Rail rider question

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wd13
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Rail rider question

Post by wd13 » Mon Feb 02, 2015 11:40 am

Hello, I'm new here and fairly new to the pinewood derby aswell. This will be my son and I's second year doing the derby. Last year we had some success placing 1st in his den/pack, and 3rd in district (119 cars). My son and I were pretty happy with that especially since neither of us had ever built a car, however, we set the bar pretty high for ourselves and would like to improve on that if we can.

My main question is about doing a rail rider setup. I can see a benefit to this and would like to somehow incorporate this into our car this year. The trouble I'm having is figuring out how. The rules leave us little to work with when it comes to this based what I've seen for the typical rail rider. We can have extended wheel base, etc however, all 4 wheels have to set flat on the track. No canting, no 3 wheeler, etc. So, is there a way that I can make this a rail rider working within the rules we have?

My other question is on COM. Last year we set COM at 1" in front of the rear axles. Not knowing the type or condition of the track (and being our first time) we opted to go a little conservative. Once at the race, I quickly realized that we could have gotten more aggressive and been fine. This year I'm thinking of going somewhere in the 5/8" - 3/4" COM on an extended wheel base car. Does this sound acceptable?

Here's a couple pics of last years car. Thanks for any and all input.

Image
Image
Last edited by wd13 on Mon Feb 02, 2015 2:42 pm, edited 2 times in total.



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Vitamin K
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Re: Rail rider question

Post by Vitamin K » Mon Feb 02, 2015 12:32 pm

I think 5/8 - 3/4 is a good range for a Scout car. If the track is good, I'd edge closer to 5/8th.

I've never made a 4-wheel rail runner, but this post by Sporty may prove helpful.



ngyoung
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Re: Rail rider question

Post by ngyoung » Mon Feb 02, 2015 1:10 pm

You can still a lot of the rail rider techniques. You should be able to set your steer still using a bent axle as well as allowing the wheels to rest flat. If you keep it around 1 degree the slop in the wheel bore will still allow it to ride flat. Same with the rear wheels, you can still apply a 1* of cant to give a better bias for your wheels to ride at the axle head but still sit flat. The 1* angle is so small that even if most scouts were trying to install axles in straight they would likely have about that much deviation anyway. Building a 4 wheel flat setting car is pretty challenging for the average father son team.



wd13
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Re: Rail rider question

Post by wd13 » Mon Feb 02, 2015 4:16 pm

Thanks for the info guys, very informative. Sportys instruction makes perfect sense but leaves a few details fuzzy. I get the toe in on the dominate front wheel and toe out on the non dominate wheel. However, for the rear wheels, I want a slight toe out on the wheel behind the dominate front or just leave a little extra clearance? What about the other rear wheel? Slight toe in or leave it straight?

And, good points on using a small degree of cant to keep the wheels against the nail head. The "slop" in the wheel bore will still allow the wheel to ride flat on the surface and this is something I had not considered.

The learning curve is getting steep for us this go round, I thought we were doing good until I got to reading up on here. haha.



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sporty
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Re: Rail rider question

Post by sporty » Mon Feb 02, 2015 5:24 pm

Wd13.
I spent many hours developing 4 on ground to be fast. Had to learn it all on my own and trial and error. We won and won alot with it.
I know of know one prior to me. Who has shared ta method.
so there may be another way. But I was the first as far as I know. To share how to on here.
I bet I spent over 100 hours coming up with the method I and the kids used.
we still hold the track record 4 years later.at the local pack.

You can cant 1 degree in the rears and still be flat wheel.
the front tuning for rail rider is a bit tricky at first. But once you have that. Ah hah moment. It comes toget her fast after that.
to much to re type on the phones small key board here.
feel free to contact me. A phone call may help you best.
sporty



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Re: Rail rider question

Post by ngyoung » Mon Feb 02, 2015 5:27 pm

I do not believe he advised you to toe the rear wheels. You don't want them doing any of the steering. His suggestion to toe out the NDFW is good. If it is going to have any effect on steer you want it helping the DFW, not fighting against it.

How are you attaching axles? Drilling holes or using slots? I assume with extended wheel base they're letting you drill your own.

If drilling what jig are you using? Depending on the one used there is a solution to get a 1* hole drilled. If just using the slot you should be able to bias the rear axles to angle up slightly when installing. You can even pry up on the axle tip slightly after installed to give it a the angle or make a little shim in the slot with something like wax paper.



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sporty
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Re: Rail rider question

Post by sporty » Tue Feb 03, 2015 6:29 am

no toe on the rear wheels.

there our different ways to get that 1 degree cant on the rears. I prefer drilling the cant, over bent axles in the rear.


The rail riding four on the floor, if we took a example of drift of 3 inchs at 4 feet.

I want the DFW to drift about 2inch in 4 feet by itself. I want the non dom wheel to drift about 3/4 of a inch at 4 feet. buy itself.


the trick with all of this, is mild bend of axles. to much and you will not get the other wheel to touch or roll right. the non dom wheel, will want to roll into the car body and rub the hub.

That's the hiccup with it. that's why the non dom wheel has to have a little toe out and drift a little. if you over bend the DFW, it will give you the drift you want, but it will not allow the non dom wheel to touch the track and pass inspection.

because the DFW also has the opposite cant, the wheel goes lower, raising the non dom wheel on the front.

So you have to, do less cant to get this to work. to pass inspection.

the draw back, is that the non dom wheel has to do a little bit of work, a little bit of drift to help keep the car to the rail.

again not hard once you get it figured out, it just takes some tinkering time, a few extra axles with some mild bends, 1/2 a degree. 3/4 degree. 1 degree and 1.2 degree axle bends.

I cant give exact bends, every car build, weight on the front end and balance point is different, along with axle location. So a few extra axles with different bends, is the best way to find the degree of bend, that will get you to the 4 on the floor rail rider method.

it is faster then not doing it ! well proven.

Sporty



wd13
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Re: Rail rider question

Post by wd13 » Tue Feb 03, 2015 9:41 am

ngyoung wrote:How are you attaching axles? Drilling holes or using slots? I assume with extended wheel base they're letting you drill your own.
If drilling what jig are you using? Depending on the one used there is a solution to get a 1* hole drilled. If just using the slot you should be able to bias the rear axles to angle up slightly when installing. You can even pry up on the axle tip slightly after installed to give it a the angle or make a little shim in the slot with something like wax paper.
We drill our own holes. I have a "Pro Body Jig" that I thought we would use this year. I also have the single "Pro Body Tool" that I used last year, didn't quite get the accuracy I was looking for with it.



wd13
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Re: Rail rider question

Post by wd13 » Tue Feb 03, 2015 10:00 am

sporty wrote:no toe on the rear wheels.

there our different ways to get that 1 degree cant on the rears. I prefer drilling the cant, over bent axles in the rear.


The rail riding four on the floor, if we took a example of drift of 3 inchs at 4 feet.

I want the DFW to drift about 2inch in 4 feet by itself. I want the non dom wheel to drift about 3/4 of a inch at 4 feet. buy itself.


the trick with all of this, is mild bend of axles. to much and you will not get the other wheel to touch or roll right. the non dom wheel, will want to roll into the car body and rub the hub.

That's the hiccup with it. that's why the non dom wheel has to have a little toe out and drift a little. if you over bend the DFW, it will give you the drift you want, but it will not allow the non dom wheel to touch the track and pass inspection.

because the DFW also has the opposite cant, the wheel goes lower, raising the non dom wheel on the front.

So you have to, do less cant to get this to work. to pass inspection.

the draw back, is that the non dom wheel has to do a little bit of work, a little bit of drift to help keep the car to the rail.

again not hard once you get it figured out, it just takes some tinkering time, a few extra axles with some mild bends, 1/2 a degree. 3/4 degree. 1 degree and 1.2 degree axle bends.

I cant give exact bends, every car build, weight on the front end and balance point is different, along with axle location. So a few extra axles with different bends, is the best way to find the degree of bend, that will get you to the 4 on the floor rail rider method.

it is faster then not doing it ! well proven.

Sporty
What you're saying makes perfect sense and I'm confident we will be able to figure it out now that I have something to go on. Its always scary jumping into this without advice from someone who has done it. With no way to actually test myself, the last thing I want to do is try something blindly and have it completely backfire on us come race day. So, I really appreciate you sharing your experiences. I do have several sets of extra axles that we can play with to find what bends will work to keep us flat while getting the proper drift. I'm sure it will take a good bit of trial and error but that's half the fun!



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Re: Rail rider question

Post by Vitamin K » Tue Feb 03, 2015 10:07 am

wd13 wrote: What you're saying makes perfect sense and I'm confident we will be able to figure it out now that I have something to go on. Its always scary jumping into this without advice from someone who has done it. With no way to actually test myself, the last thing I want to do is try something blindly and have it completely backfire on us come race day. So, I really appreciate you sharing your experiences. I do have several sets of extra axles that we can play with to find what bends will work to keep us flat while getting the proper drift. I'm sure it will take a good bit of trial and error but that's half the fun!
If you build a tuning board with a test strip down the middle, you'll at least be able to verify whether or not the car is following the rail, and if the rears are staying off of it. That's an important observation, in and of itself.



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Re: Rail rider question

Post by wd13 » Tue Feb 03, 2015 10:27 am

Vitamin K wrote:
wd13 wrote: What you're saying makes perfect sense and I'm confident we will be able to figure it out now that I have something to go on. Its always scary jumping into this without advice from someone who has done it. With no way to actually test myself, the last thing I want to do is try something blindly and have it completely backfire on us come race day. So, I really appreciate you sharing your experiences. I do have several sets of extra axles that we can play with to find what bends will work to keep us flat while getting the proper drift. I'm sure it will take a good bit of trial and error but that's half the fun!
If you build a tuning board with a test strip down the middle, you'll at least be able to verify whether or not the car is following the rail, and if the rears are staying off of it. That's an important observation, in and of itself.
Very good idea. Last year I put a piece of tape on my concrete floor. This year I'd like to use a sheet of mdf or something with an actual guide strip screwed to it on one side so that I can watch for that sort of thing (with the rear wheels) aswell as a tape strip or what not on the other side just for alignment purposes.



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Re: Rail rider question

Post by LightninBoy » Tue Feb 03, 2015 1:16 pm

Sporty ... this seems to be more and more relevant as each year passes. I'm not sure if its because more people are seeking internet advice or more Packs are adopting the "4 on the floor, not axles canting" rule set. In any event, your thoughts on this might be worthy of a sticky thread.
sporty wrote:no toe on the rear wheels.

there our different ways to get that 1 degree cant on the rears. I prefer drilling the cant, over bent axles in the rear.


The rail riding four on the floor, if we took a example of drift of 3 inchs at 4 feet.

I want the DFW to drift about 2inch in 4 feet by itself. I want the non dom wheel to drift about 3/4 of a inch at 4 feet. buy itself.


the trick with all of this, is mild bend of axles. to much and you will not get the other wheel to touch or roll right. the non dom wheel, will want to roll into the car body and rub the hub.

That's the hiccup with it. that's why the non dom wheel has to have a little toe out and drift a little. if you over bend the DFW, it will give you the drift you want, but it will not allow the non dom wheel to touch the track and pass inspection.

because the DFW also has the opposite cant, the wheel goes lower, raising the non dom wheel on the front.

So you have to, do less cant to get this to work. to pass inspection.

the draw back, is that the non dom wheel has to do a little bit of work, a little bit of drift to help keep the car to the rail.

again not hard once you get it figured out, it just takes some tinkering time, a few extra axles with some mild bends, 1/2 a degree. 3/4 degree. 1 degree and 1.2 degree axle bends.

I cant give exact bends, every car build, weight on the front end and balance point is different, along with axle location. So a few extra axles with different bends, is the best way to find the degree of bend, that will get you to the 4 on the floor rail rider method.

it is faster then not doing it ! well proven.

Sporty



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Vitamin K
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Re: Rail rider question

Post by Vitamin K » Tue Feb 03, 2015 1:38 pm

LightninBoy wrote:Sporty ... this seems to be more and more relevant as each year passes. I'm not sure if its because more people are seeking internet advice or more Packs are adopting the "4 on the floor, not axles canting" rule set. In any event, your thoughts on this might be worthy of a sticky thread.
Seriously, second on the sticky for this particular guide. Maybe in a cleaned-up, annotated format, with images.

Though, I really hope this 'four on the floor' trend doesn't persist. It's such a silly rule.



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sporty
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Re: Rail rider question

Post by sporty » Tue Feb 03, 2015 2:05 pm

I would enjoy doing a new article on this. If it would be stickied.



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Re: Rail rider question

Post by ngyoung » Tue Feb 03, 2015 3:00 pm

Can't you do it as a moderator? I think the link VK referenced from you plus what you already wrote on here would make for a good sticky post on 4-wheel rail riding.
sporty wrote:I would enjoy doing a new article on this. If it would be stickied.



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