothing more. When I say uneven wear I mean wear not centred in the middle of the cage. This would take years to occur.

Personally I would replace one then drive it around for a week (enough time for it to settle) and then compare left/right ride height.

[JRL]

Replace one and if the ride height is close, say within 1/2 inch, then don't replace the other.

I would like to hear the unified theory of how ride height will influence AWD performance.

Steve, seriously
1/2" side to side is a HUGE difference!!
Under 1/4" then I suppose OK but not 1/2"

[oragex]

Replace one and if the ride height is close, say within 1/2 inch, then don't replace the other.

Very wise although 0.5 inch is a bit too much for me. My car is 0.75 inch lifted in one corner and I can definitely feel it. I'd say don't go more than 1 cm, even better no more than 0.5 cm.

Everybody will say to replace in pairs, but this way you simply will find out if that is really needed. You may as well test the car on the highway and check the stability (shake a bit the steering wheel).

On the other side, the XC70 is known to break the springs. Not all cars, but it happened quite a few times. Just google up "XC70 broken spring". So it may happen again on the remaining 3 ones, keep your fingers crossed.


My 2c, personally I think it's a matter of design as it doesn't always seems related to severe rust. It's mostly only the XC70 who breaks springs (rarely on S60). Perhaps they've stretched the springs from the S60 to make them longer for the XC70 without reinforcing them enough. Just an opinion, of course.

[abscate]

It's a part failure, if you really want to study root cause you could snap a closeup of the broken end and post. Nothing to do with driving habits or climate

I'm sure most of us have driven with ride height differential from carrying the dog food home on one side

[jonesg]

The shops are referring to the old haldex system which became damaged if mismatched tires were installed. That doesn't apply to your 2007.
I wouldn't have any problem doing the one spring.

Get out and enjoy the roads a bit more.!!

[abscate]

I replaced a single pigtail break on a BMW X3 about 50 thousand miles ago

I can't remember if I got advice on this, probably not , as I would have ignored it anyway