heavy steering under hard acceleration

[ampage]

Hey
I have a 2007 XC90 V8 sport with 112K miles. Great car and I enjoy it every time I get in it.
I have had it for several years and have had 3 different sets of tires on it. Also had the alignment done 3 times.

When I accelerate hard from almost any speed the steering gets very hard. No vibration or judder and no noise that im aware of (I dont hear well and wear hearing aids). The engine pulls well and runs well.

The hardness in changing directions is directly proportional to the rate of acceleration. if you floor it from say 40mph then you had better be ready because if you make even a slight steering correction the car will hold the correction angle and you have to be very careful with the counter correction otherwise you will be heading off at an angle and have to correct that as well. If you accelerate at a "normal" rate - say leaving a stoplight in a line of cars - it doesnt happen and things feel "normal".

It is annoying and I feel you have to be ready for the steering when you get on the gas. Otherwise if not ready it could send you into another lane.

It is scary passing on a two lane twisty road if you accelerate hard to get around someone.

Its done this since I have had the car. At first I thought it was some torque steer related to the bigger tires or maybe it was a differential issue in the font drive. Now I have no idea. I think I have proven its not tires or alignment. Differential - maybe that can be it.

If it is a clutch type limited slip in the font axle then Im wondering if thats it.

Anyone else experienced this? I have searched this and other forums and the web in general with no luck.

I can live with the problem but it would be nice to get rid of it as I love the feel and sound of the V8 with open throttle.

Thanks for any insight!!

[Roger_850T]

Have you ever replaced the A-Arms? (aka Control Arms)? They (or more specifically the bushings that connect them to the sub-frame) undergo a LOT of stress in daily use, and can fail. It's possible to set the alignment with bad bushings, too, so having a successful alignment doesn't necessarily mean the bushes are good. You can get underneath and inspect - look for torn rubber in the bushes.

Your car may also have the speed-sensitive steering. Mine does. ('05 V8). I'm not sure what the failure mode of that would be, I'm pondering if that could be involved. (I don't know, I haven't experienced your issues before.)

With mine, I would get really "squirrely" steering with bad control arm bushings. I've put on "Heavy Duty" ones and had them fail after 12k miles. These days I will only buy Volvo brand control arms - my experience is that they are twice the price, but last at least 5x as long, so it's worth it to me.

I'm presently dealing with a potential wear issue in my steering gear. It seems like a bad inner tie rod end, but I've replaced them and the problem persists. I may end up changing the whole gear to fix the issue. Or, maybe not, as it's the wife's vehicle, and she doesn't notice it.

There's a video of the control arms somewhere - another user put a GoPro under his XC90 and took it for a spin. It's quite dramatic. If I can find it, I'll post a reference on this thread for you.

Good luck!

Roger

[Roger_850T]

Re-reading your original post... Would it be accurate to say that under acceleration, your steering "sticks" where it is at? If it's turning it takes a lot of effort to straighten it, and if it's straight it takes effort to turn it? Or is it a lot of effort to get it to go anything other than straight ahead?

Roger