Having a 318 c.I. Means this is a full-size "B" van. To replace the upper control arm bushings means the arm had to be removed. The two bolts that hold it on are the adjustments for "camber" and "caster" on that wheel. Those are two of the three main alignment angles. There is absolutely no possible chance you can put that arm back on and expect it to be in alignment.
To create a point of reference, the slots those bolts go through allow camber to be adjusted roughly from -3.00 degrees to +3.00 degrees. 0.00 degrees means that wheel is standing perfectly straight up and down. If you imagine the wheel being tipped out so far on top that it's laying flat on the ground, that would be 90.00 degrees. Three degrees is more than enough tipped out on top to see by eye, and negative three degrees means it's tipped in on top, also easy to see by eye. The typical alignment spec is near 0.50 degree, not easy to see except with alignment equipment.
There is a trick to get you really close with camber by using a magnetic carpenter's level, but the vehicle has to be supported solidly on jack stands so nothing moves, then you install the new parts to bring angles back to where they were when you started, but that only works with strut suspension with just adjustable camber. Caster is not a variable with that system.
The effects of caster can be explained at least five different ways. Once you understand one way, the others will make sense, but to simply know what caster is, think of the front fork on a bicycle and how it angles to the rear on top. By putting your weight on it, that's what allows you to ride no-handed. Caster is viewed from the side of the wheel. Vehicles today use positive caster. On your van, positive caster means the upper ball joint is rearward compared to the lower ball joint. By placing the vehicle's weight on the tire, that wheel is going to turn toward the center of the van with so much force, you will barely be able to pull it back by hand. The idea is the same thing happens on the other side, and with equal force. By connecting the two wheels together with the steering linkage, the two forces offset each other. The goal of the alignment is caster must be exactly equal on both sides so the two pulls offset each other perfectly and the van goes straight when you let go of the steering wheel.
Camber also affects pulling. A tire wants to pull in the direction it's leaning. For best tire wear and best handling, most vehicles call for slightly positive camber, typically close to 0.50 degrees. For least steering wander and best steering return to center after going around a corner, the best caster setting is around 3.00 degrees positive.
I forgot to mention, the control arm is a big triangle. By loosening the two mounting bolts, that shaft can be slid in and out in the front and in the rear. To adjust camber, that shaft is slid in toward the vehicle's center, or out, both bolts equally. Here's the hard part. To change only caster, one bolt is pulled out and the other is pushed in. That moves the upper ball joint forward or rearward.
So, ... First, all four adjustments, camber left and right, and caster left and right, must be set to specs for best tire wear and handling. Both are typically set within a range of less than half a degree to be in specs, while the range provided is closer to 6.00 degrees. Second, it is critical that camber on both sides be the same so it doesn't cause a pull to one side. Caster must also be identical on both sides so IT doesn't cause a pull and so the steering wheel returns to center on its own. Third, to add more confusion, and another variable, we adjust camber just a tiny bit higher on the left wheel, or we make caster just a fuzz higher on the right wheel, or we use a combination of both, to produce a very slight left-hand pull. That is to make up for the effects of "road crown". That is when roads slant to the right so water runs off.
With your control arm design, those mounting bolts slide through slots that are about an inch long. Moving one bolt in or out 1/16" can send camber from perfect to way out of specs. Same thing can happen to caster. With such tiny movements causing such huge angle changes, only computerized alignment equipment is accurate enough to do the job. The last variable is when either bolt is shifted, both camber and caster change. You might get camber set perfect, for example, but when you try to adjust caster, camber changes too, so it's a frustrating job of jockeying the adjustments back and forth numerous times until you get both angles set where you want them. The first side is pretty easy to get them to where both are in specs, but then you have to be more particular on the second side because besides getting both adjustments into specs, they also have to match the first side.
My reason for sharing the wondrous story is to point out there is absolutely no way to get the vehicle in alignment without using the computerized equipment. An experienced alignment specialist such as me can spend an hour of frustration getting both wheels set equally, then the final adjustments are "toe" on each wheel. That is the direction the wheels are steering when the steering wheel is perfectly straight ahead. That is the second tire wear angle, and it can cause an off-center steering wheel.
There's one more variable worthy of mentioning that is especially important on your van. That is chassis ride height. This is an age thing, not so much mileage, as it is caused by weak / sagged coil springs. If you look back from in front, you'll see your lower control arm is very close to parallel with the ground. The upper control arm angles downward toward the ball joint, and it is considerably shorter than the lower arm. The steering knuckle and the frame rail make up the last two sides of the parallelogram. These four parts have a very carefully designed-in geometric relationship. They cause that wheel to tip in and out on top as the suspension bounces up and down as you go down the road. That reduces how much the tread scrubs left and right across the road surface to reduce tire wear.
All of the geometric stuff goes out the window when ride height sags. Even though camber can still be set to specs and look perfect on the alignment computer's screen, that only applies to a van that's standing still. Tire wear can be miserable, as in rapid wear, because the wheel no longer goes through the desired motions when moving up and down.
Now that I've convinced you an alignment is an absolute must, let me suggest an alternative to the typical tire and alignment shop. Look for a nearby community college with an Automotive program. We were always looking for live work to give our kids real-world learning experiences, and we had about two dozen community member who knew the value of those jobs, so they would sit on a broken car until it fit what we were teaching. In my case, I taught Suspension and Alignment once per year, for eight weeks. We would not do alignments during, say, Brakes, or Electrical classes because doing so would potentially take work away from the shops that hired our graduates and supported our program. Another drawback is part of the 20 hours per week was spent in the classroom, so it could take a few days to get your van back.
On the flip side, we charged ten dollars per hour for what the job was supposed to take, not how much time the kids actually spent on it. A basic four-wheel alignment typically calls for around 1.3 hours. We also got replacement parts at very nice discounts, then marked them up ten percent to form a "breakage" fund in case we damaged something. (That, fortunately, was rare). This way, the alignment would cost less than $20.00. The instructor will be involved too to supervise and to okay the results. Your van may even be rechecked by multiple students. This will vary between schools, so talk with an instructor at more than one place if possible. They will check for broken tire belts too, and can show you how to look for that elusive type of broken belt that most people won't see. By the way, people commonly run their hand over the tire tread to look for a hump or tumor. That works with badly broken belts, but those are very often accompanied by steel belt wires sticking out. Watch out for those as they really smart when they poke your hand. That has happened too many times to me, so now I pat my hand as I go around the tire, rather than rubbing it across.
You mentioned the wobble got worse after you reinstalled the control arm. A likely cause is camber is too high now making that tire run on the outer edge of the tread. If there's a bulge in that area, you will feel it more now.
As for the noise, if that is a metallic clanking heard mostly on bumpy roads, the best suspect is a broken anti-sway-bar link. That has no involvement with the alignment and is not related to a wobble. Worn ball joints make more of a dull thumping noise only under certain driving conditions. An instructor will often use vehicles like yours to show how to inspect the various parts and how to raise and support the vehicle so undesired movement in worn parts can be made to show up. They will also have a small book that shows every year and model, where to take the ride height measurements, and what they should be. Chrysler, in particular, has a complicated method that involves taking two measurements at each front wheel, then calculating the difference, to get the reading. Their method eliminates the variable of using non-standard tire sizes. Many newer alignment computers now have ride height measuring capabilities built in.
One last comment of value, your suspension system is referred to as the "short / long arm", (SLA) suspension system. It is very heavy, and uses a lot of parts, so it was only used on older heavy rear-wheel-drive cars and trucks, but the huge advantage is far superior ride quality compared to struts and especially I-beam and twin I-beam systems. When a tire hits a bump in the road, the forces go through multiple parts and change direction each time, so very little road force is left to be transmitted into the passenger compartment.
Let me know if I covered everything, or if you'd like more detail on one of my favorite subjects.
Wednesday, May 14th, 2025 AT 12:46 PM
