Wheels Grabbing and Jerking Me To The Side on Snow Patches Topic is solved

rustylowe · Post by **rustylowe** » 14 Mar 2020, 18:09

Hey guys,
I had a weird thing happen today and wanted to ask about it. I was just driving on the highway going about 40mph or so, and there were some patches of wet slush / snow / ice here and there... but nothing major. When my XC70 would cross a patch of snow or ice, it would jerk to the side and then grab aggressively onto the dryer road causing me to sort of jerk to the side quickly. It's pretty unnerving! And it actually felt like it could cause me to oversteer or spin out at some point if I was going fast enough...
Anyone know what's going on with this and how I can resolve it? Thanks in advance!

Post by **BlackBart** » 14 Mar 2020, 21:55

Were you accelerating, or maybe even just holding the gas pedal down as you hit the icy patches? Going uphill at all under load?

I would say individual wheels were losing traction briefly, then grabbing again when they hit dry pavement. When one wheel loses traction, the other wheels are still pulling, causing some directional change. Especially in a front wheel drive system (which you are until the rear diff kicks in).

When one wheel is spinning on the ice and then grabs on the dry, it gives a little yank, which can cause another directional pull. An example of this is me at 25 yrs old driving my fwd Scirocco with crappy summer tires up an icy pass at speed (and trying to maintain speed). No limited slip on the front of a car like that, so each wheel would let go and grab again randomly. The steering would jerk back and forth with whichever wheel was grabbing. The car would jerk to one side or the other, or start sliding sideways off the road crown when both wheels were spinning.

Easy steady pedal when hitting ice - don't push on the gas, don't let up suddenly, don't hit the brakes suddenly.

Post by **BlackBart** » 14 Mar 2020, 21:58

Thinking out loud here - could it also be something not right with the AWD system, kicking in unevenly left to right and pushing the car from the rear?

rustylowe · Post by **rustylowe** » 14 Mar 2020, 22:03

I think you're probably right @BlackBart. I just got this Volvo... I'd been driving a Land Rover, which also had full-time 4x4 - but I think it's a different system, and it wouldn't do that, it would just charge through it and you wouldn't even feel the snow or ice at all.
That said - I also felt like this XC70 did every bit as well or even better in the snow than my Land Rover did! So I think maybe I'm just not used to it yet. I wasn't accelerating necessarily - just going along at a steady clip at 45 or 50 mph - and it seemed like maybe the AWD system was trying to adjust quickly and it would yank me to one side or the other when it hit dry road again. I'll try to make sure I let off the accelerator more next time and hopefully that'll solve it. Primarily wanted to be sure it just wasn't out of alignment or faulty or something.
Thanks!

rustylowe · Post by **rustylowe** » 14 Mar 2020, 22:06

BlackBart wrote: ↑14 Mar 2020, 21:58 Thinking out loud here - could it also be something not right with the AWD system, kicking in unevenly left to right and pushing the car from the rear?

That's exactly what I was worried about -- almost like it was out of alignment, and it was evidence of one or two of the wheels spinning at a faster rate all the time, but it wasn't noticeable until it hit some ice and had a chance to free-up and slip, then when it re-grabbed the road - it would jerk it to one side to compensate... I really hope it's just that I'm not used to it -- but it did feel pretty sketchy, honestly. I was kind of surprised, and thought to myself - that can't be right for this vehicle...

Post by **BlackBart** » 14 Mar 2020, 22:17

Yeah, a Land Rover is a linked-up-all-the-time 4wd. Always pulling with all four. My son has had a RR Classic, a Discovery 1, and an LR3. Such good traction.

Another idea - crappy (or not crappy) all season or summer tires? Not suitable for < 40º pavement? That would make them let go easily.

rustylowe · Post by **rustylowe** » 14 Mar 2020, 22:29

Good call re: tires. That could definitely be it. They're due for an upgrade, for sure.
The more I think about it, the more it seems like it just had to have something to do with the fact that all 4 tires were sort of on different conditions for a moment when this was happening -- one on slush, one on a dry patch of road, one on ice, one on a wet patch of road with snowplow pea gravel on it... it seemed like maybe the computer was just getting discombobulated trying to tell each wheel what to do or something, and as a result it would sort of snap back into place as soon as it figured it out, causing it all to jerk back into going straight all at the same time.

Post by **BlackBart** » 14 Mar 2020, 23:46

And if you hit deep slush with one wheel, it's like hitting the brake hard on that wheel, like hydroplaning, and it will pull hard.

Post by **oragex** » 15 Mar 2020, 06:03

How many miles on it? As said above, hitting a water puddle at speed, not necessarily a deep one, gets the tires into hydroplaning and can easily get dangerous. But given you are talking about wet slush snow, that's less strong, but since the road will be much more slippery, the tires may loose adherence slide sideways. 40 mph is not that much, but will depend how deep and how wet those patches were. And will also depend how deep the rubber treads are, and perhaps on the rubber quality too (tire brand). My guess is, with a good brand fresh set of winter tires the whole thing will much improve - I suggest getting snow winter tires, not ice winter ones, snow ones have more space between the treads and do much better in slush and packed snow patches. Ice tires (like the Michelin Ice X) have very close treads and grip better on ice but do quite poor on deep snow - these are better suited for very slippery and with less traffic secondary roads, usually more up north.

I have snow winter tires on my S60 and it's only fwd, have to say these patches of snow - usually located between road lines, do require some attention when changing lines but usually I would just change lines very slowly and hanging well on the steering wheel. Not really a problem but I do pay attention. So I would guess it doesn't have to do with awd. If you have a DSTC button on the center console, the car has dynamic stability control, which applies brakes or antilock if the car slides sideways, so if it was braking on slush that may fool the system - just a guess. If you only have STC, then it doesn't have stability, only traction control which cuts the gas when drive wheels start slipping - good to know because it needs turned off (depress button for 2 sec) when stuck in snow or climbing hills. Worth checking when you turn the key to POS II, see if all dash warning lights turn properly on - this is a good check when buying a car, just in case there is a problem and a smarter seller may try to 'cut off' a check light - this are the lights on my S60 for comparison www.youtube.com/watch?v=wQYkR6JlMh4

Post by **abscate** » 15 Mar 2020, 06:26

A FWD Volvo with good snows on all four wheels is a great winter rat, you get 90% of the AWD ability with somewhat reduced maintenance