Stein

iTrader: (46)

They are REALLY soft--wouldn't even register on the Rockwell C scale. I didn't bother to change the tips and weights on the hardness tester to check on the Rockwell B scale. Suffice to say, they can be made from pretty much any steel and be harder than these parts.

Zabac

iTrader: (39)

Wait, you already done? WOW!!!1!1!! I am impressed!

Now, to those of us without selective tretiary in this field, what do they compare to? You say they are really soft, but how soft. I am trying to get an idea of what to look for from the new gears. For example, what compares to the lowest Rockwell C scale level? Cams, rods, pistons, butter? You know what I mean?

Also, do you have any input on what type of alloy we may need to use in this appllication? I know strength is key, but as I understand there are different types of strengths to metals, no pro here, but don't some metals snap sooner than they will bend and vice versa? What type of properties do we need to look for in our app.?
Due to the nature of what these gears do and what they have to withstand, it may be a great idea to have them coated as well. Myabe dry film lube would suit us best, but since we really do not need corrosion protection since these are constantly oiled...

Those are not familiar with coatings, read this to get an idea.
http://www.enduracoatings.com/prodma...FQG5PAodZgH8zw

y8s

iTrader: (8)

http://www.gordonengland.co.uk/hardness/rockwell.htm

Stein

iTrader: (46)

They are probably as almost as hard as normal mild steel that you are familiar with. Harder tham aluminum. They cut easily with a file. They are sintered metal parts. That means powdered metal that is packed in a die by a high pressure press until it holds it's shape and then run through an oven that heats just to the melting point, allowing the particles to fuse together. That being the case, because the part is not COMPLETELY solid like a billet part, it could affect that hardness rating. Harness is tested by forcing a pointed diamold into the metal. The softer the metal, the more it presses into it. Because it is sintered, the reading may be artificially softer than the part, but not significantly.

patsmx5

iTrader: (16)

Just a regular steel will work. No fancy super everything alloys are needed. The stock gears are sentered and are brittle compared to a steel. A steel gear will do it. I would NOT coat these gears. No point. Let's make them cheap.

y8s

iTrader: (8)

John, you may want to do the B steel ball test just to get a number to compare to. Unless it's a huge hassle.

one of the things with sintered materials is that they dont have a lot of interstitial strength because of the limited recrystallization of the metal. on a microscopic scale you can imagine it looks like styrofoam. a bunch of beads all heated and pressed together.

you *could* keep reheating the part to red hot and slowly cooling it back down to improve this and essentially 'reflow' the steel, but it's time and cost intensive and for less money you can get billets and machine them.

Zabac

iTrader: (39)

You can coat them yourself after the fact through local shops, I will do it regardless if anyone else does or not. It reduces friction and heat adn contributes to making the metal harder, why would you not do it?

Stein

iTrader: (46)

I can do it next week. Blowing out of here at noon for the rest of the week.

Loki047

iTrader: (6)

That is awesome news!

I am just worried about toughness and that the new gears will be too brittle

Zabac

iTrader: (39)

Does anyone know anything about teflon? I know Audi uses telfon gears in their diffs, maybe we could use teflon for gears, I assume it would have some flexibility and hardness and a non-stick surface which would all be benefits if it was strong enough.

Loki, why do you think would the new gears be too brittle?

Ben

iTrader: (33)

It's probably a teflon *coating*. I doubt very much anyone uses teflon gears.

Get a batch of these made and I'll have them cryo treated. It won't add much cost and they'll have better wear resistance without getting harder. Of course, then we'd need to worry about the gear that drives the pump gear.

Zabac

iTrader: (39)

I am pretty sure the guy said that they are teflon, but then again, I am relying on someone elses information and that went well before :sarcasm:

patsmx5

iTrader: (16)

Steel is less brittle than sintered parts. Steel's like 10x less brittle than sintered stuff. Believe me steel gears will be a HUGE improvement. And I still see no point in coating the gears. Friction, heat are not a problem, I mean come on, it's a damn oil pump. It's the most lubricated thing in your engine. The oil pan is jealous. Coating those gears seems so incredibly pointless to me. You wanna do something to make the pump better? Cryo. treat the housing that holds the gears. It's cast aluminum no? That's the new weak link. But really it's not because a cast aluminum is a lot tougher than sintered metal anyway.

IMO they don't need to be coated in dry film, Teflon, gold, or anything else. It's about to be the strongest part in the pump with steel gears. The sintered gears are brittle. When the crankshaft flexes it tries to twist along an axis parallel to the crankshaft it's mounted to. Sintered parts will not bend, they just break. Steel will no break. It's a lot tougher, stronger, less brittle, and will hold 10x better in this situation. I guess some of you aren't farmiliar with sintered parts.

y8s

iTrader: (8)

sintered steel parts are still steel if I am not mistaken...

patsmx5

iTrader: (16)

Indeed, I should have been more clear.

Zabac

iTrader: (39)

**** steel, I want alloy

MazDilla

iTrader: (7)

um yeah... last time I checked steel is an alloy (of iron and carbon)

patsmx5

iTrader: (16)

Ok....

http://en.wikipedia.org/wiki/Alloy

y8s

iTrader: (8)

how about if we just make them out of carbonitrided martensite.

Loki047

iTrader: (6)

Basically the softer a metal the easier it deforms, the harder a metal the more likely it is to shatter, and with everyone mentioning OP shattering, i sorta assumed the stock gears were already on the brittle side.

John and I had a discussion on the failure mode that the gears are seeing and based on the results of the rockwell testing I am agreeing with his stance that the gears are misaligning when the crank flexes causing a small peice to fail and that small piece will result in the gears shattering. My thought process originally that the gears were misaligning and shattering (imagine the gears are made out of glass).

There is a metal supply house down the street from me. I will go through what they have on the cheap that will work for us.