[Who_are_you]

As the label implies, this is not unlike the way a dog trots or a crab walks - a little bit sideways. This is caused by a misalignment of the rear wheels on any given vehicle and can be caused by bumping a curb while backing up or by driving through deep potholes. This is easier than you think nowadays because cars are built lightweight and don't have the structural integrity of vehicles from days gone by.
In a perfect world, the rear wheels are exactly parallel with the centre-line of the vehicle. This is critical as the rear wheels are used as the start point for a proper wheel alignment. You may have seen advertisements for four-wheel alignments. This is not a come-on; this is a legit process that any reputable alignment shop will perform. They must set the rear wheels straight first because all the measurements and settings for the front wheels are based on the rear tracking straight.
If the rear wheels are skewed to the left, as an example, the rear of the car will want to angle or dog track to the left. This gives the appearance of the car going down the road sideways, just like a dog trots - with its rear end off to one side.
This has a very serious effect of the handling of the vehicle - not the least of which is turning a corner.
If the vehicle tracks to the left, each time the car makes a left-hand corner, its rear end will tend to under-steer. The back end will want to stay to the left as it is already "steering" in that direction. This means that the left rear tire will either cross the centre-line of the turn or if there happens to be a curb on the left side, the tire could possibly hit the curb, in essence, the back end will always try to cut the corner.



Turning to the right has the opposite effect. The rear will over-steer. The left "steering" back end will want to swing wide around every right-hand turn. The driver should notice the fact that it takes more steering input to turn right than left because the steering wheel will have to counter the forces created at the back of the car not to mention that the trying to drive in a straight line will require the steering wheel to be offset to the left as well as a constant fight to keep the car in that straight line.
Any vehicle exhibiting these characteristics needs to get its rear end into an alignment shop sooner rather than later.

Source : https://www.theglobeandmail.com/glob...rticle1367167/




Extreme Dog tracking: https://i.imgur.com/7iX3f4T.gifv



Video Tutorial about Dog tracking

https://www.youtube.com/watch?v=4cJ18D-r1BY

Few more example I found on Youtube. Please beware of foul language in the video.

https://www.youtube.com/watch?v=PPLl93BeD9I

https://www.youtube.com/watch?v=jMFTdjNVPGE

[GTO]

Learn something new everyday - thanks for sharing! The only cars I've seen 'crabbing' are old body-on-frame UVs like Mahindras & Sumos from the 90s. Always thought it's because of a cheap & hushed up accident repair job.

Here is an excellent article from one of my favourite websites - Jalopnik:

I’ve seen such cars a number of times on Michigan roads, and it’s just a bizarre sight. So what’s going on?

To find out, I called up Woody Rogers from Tire Rack, who knows a thing or two about alignment, and I rang up Ken Lehto, a former Ford chassis engineer who worked on a bunch of leaf-spring suspension systems, including the one under the rear of the second-generation Explorer shown in the video. (Full disclosure: Ken is also the brother of onetime Jalopnik contributor Steve Lehto).

Rogers told me that Dog Tracking happens often in straight axle vehicles: The rear gets out of whack, and the solution is often just to adjust the front end to make the car drive in a straight line. “Often times, it comes after some kind of accident,” Rogers told me. “It’s a symptom of probably a much bigger problem.”

Lehto agrees, beginning by describing what’s going on. Essentially, he told me the rear axle is not lined up perpendicular to the axis of the car, and because the rear solid axle always travels essentially perpendicular to its own axis, that’s going to cause some issues.

“The rear axle is trying to steer the rear of the truck to the left,” he wrote me in an email. “If the driver were to hold the steering wheel straight, the rear of the truck would want to come around from the left and cause the truck to make a right turn - hence the driver must compensate by turning the wheel to the left.”

What Lehto is describing here is a concept called “Thrust angle,” which Tire Rack defines on its website as “an imaginary line drawn perpendicular to the rear axle’s centerline” that “compares the direction that the rear axle is aimed with the centerline of the vehicle.”

In other words, what’s happening with the Explorer is that there’s a large negative thrust angle, which means the rear axle’s heading is markedly different than the chassis’ heading. Here’s a more thorough description from Hunter Engineering, a company that’s been manufacturing car alignment devices for decades:

[ashis89]

Thanks for the detailed post.

I have seen this in many cars on the road, small and big alike, but never knew what it was called. I always thought it was a 'bent' chassis which caused this issue. That said, dog tracking is observed in many two-wheelers as well. As GTO pointed out, this could be because of poor repair work post an accident.

[pavi]

Wow! I got solution for a doubt that is in my mind for some weeks, so it is called dog tracking or crabbing. I have seen so many Mahindra Boleros which exhibits extreme dog tracking, even sometimes I felt they are built from factory like that. I don't remember any Bolero I have seen which does not have crabbing issue. Why is it so common in Mahindra Bolero?

[francis_vaz]

Does this term apply to motorcycles as well?
I have seen some old motorcycles with the rear wheel completely out of alignment.

[Who_are_you]

Originally Posted by francis_vaz

Does this term apply to motorcycles as well?
I have seen some old motorcycles with the rear wheel completely out of alignment.

AFAIK in motorcycle, it happens when the rear wheel bearing is broken/worn out.

[francis_vaz]

Originally Posted by Who_are_you

AFAIK in motorcycle, it happens when the rear wheel bearing is broken/worn out.

I couldn't check it out completely, just saw something weird with the motorcycle so it just clicked when I came across this thread.
It could have been a bearing or even some stunt gone wrong, probably a stoppie.

Although on a serious note, can just a bearing cause such misalignment in the wheel, that it moves to one side like about two inches or maybe more? Or the chassis also plays a part in this.

[Jeroen]

Thanks for sharing!

Rear wheel drive cars with fixed rear axles and trailing arms set up are prone to this as well, due to simple wear and tear. It should not get as bad as in some of the video's. Not anywhere near it, but it is usually very noticeable and visible by stepping on the accelerator and or the brakes.

As the rubber mounts in the trailing arms wear, they begin to get some play. Effectively the whole of the rear axle can start to "wobble" a bit.

It is an effect that many owners on older cars might have come across. It feels as if the back of the car gets pushed left or right and you compensate by steering the other way. For some reason I have always noticed the effect to be more pronounced during accelerating then with braking. (Probably to do with the fact that most braking force comes from the front wheels).

You step on the accelerator and the rear of the car moves a bit sideways. On a straight end, normally not a huge deal. But in a bend, where you like to accelerate and make use of rear wheel drive characteristics, this could spoil your day. It really upsets the handling of the car.

It is a known area of attention of for instance earlier Alfa Romeo's. The easy fix is to replace the rubber bushings in the trailing arms and the diablo rubber that holds the differential in place under the chassis.

Original Alfa Rubbers would not last more then 50-75.000 kilometers. These days with modern rubbers they could last a lot longer. But ultimately they will wear down. And needs replacing.

Jeroen