Posted by Vaughn on Wednesday, October 04, 2006 at 9:15PM :
This is one for your PW scrap book of problems and solutions. What turned out to be a simple front brake shoe adjustment turned into two months of problem tracing and fixing before I found the problem.
It all started by adjusting the front brake shoes and immediately afterwards, I had a front end shimmy at about 10 miles and hour and again above 40+ miles an hour. I thought maybe the drums might be the problem, they were a little out of round, so I backed off the shoes – didn’t work – shimmy still there.
Next, I jacked the truck up and starting looking at possibly loose bearings or worn tie rods. What I found was the right tie rod was loose in the steering Knuckle Flange (KF). About 10 years ago I bought NOS tie rods ends from VPW and the fit was not the same for the left (black) and right (OD) tie rod ends in the KF. The left had a ¼ inch gap between the end and the KF and the right was fairly flush against the KF. Up inspection of the right tie rod end, the stud protruded about 1/8 of an inch up the KF (1/8 without threads). Although the tie rod end appeared tight, the stud worked an oblong hole in the KF requiring replacement of the KF.
Lesson Learned – When you get NOS replacements and there is less than ¼ gaps, tighten the end using a lock washer and then back off the nut and check to ensure the stud is not visible – you should only see threads. If the stud is visible, you may need to use washers to ensure you have a tight end.
Also during the rebuild 10 years ago, I replaced the bronze cone with NOS. The cone I got had grease grooves down the side but not a spiral groove. The lack of a spiral groove caused the cup to wear due to lack of lubrication even though I greased the caps regularly.
Lesson Learned – Use cones that have both a spiral and straight side grease grooves
Since I did the right KF, I also did the left since both sides needed the felt seals replaced anyway. Ok, font all rebuilt and problem still there – darn!
Ok the next item was to replace the worn spring bolts/bushings, so I ordered new bushings and bolts, rebuilt, and checked the toe-in which was fine, but problem still there – dang it! You can get front bushings for $5 dollars on the net. They are steel on bronze (1/3 bronze, 2/3 steel)
The next thing I did was to start focusing on the drive train. When the problem appeared at about 10 miles and hour, I grabbed the shift lever and could feel a jerking sensation that would come and go with the front end shake. So today I rotated my tires and in doing so I jacked up the rear wheels and worked the driveline and found the front UJ of the rear propeller shaft had some play in it, so I replaced it – problem solved, hurray!!
In chasing this problem, I never considered wheel balancing as an issue since the problem appeared instantly, but I also can’t explain what caused it to appear when adjusting the brake shoes. Just one of those weird things!
Interchanges
M37 tie rod ends do in fact interchange
M37 small UJ does in fact interchange
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