Since we had our 2004 Corvette Z06 transmission apart to crack check everything before its rebuild, we figured that everything deserved a proper shine. Actually, GearFX Driveline figured that, because they know better, and we’re products of the Florida public school system and wouldn’t know better anyway.
The key concept here is REM polishing, a very mildly abrasive polishing process that imparts …
Sorry if I missed something. I just glanced at the thread. Seems to me that rather than subjecting an unshiny-gear transmission and then an assumed identical shiny-gear transmission to a chassis dyno (well, I guess it could be a before and after of the same trans), why couldn't the story be told simply by the fluid temp? If I'm losing 5 hp on the unpolished gear set, seems to me that the only place it could be going is into fluid temp. I don't know how many quarts are in that thing and the efficacy of the cooler but that seems like a lot. It almost seems like you could save a bit of weight by ditching the cooler.
A 401 CJ said:Sorry if I missed something. I just glanced at the thread. Seems to me that rather than subjecting an unshiny-gear transmission and then an assumed identical shiny-gear transmission to a chassis dyno (well, I guess it could be a before and after of the same trans), why couldn't the story be told simply by the fluid temp? If I'm losing 5 hp on the unpolished gear set, seems to me that the only place it could be going is into fluid temp. I don't know how many quarts are in that thing and the efficacy of the cooler but that seems like a lot. It almost seems like you could save a bit of weight by ditching the cooler.
Well, the testing was performed as part of the research for an SAE paper, and done in conjunction with a bunch of NASCAR teams. So whenever we can leverage someone else's hard work for a cool story, we're going to grab that chance. Fluid temp tells a big part of the story, though. But reduced friction also pays off in reduced mechanical interfaces between the zillions of imperfections in surfaces, each of which could be an eventual failure point.
I get that you use the work that's already been done and I applaud you for it. And when I said "story" I wasn't referring to the GRM story per se but rather just positing that it might be easier to show whether or not it works with a temp gauge than with a dyno. That's all.
I would imagine that time alone would destroy the micro imperfection though. I have pulled some seriously shiny gearing out of transmission on the small industrial scale that did not go in with that finish. when they were perfectly lashed.
5HP worth of heat is hard to quantify in my mind. I have never seen a conversion setup to do something like that.
EDIT
5hp is 3750 Jules per second. Which if I remember is one Jule = 1 watt.
So back of the napkin calculation is 10F increase in 5 gallons of oil every 3 minutes in friction heat in a perfect system with no cooling.
In reply to A 401 CJ :
How would you ensure that the trans cooler temps before and after was comparing like to like? You would have to do a run on a track and compare a before and after. Outside temps, humidity, a sunny or cloudy day will change the readings of the data you get on the track and sure you could account for all that noise in the system
Or you could do a dyno pull or two where all of those things are already accounted for.
Unless I'm missing something in what you're saying?
I'd make several runs in each configuration. Then I'd have the law of big(ger) numbers working for me.
How would your dyno runs be like to like? Do you have a button to press that automagically puts the shiny happy gears in?
i'm just thinking aloud. They did what they did and I'm happy GRM reported it.
Ambient conditions inside a shop are going to be much steadier than on a track, there's also no driver error, no track conditions, tire slippage, or other issues to worry about and factor out. If its absolutely necessary to get as close to similar conditions as possible you run the dyno with an electric engine as the input and put the trans output straight into the brake portion of the dyno.
1.3% is such a small difference that you want to limit as much noise in the signal as possible. A track is the opposite of that.
This study is a little fishy. The author works for a company who sells this polishing surface commercially, so there's an incentive to reach a positive conclusion.
The test results are also a little too cut-and-dry. The fact that 100% of the non-polished parts reached failure but 0% of the polished parts failed seems a little artificial. Why did the study look at just two kinds of parts: non-polished and super finely polished? It would've been illuminating to see the lifespans of different surface finishes, not just the two extremes. At the very least, one of the fully-polished parts should've been run to failure.
There's also the fact that this test was run dry with no oil. Typical transmissions would be lubricated with oil and there are some applications where a rougher surface finish produces lower friction by saturating itself with oil, such as cylinder bores.
It's still possible this process does help and the dyno numbers show that, but I'd be interested in seeing how much material's been removed from the gears and the increase in gear lash.
SAE is the Society of Automotive Engineers. This would have been scrutinized just like a paper on some kind of medical research. It's no different than GM releasing a paper on the internal combustion engine even though they are in the business of selling them.
Paging Gale Banks.
You disproved fancy-pants high capacity diff covers. This should be next.
In reply to Patientzero :
Some medical studies are poorly researched and should not have been published.
Different for sure but I was part of a study where we implemented this process on aerospace components in the combustion section. The polished parts had better wear properties and surface temperatures in process measured under load. It was a surprise for the head engineer and myself that it would have such a measurable improvement.
Needless to say we created a nice cottage business for the gents who sold the vibratory equipment and media.
tyronejk said:In reply to Patientzero :
Some medical studies are poorly researched and should not have been published.
Published and endorsed by the governing body in that field are completely different things.
In reply to Patientzero :
Maybe I missed it somewhere, but it looks like this paper is just published in an SAE conference, not formally endorsed (although you could argue that accepting a paper to begin with is a form of endorsement).
I'm not saying this result is completely wrong just because the people who wrote it are in the business of selling the service. I'm saying the methodology in the paper isn't rigorously thought-out.
I have have often wondered if polishing the non-bearing/meshing surfaces in an engine would also cut down on windage? If after balancing and recontouring the crank and it's weights to slip through the oil spray easier, would polishing them up also keep the oil from sticking to them?
In reply to mad_machine :
Yes.
As a bonus, oil returns to the pan quicker rather than being stuck in the motor so you can run less oil and further reduce windage. On many motors you can open up the passages in the heads and valley to help the oil get to the pan faster. A smoother surface is just going to help that.
Look up a picture of a Bryant crankshaft, they are almost mirror polished for that very reason.
Be curious to see that versus say, WPC treatment.
How much did the treatment cost? Apologies if I missed that in the story, I did a quick scan.
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