Sudden sharp swerve

[jallard]

Any insight? Travelling @ 100km/h with DTC light on in light snow conditions along a perfectly straight section of highway without accelerating or braking when car suddenly swerved sharply to the right (from the front - no slip / fishtailing from the rear). Able to quickly correct before the car entered the next lane over. Didn't hit anything but it was as if the front right brake came on for a moment then all was okay. Any ideas what happened? The shop checked: brake calipher okay; suspension okay; no pulling to either side; tire pressure ok; no mechanical damage visible under the car, in the wheel wells or on the tires; balancing and alignment fine. There may have been some black ice on the road (but am thinking this would have caused the rear of the car to swerve, not the front), no potholes. Cars traveling ahead of me didn't swerve. I swerved at least 30-45cm before being able to correct. All happened in less than 2 seconds.

[Taymaishu]

Originally Posted by jallard

Any insight? Travelling @ 100km/h with DTC light on in light snow conditions along a perfectly straight section of highway without accelerating or braking when car suddenly swerved sharply to the right (from the front - no slip / fishtailing from the rear). Able to quickly correct before the car entered the next lane over. Didn't hit anything but it was as if the front right brake came on for a moment then all was okay. Any ideas what happened? The shop checked: brake calipher okay; suspension okay; no pulling to either side; tire pressure ok; no mechanical damage visible under the car, in the wheel wells or on the tires; balancing and alignment fine. There may have been some black ice on the road (but am thinking this would have caused the rear of the car to swerve, not the front), no potholes. Cars traveling ahead of me didn't swerve. I swerved at least 30-45cm before being able to correct. All happened in less than 2 seconds.

How warm were your brakes? Black ice won't make the front swerve suddely like you describe - there's no drive in the front wheels.

You may have hit a puddle of water (melted snow) which pulled your car to the right... Only thing i can think of!

[Kamal]

what tires do you have on there? They could've filled up with ice/slush/snow and momentarily slipped. If everything check out ok then just be glad you're ok!

[Dackelone]

Aquaplaning? Did you hit a puddle of water maybe?

[jallard]

Thanks for comments: tires are run flats - winter style. Outside temperature was about -5degC. May have been some salty water on the road (the snow ploughs had been out. The lane was clear of visible snow.)

Brake temperature would have been somewhat cold due to outside temperature - had been on the highway for 40 minutes, using brakes only occasionally to adjust speed to pass. Hadn't felt anything out of the ordinary before this incident.

[1SerieStud]

I agree with the guys on top...there was a difference in density of the medium on which your front right tire was traveling (snow vs. water) that caused your right tire to slow down, making your car swerve to the right.

[BlackjackMulligan]

I would say either tramlining or hitting a puddle of water as stated above was the cause.

[leftyone]

You seemed to have hit an extra slippery spot on the road.

[JimD]

If the front tires are pointed straight ahead I don't see how a difference in traction between them causes the car to move at an angle. A difference in the rear could but then the tire with low traction should speed up and the DTC activate before the driver has a chance to. But maybe by the time the DTC activated the tires had equal traction again so the car jerked? Maybe. The DTC also detects yaw but maybe this was not a big enough movement to activate that part.

Jim

[bogart]

Originally Posted by jallard

Any insight? Travelling @ 100km/h with DTC light on in light snow conditions along a perfectly straight section of highway without accelerating or braking when car suddenly swerved sharply to the right (from the front - no slip / fishtailing from the rear). Able to quickly correct before the car entered the next lane over. Didn't hit anything but it was as if the front right brake came on for a moment then all was okay. Any ideas what happened? The shop checked: brake calipher okay; suspension okay; no pulling to either side; tire pressure ok; no mechanical damage visible under the car, in the wheel wells or on the tires; balancing and alignment fine. There may have been some black ice on the road (but am thinking this would have caused the rear of the car to swerve, not the front), no potholes. Cars traveling ahead of me didn't swerve. I swerved at least 30-45cm before being able to correct. All happened in less than 2 seconds.

Just a question, did you have your cruise control on by any chance? This same thing happened to me one day when I was driving on the highway. I had my cruise control on, and I am aware that you should not drive with cruise control on when the roads are wet or snowy, but the roads appeared to be okay. It had just rained after being hot for a while, so I assume there was some oil on the road that got wet. Anyways, I'm traveling on a straight section when all the sudden the car sort of jerks to the left. The car automatically turned off the cruise control and the traction light blipped on the display. The car didn't go crazy out of control, it just sort of did its thing to keep me out of trouble. So maybe that happened? If not, I would also agree with the hydroplainning or change in road surface (ie dry/wet to slushy).

[jallard]

Good comments - no, the cruise control was not on. There was lots of traffic around and I was doing the same speed as the other vehicles - so not excessive.

Suggestions from collegues:
1. ice build-up inside the wheel well breaking loose and momentarily slowing the wheel before dropping onto the road; and
2. erroneous application of brake on front-right wheel due to software glitch in DTC-control computer or sensor failure. Question: does the DTC/DSC system use braking action on the front wheels? ie is this suggestion feasible? (I know how it works on the back wheels.)

[Taymaishu]

Originally Posted by jallard

Good comments - no, the cruise control was not on. There was lots of traffic around and I was doing the same speed as the other vehicles - so not excessive.

Suggestions from collegues:
1. ice build-up inside the wheel well breaking loose and momentarily slowing the wheel before dropping onto the road; and
2. erroneous application of brake on front-right wheel due to software glitch in DTC-control computer or sensor failure. Question: does the DTC/DSC system use braking action on the front wheels? ie is this suggestion feasible? (I know how it works on the back wheels.)

DSC activates braking changes on all four wheels. However, if you are not cornering or under brakes, it should not adjust braking balance.

I think you hit a puddle

[Randomjesso]

Originally Posted by bogart

Just a question, did you have your cruise control on by any chance? This same thing happened to me one day when I was driving on the highway. I had my cruise control on, and I am aware that you should not drive with cruise control on when the roads are wet or snowy, but the roads appeared to be okay. It had just rained after being hot for a while, so I assume there was some oil on the road that got wet. Anyways, I'm traveling on a straight section when all the sudden the car sort of jerks to the left. The car automatically turned off the cruise control and the traction light blipped on the display. The car didn't go crazy out of control, it just sort of did its thing to keep me out of trouble. So maybe that happened? If not, I would also agree with the hydroplainning or change in road surface (ie dry/wet to slushy).

This happened to me last weekend driving back into sydney on the highway in fairly heavy rain. Straight run with cruise control on at about 130 Km/h. All of a sudden the rear kicks out and I'm drifting at highway speed in the rain. Corrected it and reset the cruise control. Happened another two times at 110 km/h and 100 km/h. I have driven cars that where old and trashed worth $500 and I have never had this kind of thing happen to me in heavy rain. Could anyone help explain this?

[mryakanisachoad]

Sounds like she just broke loose on you.

A remote possibility: the brakes will engage if you suddenly remove throttle push. The brakes also dry themselves by lightly engaging if they become wet. Either of these event could cause a slide-out in bad conditions...

[bogart]

Lol, talk about a thread brought back from the dead!!

[Greenkirby21]

Was it windy? Ive had a couple of times the wind was so strong it pushed my car

[rking117]

<insight>black ice left front tire (not the whole tire just a portion otherwise you would have been in the ditch). It was pretty cold out there. it was around 9am. no fog. light traffic considering. </insight>
Seriously though it was likely just a patch of ice on the left side. when you hit is all the traction on on the right tires = pull right

[cpsquare8]

Originally Posted by jallard

Any insight? Travelling @ 100km/h with DTC light on in light snow conditions along a perfectly straight section of highway without accelerating or braking when car suddenly swerved sharply to the right (from the front - no slip / fishtailing from the rear). Able to quickly correct before the car entered the next lane over. Didn't hit anything but it was as if the front right brake came on for a moment then all was okay. Any ideas what happened? The shop checked: brake calipher okay; suspension okay; no pulling to either side; tire pressure ok; no mechanical damage visible under the car, in the wheel wells or on the tires; balancing and alignment fine. There may have been some black ice on the road (but am thinking this would have caused the rear of the car to swerve, not the front), no potholes. Cars traveling ahead of me didn't swerve. I swerved at least 30-45cm before being able to correct. All happened in less than 2 seconds.

Any chance you have newer tires on the front of the car as opposed to the rear? If tread is greater on the front and less on the rear the over steer you seem to describe could have happened even with water, snow, black ice etc.

[slim_e90]

This has happened to me while changing lanes. Lane markers (white lines) are usually sliprier than the asphalt.

Did you slightly get out of your lane?

[Randomjesso]

It wasn't that windy on the section of highway was on nor was I changing lanes. I'm thinking that it must have hit a puddle and aquaplaned and as I have found out aquaplaning with cruise control on can be scary.