Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Chrome Vs. Stainless Steel King Pins

Can someone clarify the positives and negatives for these two types of replacement king pins? Since stainless steel contains chromium for hardness why one or the other? Is there a substantial difference between the various stainless king pins available by the lead sellers like Mulfab, New Elms, etc. Thanks,

Best follow this recent thread: http://www.talkmorgan.com/ubbthreads.php/topics/486519/1

The chromium content in a low strength soft stainless pin is there to increase the corrosion resistance, not to increase the material hardness or strength. Stainless pins are quite soft compared to the surface hardness of a hard chrome plated steel pin.

My stainless pins were badly worn at 5000 miles when I got my Roadster. And with four dealer stamps.

Roger uses the term "hard chrome" and that's the salient point.
I don't know the metallurgical reasons but the point is that not all chrome plating is the same.

Decorative chrome plating is not very hard at all and can easily be scratched whereas hard chrome plating is a specialised engineering process with the specific intent to leave a very wear resistant surface.

The Chromium in Stainless Steel is in relatively small proportions and is to provide corrosion resistance not wear resistance.

However, regardless of the metallurgical reasons, I think the overwhelming conclusion on TM is that Hard Chrome Pins outlast Stainless Steel Pins by a very large order of magnitude.

Hard chrome is definitly a hard wearing engineering product. We used it in the aerospace industry to recover undersize components after salvage. The finish was labarotory tested to be as good as the original surface properties.

If I recall, I think motorcycle front fork stanchions are hard chromed to negate excessive wear.

Steve, yes they are. Hard chrome is used for hard wearing surfaces. Most stainless & certainly AISI304 is relatively soft.

Bike forks also use Titanium Nitride, golden in colour.

There are indeed better solutions these days than Hard Chrome but as we tend to use stock hydraulic rod they would be a bit more expensive.

I have often pondered the thought of using a more modern coating such as Titanium Nitride or a Carbon based coating such as Nitron MC with Button's favourite "Vesconite" bushes.

Extremely low coefficient of friction and according to all the science, self lubricating so no grease to turn into grinding paste.

But that's the theory and what I've learnt so far in my very short Morgan time is that Morgan's don't always conform to sound engineering logic.

I shall continue to dream.

I have found there are two varieties of Hard Chrome Hydraulic Rod. One is "Induction Hardened" under the chrome and the other is not. From conversations with a Machinist Morgan Friend of mine, He speculates the "Induction Hardened" rod gives a better base for the thin layer of chrome. My King Pins are of the "non hardened type" as they are from the first batch I made. At 50,000 miles I inspected them and there was some damage to the chrome. I turned them 180 degrees and reinstalled them with the original vesconite bushes. I also did not grease for 2 years and I guess 10,000 miles with out greasing. Seemed OK to Me. I now grease once a year at Spring maintenance time.

I did replace stainless KP's and Devol bushes for a friend in Texas, the pins were badly worn but Devol bushes were OK. I replaced the Devols with Vesconite.

On My +4 I used Devol Bushes and chrome KP's. I have kept this system greased regularly. Seems to be OK. Over 40,000 miles on this rig. (My estimate) One of the attributes of Devol bushes is the "Resultant Fit". The axle tube is reamed and I had it honed. I have a set of Devol bushes in My spares.

Remember I live in Seattle, Washington, USA. The closest Dealer is 1,000 miles from Me. In British Columbia, Washington and Oregon there are about 150 Morgans. Not many of these are Road Worthy nor driven very much.

The use of Vesconite was pioneered by an Australian Mining Engineer. I found a source of this Material and introduced it locally. Vesconite if a South African product used in pumps for mines and the marine industry as well as other uses as a replacement for Bronze bushes.

If I were a Brit I would use Peter Mullberry's products. I am not and find making the pins out of hydraulic rod and bushes out of Vesconite is much less expensive and has done the job very well for Me.