2020 RAM 2500 Cummins - Left Hand Pull

[Lift89]

Had truck aligned. Left caster 3.1, right caster 3.9, toe was .01 & .02.

Those were aligned to thuren specs.

The truck has a slight left-hand pull/drift now.

My wheel and tire set up are Nitto Ridge grapplers. 33/12.5r20 -40.

I heard that those tires can pull left; any ideas or experiences with left pull on these trucks?

I was told to get a lower steering stabilizer like Fox, so the positive pressure from the stabilizer will push right to counter left-hand pull?

Thanks.


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[Chrisn162001]

Swap tires left to right if that doesn’t fix it try the damper.

With toe set to Thuren specs the toe is straight ahead and won’t mask slight pulls like the factory toe in specs will.


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[Lift89]

Swap tires left to right if that doesn’t fix it try the damper.

With toe set to Thuren specs the toe is straight ahead and won’t mask slight pulls like the factory toe in specs will.


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I did swap tires and it was the same with both so it’s not a bad tire.

I’m assuming it’s just the rumors of Ridge grapplers pulling left on some trucks is true.

So I ordered the fox 2.0 low mount steering stabilizer.

I might go back to les Schwab and have them put it to factory specs and see what happens.

Beginning to think thuren specs aren’t really “THE BEST”.


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[Chrisn162001]

I personally like ridge grapplers on these trucks and haven’t had many issues with pulling.

Thuren specs are good.

They get rid of the inner tire wear. I’ve set up a lot of trucks with them including my own.

They do require more steering input since the tires are no longer fighting each other.

Factory toe in keeps the truck driving straight but at the expense of slight tire wear due to the tires slightly turned in.


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[CrazyTrain]

Factory specs flat out chew up tires.

Always use the Thuren specs.

That said, others are correct that Thuren specs will not mask any other issues. Hopefully the stabilizer will help.

Basically, anything could be contributing to a pull, slightly draggy wheel bearing, brake, etc.

My only thought on factory specs: if they can have such terrible ranges on alignment, what other spec ranges are out there during production?

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[Lift89]

Factory specs flat out chew up tires.

Always use the Thuren specs.

That said, others are correct that Thuren specs will not mask any other issues. Hopefully the stabilizer will help.

Basically, anything could be contributing to a pull, slightly draggy wheel bearing, brake, etc.

My only thought on factory specs: if they can have such terrible ranges on alignment, what other spec ranges are out there during production?

Yea I aligned it to Thuren specs and had a slight pull left (I do have Nitto ridge grapplers with - offset).

So I’ll be getting the low mount Fox 2.0 stabilizer which pushes left.

Hopefully that works, if not, I’ll get the Carli and adjust the psi till it makes the truck drive straight.

The guys who actually got it to drive straight put 100% cross caster in it and I didn’t know.

One can was pointed forward the other was pointed back.

Took me awhile to notice until I saw my truck from afar and saw it had a lean to it.

So I want neutral caster with .00-.05 toe and

I’ll use a stabilizer to counter act tire pull.


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[Lift89]

So the only way to get my truck to drive straight is to put a little cross caster in the front axel.

Thuren specs didn’t work at all.

My truck has a passenger lean of 3/4,” but the truck drives straight as an arrow now.

Thinking it may have to do with the wheel and tire set up?

33/12.5r20 -40 offset.

Let me know what you all think.


2020 Ram 2500 Cummins.






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[toyota_mdt_tech]

I did swap tires and it was the same with both so it’s not a bad tire.

I’m assuming it’s just the rumors of Ridge grapplers pulling left on some trucks is true.

So I ordered the fox 2.0 low mount steering stabilizer.

I might go back to les Schwab and have them put it to factory specs and see what happens.

Beginning to think thuren specs aren’t really “THE BEST”.


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Well, ideal for caster is to be as close side to side. Caster can create a pull if side to side varies too much and the pull will be to the side with the lesser positive caster. All caster should be positive. How much can vary. 3 degrees will give you good straight line stability. But too much positive caster, the wheels tilt and tend to lift the nose up, so its limited because for that reason. Old rigs with manual steering have very little for this reason. Caster isnt a tire wearing angle.

Camber, ideal is straight 0, but again, side to side with little variation is ideal. If you have 1/2 degree negative on one side, you want close to the same on other. Camber is the wheel tilting inward at the top or outward. Positive tips outward at the top. Inward is negative. As front ends wears, camber goes negative. Bad ball joints, lose wheel bearings, make it all negative.

Negative or positive will give you a pull, think of it like a styrofoam coffee cup, empty on the counter on its side, roll it, see how it goes in a circle. So RF positive camber will make it pull right, if RF is negative, pull left. But if opposite side is same, ie both negative by same amount, no pull, forces will cancel themselves out. Camber is a tire wearing angle, will wear inside or outside edges, but not in a feathering pattern. Feathering is from a toe out of adjustment. This forces the wheel to scrape down the road sideways. If you walked toes outward and then drug your feet like Frankenstein, you get the wear on shoes like a toe out of adjustment would do.

Most will have excessive toe out. This is normal with wear or age. A rack and pinion steering have much fewer parts while ours with steering box, drag link, pitman arm, idler arm, 2 tie rods all have some slack and that slack can all be stacked to add up to a bit. Your toe will automatically even out on both sides as you drive. What I mean is if one side is a 1/2" toe out, but other is perfect, you will correct automatically for the driving to the right by turning left giving both sides the equivalent of a 1/4" toe out. Rapid wear with feathering. So with our front ends, a 0 toes isnt perfect because once you go down the road, it will pull outward, so a smidge of toe in, so you end up with a 0 toes as you drive.

OK, for those who lift, straight axles caster is built in. A lift reduced the positive caster giving you less stability going down the road, more so with the wrong offset tires and screwed up scrub radius. Now adjust your caster by rolling axle (front axle pinion downward) and now you created a tighter kink in front u-joint, different plane as one exiting T case, see how all this snowballs.

Scrub radius is really important, but most dont know anything about it. This is what the engineers designed into your stock tire/wheel combo. Draw an imaginary line through your ball joints. That line should meet the road surface dead center in your tires footprint at the roads surface. If it doesnt, you wont be turning your tires, you will be swinging them on turns. As you turn, the pivot point is dead center on the wheel. When you put in a taller tire, that moves outward, so you put a tire that is wider to get it back. But now it sticks out further and now gives you a darting affect on irregular road surfaces which overload steering components.

It severely overloads the wheel bearings too. instead of the forces going straight up on the wheel bearings inner and outer row of rollers, now the weight is way outward, acting as a long lever putting max load on outer row of rollers.

To give you a good idea on scrub radius, take a sheet of notebook paper, set it on the counter, this is your tires footprint on the road. Now take a pencil with an eraser, eraser down, this is your steering axis inclination or centerline through ball joints. Stick eraser in center of paper (representing tire footprint) and slide it down the counter. Paper stays straight, now move pencil eraser to one edge, do the same thing. Notice how the paper wants to turn sideways. This is what your wheel is trying to do, but being held straight by components, but heavily loading them for shortened life. This will give you the darting or wandering from irregular road surfaces.


OK, front end engineering explained. This can make people think about altering vehicles. I am certainly not going to tell anyone not too, just be aware of all this and you are good to go.

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[toyota_mdt_tech]

So the only way to get my truck to drive straight is to put a little cross caster in the front axel.

Thuren specs didn’t work at all.

My truck has a passenger lean of 3/4,” but the truck drives straight as an arrow now.


Looks like they have a Hunter Alignment machine too.
Thinking it may have to do with the wheel and tire set up?

33/12.5r20 -40 offset.

Let me know what you all think.


2020 Ram 2500 Cummins.


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Looking at your specs: You problem is your caster, first off, the high positive numbers you have are more appropriate for a sports car.

As you turn, you are really lifting your truck up, which puts a heavy load on steering components.

You want to see even, side to side with no more than a 1/2 degree make separation, you have over a degree and caster pull from too much separation will always be to the side with less caster.

The camber isnt really adjustable without a special ball joint, but yours is good, get that caster closer to factory specs around 3 degrees, make it as close side to side, then set the toe and you are good to go.

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[Corkey]

Looking at your specs: You problem is your caster, first off, the high positive numbers you have are more appropriate for a sports car.

As you turn, you are really lifting your truck up, which puts a heavy load on steering components.

You want to see even, side to side with no more than a 1/2 degree make separation, you have over a degree and caster pull from too much separation will always be to the side with less caster.

The camber isnt really adjustable without a special ball joint, but yours is good, get that caster closer to factory specs around 3 degrees, make it as close side to side, then set the toe and you are good to go.

I tend to agree with this statement.

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