King pin honing.

RHD

RHD

Well-known member
Kingpins.
If the diameter of a new kingpin is 0.8125", what should the final honed bush inside diameter be? I would have thought 0.8127. Or is that a little on the tight side?
Any thoughts please?
 
RHD said:
Kingpins.
If the diameter of a new kingpin is 0.8125", what should the final honed bush inside diameter be? I would have thought 0.8127. Or is that a little on the tight side?
Any thoughts please?
Click to expand...

Look at this original Ford drawing:

https://www.thehenryford.org/collec...l-collections/artifact/464587#slide=gs-337383

You can blow it up to clearly read the dimensions. If I post a copy of the drawing here, it will be low resolution (fuzzy).

As I read the drawing (check me) they are saying ream and burnish the bushing to 0.813 to 0.8135".

Based on that, what you are suggesting sounds a bit tight.

There are a lot of original drawings available on the Henry Ford archive website.
 
The king pin reamers on the market are 0.814" diameter, so the hole they will produce will be 0.8145" at best.
 
A FWIW, I have been toying with using a hardened ball to burnish bushings on items like spindles, pedals, and oil pumps. This is a great example where a bushing can be installed and reamed undersized. This will insure both bearings are in exactly the same plane. Then use sized balls to push thru the bushing which first expands it, then it burnishes it. The pressure by which this is done almost polishes the surface finish and makes the bushing extremely hard where longevity is increased.
 
I have always used an adjustable reamer and pilot,ITs is only used on the king pin bushings, nothing else so is still like brand new,
An expensive one off cost ,but does a first class job and will last for years.
Lawrie
 
A lot of piston pin bushings were ball burnished for a hand push fit. I have a king pin reamer that is long enough to pilot and has slots cut in it for a slight expansion. It was made to do the larger Mercury king pins for the mid century cars. They were likely available for the Ford car sizes as well.
 
The Ford drawing says "0.813-0.8135 D line ream & burnish in place".

It does not say just ream. It does not say ream to 0.814.

I would say line ream undersize and then line hone to final diameter would be a close alternative. But as Brent says, burnishing would probably give you a harder, longer lasting surface.
 
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Dan McEachern said:
Ball burnishing is nice bit it does little to align the two bores. Hone to a light push fit.
Click to expand...

I think we need to keep in mind that whatever the number, it’s the performance of the kingpin in the aligned bushings that is critical at the end of the day. Kingpins have their own tolerances for diameter, and what is the proper burnished diameter for one kingpin may not apply to another. Line hone to fit. If, as Brent proposes, you can get a tight fit with honing and then burnish to final diameter, great. Also recognize that very few of us (Synchro possibly excepted) will put the kind of mileage on our cars where the difference between honing and burnishing will be noticeable. If I need to rebush the spindles every 30k miles (I’m throwing out a number here, I have no idea if it’s realistic) then it’s conceivable that the tie rod and drag link bushings, and spring shackles, might need servicing as well. That would call for a complete front end rebuild.

As always, this has been a very interesting thread.
 
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