The Studeblogger

Tuesday, September 04, 2007

Front End Rebuild, Pt. 7: Kingpin Installation

Well, it's been hotter than Hades the past few days. Too hot for working on cars, really. But I've been at it anyway :)

On Saturday, I began putting the Lark's front suspension back together. It didn't feel like I got a lot done; I started at 10AM and finished at 7PM, working pretty much straight through, and what I got done was reinstalling the upper A-arms on both sides, cleaning, priming and painting the front frame cross-member, bolting in the steering bellcrank center pin and installing the steering bellcrank. 9 hours for just that!

One of the SDC Forum guys mentioned that the cleaning and painting always takes the most time when you're doing repair work, and I think he's spot-on. I spent more time scrubbing and de-greasing that cross-member than doing anything else! But the results are worth it.

(I told my wife that the problem with making one part nice and shiny is that you want to make them all look that way! She wasn't laughing.)

Anyway, I got the goodies back on and was pretty happy at the end of the day. I learned a few important things, too:

  • Get Grade 8 hardware for reattaching all the suspension components. Yes, I know the parts that came off were Grade 5, but after watching four split-ring lock washers twist in half and the bolt heads become deformed while bolting in the center pin, I decided Grade 8 is the way to go for anything this important.
  • Use Loctite. Lockwashers are notoriously ineffective, and you don't want an A-arm dropping off at speed.
  • Buy a good torque wrench. Did you know that the error tolerances given for a torque wrench are for the maximum torque setting that wrench is capable of (unless otherwise specified)? So if you buy one of those cheap Chinese $15 wrenches at Harbor Freight that are rated at ± 4% accuracy and will handle from 10 to 150 ft-lbs., that's 4% of 150 - six pounds plus or minus. Big deal, you say? It is if you're trying to torque a bolt to an indicated 10 ft-lbs.! What you're actually getting could be anywhere between 4 and 16 ft-lbs.! Not acceptable, and not worth betting your life on to save a few bux. Go buy a good Craftsman wrench with a direct-reading scale. You can't put a price on peace of mind.
  • Studebaker's shop manual lists torque specifications for both the bolt and the nut for some fasteners, especially those pertaining to the front end. That means you must install the fastener by torquing the bolt first, then torque the nut separately to the specified amount. Watch out for these; they're easy to overlook.
  • Upper A-arms are identical on both sides. Lower A-arms are not; there is a different part for the left and right sides. Kingpins and steering supports likewise are different parts for each side. Make sure you cross-reference the part numbers and double-check before installing them!
On Labor Day, my brother-in-law Dave came over to help me get some more of it together. I'm glad he was here, since he helped me puzzle out a few things that didn't quite make sense, even though I'd been going over them in the shop manual for months.

Before Dave came, I installed the inner shafts and bushings in the lower A-arms (freezing the bushings helps a lot! Just be sure to wipe off the condensation before pushing them in). By 10AM when he arrived, it was already 90 degrees.

We installed the lower A-arms and then moved on to the hard part - the outer pins, kingpins and steering supports. This has to be one of the most-talked-about operations on the SDC Forum, since it's a slightly complicated procedure that involves calipers, measurements to 1/1000-inch, a special spreader tool and 170 lbs-ft. of torque for each bushing! And if you do it wrong, all your hard work will be destroyed after a few thousand miles. No pressure!

We got the driver's side steering support on, only to find that the shaft would not rotate freely after installation. We undid the assembly and I called StudeBob Kabchef, who was nice enough to lend some phone support. Even though the manual doesn't say so, it helps to pre-grease the inside of the bushings (not the outside!). Also, I had measured wrong with the calipers :P

We re-did the lower pin, and this time it worked. The manual says that the pins must "rotate freely" when the spreader is removed from the A-arms, but what they mean is that it must rotate freely with several hundred pounds of metal imparting inertia. In practice, if you can move the assembly with your hand with some effort and the bushings do not rotate, you are good to go.

We then put on the upper pin (the one the kingpin rides on).

I'd been counting, very carefully, the number of turns each bushing had been turned, making sure that they each received an equal number of turns. But for some reason, on the top pin, the kingpin was not centered no matter how hard I tried! One of the grease seals was massively pinched between the kingpin and the bushing; the other side was barely compressed. I posted to the Forum, and we decided at 2PM to knock off for the day - it was just too damned hot.

Bless the guys on the Forum! My kingpin wasn't centering because it was designed that way. You see, that upper pin is an eccentric; it's used for setting both the caster and camber of the front wheels. You make adjustments by removing the Zerk fitting from the rear bushing, inserting a 1/4" hex wrench, and turning. One full turn adjusts only the camber of the wheel; many revolutions of the pin slides the kinpin forward and backward to adjust the caster. (If you want more details, read this Forum thread.)

Armed with this knowledge, I went out this afternoon and cranked the pin several turns to center the kingpin. Much better!

Tomorrow I'm going to try to get the coil spring and steering knuckle on the driver's side, then on to the passenger's side later in the week. Stand by.

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