King pin

There are good instructions in Les Andrews books on how to disassemble and reassemble the front axle components. You can replace the king pins and bushings at home but you will need a good king pin bushing reamer or a king pin bushing hone. Better yet, do all the disassembly and reassembly work yourself and take the spindles with the new bushings installed along with the kingpins to an automotive machine shop and let them hone the bushings to the proper size.

My opinion,

Chris W.
 
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Make sure your machinist knows the correct clearance for Model A kingpins. I assumed my machinist knew, and he got it wrong. And he is one of the most respected and experienced machinists in Portland!
 
Make sure your machinist knows the correct clearance for Model A kingpins. I assumed my machinist knew, and he got it wrong. And he is one of the most respected and experienced machinists in Portland!






How could a good machinist get this wrong ?
 
With new pins, bushings, and a reamer the job is doable at home if you have the means to press in the bushings. The pressing and reaming must be accomplished in a special sequence to ensure concentric bores - but not difficult. Do some homework and go for it !
 
How could a good machinist get this wrong ?

The answer: poor training and a feckless disregard for proper attention to a steering component. When I had to replace the kingpin on one side of my coupe, the machinist returned the spindle to me so loose that the king pin easily fell out by its own weight. When I commented on this he answered with a smirk and sneer that it would be just fine with a shot of grease. To add insult, his charge for this "service" was 60 dollars.

Enough, I said! I drove out the bushings (0.003" clearance!) and replaced them using a piece of 3/4 inch all-thread, washers, and bolts on each end. I covered the threads potentially in contact with the bearing surfaces with duct tape to a thickness close to that of the kingpin.

Next, I wrapped a 6 inch section of 3/4 inch hardwood dowel with several wrappings of 400 grit sandpaper and pressed the unwrapped 1 inch end into a socket that allowed for a tight (and centered) fit. I placed the socket and sandpaper piece into a short bit of 3/8 inch square keystock, chucked this into a variable speed drill, and started honing out the bushings in the spindle. After multiple iterations of this I had it pretty close and finished up with a wrapping of 600 grit wet/dry sand paper, with water added during the process.

The result: a perfect fit with a smooth bearing surface top to bottom and at a cost of a few dollars and a few hours spent. I will never take spindles to a machinist again.
 
Is there a method for doing them at home ?

No problem if you have access to kingpin reamer.
A kingpin reamer is a precision reamer that is long enough to go through both bushings at the same time. They are kind of expensive but nice to have.
Bill
 
Quick question - should the cup be facing up with felt against the axle, or upside down with felt against the lower king pin bushing?
 
I'm starting to trust myself in these times than someone I don't know
that is a machinist. Said that, If I knew one real well, than maybe.
 
I once had a set of king pin bushes a little too tight. The car was impossible to control at anything over 40 mph so I took it all apart again and figured out the way I now always do it. I ream them a bit tight, then using the part of the old king pin that was in the axle (and therefore unworn) and some valve lapping paste, I lap till I get the correct fit. The bushes might be only 0.0005" too tight but that is enough. Wash and clean thoroughly and assemble. It works better than any other method I have used or even seen used. The proper fit is when you can push the oiled pin through the bushes with your thumb without straining.
 
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