King pin steel

[gundog99]

What is the correct type of steel to make King Pins with?

[1929Chrysler]

Not sure what type of steel to use but what I was going to do with mine before I found a set was I was going to have the originals hard chromed and then have them lathed back down to the original specs. Would this be an option for you?

Dan

[gundog99]

It's a very good option; but these jobs always take longer than you think and I don't want my car of the road for too long.

[Bhigdog]

If you have them hard chrome plated you will have to have them centerless ground to size (unless they have center holes in which case they can be center ground). If I needed to make king pins I would buy a length of drill rod from McMaster-Carr, use it unhardened, and ream the bushings to fit. If you must have them hardened, buy oversize, have them heat reated and ground but it's going to get expensive fast.........Bob

[Jay Wolf]

Several years ago I had a machinist make me a set for my 1916 Elgin.

Make sure you and the machinist are on the same page.

I left the process up to him as he had made some for some of my friends.

I thought he would just take some steel and turn it down on the lathe and I would have a king Pin.

If I would have just put it on I would have had no problems.

BUT

He put a modern 1/8 zerk grease fitting on the top.

The old one had and I wanted a 1/4 grease cup on it.

Figuring he didn’t have the grease cup so he just stuck the zerk in for me in case I didn’t have one

I removed the 1/8 zerk and could see what I thought was a 1/4 to 1/8 adapter in the top under the zerk.. I tried everything to get the adapter out. Figuring he must have locktited it I decided to drill it out and retap it. When I drilled it I ended up with 2 pieced of metal the pin and the cap.

What he did was buy hardened steel rod then drill and tap the end and put a steel cap the correct shape on it (round with a flat side). And bolted the two together with a hollow bolt and put the zerk in the top center.

The shape and size of the pin didn’t allow him to bolt it together with a bolt large enough to put a ¼ fitting in it.

So I do not know what the correct answer is, I just know if you want it to look original don’t do it the way I did.

[Ivan Saxton]

You ideally use an alloy, low carbon content casehardening steel, similar to what you might use to make transmission gears. The hard case comes from absorbtion of carbon in the surface during heat treatment. The core remains low carbon content, so it is tough rather than hard. I tried to look up numbers for you of similar steels that we would use here, but the tables in Machinery's Handbook are a dog's breakfast and not set out conveniently by my logic; so I shall just give you a range of compositions. Probably the most suitable and economical has 0.12% carbon, 0.5%manganese, and 3.0% nickel. Better for high strength gears is 0.12% carbon, 0.5% manganese, 3.2% nickel, and 0.9% chromium. This would be good enough for heavily loaded truck transmission gears. A better alloy still which an engineer friend prefers when he has to make a new camshaft, is 0.15% carbon, 0.5% manganese, 4.2% nickel, 1.2% chromium, and 0.2% molybdenum. Where a manufacturer is making huge quantities of an item, obviously there is subsantial cost saving in a cheaper alloy that will do the job. Philosophy when making something in the restoration of an antique car that you are going to drive, is that the difference in money between grades may be trivial compared to the cost of making the item, so you may choose a better and more expensive material. But if your heat treatment firm has to do your little job by itself because its requirements are special, it will cost you. So the bottom line is that you should ask what the heat treatment man recommends. It is a shame I am much to far away to help you. I have a big centreless grinder that could hold two tenth's of a thou all day without dressing the grinding wheel. Ivan Saxton