READ THIS FIRST
If you don't have the time to read this full page, or you are ready to head to the alignment shop, print the page from the below link to take to your alignment shop.
These Dodge Ram solid axle trucks are the most simple vehicles ever to align. Toe and caster is all there is! For some reason more and more alignment shops these days seem to really struggle with these trucks, or are just being extremely lazy. On top of that, the OEM Dodge specs are really pretty terrible, mostly regarding toe-in. I have my own specs below that are different than OEM, and a decade of testing shows that my specs will net much better results than OEM Ram's.
Lets start with clarifying the steering difference on the 2003-2007.5 trucks. These trucks have the OEM "Y" linkage steering, and it really needs to be upgraded. The Y-style steering is really inconsistent, especially with tire wear, and the info I give here will not work correctly with the "Y" steering on the truck. All this information given below will assume you have the 2008+ OEM upgrade "T" steering, or aftermarket steering with a solid tie rod that goes directly from knuckle to knuckle.
All solid axle trucks from 2008 to present have solid tie rods factory, so the below info applies.
Getting an alignment? Arm yourself before you go!
Read the below info, and arm yourself with this info before you get an alignment. When you go into the shop be sure you mention these things.......
1) Tell them you need an alignment, and tell them that the specs are not stock. Make sure they are OK with that.
2) Tell them you will want to take a printout home with you, and you'd like them to point out the TOTAL toe and caster before the truck is taken off the rack.
3) The specs you need to ask them for is 0.00 to 0.05 TOTAL toe, and 3.2-4.8 degrees caster depending on year and model. See the spec sheet PDF for those details.
4) The driver side and passenger side caster degree will never be the same. There is more positive caster welded into the axle, on the passenger side, so with the caster cams close to mirrored, just shoot for a good caster average between sides.
Here is why the Toe setting is key
On these Dodge Ram trucks, as long as all the components are in decent shape, ZERO toe in will give you the best handling and tire wear. I try to align to 0.00 to 0.05 degree's TOTAL toe in. Basically dead on zero, none. Even 0.08 degree's is too much. Here is why this works on these trucks.......
Toe-in in regarding most vehicles with independent front suspension, toe-in is there to stabilize the front wheels. This is because on non-solid axle vehicles, there are so many flexible bushings and variables letting inconsistencies happen, the front suspension will dart all over the place without some toe-in to stabilize the chassis. These Dodge RAM trucks have NO rubber bushings controlling the wheels, and virtually ZERO deflection/flex to alter toe. If the ball joints are in decent shape, and the tie rod ends at the steering knuckles are in good shape, the wheels stay pointed where they are set with the toe adjuster.
Why Toe-in can cause problems on solid axle trucks
Here is the problem. Since these solid axle trucks have a very rigid, simple, high accuracy assembly between the wheels(solid axle), toe-in actually will make the tires fight each other. Road surface, cross wind, etc can always make the truck want to dart side to side, and never really go straight. The front wheels are basically turned in towards each other, and going down the road one tire will always win the fight. This almost simulates an a-arm car/truck chassis that is aligned with NOT ENOUGH toe-in. So, this toe-in that is supposed to stabilize the chassis, end up doing the opposite on these solid axle trucks.
Toe-in working with Caster
Toe-in being set as close to ZERO as possible is the key factor. Do this first before messing with caster. This will let the Caster function do it's job. If there is measurable toe-in degree set in the alignment, the more you add Caster, which is supposed to make the truck drive itself straight, the more it does NOT drive straight. Trying to adjust caster with too much toe-in is pointless, and you may get backwards results like mentioned. Get the toe in set to zero first!!!! The reason for this is that Caster is basically leaning the axle back, letting the weight of the truck drive itself straight. If you lean the axle back with Caster, and too much toe-in is making the tires point in toward each other, now both tires have most of the load scrubbing on the inside of the tread, and the truck will always be trying to "find a side". We want it to "find straight". Zero toe, will let the tires ride on the tire tread, perfectly square to the road. This lets the truck run on a lower degree of caster, while still driving great, which is what we want. This also makes the tires wear longer, better fuel mileage, less wear on steering components, and a more relaxed driveline angle. ALL WINS!
Caster in general terms, is using the weight of the vehicle to have influence over the front wheels, manually having them work together, to point the vehicle straight. That said, both front wheels are actually fighting against each other, equally, to create this imaginary straight forward effect. If you were to magically make one front corner of the vehicle super light, the vehicle would auto-steer to that lighter weight side, as the caster forces would not be equal. This is one reason why zero toe-in really helps us. Zero toe puts the weight even across the front tires, making sure the outer edge of the tread is loaded. This increases the hard caster forces, as there is full possible leverage around the ball joint pivot line, letting us run less actual Caster degrees. Again, we want this. Less Caster degree puts less force on components.
Caster settings, tips, quirks, and range of adjustment
Regarding a 2-3" lift, the best way to quickly check and see if your caster is close to where it should be, is to look at the angle between the driveshaft and the front differential pinon flange it bolts to. Basically, there should only be a SLIGHT angle difference between the two rotational axes. If you crouch down and look from the side, the axis if the differential pinion flange will be a LITTLE closer to parallel to the ground, compared to the drive shaft itself. If the truck is stock height, the two axes will basically be in line with each other. Increasing the caster angle degree will normally make the steering wheel feel more heavy, and sluggish, assuming the toe-in is set close to zero. Decreasing the caster angle will make the truck feel more responsive and light.
2013+ newer radius arm truck caster notes....
-- The adjustment cams are backwards on these trucks, compared to the solid axle Rams from the last 20 years. The cam bolt is actually inside and moving the axle itself, while the cam washers are located by the arms, unlike previous generations. This means moving the arrow on the cam to the rear of the truck, is increasing caster degree.
-- There is plenty of caster adjustment on these trucks to work with up to about 3.5" of lift, even with stock arms and no radius arm pivot drops.
-- It is VERY important on these trucks that you don't adjust the driver and passenger side cams too far out of balance. In other words, make sure there is not much manual cross caster. If one cam is for example pointed straight down, the opposite side cam should be no more than one mark forward or back. I have seen alignment shops do some crazy things here. If you do put them far out of balance, you can get some drastic lean in the suspension. Reason being, radius arms make the front axle act like one big swaybar. With the caster cams far out of balance, it gives a similar effect as having different length swaybar links, which would force a chassis lean. If you do need a little caster bias fine tuning, which is pretty normal, loosen the upper radius arm bolts at the axle also, then re-tighten once the handling is good. This will let the axle center up as best as it can, by using slop in the hardware to help the chassis find neutral.
-- With our 2.5" coils, the approximate good handling cam indicator position, is about the first mark to the rear of the truck.
2003-2013 4-link Ram solid axle trucks, caster notes.....
-- The adjustment cams are backwards on these trucks, compared to the newer radius arm 2013+ trucks. This means moving the arrow on the cam to the front of the truck, is increasing caster degree.
-- As you lift these trucks, if you leave the caster adjusters alone, the factory geometry causes the caster degree to increase. Normally after lifting 2-3", you need to back off the caster a little.
-- With a 2-3" lift, the caster cam "straight up", is generally the sweet spot. If you have wider stance wheels, or very heavy tires, often one mark closer to the rear of the truck can feel more stable.
Notes on tire pressure
With any pick-up truck being much lighter in the rear, compared to the front, you should run less tire pressure in the rear. With the engine assembly being so heavy on these heavy Diesel Rams, that bias number is about 20psi less in the rear compared to the front, and this is assuming you are unloaded or lightly loaded. Naturally if you had a slide in camper, or a heavy 5th wheel or something, air up as you should. Different tire brands, models, and construction types can desire TOTALLY different pressures.
Smaller D rates tires may like more pressure, while larger heavier E rated 10 ply tires will use much less. Start with finding a pressure for the front which lays the tread flat on the ground, then add about 5-10psi. This will usually net great handling that is not "squirmy", rolling over giving lazy handling, and wearing the outer lugs of the tires. Once you find this good front pressure, drop the rear about 20psi compared. This will net balanced tire wear, and a more comfortable balanced ride.
Tire wear regarding alignment
You can find tons of generic tire wear info on the internet. To keep this simple and focused on these solid axle trucks, I'll just say that a great indicator of your toe setting is what your front tires look like. If the outside edges are more worn off than the center and inside edges, you have too much toe-in. Insides edges worn, toe is out too far. There are always exceptions, but in general this guideline can be followed.
Ball joints. They can be confusing
Ball joints are a touchy subject on these Dodge Rams. We hear it SO often, that with 15,000 miles on the truck, customers are being told by repair shops that their ball joints are already worn out. I have really never seen OEM Mopar ball joints with less that 75,000 miles, that NEEDED to be replaced, and I have seen ball joints with 200,000 miles that were fine. The main confusion is vertical movement through the joints. Vertical movement through the ball joints is totally normal, and the truck comes off the dealer lot like this. Lateral/side-to-side slop is what we don't want, and what should be checked for. I can't tell you how often shops will put a pry bar under the knuckle, show the customer the vertical play, and maybe unknowing, sell a big money job that does not need to be done. Maybe they do know what they are doing. Hard to say. Just be careful and smart on this.
I also have run into many times ball joints being seized up. This is a HUGE factor on handling. If the ball joints are locking up internally, the truck will almost never want to drive itself straight(caster forces). These caster forces need a very slippery free-moving set of ball joints, to let the truck self center, as you drive down the road. If you keep replacing components and the truck just always seems to wander all over the road, check and make sure the steering knuckles are nice and loose, smooth, and swing easy. I mostly see this with aftermarket ball joints, even with the very high end aftermarket ones.