rod bearing retainers

[zig1]

Building a 47 U motor and the new rod roller set has aluminium retainers and 17 slightly shorter rollers . The original steel retainers are good and have 18 rollers ( approx .035 longer ) that need replacing. What is the opinion on steel versus aluminium roller retainers please , Thanks in advance

[larry]

You might want to measure the rollers that came in a "set".

[41craig]

Zig1 you bring up something that I have wandered about for years. Would using the lighter weight aluminum retainers interfere with the flywheel assembly balance ? Being that the stock factory set up was balanced with the slightly heavier steel retainers.
Craig

[T. Cotten]

Zig1 you bring up something that I have wandered about for years. Would using the lighter weight aluminum retainers interfere with the flywheel assembly balance ? Being that the stock factory set up was balanced with the slightly heavier steel retainers.
Craig

Craig!

There is only one rotating weight, and one reciprocating weight in balancing technique.

Aluminum cages just make the rotating weight slightly less.

A fart in a hailstorm.

....Cotten

[41craig]

Thanks Cotten ! I figured it would be minimal. Especially on a side valve.
Craig

[chuckthebeatertruck]

Building a 47 U motor and the new rod roller set has aluminium retainers and 17 slightly shorter rollers . The original steel retainers are good and have 18 rollers ( approx .035 longer ) that need replacing. What is the opinion on steel versus aluminium roller retainers please , Thanks in advance

Please post pictures of what you have. There are some really crummy replacement rod sets that use the retainers from much later harleys. Some of these sets have pins that are .010 oversize to boot!

If you have wheels fit for a straight shoulder crank pin, then you can use either steels or alloy. I greatly prefer steel vs the alloy cages, but it is getting tougher to find good ones. Lots of terrible aftermarket, but few I'd want to run hard.

Alloys help with roller alignment, but you have to pay attention to roller length to avoid any roller hanging in a window of the cage. They offer the ability to hone races an extra thou before a full rebuild, but that's about it. NOS alloy cages are plentiful, steels are hard to come by.

On some wheels, you do have to worry a bit about alloys picking up grit from the oil, which embeds in the cage outer shell and more rapidly wears the inner face than would a steel. How much faster is dependent on too many other factors to say whether it's really gonna be an issue for you or not. Likely not, but the worst case is machining the wheels to repair. Not the end of the world.

We are living in an era of increasing compromises with parts. When in doubt, do it as close to factory as possible.

My '46 UL is currently on alloy cages, but that is another story.

[aumick10]

Building a 47 U motor and the new rod roller set has aluminium retainers and 17 slightly shorter rollers . The original steel retainers are good and have 18 rollers ( approx .035 longer ) that need replacing. What is the opinion on steel versus aluminium roller retainers please , Thanks in advance

zig 1,
I have used both types of retainers and I haven't found that either one has an advantage over the other when used in a flat head. High performance late motors may take a small advantage of the lower weight Al retainers.
I assume your rods have been honed round again, and measured for the correct oversize rollers. You probably cannot use a standard roller OD again, unless the rod races have been replaced.
The extra bearing in the steel cages may give you slightly more life, with the extra bearing surface, but on a flathead, it is unlikely you could even measure this.
I have found that all rod bearings can vary in size, but the difference is so small, you need good measuring gear to even see it.
Good luck.

[T. Cotten]

Two advantages of steel over aluminum, Folks,...

Aluminum can embed with abrasive particulates, and steel can be parkerized to retain an important film of oil.

There may be more...

....Cotten

[kitabel]

Easy test for distortion, bending, etc. in steel cages: face the open ends toward each other and rotate them so that the fingers enter the opposite slots. They should move freely to full depth w/o binding. Now rotate it and try different pairs. Any resistance: try each one with a 3rd cage to see which is bad (could be both).

There are also 2 types of 3/16" rollers and cages with the same width and diameter, but the later ones (1948?) having slightly thicker rims and shorter slots and rollers. The early (long) rollers are not safe to use in the late cages - not enough freedom. To test: lay the cage down with the fingers up and the rollers inserted. There must be free space above each roller (below the finger top). The late (short) rollers should be safe in early (long slot) cages, but I haven't done it.

[zig1]

Thanks for your replies. Here is a pic of the old and new , new is approx 0.002 narrower than than the steel . Thanks20190704_085445.jpg20190704_085522.jpg

[chuckthebeatertruck]

Steel in my world. Did the motor sit, or am I seeing false roller darkening in spots on the "old" picture?

Just curious . . .