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Mazdax605
Mazdax605 SuperDork
8/12/13 8:23 a.m.

Hey guys,

This has been bothering me for a while, and I thought I would ask. In my area I see a lot of cars and trucks that go down the road like a crab. By that I mean the car is driving straight, but the body is askew from the travel of the wheels. Is this something that comes from "harsh New England winters" or just from people not fixing their obviously wreaked cars? Do these people know there cars are crabbing down the road? I understand how it happens on a truck or any vehicle with a frame, but I see it on uni-body cars as well. These people must know the car is messed up, correct? Or maybe not? What if I am driving a crab car, and don't know it? Oh who am I kidding, I would know if my car was going down the road sideways. Are these people lazy, broke, or both?

Swank Force One
Swank Force One MegaDork
8/12/13 8:24 a.m.

This could also be caused by something so simple as a bad alignment.

That said, it seems that at least 80% of the "Crab vehicles" i see are Ford vans or pickups.

Alan Cesar
Alan Cesar Associate Editor
8/12/13 8:27 a.m.
Mazdax605 wrote: These people must know the car is messed up, correct? Or maybe not? What if I am driving a crab car, and don't know it? Oh who am I kidding, I would know if my car was going down the road sideways. Are these people lazy, broke, or both?

You'd be surprised. The GRM van had a good 5 to 10 degrees of "crab" (or dog tracking), and we didn't know it until I was following the van in a car. It also had (possibly unrelated) steering issues that we definitely noticed while driving it, but the dog tracking is not something you can see from behind the wheel.

RossD
RossD PowerDork
8/12/13 8:37 a.m.

After we did an axle and drivetrain swap on our full size jeep J300, the first drive around the block was high fiving. The second drive around the block was with a chase car seeing if it was crabbing.

iceracer
iceracer UberDork
8/12/13 9:01 a.m.

crabbing or dog tracking is caused by misalignment of the rear suspension. Can be noticed by steering wheel being off center. Unless it has been corrected.

Now when you notice the wheel off to the right and then the next time you see it off to the left, you realize you own an MG 1100.

GameboyRMH
GameboyRMH UltimaDork
8/12/13 9:06 a.m.
iceracer wrote: Now when you notice the wheel off to the right and then the next time you see it off to the left, you realize you own an MG 1100.

In a Samurai you have to correct one way under accel and another way under decel. It's a combination of a little engine gyro effect and a lot of bump steer.

Ranger50
Ranger50 PowerDork
8/12/13 9:27 a.m.

I have noticed this a lot lately and I really believe it is your own eyes playing tricks on you. Tires that stick out or sunken in in relation to the body, the gradual narrowing of a vehicle towards the rear, differing front and rear track widths, etc all play a part in what looks like a vehicle being a crab.

wae
wae Reader
8/12/13 9:33 a.m.

I can't find it now, but I would swear that Ford had a TSB out for the E-150 that covered a customer complaint of a van crabbing/dog-tracking and said that it was commonly an optical illusion.

Duke
Duke PowerDork
8/12/13 9:38 a.m.

I've noticed the Ford truck issue many many times, and I have convinced myself it's because the rear track is narrower than the front.

914Driver
914Driver MegaDork
8/12/13 10:08 a.m.

60's & 70's Chevies had pins that centered the axle on the leaf spring. After a while the pins rusted away and one burn out later you're dog tracking down the road.

Dan

yamaha
yamaha PowerDork
8/12/13 10:19 a.m.

Theres a mid 90's s-10 running around muncie that takes up the full lane width wise due to literally crab walking......

Vigo
Vigo UberDork
8/12/13 10:24 a.m.

Yep, misalignment of the rear axle to the vehicle in most cases. You'll notice 99% of the vehicles that do this have stick axles bolted to leaf springs..

SilverFleet
SilverFleet SuperDork
8/12/13 10:27 a.m.

I remember when I was a kid there was a guy in town with a Chevy LUV pickup that would do the "crab" so bad you could see his whole FRONT tire looking straight on from the rear! It was hilarious.

Other than that, I have nothing to add.

JoeyM
JoeyM Mod Squad
8/12/13 10:30 a.m.
Vigo wrote: Yep, misalignment of the rear axle to the vehicle in most cases. You'll notice 99% of the vehicles that do this have stick axles bolted to leaf springs..

More importantly, how can this be fixed?

HappyAndy
HappyAndy SuperDork
8/12/13 10:30 a.m.

With the ford E series vans with twin beam the front track is a bit wider than the rear so it does give an illusion of dog tracking, but take it from me, on more than a few of them its not an illusion.

About a year ago I saw a 4ws prelude with something damaged in the rear suspension/steering, now that was crabbing.

ransom
ransom UltraDork
8/12/13 10:31 a.m.

Damn. This is going to be the next big thing in driftstance... Cars that appear to be in a moderate drift just heading down the interstate...

It's the same mod resulting in 15 degrees neg camber on a Civic, just rotated 90 degrees, right?

yamaha
yamaha PowerDork
8/12/13 10:42 a.m.

In reply to ransom:

integraguy
integraguy UltraDork
8/12/13 12:11 p.m.

I bought a 914 back in the early '80s (before I knew about the infamous cracking frame rail under the battery box) and while that car drove nicely and handled great....on the way home from the dealership my friends told me the car's rear wheels were NOT following the fronts all that closely.

Some newer cars look like they are crabbing but some of it is an illusion and some of it is aerodynamics in that cars are slightly wider in the front than the rear.

BTW, another big-time crabber "out-of-the-box" were the Dart Scamp hardtop twins. Definitely a wider front track than a rear one.

GameboyRMH
GameboyRMH UltimaDork
8/12/13 12:17 p.m.
JoeyM wrote:
Vigo wrote: Yep, misalignment of the rear axle to the vehicle in most cases. You'll notice 99% of the vehicles that do this have stick axles bolted to leaf springs..

More importantly, how can this be fixed?

With an alignment machine that uses FRICKIN' LASER BEAMS

plance1
plance1 Dork
8/12/13 12:21 p.m.

good chance the vehicle has been wrecked

Vigo
Vigo UberDork
8/12/13 12:22 p.m.
More importantly, how can this be fixed?

Usually, by an alignment tech on an alignment machine (preferably at a body shop). I mean, you can separate the axle from the leafs yourself and see if whatever is 'locating' the axles to the leafs is damaged or missing and try to fix that, but sometimes it isnt that simple and imo it's a case of it being worth it to send it to someone who knows what they are looking at. The reason i say preferably at a body shop is because there's a chance it could have something to do with some bent mounting components or actual frame distortion and people at body shops are going to be a lot better at spotting that stuff than a guy at a tire shop like NTB, et al.

This is just my .02. Im usually very pro-DIY but even with all my experience i would probably only go so far as looking for 'obvious' stuff, and if i didnt see anything obvious without dumping a bunch of labor into it id send it straight to a body shop to get put on their alignment machine and have their guys look at it. Body shops are full of people who can spot things that even an experienced 'regular mechanic' will overlook or not know how to recognize.

44Dwarf
44Dwarf SuperDork
8/12/13 4:00 p.m.

As 914 said locating pins offten snap the nub seen it alot here in MA after tough guy pulls someone out of a ditch, shock loads to the rear end pop the knub off. As so bad front bushings in the main leaf will let the axle lag some.

Mazdax605
Mazdax605 SuperDork
8/12/13 4:41 p.m.

I have seen a mid 2000's civic running around like a crab a lot lately and I can't figure out what is wrong with it, but it is almost going down the road sideways. Maybe it's just me but I have been seeing more and more of these crab cars and it isn't always the stick axle vehicles. They are among us.

I see crab cars.

Streetwiseguy
Streetwiseguy UltraDork
8/12/13 4:49 p.m.
Vigo wrote: Yep, misalignment of the rear axle to the vehicle in most cases. You'll notice 99% of the vehicles that do this have stick axles bolted to leaf springs..

I'd argue that its easier to bend a lateral link on a front wheel drive car, which changes the rear toe but I may be biased due to the many times I have straightened them in my various front wheel drive race cars.

Zomby Woof
Zomby Woof PowerDork
8/12/13 4:57 p.m.
HappyAndy wrote: With the ford E series vans with twin beam the front track is a bit wider than the rear so it does give an illusion of dog tracking, but take it from me, on more than a few of them its not an illusion.

I was going to say, I've seen a lot of these vans taking up the whole lane and going down the road sideways. It was definitely not an illusion.

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