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Who makes aluminum rods?

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Posts: 13
Eminent Member
Topic starter

I need someone to make two aluminum rods for my 1905 Logan.
Approximately 10 inches long, 1.6 by 2.5 rod journal by 1 inch wrist pin.

<tom> or 607 592 2092

Posted : May 18, 2009 4:12 am
Posts: 11
Active Member

Just Google "aluminum connecting rods" and quite a list comes up.
Leroy Francies

Posted : May 18, 2009 2:00 pm
Posts: 307
Honorable Member

Did your Logan originally have aluminum rods and pistons?


Posted : May 21, 2009 6:54 pm
Posts: 13
Eminent Member
Topic starter

I am assuming it did not originally have aluminum rods I don't have any connecting rods and will have to have them made anyway. The crank shaft was so out of balance we had to make counter wights. So I have decided to lighten as much as can. I am using alumimun pistons. It had cast iron before.

I talked with Garyl Turley and probably will attempt to make my own. As Garyl says, "it is not rocket science". I have a couple of friends who are machinist and will ask them if I don't find someone.

Posted : May 22, 2009 4:14 am
Posts: 12
Active Member

The conrods used by Stutz and others were an alloy called Duralumin, which is much stronger than aluminium itself. They were good, but the book instructed that the big end bolts should be tightened with a spanner no longer than 6 inches.
Now when they changed from a Dural. cap to steel in the 1929 M series and the 6 cylinder ohc Blackhawk they more than doubled the risk of conrod breakage. With a steel conrod, when you tighten a quality conrod bolts to correct (lubricated) torque setting, you will find that the bolts have stretched (within their elastic limit).
With alloy rods the steel bolts do not stretch, but the rod is compressed and stressed around the bolt holes. I have quite a few Stutz conrods that are cracked at 10 oçlock and 2oçlock, starting beneath the heads of the bolts.
The other thing that can be a problem is the bond between the rod material and the tin-based bearing metal. The way it was done originally and still works is to scratch-tin the heated surface with a stick of pure tin, while scraping with a sharp stainless instrument to remove the inert surface layer of aluminium oxide. You then build up the thickness of the tin as desired, then pour the bearing metal as normal. The problem is then to determine whether you have proper metallurgical bond: a dull sound when you strike the rod indicates that there is no bond or precious little, whereas a ringing sound shows that you have some. I have peeled the original bearing metal out of Stutz conrods with a pocket knife; so I suspect that the bond strength may deteriorate with time or use.
You can overcome this with a wire- feed Metco sprayed metal coating system; but you have to find someone who will bother to do a fiddley small job for you. The danger with a bearing becoming detached is that it can lock the conrod on its journal, bend or break the rod, and achieve an unplanned crankcase ventilation.
And always remember that the difference in material cost is insignificant compared to the effort and cost of making the part, and the cost of fixing disaster. Ivan Saxton

Ivan Saxton

Posted : June 25, 2009 5:35 pm
Posts: 4
New Member

Ivan had good ideas but here is a few more things to think about, aluminum rods have to be larger in order to equal the strength of a steel rod. (you may have a clearance issue). If you make the rod out of 4140 chromoly you will have a strong rod with not much wieght as a origianal rod. If you are stuck on alluminum I would say to go with a 7075 T651 alluminum rod and make bronze back inserts so you don't have to worry about the babbit breaking free. Also If you have not bought your pistons yet try to find a off the shelf piston that has a bore size that you can use and make your rods to the right length to match them. It might save a few bucks. Most new pistons have a free floating wrist pin and that makes the rod easyer to make if you install a bronse wristpin bushing and get the all up rod line honed to make sure everything is stright. Just my thoughts I would make nice light wieght chromoly rod and sink some ARP rod studs in it and call it done.

Posted : June 30, 2009 6:36 am