Allignment Issues

Hi all, I have a 96 explorer I replace front susp. ball joints tie rods & rack. I took it for allignment & my specs are all in the green, but for some reason i have a slight pull to the right. I am not sure what to check next. My specs are Left front camber -0.25 / caster 4.10 / Toe 0.04 Set back 0.25. The right side camber -0.79 / caster 3.92 / toe 0.03 Total front toe 0.07. Please I need some help here:screwy: Any help would be greatly appreciated. Thank you in advance

Have you swapped tires front to rear or side to side on the front to see if the pull changes/goes away?

Yea I tried that. Plus the tires are 6 months old. The pull stayed the same.

Does it just pull to the right in city driving or does it also pull on the highway, assuming no appreciable wind? Many city streets have a crown to them to aid in water run-off. This can contribute to a vehicle pulling towards the curb, which is usually on the right. The crown on highways will be MUCH less pronounced.

-Rod

Three terms in wheel alignment that can affect pull or drift not mentioned are:

Thrust angle is the direction the rear wheels are headed in relation to the centerline of the vehicle. If the rear wheels are headed to the right, the vehicle will drift to the left, and vice versa.

Cross camber and cross caster: They are the difference in the adjustments from left side to right side. As a rule of thumb, the tolerance is .5 degrees. Caster will affect pull approximately twice what camber will. For example: .5 degrees of camber will cause the same amount of pull or drift that .25 degrees of caster will. If cross camber is .5 degrees favoring the left and cross caster is .5 degrees favoring the left, technically the vehicle is within specs BUT, the vehicle will pull like a big dog to the left if you let go of the steering wheel. This is where an experienced alignment technician is a must. He needs to know how to deal with cross camber and cross caster and how to compensate for it, while also paying attention to thrust angle.

Your specs:
Cross caster is .18 degrees and will cause a slight drift to the right.

Cross camber is .54 degrees which will cause a stronger drift to the left that will more than cancel out the cross caster. Bottom line is you have a .36 degree drift to the left. Take into consideration road crown, and the vehicle should track very well.

If the vehicle is pulling to the right, something other than the alignment is causing it. There are other things that can cause a pull or drift such as:

Radial tire pull, (already mentioned).

Memory steer: caused by incorrect replacement procedure of outer tie rod ends, idler arm, pitman arm, upper ball joints, & lower ball joints. When any of these parts are replaced, the wheels must be straight ahead when tightening the fastener.

Thrust angle: The direction the rear wheels are headed, checked during alignment.

Problem with spool valve or centering valve, in the power steering gear box.

Hope this helps.

How about a dragging brake?

How about a dragging brake?

Good point! That'll open up a whole 'nother can of worms ;) Restricted hose, stuck caliper piston, seized hardware, hung up parking brake, etc etc.

I checked the draging brake issue. And swaped tires but no luck. Thats what i thought was causing it. Also it pulls in city & highway. So, I am looking in the wrong area:screwy:

Would the ride height affect the allignment. I checked ride height and left/driver side is a 1/2 inch lower than the right/pass side. If anything i would think it would pull to the left. It should pull to the lower side if i am correct. Thanks for everyone's help

Chassis ride height should be checked and corrected if necessary BEFORE doing the alignment. It will require spring replacement to correct it on your Explorer. If the alignment is done before correcting chassis ride height, it will not cause a drift or pull. If ride height is different side to side, it may cause a brake pull to the lower side.

My torsion bars have adjusters. So the ride height can be adjusted. Thanks old_master

I stand corrected, I thought it had coils in the front. At any rate, if ride height is adjusted AFTER the alignment it will affect toe and probably camber also. Caster will change, but very little.

there is no mention of the rear alignment numbers...they did do a four wheel alignment not two...right?

have had this happen before...cranked the alignment numbers to compensate for the pull and did not correct it. cross rotated tires, front then rear; no change. swapped 4 tires and wheel assemblies from a similar vehicle and then it drove straight. Would have liked to road force the original tires to see what the radial variation was but just recommended tire replacement.

Are the tires an economy or a quality tire?

I stand corrected, I thought it had coils in the front. At any rate, if ride height is adjusted AFTER the alignment it will affect toe and probably camber also. Caster will change, but very little.

why does a brake pull occur with ride height difference?

there is no mention of the rear alignment numbers...they did do a four wheel alignment not two...right?

The '96 Explorer has a solid rear axle with no adjustments/shims/camber kit capability, therefore no 4 wheel alignment. The best they could do is a thrust angle alignment.

-Rod

Weight distribution. The lower side isn't braking harder, it just has more weight on it so it can brake more effectively than the higher side.

The '96 Explorer has a solid rear axle with no adjustments/shims/camber kit capability, therefore no 4 wheel alignment. The best they could do is a thrust angle alignment.

-Rod

Correct, there is not an adjustment. But, if the axle isn't straight with the vehicle it will cause the thrust angle to be off center and cause a pull regardless. I'm not sure how old_master would recommend correcting this possible condition :)

why does a brake pull occur with ride height difference?


When there's a difference, (side to side) in front chassis ride height, there's a substantial weight shift which increases traction on the lower side and decreases it on the higher side. Also, the entire geometry of the front suspension and steering linkage changes which creates other handling and control issues. The main concern is that the steering linkage does not remain parallel with the ground which causes bump steer.

Correct, there is not an adjustment. But, if the axle isn't straight with the vehicle it will cause the thrust angle to be off center and cause a pull regardless. I'm not sure how old_master would recommend correcting this possible condition :)

We've all followed a vehicle down the road that appears to be going almost sideways, it's caused by excessive thrust angle. Thrust angle is the angle created from the geometric centerline of the vehicle and the direction that the rear wheels are headed away from the centerline. In most cases the root cause of excessive thrust angle is from the axle housing shifting on its mounts due to rust or an accident. If the thrust angle is less than .25degrees, the drift, or pull, can be compensated for with camber and or caster adjustments. If it's greater than .25 degrees, a frame shop is usually involved to correct it.

Gotta love those late 70s-mid 80s Novas :)

The '96 Explorer has a solid rear axle with no adjustments/shims/camber kit capability, therefore no 4 wheel alignment. The best they could do is a thrust angle alignment.

-Rod
I agree. pretty much all pick-ups are that way but you should always have a 4 wheel alignment done. 2wheel alignment anymore are a no no. If only a two wheel is done you'll never know if the thrust angle is out and your steering wheel will be off-center (if the thurst angle is out) as the front toe will be set to the geometric centerline instead of the true thrustline.

even though there are no spec's for the rear the thrust angle should be under 0.3 degrees or you'll dogtrack.

thanks old master for the info...your probably not old at all but rather a teenage super-genius!!

have made small corrections (when readings don't indicate bent axle) to the rear axle thrust angle by lifting the rearend by frame, loosing the u-bolts and pulling the axle with pullstraps to the angle i need then tighening the u-bolts.

cheap lift kits with blocks on the axle seem to always change the thrust angle.

thanks old master for the info...your probably not old at all but rather a teenage super-genius!!

have made small corrections (when readings don't indicate bent axle) to the rear axle thrust angle by lifting the rearend by frame, loosing the u-bolts and pulling the axle with pullstraps to the angle i need then tighening the u-bolts.

cheap lift kits with blocks on the axle seem to always change the thrust angle.

Haven't been a teenager in 30 some odd years, but thanks ;)

By the procedure you described, you might be a "teenage super-genius" though ;) Most techs don't bother taking the time to go the extra mile like that, keep up the good work.