Reaming Axle Spindle to fit King Pin

[Keith]

I just installed new bushings in my axle spindle and reamed with a brand new reamer from one of the suppliers. New King Pin is extremely tight starts to go but then gets very tight. Any tricks after reaming to make a slip fit.
Keith

[1931 flamingo]

Take them to a local machine shop and hone them to fit.
Paul in CT

[Martinbuilt]

I had one like that, the pin was slightly bent.
Maybe check that as well.

[Fhane]

Ream again. Never turn a reamer backwards. Use a good cutting oil for reaming. Make sure reamed hole and king pin are absolutely spotless. Now try it. If sill a problem call the vender. Hopefully you bought the reamer and kingpins from the same vender.

[Keith]

thanks to all will run the ream through again

Keith

[Jim/GA]

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I ran across the following video about reaming spindle bolt bushings a few days ago and I thought it was very well done.

https://youtu.be/q6H9VL22NNc

Lots of cutting oil, never turn the reamer in the opposite direction, clean the reamer often, and gently take a second pass through the bushings.

This guy does it outdoors on an old picnic table!

[Synchro909]

Originally Posted by Jim/GA

I ran across the following video about reaming spindle bolt bushings a few days ago and I thought it was very well done.

https://youtu.be/q6H9VL22NNc

Lots of cutting oil, never turn the reamer in the opposite direction, clean the reamer often, and gently take a second pass through the bushings.

This guy does it outdoors on an old picnic table!

That's not a bad video but I saw something VERY wrong as he reassembled the king pin. A hammer should never be used on the head of the cotter pin - pulling it in with the nut is quite enough. Hammering is very likely to stretch the eye in the end of the axle, ruining it. I've seen it done too many times.

Back to the OP's question. If the king pin bushes are too tight, the car will be impossible to control. I use an adjustable reamer and stop just short of finished size. I then use the unworn part of the old king pin (the part that was in the axle eye) with some valve lapping paste on it and lap to a nice fit. After THOROUGHLY cleaning the bushes, add a drop of oil and check for a good fit. A good fit is when you can push the pin through the bushes with your thumb without straining.

[Keith]

Found the cause for the King Pin binding when fully inserted into the spindle. There is a slight taper ~ 0.001" on the king pin diameter, larger at the closed end toward the half ball end. Used 1200 grit emery while spinning the king pin did the trick. I also found the grease groove that runs along the length of the king pin was sharp. I stoned it and now the fit is good.
Keith

[Phil Brown]

Originally Posted by Keith

Found the cause for the King Pin binding when fully inserted into the spindle. There is a slight taper ~ 0.001" on the kingpin diameter, larger at the closed end toward the half-ball end. Using 1200 grit emery while spinning the kingpin did the trick. I also found the grease groove that runs along the length of the kingpin sharp. I stoned it and now the fit is good.
Keith

Happy that you got the problem resolved, but sad that something that needs tolerances as tight as a kingpin can not be held in the manufacturing

Care to share the brand of these inferior parts for others to watch out for ?

[Keith]

I purchased them a few years back and were from either Snyder or Bratton, my guess is that when they were ground between centers by the mfg. and that the wheel was dressed or worn with a slight taper on the side which comes up against the half round cut end and flange. Keith

[CT Jack]

You need to follow Keith's suggestions. Measure, measure. Reamers are usually very uniform in diameter over their length. As he suggests king pins can contain taper over their length. If you accurately measure the king pin diameter at several places along it's length you will probably notice a small change. King pins which are hardened steel are usually machined by grinding. As the grinding wheel moves from one end of the pin to other it wears causing less material to removed toward the end of the pin. If the machinist doesn't compensate for this condition this is how the pin diameter becomes tapered. In general, the amount of taper is usually less than .0005" which is enough to create a no-go condition. Polishing the tapered area of the pin with a fine emery type abrasive usually fixes the problem. Repeatedly running a hand controlled reamer through the hole is not a good idea as it increases the chances of changing the precision of the newly cut diameter.

[Dodge]

If their a little tight I use a ball hone for that last little bit.

[alchemy]

Originally Posted by Synchro909

That's not a bad video but I saw something VERY wrong as he reassembled the king pin. A hammer should never be used on the head of the cotter pin - pulling it in with the nut is quite enough. Hammering is very likely to stretch the eye in the end of the axle, ruining it. I've seen it done too many times.

I disagree. I have snapped the threaded portion off a kingpin lock when trying to pull it in. Now I always take a punch and hammer to tap the lock into position. I’m not whamming hard on the thing, but I make sure it’s very snug in there. I am never hitting the axle with the punch or hammer.

[Synchro909]

Originally Posted by alchemy

I disagree. I have snapped the threaded portion off a kingpin lock when trying to pull it in. Now I always take a punch and hammer to tap the lock into position. I’m not whamming hard on the thing, but I make sure it’s very snug in there. I am never hitting the axle with the punch or hammer.

Did you line up the king pin in the hole by eye before inserting the cotter pin? I put the pin in the hole, then turn the king pin by hand and set it at the middle of the range to allow the cotter pins to slide in easily. The brake actuating arm can make that a bit challenging but the further the pin goes in, the less it will turn.

[Bruce of MN]

I had a tough time inserting my cotter and wished I had tried it first without the kingpin to check the fit.