Setting Knuckle Pre-Load

[davide]

In anticipation of getting all of my goodies for the front end, I am trying to understand the test procedure for the kingpin bearing load test. There were shims in both upper bearing caps and I have kept them as they were when I tore it down. And BTW, both side kingpin bearings were shot. Drivers side upper was the worst (I think I posted a pic of one previously).

The Universal Series Service Manual talks about a scale reading of 12 to 16lbs when the knuckle has started its sweep. I understand the sweep of the knuckle, but don't know of a simple way to measure this load. How critical is it to get it spot on? Will a "resistance feel" tell me the same thing?

[51 CJ3]

Fish scale works well. Take the reading when the knuckle starts moving. My guess is too tight might affect steering. Too loose could let the front end shimmy.

[bmorgil]

Jeff is correct on both points. A fish scale works well. Too tight and the wheel will have difficulty returning to center after a turn. Too loose and you will get shimmying and if it is loose enough, it is the cause of "Death Rattle". An out of control front wheel shake when the looseness starts to resonate. "Death Rattle" can shake the vehicle right off the road. I like to keep the load on the high side. I wouldn't worry if it gets a little too tight. Much better than too loose. You are looking for a good smooth pull around 16lbs or so. Keep the scale at 90deg to the hub as you pull.

[LarrBeard]

" "Death Rattle" can shake the vehicle right off the road."

Been there, had it happen. It didn't shake me of the road, but it did make me have to come to a complete stop in the middle of a busy state highway.

[davide]

As it turns out, my wife picked up a digital scale to check luggage weight. I razzed her about that and now have to eat some crow as I have borrowed it to use for this.

Bob, I noticed that your picture has the hub fully assembled when performing the test. My axle is fully striped down with only the steering knuckle attached via the kingpin. This seems to be how the Universal Manual describes the procedure. Should I assemble the entire brake/hub assembly when doing the test?

[bmorgil]

No need to have it assembled all the way. The important thing is to keep the scale 90 deg to the spindle and a fairly smooth pull. That photo is a grab of a different type of vehicle. I think it is a truck. The process is the same however. Just hook the scale into the tie rod hole and pull maintaining that 90. You shouldn't have any seals assembled. Theoretically you don't want to add any drag from the seals.

[davide]

I got the last of my front end parts a couple days ago and have started getting things back together (almost).

With the tie rod ends off the steering knuckles, I got the passenger side knuckle at 15 lbs after removing two shims. The drivers side, with the original shims back, is at 18 lbs. I haven't added any shims yet to lower the pull weight, but I have two to work with.

As long as I was having to remove the tie rod ends, I wanted to replace the boots on them as a couple were rotted with time and oil. When I got the steering rods out and cleaned up, I saw that 3 of the 4 tie rods ends looked worn and oblong. They were all still fairly tight, but I figure that these need to be replaced too. Here are some pics to show. Also note that I have a steering damper shock bracket on one of the rod tubes. I don't think that this is stock, but am not sure (and yes, there is a steering damper attached).
9464 9465

[bmorgil]

The tie rods look pretty beat up. I would replace them. The assembly with the tab welded on is modified. The steering damper is not stock. The tab and the piece of pipe slid over the rod and welded in place, are "fixes". The tie rod was bent and the pipe was added and welded in to try to keep it from bending again. This reinforcement is common in off roading. The tab was probably added to make the stabilizer mount more permanent. I would replace it all and not use the stabilizer. 18# is a good number. A little tight is much better than a little loose. As long as its a fairly smooth pull.