Dabney's "Darting" Dart
Dabney had promised himself to do a thorough lube job on his 1964 Dodge Dart, so on one particularly pleasant morning he backed the old "plain-Jane" Dodge into the lift bay and raised it up. Once the car was in the air he cleaned all the grease fittings and made sure each was properly filled and re-cleaned.
While the car was in the air he spun the front wheels and found the right one dragged a little, so he lowered the car to a few inches above the floor and removed the wheels to repack the bearings. Donning latex gloves, he cleaned and repacked the inner and outer bearings and reinstalled them into the axle hubs.
About that time the Doctor came by, so Dabney invited him to take a test drive in the Dart. "These old Darts were pretty basic," said the Doctor, "but they were rugged and dependable."
"That's true, Doc," said Dabney, "the slant-six engine and strong body structure made them a breeze to repair and millions of owners loved them during the years they were built."
They drove for a while and Dabney started noticing a tendency for the car to steer in a slightly skitterish way. "You know, Doc, this thing is darting from side to side in its lane," said Dabney.
"Well, it is a Dart," joked the Doctor.
"No, I'm serious," said Dabney, "it's not steering straight. When I lubed the car this morning I noticed the right tie rod end was pretty easy to move. Maybe it's ready to go. Let's take it back and put it on the lift."
They did so and Dabney twisted the tie rod end to show the Doctor its condition. The Doctor agreed that the tie rod end was a bit loose, but said, "I don't think this is loose enough to cause the poor steering tracking, old Boy."
"Well, I have a new tie rod end here in the parts shelves, so let's put it on and test the car again," replied Dabney.
You know what happened, of course. They installed the new tie rod end, being careful to count the threads showing on the old one so that the basic toe-in alignment wouldn't be altered too much. Once on the road the car still darted from side to side in its lane.
Back at the shop, the Doctor told him to put the car back on the lift. Once the car was in the air the Doctor shook the wheels from side to side, holding them at the 9:00 and 3:00 positions.
"See, Dabney," said the Doctor. The steering components aren't that loose. Notice that there's very little play when I shake the wheel. Try it yourself to feel the effects."
Dabney did so and agreed that he couldn't feel any significant looseness.
"Now I'm going to shake the wheel from the 12:00 - 6:00 position," said the Doctor. He did so and there was clearly a large amount of play at the hub. "Feel this, old Boy," said the Doctor.
Dabney felt the play and agreed that the wheel was loose at the hub.
"When were these wheel bearings last greased," asked the Doctor.
"I'm embarrassed to say that it was this morning," said Dabney.
"Looks like you didn't properly set the pre-load on them," said the Doctor.
"I ran the hub nut up tight and then backed off just enough to get the cotter pin in," said Dabney.
"I know, that's the way every mechanic always did it," said the Doctor, "but it should be done with a torque wrench. You didn't get the bearings set properly because the new grease wouldn't compress quickly enough. Let's do it right."
They consulted the manual and torqued the bearings properly. Needless to say, the car tracked straight after that.