Graphite in the oil

[strad]

This has been bugging me....Why in the world would I lie about owning that car?
Why would you say I didn't?

[Scuderia Nuvolari]

so you have a couple of pictures, still doesn't prove anything

figure out about the graphite

[Ciro Pabón]

This has been bugging me....Why in the world would I lie about owning that car?
Why would you say I didn't?

... to bug you, of course.

[xpensive]

I'm on a roll tonight after been away for awhile!

Most people I know have all sorts of strange particles in their oil, aluminum, graphite, steel, rubber, Loctite, teflon-tape and god knowns what kinda leftovers from the last rebuild.

The point is that you want none of it, the hydrodynamic lubricant-film you are dealing with is typically in the range of 25-50 microns (one thou to two thous), why you want as litte as possibe of crap around.

So that't it folks don't ad up --- you don't know.

[flynfrog]

so you have a couple of pictures, still doesn't prove anything

figure out about the graphite

prove he didn't own it. Burdens on you

[Formula None]

FWIW strad I don't think most of us doubted you. You strike me as occasionally grumpy, which is to say, honest if anything else! Seems like an odd thing to lie about, anyway.

What were we talking about again?

[strad]

Obviously they couldn't be bothered clicking on the photo to play the video.
They put in graphite or use an oil that already has it in it, for the rear end.
As was suggested by I think Riff Raff, and others
And for the purpose suggested.
And yes I'm a grumpy old man.
If anybody is paying attention, I didn't think they put graphite in anything and by publishing the video, which I didn't have to do, I am admiting I was wrong about that.
I did say

However, that doesn't mean they don't or that something I'm unaware of hasn't changed

Appearently it has and I did find out and I reported what I found.

[Formula None]

Wouldn't you get the same benefits of reduced friction whether or not its a dry bearing or the graphite is suspended in oil? Also, will we eventually see nanotubes and buckyballs in this stuff? Seems to end up in lots of things these days. They'd be small enough to not clog oil filters (nano scale, oil filters catching micron scale stuff) but I'm not sure if they have the same friction properties as graphite (although as strad pointed out its just for the pumpkin in drag racing so no filters to worry about). I'm just imagining a thick enough soup of buckyballs creating a fluid bed of nano ball bearings. I guess at that scale though even a ground finish starts to look like the Himalayas.

Buckyballs in Benzene:

[Ciro Pabón]

Thanks, Strad. Graphite in the rear end. I already knew that.

Meaoww. Meaoww. You won't forget the point...
[youtube]http://www.youtube.com/watch?v=eBPWKS5p3z0[/youtube]

Now we know why we're grumpy old men. It's some people in this thread trying to put graphite in our rear ends.

I cannot see the cat buckyballs, Formula None, but I'm sure they're there, somewhere. They must be nanoballs. That's why cats don't race while Mickey Mouses does.

[bcoxa]

so you have a couple of pictures, still doesn't prove anything

figure out about the graphite

I have some proof, Strad what's your name champ?

[xpensive]

As long as you're striving for full-film friction, without metal to metal contact and a theorethical endless life, any particle, come steel, teflon, graphite ot outright Colombian crap is an evil you do not wish to deal with any day of the week.

But if you're happy with the more typical day-to-day boundary-layer friction with an accepted wear-rate you can live with, you can discuss anything from STP to Tabasco for life-xtending enhancements.

[strad]

Odd you should mention STP. As you know companies like STP pay what's called contingency money...if you have the decal on your car. So everyone carries an STP sticker on their car..to collect on it,,,but nobody actually runs it in the oil. Since most everyone knows you don't want thick oil in your wet sump racer we would say if asked that we put it in the rear end to cushion the gears..We didn't of course,,but a 100 bucks is a 100 bucks.

[Caito]

I post this, that autogyro wrote somewhere else:(hope nobody gets angry)

From one dragster championship winner, junior mid 70s, to another.
The rear end on modern dragsters uses gearing that could be described as midway between a bevel set and a hypoid bevel set.
There is a great deal of in mesh slidding under very high load.
It has always been the practice to mix a friction modifier in with the thicker oil used in commercial high torque gearing and graphite is a good choice.
There is no problem in a rear end in regard to filters blocking or break down of oil film on shell bearings, there are non. However the axle does need to be checked and the graphite re-mixed, because it tends to fall to the botttom of the case.
Of course graphite would not be used in this way in an engine.

[Formula None]

What happened to that guy? Haven't seen him post in a while.

[riff_raff]

"The rear end on modern dragsters uses gearing that could be described as midway between a bevel set and a hypoid bevel set.
There is a great deal of in mesh slidding under very high load.
It has always been the practice to mix a friction modifier in with the thicker oil used in commercial high torque gearing and graphite is a good choice."

Caito,

The rear end R&P are hypoids (a spiral bevel with an offset pinion axis). Hypoids are preferred for rear ends because they have excellent torque capacity, due to their inherent high face contact ratios.

And yes, there is a great deal of relative sliding at the mesh. The sliding hurts efficiency. Some of the sliding is inherent in the hypoid tooth geometry, and some of the sliding is due to mesh misalignments created when the gears deflect under load. The R&P gear contact pattern is checked and adjusted by shimming at assembly. But this contact pattern check is done with lightly loaded gears, so it does not give the same result as the gears experience under race loads. The shimming adjustments can compensate for some geometry errors (like housing machining tolerance variations), but correcting for other conditions (like lead misalignment due to torsional wind-up) must be compensated for during grinding.

A properly designed gear mesh using oil lubrication should operate mostly under hydrodynamic conditions, and as xpensive notes, what matters under this type of contact are oil viscosity properties, flash temperatures and relative tooth surface roughness. The efficiency losses in a hydrodynamic gear contact are mostly due to oil film shearing under sliding, so using an oil with the lowest viscosity that still can maintain full film conditions gives best efficiency.

Graphite would only help as an EP additive under boundary contact conditions. If the top fuel guys find that adding graphite is helpful, then one can logically assume that their gears are experiencing boundary contact conditions. However, there is an important point you must understand about how EP additives work. They don't function by reducing friction at the contact zone. Instead, what EP additives are designed to do is form a non-reactive surface film on the gear teeth that inhibits the micro-welding effect between the tiny contacting asperity tips under boundary contact conditions. This repeated joining and breaking between asperity tips at each gear tooth contact cycle produces the classic micro pitting and spalling failures seen in gears.

riff_raff