Do alignment shops do or check four wheel alignment on a rear straight axle?

Or is that part of the alignment procedure and I just never noticed it being done?

Newer equipment with 4 heads will verify rear alignment, at least the last machine I used did. It was a Baer (Bear)?

They can and should do that, but I bet some of them do not, especially if there is a young guy running the machine who thinks there is no value in checking a solid axle rear. The four wheel alignment can tell you thrust angles and camber angles of the rear, which aren't bad things to know.

couldn't a person add a thin plate as needed between the front shackle & the frame recess with the 4 holes to move the axle back on a particular side. Not sure about the cost benefit but just saying

Every machine Ive used in the last 30 plus years read the rear.It gives the thrust angle and toe.Just dont offer to do a rear alingment on a Vette with shim packs and rusty bolts.What a pain that was.Rocky

Haha! Stinking plastic Pigs! Gawd how I hate em after growing up repainting them! 6yrs old, they'd already have 5 crud paintjobs over the original GM garbage job... Ugh...


Anyways, I was just thinking about this topic last nite as a finally dug into my latest issue of Hemming Muscle Machines. They tried to run down the authority of the 70 HEMI Charger's handling. But I've had enough B-bodies to know their assertion's just shouldn't be true about wandering and floating at surface street speeds. So I was wondering if it wasn't running something like an "authentic" alignment spec? Like would allow a skinny set of bias ply's be happiest instead of actual radial rubber's more agressive specs? I remember when Radials were pretty new and the tire shop's insisted on using the factory spec's instead of adapting Radial specs to older cars. Nobody enjoys driving a car that dogtrack's because the rear alignment hasn't been checked and accordingly shimmed for correction of line assembly after a rebuild. But who either enjoy's driving a car at less than moderate hiway speed's which isn't 'tuned' for the tires it's wearing? I won't diss the car for what may be, but I wonder if it wasn't set up for tires different than as tested? I know that none of my Coronet's required much input from me at any speed where forward was the goal!

After getting the front aligned then at home should a person add shims/plates on the front shackle to move the rear axle back on whichever side as needed till the wheelbase (spindle center to axle center) is identical side to side or would that not be precise enough?

The alignment machine is not going to read the wheel base. All it will tell you on the rear is camber and toe for each of the two rear wheels and the total toe which will give you a thrust angle. Rear alignment specs do not generally affect how a vehicle drives.

Ever see a car going crab style down the road.That because the rear is way out.Ive seen quite a few here.Most were rear drives.It will want to go to the side.You pretty much have to steer away from the side that it wants to pull toward.Rocky

Correct, usually, the rear is not so grossly out of line that it causes issues, plus if the variations are minor, most drivers won't know they even have an issue. However I'm sure we have all seen examples that are waaay out of wack too.

Rear alignment can impact the way it drives nad handles by the classic "dog leg" or crab walk. This can cause excessive wear on the tires as well as making the car feel inconsistent between left to right turns.

During a turn, a leaf spring car's wheelbase changes as the springs compress and extend. If you have excessive angles with the rear housing, this motion becomes creates the inconsistent feeling between left and right turns since this motion is not transmitted equally side to side.

Certainly bent housings can impact things as well if it is bent into a toe or camber direction that again, creates a disparity between left and right. However, this can sometimes actually create an advantage to the handling if the bend produces a nominal amount of toe out or negative camber. I have known oval track racers who purposly bent rear housings to add camber to a live axle. It accellerates wear on parts as well, so its a touchy proposition on a street car.

So yes, understanding where the particular angles are on the rear is helpful and knowing them means you can correct/modified to some degree. If a shop will offer a 4 wheel print out, I certainly would take them up on it, but like Steve pointed out, for a live axle RWD car, it isn't going to include any adjustments on the rear, just information on where it is.