Rail Riding - "How To Guide"

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.

Have you had success with a "rail rider"?

Yes
90
49%
No
8
4%
Somewhat
12
7%
Haven't tried yet
72
40%
 
Total votes: 182

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derbyspeed
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Re: Rail Riding - "How To Guide"

Post by derbyspeed » Thu Mar 01, 2012 10:58 pm

PWRookie wrote:Perhaps, and Mr. Pope posits, the alignment and cambering made to intentionally rail ride will make the losses of the dominant wheel less than what the fixed wheel would be (even if the fixed wheel were polished on the inside where the contact would occur)?

Further thoughts or comments?
I also believe the dominant wheel, when aligned to ride the rail, will also act as somewhat a shock absorber for joints/bad spots in the rail, whereas a fixed wheel or otherwise would not be as forgiving.

You also have to remember, the main reason (at least in my opinion) for rail riding was to keep the raised wheel from touching the rail to almost take that wheel out of the friction equation (you still have weight and some spinning involved) and that's a pretty big improvement to beat. Not to mention keeping the heavily weighted rear wheels off of the rail.

You would most likely need 4 spots on the car with nylon or your feeler of choice to keep the car centered and off of the rail, I would think that, that would cancel out any improvement upon riding the rail with just the one wheel. :idk:


Mike Webb

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Re: Rail Riding - "How To Guide"

Post by PWRookie » Fri Mar 02, 2012 3:20 pm

On a similar note, a Rail Riding article is posted at the following location: http://www.maximum-velocity.com/pinewoo ... imes-v8i4/

Within this article, the author states that:
"Now let's add one other factor: a raised wheel. The purpose of the raised front wheel is to reduce the energy required to start the wheels rolling. If the raised wheel can be prevented from spinning, an advantage will be gained. But if the raised wheel contacts the guide rail, even one time, the advantage will be lost."

Is this sound reasoning? If so, I would think gluing the wheel to prevent it from rolling would help as well...?

Just to clarify, I am not advocating the use of a feeler or bushing, just hypothesizing whether or not steering the car to the rail towards a glued wheel could serve the same purpose as a feeler, and offer a benefit greater than steering the car to ride the rail with the dominant (rolling) wheel.

I don't have a track set up to attempt such an experiment.



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FatSebastian
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Re: Rail Riding - "How To Guide"

Post by FatSebastian » Fri Mar 02, 2012 3:45 pm

:welcome: PWRookie
PWRookie wrote:Is this sound reasoning? If so, I would think gluing the wheel to prevent it from rolling would help as well...?
You might want to review this topic, and direct additional comments and questions about glued wheels there?



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FatSebastian
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Re: Rail Riding - "How To Guide"

Post by FatSebastian » Fri Mar 02, 2012 4:33 pm

derbyspeed wrote:You would most likely need 4 spots on the car with nylon or your feeler of choice to keep the car centered and off of the rail, I would think that, that would cancel out any improvement...
MaxV's 2006 study did well to show that stationary "whiskers" were slower relative to rotating bushings. I liked derbyspeed's response, which highlights the fact that the study really did not involve rail-riding at all. To draw additional conclusions about the benefits of rail guides within the realm of rail-riding then, an apples-to-apples test would be helpful. One appropriate test might be to affix a rail rider with a roller bushing behind the non-DFW. In one test, tweak the toe of the DFW to let the roller bushing take on the rail (without spinning up the non-DFW!); in the other case, let the DFW take on the rail. (We wouldn't need to complicate this test by adding bushings on all corners; almost certainly more bushings would just drag down the car down even more as derbyspeed suggests.)

In this situation, I would suspect that the car could be slowed by roller-bushing contact with the rail. While we take away some sliding and rolling friction between the rail and DFW, we add sliding friction between the bushing and its large-diameter pin and rolling friction between the guide and the rail. The change in performance (good or bad) would likely be a function of the size and type of bushing, etc.

And as was mentioned, even if a guide bushing could be made faster, it would probably be ruled illegal as most rules prohibit "bushings."



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derbyspeed
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Re: Rail Riding - "How To Guide"

Post by derbyspeed » Fri Mar 02, 2012 9:27 pm

FatSebastian wrote: I liked derbyspeed's response, which highlights the fact that the study really did not involve rail-riding at all. To draw additional conclusions about the benefits of rail guides within the realm of rail-riding then, an apples-to-apples test would be helpful."
Actually in all fairness the test does involve railriding it's just a different element riding the rail instead of the wheel (albeit it may not keep continuous contact with any one feeler all the way down the track), but I like the test scenario you have put together Sebastion to see if keeping all 4 wheels off using just one bearing would be significant.

I think this experiment would be a good test comparing it to one wheel riding the rail if he could've taken the same car and tested again without the feelers (bushings) and adjusting the Dom wheel to ride the rail.

That would give us a better idea on how big of an improvement (one wheel) railriding is or is not. If that makes sense? :2cents:


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Positive camber on DFW

Post by Slalom » Thu Mar 29, 2012 6:34 pm

Hi, Quick question, maybe I am screwed up but have aligned rear wheels using sporty's graphite no front wheels technique, RUn bent axles with negative camber rear, and bent front dfw with Positive camber, The positive camber seems to "encourage" the DFW to ride against the car body, rather than the axle head, is there any way around this? Or is the nature of running DFW with + camber, thanks in advance. :mrgreen:



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FatSebastian
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Re: Positive camber on DFW

Post by FatSebastian » Thu Mar 29, 2012 6:51 pm

Slalom wrote:The positive camber seems to "encourage" the DFW to ride against the car body, rather than the axle head, is there any way around this? Or is [that] the nature of running DFW with + camber
That is the expected behavior.



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Re: Positive camber on DFW

Post by Slalom » Thu Mar 29, 2012 7:10 pm

FatSebastian wrote:
Slalom wrote:The positive camber seems to "encourage" the DFW to ride against the car body, rather than the axle head, is there any way around this? Or is [that] the nature of running DFW with + camber
That is the expected behavior.
Thanks thought maybe speed would push it out, maybe the rail



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Re: Positive camber on DFW

Post by FatSebastian » Thu Mar 29, 2012 7:23 pm

Slalom wrote:Thanks thought maybe speed would push it out, maybe the rail
Your description of seeming to "encourage" the DFW was actually right on. If the DFW hits a defect in the rail, it will slide a bit outward on the lubricated nail before it hits the nail head and jars the front of the car body. To help maintain that shock-absorbing effect, it is desirable that the wheel hub nominally rides against the body rather than the nail head. (And don't forget to indent the body ~1/16", if allowed.)



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Re: Positive camber on DFW

Post by Slalom » Thu Mar 29, 2012 7:28 pm

FatSebastian wrote:
Slalom wrote:Thanks thought maybe speed would push it out, maybe the rail
Your description of seeming to "encourage" the DFW was actually right on. If the DFW hits a defect in the rail, it will slide a bit outward on the lubricated nail before it hits the nail head and jars the front of the car body. To help maintain that shock-absorbing effect, it is desirable that the wheel hub nominally rides on the body rather than the nail head. (And don't forget to indent the body ~1/16", if allowed.)
Thanks, I just sanded sown that side of the body 1/16th rather than dent, the rear wheels seem to avoid the track. Thanks again!



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Re: Rail Riding - "How To Guide"

Post by Noskills » Fri Mar 30, 2012 10:11 am

shock-absorbing effect
I have conceptualized the RR effect and positve camber as the ying and yang of the DFW but I like the concept of the shock-absober!

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Re: Rail Riding - "How To Guide"

Post by Slalom » Thu Mar 14, 2013 4:09 pm

HI. So we have car built, looks really sharp good aggressive COG, aligned rear wheels using sporty's technique with front wheels off, some scotch tape and lube under the front. rear wheels aligned, ride on axle hub back and forth, sanded off 1/8th inch from DFW. Still even with DFW just kissing the rail, rear wheel does as well. So I did stan's technique of accomodating by toeing rear wheels. Once past threshold that brought rear wheel off the rail, the DFW had to be toed out in order to get even semi reasonable drift to rail. This seems to be not a good situation with the front and back fighting hard and twisting to maintain good alignment. SO I shaved another 16th inch or so off the DFW side, re aligned, and exact same thing....what am I missing?

Thanks in advance!



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sporty
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Re: Rail Riding - "How To Guide"

Post by sporty » Thu Mar 14, 2013 5:10 pm

Slalom wrote:HI. So we have car built, looks really sharp good aggressive COG, aligned rear wheels using sporty's technique with front wheels off, some scotch tape and lube under the front. rear wheels aligned, ride on axle hub back and forth, sanded off 1/8th inch from DFW. Still even with DFW just kissing the rail, rear wheel does as well. So I did stan's technique of accomodating by toeing rear wheels. Once past threshold that brought rear wheel off the rail, the DFW had to be toed out in order to get even semi reasonable drift to rail. This seems to be not a good situation with the front and back fighting hard and twisting to maintain good alignment. SO I shaved another 16th inch or so off the DFW side, re aligned, and exact same thing....what am I missing?

Thanks in advance!

A few clarifications. That process, That you mention, In regards to the rear wheels off and tape under the nose of the front end, with no wheels on, the wood does need to be true under the front end. untouched as i call it.
I also make sure the board is not all twisted and its level thru out the board.
And you have to use a 4 foot long board and raise it up enough for the car to run down it.

However, this is to check to see if the car is running strait and true. It is not how to correct or fix a issue. It only points out issues.

If it faiils the test, I toss the car and start over. I do not atempt to spend hours trying to resolve the problems. Just to much work and added frustration that is not needed.

Now, How you adjust and try and resolve the problem is mentioned on here from many people, but hard to grasp by reading and if the issues are to severe, then it's very difficult to resovle with bent axle tuning and so forth.

Perhaps you might post some good pictures and close ups, if you are really stumped for us to better help you.

So post some pictures. I cant recall if you drilled axle wholes or are using slots.

Sporty



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sporty
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Re: Rail Riding - "How To Guide"

Post by sporty » Thu Mar 14, 2013 5:12 pm

FYI, The rail rider guide should be a closed topic.

All the add on's and posting, detours from the guide, versus a serious of posts after the fact.

I recommend and ask, all future questions be posted elsewhere in the forum and let this info be a guide to read only.

Sporty



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