Still new here. Dont know if this is the right forum but I'll post it anyway. Have a 96 QC short bed F250 with the PS. I've put brand new Moog ball joints in about two weeks ago. When in reverse the tires cant inwards extremely bad. The top of the tires cant in and the bottom out. As soon as I go forward about five feet they straighten out. I tightened all the bolts on the tuff country lift until i broke a few and had to replace them. I'm ready to fire bomb the truck!!!! What is causing this?? Please help. My wife is pissed I've been dumping soo much money into this truck.

 

Its normal operation for the front axle of your truck. I don't know why they do it but most of the 250's do it. The 350 use a different axle and doesn't have that problem.

 

Its a side effect of the inverted "Y" steering linkage. "Y" is based on its looking like a letter y the main rod from the the pitman arm to the pass side steering knuckle. and the driver side tie rod from the driver side knuckle to the mid point of the opposing rod. In order for the the twin beams to be able to flex independantly ford started reusing this steering linkage. Unfortunately the linkages allow for more play than any of us would like. When actuated it requires one wheel to be pushed while the other is pulled and by design has more flex and thus stress points to start to wear out and cause play, which inturn doesnt hold the alignment tight. The inverted "Y" was first tried in the seventies on solid axle D44 front ends and had problems that it allowed itself to change toe in and out on its own due to where the rod flex points are this was later swapped out for the inverted "T". The inverted "T" is stillin use today it is simply a tie rod between both front knuckles on a solid axle which therfore doesnt have independant flex. and then has a large draglink from the pitman arm to a joint about 3" from the pass side knuckle allowing it to move both wheels together by pulling or pushing. I have seen some aftermarket fixes for this, though they are few and far between, as well as pricy. If its that big of a problem you may want to look into one. Probably a stupin question but, since you just replaced your ball joint did you get your alignment rechecked afterwards, these fronts are REALLY touchy about their alignments. Also due to the re not being a solid connection like a inverted "t" tire rod when in reverse your wheels toe in and out can be pushed and the flex in the "y" pushes both ends in til they reach their limit causing a toe out effect on the back side of the steer tires while in reverse. Yet whil moving forward they are pulled outward rather than in, so the general alignment is based on the forward drag factor to align to a center there. I hope this helps.

 

Good information Oversize. Reps sent.

 

Not saying Oversize is wrong cause I don't know the answer but I can't see how the tie rod design changes camber when you back up. Like I said I can't explain why but I don't think it has to do with the tie rod design.

 

When I had the ball joints replaced the guy said it "felt" close enough that it didnt need an alignment. It is so severe in reverse it makes me cringe when I actually see it!!

 

It "felt close" that would worry me if they didnt put it on the rack and do measurements Id be guessing they are too tight on the front and thats causing excess play to the rear. You might want to have somebody professionally look at it. I have basically the same truck and oversize tires which causes exajerated rag effects and it doesnt do that, a good alignment shop should find any problems, it may "feel" tight at the ball joints but your tie rod ends or the joints that connect them may be worn out so the ball joints are good so it doesnt wobble, and the camber may appear correct but the control rods arent nessasarily holding tight and are allowing your tires to wander. And as I stated before in reverse is when this effect would be most dramatic. Id suggest taking it a getting a second opinion. If your laws are like they are here thay have give an estimate before performing any work so they should be able to look at the linkages and move them around a little before quoting you any repairs. Also if they find any movements they should be able to show you where and what theyre doing.

 

When in reverse the effect is primarily the toe in and out changing and when there is enough toe out effect. it causes side wall drag which will pull out on the tires at the base and in turn as a matter of pure leverage will for spring flex giving the appearance of a camber issue.

 

off topic,... sheesh I must be tired,... readin ing my own riting and realaize how many typos and broken words are ther, been writing too many long explanations tonight. lol

 

I had this same effect we I had my TTB axle and this is what I concluded. Think of a drag car; when you launch it the front wheels might come off the ground. This means when going forward, the front end of the truck has less downforce on it and sits at its neutral position. Now when in reverse, the front of the truck actually wants to push into the ground, because of the direction the rear wheels are turning. So in reverse there's a lot of downforce on the front suspension. And with this type of axle, the leafs will compress and tires will come up, thus changing the geometry of that axle arm, which will give you the negative camber. And I assume the leafs will hold this downforce until you pull forward a few feet. At least thats been my experience.

 

A simple way to try and determine your problem is to take a floor jack and lift one side only of your steer axle make sure your column is locked and can be turned then get somebody to watch the tire on the side on ground. They are looking tmkae sure there is no movement whatsoever. the side that is lifted having moderate resistance from your linkages will show you, if you have a problem. Try to move the lifted side side to side simulating a turn. Assuming the tire on the ground does not move at all if you experience any movement even as much as 1/4" this will be your problem because under the weight and load of your truck the effect will be greatly exaggerated to more like 1" or more. this would mean your linkages are worn and in need of repair or replacement. because when its under load on the ground the effect will cause your tires to point out at the back effectively causing a toe in effect, the tires will drag on their side wall, the side wall resistance will force a lift like leverage pulling out on the bottom causing your camber like effect. This is based on the ttb having a fixed point in the center to pivot from, for individual whel articulation and indipendant suspension effect. the y is essentially a flexible fork on the front end, and your toe in will be flexing it till the point where it is forced to stop. when it stops it binds and begins to flex the springs from lower angle pull caused by the leverage of your tires. In simplest terms your tie rod, and or drag link are worn out. Im willing to bet your tire wear is uneven where as the ball joints will cause wear on the inside edge the alignment play will cause it to be more like accross the inner half of the tire rather than just the inner 1/4. im also willing to be that if your turn while backing the effect goes away fairly as fords design leans the tires toward an edge of the tire causing less surface drag. while it will still be ther it will be less pronounced. Get your steering linkages checked out, it is usually part of a good alignment job. Im willing to bet money that one or more of your likage joints is worn.

 

Or the alignment is definately out, of adjustment.

 

I do appologize if this eplanantion has been rathe drawn out and hard to follow, this is essentially a mathematical equation requiring a lot of understanding of geometrical angles vs applied force, and variable change. I used to alot of specialty engineering which gives me a better understanding of these. Im therefore very knowlegable about mechanical engineering which directly applies to steering, suspension, and things that revolve around these kind of equations. I hope I explained it well enough that you could understand it. If not please let me know and I will try to give you a more personal explaination by answering any questions in a way easier to understand. I dont want to appear to be monopolizing this thread, just trying to help.

 

I'd have to say I'm with TJ on this. The original question involved the movement at the top and bottom of the tire, thus being camber. If we were talking about movement from the front and back of the tire, that would be toe. I agree with Oversize that the steering linkages could affect your toe in this situation, but the camber is likely due to the forces of the engine depending what direction your moving.