Oil vs graphite

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Speedster
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Oil vs graphite

Post by Speedster » Sat Feb 20, 2016 6:40 am

I've been reading info under this topic using the Search function. I wanted to tease a friend by building a car and using oil for lube against his graphite. I was very surprised to learn many times it was said a good graphite beats an oil. I thought a properly oil lubed car was always much faster. I checked the 2015 Mid America times and the Oil cars for scouts were consistently .02 faster then the graphite. That might mean somewhere around a 3 inch difference. One racer changed wheels from graphite to oil and the car actually ran slower. Is prepping with oil very sensitive to doing it perfectly correct?



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Vitamin K
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Re: Oil vs graphite

Post by Vitamin K » Sat Feb 20, 2016 9:26 am

Speedster wrote:I've been reading info under this topic using the Search function. I wanted to tease a friend by building a car and using oil for lube against his graphite. I was very surprised to learn many times it was said a good graphite beats an oil. I thought a properly oil lubed car was always much faster. I checked the 2015 Mid America times and the Oil cars for scouts were consistently .02 faster then the graphite. That might mean somewhere around a 3 inch difference. One racer changed wheels from graphite to oil and the car actually ran slower. Is prepping with oil very sensitive to doing it perfectly correct?
Here is my understanding about all things oil. This may be very flawed, so take [censored] grano salis.

1) Oil (Kryox) by itself is roughly as fast as a good graphite lubrication. If you want to really unlock the speeds of oil, you have to follow the process, which involves coating the wheel bores with a synthetic wax (like Liquid Glass or Rejex) and coating the axles with a dry-lube spray (like Jig-a-Loo or Chain Saver). When this is done, it sandwiches the oil between these two slick layers and produces (I am told) a hydrodynamic bearing which is incredibly fast.

2) Oil is much more sensitive to flaws in the prep, and also things like dust and dirt. Oil really needs to be applied in as clean an environment as possible. If you're following the process, you need to block out a lot more time for things like wax curing and the like. Also, things like adding too much oil also rob speed.

3) A wheel that's run graphite is usually not good to run with oil. All of the fast racers I have seen asked about it have consistently said that once there's graphite on the wheel, it is no good for oil.

4) One nice thing about oil is that the prep lasts a /long/ time. I see speed fall-offs for graphite in as little as 4 runs. Oil lasts much, much longer, and, in my limited experience, actually speeds up after a few good runs down the track.



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whodathunkit
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Re: Oil vs graphite

Post by whodathunkit » Sat Feb 20, 2016 9:54 am

Vitamin K,

If the roll's were reversed for a race.. and if a special race was to be held inside a large freezer.
would you say that the graphite lubed car would be faster then the oil lubed car?

Never tested this for myself.. but i would have to guess that the oil lube would thicken up in colder temps
were the graphite lube would be a little more forgiving in colder temps.

just thought.. i'd throw this thought in on the topic as well.


What type of automobile can be spelled the same forwards & backwards?

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Re: Oil vs graphite

Post by Nelvis » Sat Feb 20, 2016 10:21 pm

Great topic! I'm interested to hear more responses. I have an incomplete "dad car" that is stained and polyurethaned that I would prefer to not foul up with graphite. Naturally, I also want it to be fast. In addition, I want it to be used as a test car for a number of years so I suppose long term survivability/repeatability are also things I'm interested in hearing from both sides of the camp.



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Vitamin K
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Re: Oil vs graphite

Post by Vitamin K » Sat Feb 20, 2016 11:19 pm

whodathunkit wrote:If the roll's were reversed for a race.. and if a special race was to be held inside a large freezer.
would you say that the graphite lubed car would be faster then the oil lubed car?

Never tested this for myself.. but i would have to guess that the oil lube would thicken up in colder temps
were the graphite lube would be a little more forgiving in colder temps.

just thought.. i'd throw this thought in on the topic as well.
That's an interesting question, and one for which I don't have a clear answer.

Krytox clearly does become thicker when cold, as, according to the manufacturer info page, the oil is about twice as viscous at 68F as it is at 105F. What I don't know is what (if any) the effect on Pinewood Derby performance actually is.

Rather funny you should mention it, because prior to our race, our cars were packaged and loaded into the back of a minivan the night before...in freezing temperatures. I was actually sweating it a bit, because all of our family cars were lubed with Krytox, and I was worried about the effect on performance. As it was, the cars were unloaded and sat indoors for at least an hour before race time. Still, would have been interesting to see how much cold affected performance.



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whodathunkit
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Re: Oil vs graphite

Post by whodathunkit » Sun Feb 21, 2016 12:00 am

Thank's for your reply Vitamin K,

( Hope that I didn't put you on the spot !)
It was kind of an odd ball question of me to ask you for some thoughts on.

So here is a different thought on lube types oil vs graphite :
That you don't here much about. (or give much thought to!)
For an out door type of race where there is bound to be wind and dust..
would you pick a graphite lube over using an oil lube for this type of race.

However :
There has to be some truth in what you are saying about the oil preps
lasting longer in heat runs at room temp then the graphite lubes for the indoor type of racing .


What type of automobile can be spelled the same forwards & backwards?

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Vitamin K
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Re: Oil vs graphite

Post by Vitamin K » Mon Feb 22, 2016 9:43 am

whodathunkit wrote:Thank's for your reply Vitamin K,

( Hope that I didn't put you on the spot !)
It was kind of an odd ball question of me to ask you for some thoughts on.

So here is a different thought on lube types oil vs graphite :
That you don't here much about. (or give much thought to!)
For an out door type of race where there is bound to be wind and dust..
would you pick a graphite lube over using an oil lube for this type of race.

However :
There has to be some truth in what you are saying about the oil preps
lasting longer in heat runs at room temp then the graphite lubes for the indoor type of racing .
These days, I think I'll almost always choose oil over graphite, if given the choice. I think when you're doing the initial prep and lubrication, those are the critical points for where you have to watch out for dust/etc. I think once the axle is safely housed in the wheel, the critical interfaces are less susceptible to stray particles.

This is primarily my conjecture, though. I don't have anything concrete to back it up.



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Re: Oil vs graphite

Post by birddog » Mon Feb 22, 2016 4:32 pm

our oil cars have always been faster than our graphite cars. I think Vitiman K did an excellent job of describing the issues.

birddog



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whodathunkit
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Re: Oil vs graphite

Post by whodathunkit » Mon Feb 22, 2016 7:52 pm

:agree: with you birddog, Vitamin K, did an excellent job with my questions and thoughts about the lube types.


What type of automobile can be spelled the same forwards & backwards?

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Re: Oil vs graphite

Post by Nelvis » Mon Feb 22, 2016 10:50 pm

I would ask again then of Vitamin K or anyone else: What would you use for a long term test car? I need something that would last several years by simply re-applying and running to test against the current year's cars. I am leaning towards oil because I have a nice wood finish on the car that I would love to keep clean, but more importantly I am wondering what is the better lube for a long term (multiple years) test car.



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Re: Oil vs graphite

Post by Vitamin K » Tue Feb 23, 2016 7:55 am

Nelvis wrote:I would ask again then of Vitamin K or anyone else: What would you use for a long term test car? I need something that would last several years by simply re-applying and running to test against the current year's cars. I am leaning towards oil because I have a nice wood finish on the car that I would love to keep clean, but more importantly I am wondering what is the better lube for a long term (multiple years) test car.
That's a good question. Oil lasts for a lot of runs (some say as many as 100+). However, I really don't know how it is affected by simply sitting in a box or bag or what-have-you for a long period of time. I want to say I heard some story about a famous league racer who pulled a car out of storage after several years and it ran competitively. Would need to dig that up, though.

On the other hand, a graphited car would not be hard to just spin some new graphite into the wheels each time you want to run.

I've actually kind of thought that the ideal car for track benchmarking would be a bearing car, since those can just run forever once set up. :)



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Re: Oil vs graphite

Post by birddog » Tue Feb 23, 2016 2:26 pm

I keep our Mid-America cars for testing all our Pack and District track setups. Some are oil and some are graphite. I've been using them for the past 2 years or so. I think the oil cars keep more consistent times. I use the fastest cars I have to validate the track setup, as we have just one stop section and I want to ensure the fastest cars will not have a problem out running the single stop section we have on our track.

If I wanted a car to last for a long time, oil would be my choice.

birddog



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Re: Oil vs graphite

Post by Nelvis » Tue Feb 23, 2016 8:58 pm

Thank you Vitamin K and Birddog. I was thinking the same as you were initially Vitamin K. In that graphite could always simply be reapplied and in effect last forever. I'm glad to hear Birddog say that he has an oil car that has lasted several years because I want to keep mine clean. I was worried that over a long period of time the oil would somehow thicken and gum up. Do you store them in some special way Birddog? Like plastic baggies? Regardless it sounds like I'll be going with oil. The only thing holding me back is that I thought it might fun to try entering it in the Adult (non-pro) MidAmerica bracket until I learned that it is graphite only??? Well it wasn't going to win any speed trophies anyway, so maybe I'll enter it in the stock pro bracket where oil is allowed just to show it off and maybe get lucky with a best in show. Thanks again.



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Re: Oil vs graphite

Post by Speedster » Wed Feb 24, 2016 4:17 am

I learn something new every time I read Derbytalk. I have heard Krytox evaporates after a short period of time. Is that true?



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Re: Oil vs graphite

Post by chromegsx » Wed Feb 24, 2016 7:33 am

Speedster wrote:I learn something new every time I read Derbytalk. I have heard Krytox evaporates after a short period of time. Is that true?
No. Oil does not evaporate unless its heated pretty high. How high probably depends on the type of oil. I switched to oil a few years ago and I test each new years car against the previous years car with no reprep or addition of oil. I don't have the track and timer to verify that the previous year car is slowing down or maintaining speed but still winning every year.



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