Broken kingpin

[Peter Naulls]

An unwelcome explanation of my wandery steering ... and I was hoping it was just a flat tyre!

   

[Ruairidh Dunford]

A batch of king pins were incorrectly hardened some 20 years ago, or more. If from that it has done well to last to date. Replace both sides with new.

I trust everyone is safe and unscathed?

[Bob Culver]

With it fractured in two places lucky no to lose a wheel. How did it get so rusty? Can hardly be greased too often. Pins of Oz Dufor manufacture have poor reputation here. Poweful brakes not entirely a blessing. The bits more securely retained with the pre Girling hubs.

[Austin in the Shed]

More of a case of using the wrong steel. Most likely En8 was used as when hardened due to the carbon content hardens through and makes it very brittle. Welding it has similar results the heat draws the carbon to the joint and produces a week weld.
Normally En32 or En 36 would be used, both case hardening steels.

[Nick Turley]

Ouch !

[Peter Naulls]

That was my first thought that it was too brittle. No idea how old it was, a lot more than 20 years though.

I reckon the first break occurred 30 miles or so before the second - the steering became sufficiently vague that I stopped to check tyres and wheel nuts. Just before home the brakes started to affect the steering quite noticeably and I knew something was wrong. Thankfully both breaks were within the height of the axle eye so it all held together, just! No harm done.

[Bob Culver]

Eons ago when my car was everyday transport I used to grease the kingpins every 200 miles or so and habitually wiggled the wheels. Discovered a broken kp. Subsequently purchased ground ht rod and had it hard chrome plated; I did not know that such may be available commercially. A problem is that being relatively soft, difficult to insert without spreading. 
A complication with the pre Girling hubs is the need for a blind reamer. Unless the backplate and brake cam bush are removed, not a major exercise.
Kingpins on some other cars ie Ford 10 are notably soft. Noted NZ special builder and owner of the Rubber Duck  Lester Reader used lengths of silver steel in his special (although of modest uts). Dunno  how well this would wear with moly grease.

[Parazine]

With it fractured in two places lucky no to lose a wheel. How did it get so rusty? Can hardly be greased too often. Pins of Oz Dufor manufacture have poor reputation here. Poweful brakes not entirely a blessing. The bits more securely retained with the pre Girling hubs.

The king pins rust because they are greased with a grease that is not waterproof. I raised this on the old forum years ago but got shot down in flames.

Use a grease that is waterproof, i.e. a calcium based grease, used to be Castrol CL but others have to be found now that Castrol have run away from the market. Lithium based grease forms an emulsion with water, leading to the damage (but not the breakage!) in the photo. I know we all have our favourite greases, oils and whatever but using a waterproof grease on the exposed chassis parts will stop the rusting illustrated.

I'll go and take cover - prepare for incoming!

P.S. tried silver steel kingpins years ago, when the debacle of overhardened, 10 thou undersize, tapered kingpins was running. They broke within 500 miles.

[Colin Reed]

HI BOB,
WHAT SORT OF FINISH DID THE HARD CHROME GIVE and did you use it As returned from the Platers

Colin
NZ

[Steve Jones]

Ruiradh's right about the origins of those king pins but more like 40 years ago than 20. Time flies when you're having fun!!

Steve