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
88
49%
No
8
4%
Somewhat
12
7%
Haven't tried yet
70
39%
 
Total votes: 178
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joe
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Re: Rail Riding - "How To Guide"

Postby joe » Mon Feb 25, 2008 11:55 am

What Dr. Jobe is referring to is NOT railriding. He is recommending a narrowed wheelbase up front to reduce the angle of impact and severity of "oscillation" for lack of a better word. For railriding, don't use Jobe's template. Just narrow the body on the front of the car on the dominant side by 1/16th, but not on the other side of the body. I don't know why Warp Speed's quote says narrowing of the tread, I think (If I can be so presumptuous) that he means narrowing of the front-end wheelbase. I'm sure some of the engineers or tricycle mechanics (this IS a tricycle isn't it?) could tell us that the closer you get to the centerline of the body with your dominant wheel, the more difficult and touchy the steering becomes. I know Warp is right if this is what he's referring to, at least when I narrowed the wheelbase before on a 4-wheeler it made the steering/oscillation a real problem when I was trying to align it for "straight." My guess is that it would cause problems with 3-wheeler too.


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Re: Rail Riding - "How To Guide"

Postby colopwdfan » Mon Feb 25, 2008 5:27 pm

Hey Joe,
Thanks for the response.

Oh, btw, I am NOT proposing anything more than Dr Jobe's method being one that may address the problem. His method. That's the reason for my questions. To understand the +'s & -'s of rh.

Does the process laid out by Dr. Jobe, not accomplish the same thing as rail hugging though? The oscillation is the same as wandering, that a builder attempting rh tries to correct, yes?

I like the "narrow only one side" method, as you present better than working both sides.

BUT... if alignment IS an issue ( as I believe, and as do most here) then wouldn't doing one side be the equivalent of a bent frame on a commuter car?

To a lesser extent due to speed, weight, etc on a pinewood derby car, of course? But still, a 100th or thousandth of a second.

Tracking issues adversely affect performance on real cars. Wouldn't it be the same on pwd cars?

Thanks,
John


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Re: Rail Riding - "How To Guide"

Postby joe » Mon Feb 25, 2008 6:20 pm

Does the process laid out by Dr. Jobe, not accomplish the same thing as rail hugging though?

John, no it does not. Dr. Jobe's "rail-hugging" is not the same as railriding. What he proposes is a design for a 4-wheel car, which would reduce "amplitude" of the front end banging. The railriding car eliminates it altogether, at the penalty (slight though it is) of constant sliding friction on the dominant wheel/rail. There is no reason to "railhug" (Jobe's definition) either a 3-wheel car or a 4-wheel car in my opinion as I believe the railrider is faster in either configuration - at least from my testing.
That being said, I have NOT tested Dr. Jobe's exact configuration. So this is only my educated guess. However, I have tested a narrowed front-end wheelbase. I THOUGHT it was going to fly! I was wrong! It caused all sorts of steering problems. But in deference to Dr. Jobe, perhaps my wheels weren't any good!

BUT... if alignment IS an issue ( as I believe, and as do most here) then wouldn't doing one side be the equivalent of a bent frame on a commuter car

You would think so! However, the Pinewood derby car does not have a driver, variable steering, etc. To paraphrase Warp Speed: I don't necessarily know all the physics, but I know which way is faster, a LOT faster!
Tracking issues adversely affect performance on real cars. Wouldn't it be the same on pwd cars?

I guess not!

I'm anticipating the next question: If railriding is so good, how come it's not outlawed? We can 'logic' and 'theory' this to death. Fact is, I've tested it over and over and over. Scientifically even. So have others.
You can go straight, theories in tow, and still win your Pack, no doubt about it! But if you go same against a decent railrider, you will get smoked!


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Re: Rail Riding - "How To Guide"

Postby colopwdfan » Mon Feb 25, 2008 7:20 pm

Joe,
OK, I'm getting on track. Sorry... ;-)

We've got 11 months until our next and last races, so I'll read all the material, and do our darnedest!

Thanks again!
J


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Re: Rail Riding - "How To Guide"

Postby derbyspeed » Thu Feb 28, 2008 8:21 am

I have read through this thread but still am unsure? Is rail riding only good for a 3-wheeler or would it benefit a 4-wheeler? Our rules do not allow any wheels to be off the ground.

Also if you are riding the rail with the front wheel shouldn't the back wheels be aligned differently (not straight) to keep them off the rail? Kind of like dogtracking?

Maybe I'm not understanding the whole concept? :)


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Re: Rail Riding - "How To Guide"

Postby derbyspeed » Thu Feb 28, 2008 8:32 am

I have read through this thread but still am unsure? Is rail riding only good for a 3-wheeler or would it benefit a 4-wheeler? Our rules do not allow any wheels to be off the ground.

Also if you are riding the rail with the front wheel shouldn't the back wheels be aligned differently (not straight) to keep them off the rail? Kind of like dogtracking?

Maybe I'm not understanding the whole concept? :)


Mike Webb



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Stan Pope
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Re: Rail Riding - "How To Guide"

Postby Stan Pope » Thu Feb 28, 2008 8:43 am

Also good for 4-wheelsers ... see thread http://derbytalk.com/viewtopic.php?t=3453

Can you move a front wheel in a sixteenth toward the center of the body?


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Re: Rail Riding - "How To Guide"

Postby Go Bubba Go » Thu Feb 28, 2008 10:50 am

derbyspeed wrote:I have read through this thread but still am unsure? Is rail riding only good for a 3-wheeler or would it benefit a 4-wheeler? Our rules do not allow any wheels to be off the ground.

Also if you are riding the rail with the front wheel shouldn't the back wheels be aligned differently (not straight) to keep them off the rail? Kind of like dogtracking?

Maybe I'm not understanding the whole concept? :)

We rail ride with 4 wheels and have seen good improvement in times by doing so.

How you keep the rear wheels off the rail will depend on what your rules allow.

If your rules allow narrowing the front end, then narrowing the front on the side you are riding with will help keep the rear wheel on that side off the rail (narrowing both sides is overkill and can create binding issues if you narrow too much).

If your rules allow beveling axle heads, you can align the rear wheels to migrate slowly to the axle heads. This will help keep the rear wheels off the rail.

If your rules allow neither of these, you can "dog track" so that the rear end shifts a little towards the side that is riding the rail (i.e. if you are riding the right side, shifting the rear to the right slightly by bending the left rear axle slightly forward and the right rear axle slightly backward will help keep an even gap between the rear wheels and the rail.

Bubba


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Re: Rail Riding - "How To Guide"

Postby derbyspeed » Thu Feb 28, 2008 11:49 am

I'm not sure we can narrow the front end but we are able to bevel the axle heads. The only rule for the width is that it shall not exceed 2 3/4".

So you are saying narrow the car 1/16" on one side and move the wheel in towards center. Correct?


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Re: Rail Riding - "How To Guide"

Postby Stan Pope » Thu Feb 28, 2008 12:08 pm

derbyspeed wrote:I'm not sure we can narrow the front end but we are able to bevel the axle heads. The only rule for the width is that it shall not exceed 2 3/4".

So you are saying narrow the car 1/16" on one side and move the wheel in towards center. Correct?

Not the whole car, just indent the RR wheel and axle by about 1/16" You can cut notches in the side of the car to give the wheel clearance, or you can narrow just the front couple of inches, or you can taper the entire side of the car to make the indentation less obvious!

The front wheels will still easily clear the 1-1/2" wide guide rails.


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Re: Rail Riding - "How To Guide"

Postby Go Bubba Go » Thu Feb 28, 2008 7:40 pm

Stan Pope wrote:Not the whole car, just indent the RR wheel and axle by about 1/16" You can cut notches in the side of the car to give the wheel clearance, or you can narrow just the front couple of inches, or you can taper the entire side of the car to make the indentation less obvious!

The front wheels will still easily clear the 1-1/2" wide guide rails.

Stan is correct. For "clarity / confirmation" sake, by RR wheel he means the Rail Riding wheel (front wheel), not Right Rear wheel.

You need to double check your notch to ensure the edge of wheel doesn't rub against the body as he indicated. We generally start our notch at the front of the car and finish it a little behind the front wheel. You can "taper" if you want to be more subtle about it. :wink:

Bubba


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Re: Rail Riding - "How To Guide"

Postby derbyspeed » Thu Feb 28, 2008 8:30 pm

Go Bubba Go wrote:
Stan Pope wrote:Not the whole car, just indent the RR wheel and axle by about 1/16" You can cut notches in the side of the car to give the wheel clearance, or you can narrow just the front couple of inches, or you can taper the entire side of the car to make the indentation less obvious!

The front wheels will still easily clear the 1-1/2" wide guide rails.

Stan is correct. For "clarity / confirmation" sake, by RR wheel he means the Rail Riding wheel (front wheel), not Right Rear wheel.


Thanks Bubba, that did confuse me a little, doesn't take much though. I am working on getting my initial alignment correct first.


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Re: Rail Riding - "How To Guide"

Postby HERBIE » Fri Mar 14, 2008 1:49 pm

They changed the rules this year to all 4 wheels on the track. Has anyone had success with this config? :oops:


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Re: Rail Riding - "How To Guide"

Postby Go Bubba Go » Fri Mar 14, 2008 1:59 pm

HERBIE wrote:They changed the rules this year to all 4 wheels on the track. Has anyone had success with this config? :oops:

Our 4 wheelers (our rules require 4 wheels touching, entire tread surface) that RR are faster than ours that don't.

Not as fast as our 3 wheel RRs (we run that config for leagues and "outlaw" races), but we can't run those in our Scout races.

Bubba


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Re: Rail Riding - "How To Guide"

Postby Stan Pope » Fri Mar 14, 2008 2:42 pm

HERBIE wrote:They changed the rules this year to all 4 wheels on the track. Has anyone had success with this config? :oops:

Grandson Stanley runs in a "4-wheels touching" council. He set up to run RR and a lightly loaded or non-loaded 4th wheel (I don't remember which ... too many cars ago!) About 0.02 over #2 and 0.05 over #3 in the pack races held on a 32' (28') Classic Piantedosi. #2's grandfather is one of "my pups", so his showing was not unexpected!

No idea how it will fare in the council races, but we better get the length up to Council standard 7-3/8" or we'll be watching a lot of tail lights!


Stan

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