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
93
50%
No
8
4%
Somewhat
12
6%
Haven't tried yet
73
39%
 
Total votes: 186

doct1010
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Re: Rail Riding - "How To Guide"

Post by doct1010 »

HERBIE wrote: My suggestion was; one day, in one gym, all day and a strip search conducted on all the Dads as they enter the room. The only rules are the ones included in the box. The pack race would come at the end of the day and all the winners would meet later that night for the district. That’s the only way I know to level the playing field.
It is possible. My son's Boy Scout troop adopted a one day build. They had 10-12 boys cross over who longed for the derby and decided to give it a try with a twist. Kits and tools were provided and they had 8 hours to build. Rules out of the box, no parents allowed in build room. Supervised by Scout master, former Scout master and two Eagle scouts. They raced at conclusion of cub's derby.
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Pinewood Daddy
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Re: Rail Riding - "How To Guide"

Post by Pinewood Daddy »

doct1010 wrote:It is possible. My son's Boy Scout troop adopted a one day build. They had 10-12 boys cross over who longed for the derby and decided to give it a try with a twist. Kits and tools were provided and they had 8 hours to build. Rules out of the box, no parents allowed in build room. Supervised by Scout master, former Scout master and two Eagle scouts. They raced at conclusion of cub's derby.
I like that idea!!!
DerbyMomma
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Re: Rail Riding - "How To Guide"

Post by DerbyMomma »

:shock:

I have a question about RR'ing. Instead of narrowing the front end, wouldn't it be just as efficient to widen the back end slightly on both sides, thus ensuring that the rear wheels don't touch the rail? Of course, you couldn't widen too much or you would exceed the width requirements. This seems like it would also aid in stability. Am I way off base? Thanks!
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Pinewood Daddy
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Re: Rail Riding - "How To Guide"

Post by Pinewood Daddy »

DerbyMomma wrote:I have a question about RR'ing. Instead of narrowing the front end, wouldn't it be just as efficient to widen the back end slightly on both sides, thus ensuring that the rear wheels don't touch the rail? Of course, you couldn't widen too much or you would exceed the width requirements. This seems like it would also aid in stability. Am I way off base? Thanks!
Our rules saw the block must be 1 3/4" wide at the axle slots. I asked about narrowing one side in the front 1/16" and was told it probably wouldn't be noticeable if we tapered it. So we did.

Widening the back end would not only possibly push the wheels to the 2 3/4" dim, but if the rear end decides it wants to shimmy side-to-side (like over the track joints) the added motion would cause the wheels to hit harder on the rail and would also scrub off speed because the rear wheels will travel a farther distance (side-to-side) down the track.
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derbyspeed
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Re: Rail Riding - "How To Guide"

Post by derbyspeed »

Go Bubba Go wrote:
Stan Pope wrote:Narrowing opposite from the RR wheel is a tough call. Stanley did not, but I can see that the "free-rolling wheel" might keep a straighter course if he had. On the other hand, a small bump of the RR wheel off the rail increases the probability that the 4th wheel rubs the rail hard. Note that Doc Jobe's tests say to narrow them both on a 4-wheeler.
FWIW we narrow both front sides, for a slightly different reason. Our cars are thin enough that we have experienced some issues with the car body twisting a little as the paint, clear coat, etc. dries, lifting one side or the other slightly in the front. The amount of twist / lift is typically not enough to raise a wheel off the track and violate our 4 wheels touching rule (sometimes it is... :(, but not usually), but if it is in the right direction it can easily be enough to change which wheel is dominant.

If we only narrowed one side, and after the painting, clear coat, etc. twist was all done the other side was now dominant, it would complicate things a bit. To avoid this complication we finish all the body and paint work, let it dry thoroughly, and then insert the wheels and axles and determine which front wheel is dominant after the "body twisting" is done. With both front sides narrowed slightly, we are then set up to RR on either side based on which front wheel remains dominant in the end.

So far we haven't seen any ill effects from narrowing both sides, but we do know a neighborhood guy who narrowed a little too much on both sides and started to see slowdown. :(

Bubba
I like your thinking on this Bubba and I am hoping to have enough time to try this out before Council. So far with my experience with a 4 wheel rail rider the less drift I have the faster the car - actually the fastest time is when it's almost not riding the rail but very close and still keeping the back wheels off, which of course is a perfect scenario.

My only problem is racing against last years car, which isn't a rail rider, it still is very hard to beat. Last year's car took 3rd in Council. So I am still somewhat skeptical about rail riding as opposed to just good alignment.

I may be overlooking something with rail riding also, but still experimenting :mrgreen:
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DerbyMomma
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Re: Rail Riding - "How To Guide"

Post by DerbyMomma »

Well our modification to a rail-rider (or hugger) seems to have paid off! My son came in 2nd at District to a boy that had lightened wheels (illegal), but it wasn't caught. We knew this boy would be at the Council race, so we needed to make some modifications to the car. We narrowed the front about 1/16th" and raised the opposite wheel. After some aligning, we got it to run just right. My son came in 1st at the Council race, even beating the boy that won at District with the lightened wheels. Yippie!
:mrgreen:
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Go Bubba Go
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Re: Rail Riding - "How To Guide"

Post by Go Bubba Go »

DerbyMomma wrote:Well our modification to a rail-rider (or hugger) seems to have paid off! My son came in 2nd at District to a boy that had lightened wheels (illegal), but it wasn't caught. We knew this boy would be at the Council race, so we needed to make some modifications to the car. We narrowed the front about 1/16th" and raised the opposite wheel. After some aligning, we got it to run just right. My son came in 1st at the Council race, even beating the boy that won at District with the lightened wheels. Yippie!
:mrgreen:
Yippie back at ya!!!

Very cool :D

Bubba
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derbyspeed
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Re: Rail Riding - "How To Guide"

Post by derbyspeed »

Congratulations DerbyMomma! Sounds like you had the right set-up at the right time!
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Re: Rail Riding - "How To Guide"

Post by shags72 »

Ok I have read the whole post and I am having problems understanding what shimming is. Could someone explane what I should be shimming. I read Stan write about it and using wax paper I think folded over like 3 times. Thanks all I really do appreciae it!

I am thinking that this is shimming while drilling the axle holes. I could be crazy.
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derbyspeed
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Re: Rail Riding - "How To Guide"

Post by derbyspeed »

shags72 wrote:Ok I have read the whole post and I am having problems understanding what shimming is. Could someone explane what I should be shimming. I read Stan write about it and using wax paper I think folded over like 3 times. Thanks all I really do appreciae it!

I am thinking that this is shimming while drilling the axle holes. I could be crazy.
The shimming they are referring to is with the wax paper. Using wax paper you can shim the axle forward by putting more behind the axle in the axle hole, more in front to shim the axle back or more on the outer edge to bring the axle down and in or shim on the inner area of the axle to bring the axle up and out (or at least the lower portion of the wheel will move out).

This process is time consuming but does work if you have the patience to experiment with it. The main thing in shimming is to always test the car after every shim and also make sure you note the position of the shim and on which wheel. Make sure you get your rear wheels in alignment first making them go as straight as you can. Then work on the front. (at least that is my take on it)

The altenative is to bend the axle, but once you do, you have forever made that adjustment as it is hard to rebound from an axle bent too far. With the shims you can always adjust, at least until you wear out the axle holes too much!

One trick that I have found to be very, very helpful before even using the shimming method (don't really want to give this secret away, but I will), I test the alignment of the car and then start rotating the axle that needs adjusted. I have found that no axle is straight, even by using the axle press, I still can't get it perfectly straight.

By rotating the axle a 1/4 turn (each adjustment) I can easily adjust each wheel and with some excellent results! No shims, no bending! If I can't get it where I want it, then I start the shimming.

Hope that helps?
Mike
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Pinewood Daddy
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Re: Rail Riding - "How To Guide"

Post by Pinewood Daddy »

derbyspeed wrote:One trick that I have found to be very, very helpful before even using the shimming method (don't really want to give this secret away, but I will), I test the alignment of the car and then start rotating the axle that needs adjusted. I have found that no axle is straight, even by using the axle press, I still can't get it perfectly straight.

By rotating the axle a 1/4 turn (each adjustment) I can easily adjust each wheel and with some excellent results! No shims, no bending! If I can't get it where I want it, then I start the shimming.
I do the same.
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Re: Rail Riding - "How To Guide"

Post by blcrow33 »

derbyspeed wrote: One trick that I have found to be very, very helpful before even using the shimming method (don't really want to give this secret away, but I will), I test the alignment of the car and then start rotating the axle that needs adjusted. I have found that no axle is straight, even by using the axle press, I still can't get it perfectly straight.

By rotating the axle a 1/4 turn (each adjustment) I can easily adjust each wheel and with some excellent results! No shims, no bending! If I can't get it where I want it, then I start the shimming.
I do this all the time also. Never had to use shims yet.
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Re: Rail Riding - "How To Guide"

Post by mbb »

Thats how we do it mostly. axles are not round, they are oval as you approach head. so turning producess effects
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Re: Rail Riding - "How To Guide"

Post by quadad »

Never thought of just turning the axles without bending them ! Great ! This might help a lot with fairly comparing car designs that we are working on.

Plan was to have unique cars cutout (not too pretty, but just for testing). Car designs are based on tungsten rounds or plates with provisons for easy movement of weights from one car to another. Then, to make for fair comparisons, I had wanted to swap axles and wheels (to isolate the car design). Testing would be with a timer, so just need to compare on the same lane of track.

Problem was, even if we use a repeatable method to drill axle holes, alignment needed to be done on each car setup. Just rotating axles however, not bending them, could make that work and allow the axles to move from car to car.

Still have to try to graphite similarly from one to the next, but I think this would offer a pretty fair comparison. Might try to work it with a couple of sets of sets of wheels/axles, but we'll have to see.

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

Post by Stan Pope »

mbb wrote:Thats how we do it mostly. axles are not round, they are oval as you approach head. so turning producess effects
Which part of the axle touches the wheel bore with the most force as the car sits at the starting gate?
... as the car is rolling a few inches past the gate?
... as the car rolls on the flat?

Not always the same, right? Maybe 30 degrees around the axle?

Does that mean that the car steers differently on the slope than on the flat?

Can you make use of that difference? Or does the difference hurt you?
Stan
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