Did they mess up my Alignment???

[Techy-D]

After I got my wheels rotated I noticed my rig will yank left or right suddenly (based on crown or defect in the road at higher speeds). It's been about a month and I tried to adjust air pressure because they pumped them up a lot from where I had them. I took it back in yesterday and they said "wow, the tires at starting to cup, so you must need an alignment". I reminded them that the rear tires (the ones that were on the front before) look great and they told me everything was wearing very evenly. Hummm.... they said I need to schedule an alignment and have it checked. So, question is, did they put the jack in the wrong spot and bend something??? I watched when they jacked it up to rebalance the wheels, and they used the pumpkin and the drivers side under the shock, as jack points with floor jacks. Not shure what they did when they rotated the tires but they had all 4 off the ground.

Thoughts?? Just happened to go out of alignment?? Something under there they need to stay way from with the jack??? Do I really need an alignment every year (their suggestion)???

[etlsport]

the manual says the front jack point with a floor jack should be the front skid plate that comes out from behind the bumper

im not sure what they mean by the tires are starting to cup.. but if its what i think (center of tread is not getting worn and the edges are) it sounds like your tires are under inflated

[Techy-D]

the manual says the front jack point with a floor jack should be the front skid plate that comes out from behind the bumper

im not sure what they mean by the tires are starting to cup.. but if its what i think (center of tread is not getting worn and the edges are) it sounds like your tires are under inflated

Maybe I can talk to the alignment guy about where they were lifting it and show him in the manual.

When they say the tires are starting to cup, it's when looking at the side of the tire treads (looking at the side of the vehicle), each tread starts off high and goes lower, then the next one is high and back down again. If you were to wrap a string around the circumferance of the tire it would only hit the leading edge of each individual tread. I believe it's a toe in type issue and caused by the scuffing it produces.

[johnnyapollo]

It could be that your tires in front have conformed to front suspension variations, same with the rear = then when you swaped them out the differences in the tires are causing things to go squirrelly. When you go in for an alignment check to see if your rears are straight (I don't think much can be done to straighten them, but it would explain variations in the rear). I'm assuming the rotation was front to back - most tires these days can only be mounted in one direction, so you're not supposed to cross rotate them.

I get an alignment every year whether I think it's needed or not - but it helps to have a lifetime Firestone alignment deal. Out of the last 5 or 6, it's been off each time except the last (about 5 months ago) - everything was fine that time.

-- John

[tom4bren]

I've always heard that cupping is caused by bad shocks.

Inner & outer bars wearing more than the center - low inflation.

Opposite - over inflation.

Outer bars wearing more than the inner bars - tow in.

Inner bars wearing more than the outer bars - tow out.

I'll have to research this to see how bad my memory is.

[Techy-D]

Thanks for all the insight. I finally made time for the alignment appointment last night. The guy at Schwabbies took extra time and let me hang around during the process (besides I don't let them have my keys)
Turns out that everything was right on, with the exception of a slight toeout condition. He corrected that and chatted a few minutes while poking around under the rig, while it was up on the lift. Everything looked good under there!
He says I probably just hit a chuck hole right after the tire rotation???
Anyway, the vehicle does feel way more free to roll (a coasting feeling), that hasn't been there before, but still does some sqirming on a bad road. I'll get more experince with it on my trip this weekend. My gut feeling is that it needed an alignment and when the tires were rotated they are not happy either, which caused a couple problems. Anyway, with the rebalance of a "hopping" tire and an alignment... We'll see after my little road trip.