Derby Talk

GravityRacer wrote:However, I don't see anything quantitative at either of these links, just "This works better".

Perhaps I would have done better to link the article from which MaxV's CoF figure apparently originates, which provides a more quantitative justification of his earlier post.

Wups! The graphite line has the steepest slope near the low pressure end, so my "extrapolation" was wrong in any event. Also, I went to the MaxV website FatSebastian linked, and indeed that is quantitative enough for me. That's how we did coefficients of friction measurements in physics labs.

Sebastian caught me on another topic and asked me if I had any follow up on the experiments I tried after talking to the German tribologist. Sporty already tipped my hand a bit, because I was working on getting a sample of BAM. Unfortunately, it's not easy to come by, so I never did get a sample.

I did run a lot of experiments using Stan's string and weight method of testing. Before I tell you the results, I want you to know that this was far from scientific, and had a lot of variance.

I started by using Jobe's recommended method of polishing axles and bores as a base line. I did two axles "by the book", I did about six more axles with various modifications to the procedures.

The method I'm about to give you is the one we ultimately used on my sons PWD car, but it only gave me slight improvement over the axles done by the book.

I ran the by-the-book axles ten times and took an average. My axles beat the by-the-book average 7 out of 10 times, but the difference was not large enough for me to say the procedure is better.

I did end up using Teflon, but not as a lubricant. I used it as a final polish.

I followed Jobes procedure on the axles, up to the step where you buff the axles with the leather strop. Before polishing with the strop, I filled a shallow basin with Liquid Wrench (start your screaming here). I did the final polish with the head of the axle and the strop submerged in the liquid wrench. After it dried, I put the axles on a cookie tray and put them in my oven, and started the self cleaning cycle. (My wife was happy I was cleaning the oven).

The next day, I used Graphite to lubricate them and ran the experiment.

For the bores, I used the sucker stick method to polish them with liquid wrench. I sprayed LW on the stick, and kept spraying the bore until the stick swelled. After they had dried completely, I polished them the same way with a graphite paste.

Like it or hate it, that's what I did. It worked well for me, but I will NOT claim that it will work for anyone else. Despite all my efforts, it could just have been blind luck that improved the performance!

OneTimeRunner wrote:...
I did run a lot of experiments using
...
Like it or hate it, that's what I did. It worked well for me, but I will NOT claim that it will work for anyone else. Despite all my efforts, it could just have been blind luck that improved the performance!

Nice write-up.

Don't sweat whether the results are definitive ... that is what "replication" is for, and I think you may have provided enough detail that your work can be replicated by others.

BAM,

ya they told me it would take me a few grand to get some BAM. But darn it, I sure want some.


As for axle polish and wheel bore prep, I have posted this elsewhere.


Sporty

OneTimeRunner wrote:Sebastian caught me on another topic and asked me if I had any follow up on the experiments I tried after talking to the German tribologist.

Thanks OTR - I really appreciate your follow up!

OneTimeRunner wrote:Sporty already tipped my hand a bit, because I was working on getting a sample of BAM. Unfortunately, it's not easy to come by, so I never did get a sample.

sporty wrote:BAM, ya they told me it would take me a few grand to get some BAM.

From what little I've read, it seems like this may not be something that just squirts or brushes onto an axle! (For some reason I imagine a complicated plating process where one ends up with something akin to porcelain axles? )

OneTimeRunner wrote:I did run a lot of experiments...

OTR, what aspects, if any, of your experiments were influenced by the tribologist? I suppose the submerged buffing was one aspect - were there others?

OneTimeRunner wrote:I did end up using Teflon, but not as a lubricant. I used it as a final polish.

How does one polish with Teflon? What kind/form of Telfon (PTFE)? Where in the process was this done - e.g., before or after graphite application?

OneTimeRunner wrote:...submerged in the liquid wrench. After it dried...

Does Liquid Wrench dry? If so, how can you tell and how long does that take?

OneTimeRunner wrote:Despite all my efforts, it could just have been blind luck that improved the performance

Well, it might be possible to show, using a statistical analysis, whether the experienced improvements were more than what would be expected due to random chance (blind luck). If you were willing to share all your timing data, one of us could attempt it (which you may not care to do, or even have the numbers anymore).