Thank you for providing a lot of good information. I've recently been helping a friend rebuild smashed trucks; only late model Dodges. We've straightened frames, replaced roofs and entire sides, rebuilt heater boxes, welded in new firewalls, etc. and have not run into any related problems. After seeing the work involved, I would not be afraid to own one of these trucks, and you're right about the price.
From my years as an alignment tech at a very nice family-owned Chrysler dealership, most of what you described sounds familiar. First of all, the wrong type of transmission fluid will cause a shudder, but usually when shifting to the next higher gear and when the torque converter locks up. That occurs in third or fourth gear, above about 35 mph, and when the engine is warmed up. You can repeat a torque converter shudder by tapping the brake pedal while holding the accelerator steady. The converter will relock a few seconds later. If the shudder occurs again every time, suspect the wrong fluid. I believe they use "ATF-6" now.
Although this doesn't exactly fit, don't overlook tight u-joints. Jack up the front end, turn the front tires to one side, then try to spin each tire by hand. A tight front u-joint will force the wheel to turn back straight ahead. Tight rear drive shaft u-joints will cause a shudder too. You might have to remove the rear one to find a tight joint here.
We just finished a dually diesel that had the engine pushed back over a foot. The front u-joint on the rear drive shaft took quite a hit, and was really tight, but you never would have known by looking at it. It was only because we had to pull the entire drive train to straighten the frame and replace firewall that we noticed the joint wouldn't swivel.
The front drive shaft should not be suspect because nothing forces it to spin when you're not in 4wd. You can also try running the truck on a hoist but it might be impossible to duplicate the noise and vibration without the load on the tires and drive train.
Before getting carried away with alignment issues, switch the two front tires. If the truck now pulls the other way, it's tire-related. Different brands will roll differently, and one new tire, even the same brand as the other one, can cause a pull. If it is tires, just switch them front to back and try it again. If you still have a tire pull, now just switch the two left or two right side tires with each other.
As for the alignment, there are three primary values. "Camber" is the tilt of the tire when looking from front or back. Too much tilt will cause tire wear on one edge. Also, the tires want to roll in the direction they're leaning so both sides must be nearly the same. The left tire can be tilted out on top a little more to make up for roads tilting to the right so rain runs off. The slanted road will make most vehicles pull right when you let go of the steering wheel. The offset camber can be used to counteract that pull, but on your truck, you have a solid axle, and camber can only be adjusted by replacing the entire housing or by installing offset upper ball joints. They might be special order from the local parts stores but they are listed in the catalogs. If the tire wear is ok, and the pull is slight, there's a better alternative.
"Caster" is the tilt of the steering pivots as viewed from the side of the wheel. Think of the angle of the fork of a bike or motorcycle. They have a lot of caster. That's what makes it possible to ride no-handed when your weight is on it. On cars and trucks, higher caster leads to better directional stability but also increased steering effort. We use power steering to make up for that increased effort. Caster has no affect on tire wear unless it's really high AND you do a lot of high speed cornering in parking lots! What it does is cause each front wheel to want to turn toward the center of the truck. Put the steering linkage between them, and if caster is equal, the two will balance each other out. On older rear wheel drive cars, caster was also often used to create a slight left-hand pull to offset road crown. On your truck, (if they haven't changed it from the 1999 models I last worked on), caster is adjustable with two cam bolts on the front of the two lower control arms. The problem is, again, since you have a solid axle, only the entire axle housing can be tipped to increase or decrease steering effort / road feel / steering wheel returnability. One side can't be adjusted without changing the other side the same amount, so it can't be used to fix a pull. Don't be too concerned if the two caster values are out-of-specs.
Toe is the direction the tires are steering when the steering wheel is straight ahead. The front of the tires should be just a little closer together than the rear of the tires. This is pretty critical to good tire wear, and is easy to adjust.
As I alluded to earlier, there are other fixes for eliminating a pull. There were some trucks that had a slight pull even after the alignment was in specs. For those vehicles, Chrysler had a kit that consisted of three spacers that went between the wheel and brake rotor. They were 2.0mm, 3.5mm, and 5.0 mm thick and made of stainless steel. If the truck pulled right, you removed the left front wheel, slid the 3.5mm spacer on the hub and reinstalled the wheel. If the pull was gone, you were done. If it now pulled left, you installed the 2.0mm spacer instead. If the pull was less noticeable but not entirely gone, you installed the 5.0mm spacer. The downside to this repair was those three spacers cost $450.00 for the set, but it was almost always covered by warranty. If the 5.0mm spacer didn't quite give enough help, there was an 8.0mm spacer available, but you also had to install longer wheel studs.
One last potential thing to look at is rear toe. All modern alignment equipment reads rear toe since most front wheel drive cars need it adjusted. Even though you have a solid rear axle, and TOTAL toe will likely be in specs, you need to look at individual toe for each rear wheel. If the left rear tire has a small positive number, it is steering to the right a little, (toe in). If the right rear tire has a small negative number, it is also steering to the right, (toe out). Those two will cancel each other out as far as tire wear is concerned, but together they might tug the truck to the right. Conventional wisdom says that if the rear axle steers to the right, it should cause the truck to turn left. You would have to counteract by turning the steering wheel to the right. This is hidden, (adjusted for) by using the rear tires as the reference when adjusting the front tires. That gives the "illusion" of a straight steering wheel. That's kind of harsh language. 99 percent of vehicles do not have perfect rear toe; that's why all we do now are four wheel alignments, even when the rear wheels aren't adjustable.
If you indeed find both rear wheels are turned a little to the right, there is a trick that saved me on two trucks. Most alignment techs won't believe you or even know what you're talking about. There is a large cast iron spacer between the leaf spring and axle housing. The bolt head on the leaf spring sits in a pocket in that spacer and a peg cast into the spacer sites in a hole in the axle bracket. I had two trucks that pulled to the right and nothing else helped. Out of desperation, I removed those spacers and ground the pegs and holes so I could shift the position of the axle housing. Keep in mind that the original offset was so small, you would not have noticed any dog-tracking if you followed it down the road, and I've seen worse readings on a lot of other cars and trucks that never had a problem. On the first truck, I did this modification after two days of no success with anything else. Anyone would have dismissed the readings except I was grasping at straws, so to speak. I ran into a second truck a year later with the same issues and the same cure. The only problem with this modification is the potential for the axle to shift back to its original position, possibly from heavy braking or acceleration. The clue would be the pull comes back and the steering wheel would be very slightly off-center, possibly not even noticeable.
To get back to the shudder, drop the rear drive shaft first to inspect the u-joints. If you have a two-piece shaft, look at the center bearing too, especially since it was hit in the front and the engine may have been pushed back. A visual clue, if it wasn't replaced, is the rubber extension of the transfer case's rear seal. If the drive train got shoved back, that rubber dust boot would likely have gotten chewed up by the u-joint.
While you're down there, look at the angle difference between the transfer case, the drive shaft, and the rear axle. The angles should not be real severe, such as when people install lift kits, but there should be SOME angle difference. Weak rear springs will allow the rear axle to move up, reducing the angle difference. This will reduce or eliminate the need for the roller bearings in the u-joint cups to move back and forth. That will set up a wear pattern of ridges in the cups that will make a howling noise when you go up and down bumps in the road.
caradiodoc
Dec 7, 2009 at 7:11 AM
