69 replies to this topic

[Lucky Me]

I know there have been several conversation's, topic's, build's, ect....

Since I destroyed my best F1 @ the Columbus F1 500 @ Tom Thumb Hobby's I have started a new
F1 build and thought I would try my hand at a "Z" rail design, I have never built this style of chassis so
I was hoping to get some opinion's, theory, ect.. on a couple thing's from some of the builder's/racer's that have built some of these as well as raced them.

This car will primarily be ran on a King track.

1.What do you like about this design and why ?
2.Any lesson's learned from the 1st one you built to the next ?

All opinion's welcomed

[MantaRay]

I'll get some pics posted later...but...the original Mike Swiss build.........had the center 3/4" weight held to the nose piece with 2 wires.....pans were then attached with wire to the center piece.........Rick Davis has some similiar attachments..........
Works well...........but heavy............little movement...............
A later build of mine has shaker pans.............The z-rail part is relatively simple..........pan attachment is a bit more difficult....BTW the pan need to be narrowed from .250...........to fit

[Lucky Me]

Thank's Ray,

I have the pan's figured out, I'm using a metric strip that measure's .236 wide and .040" thick

I am also using an FSF MB that is 1.300 wide. Will start posting pic's later on in the build.

Rail's are .063, and nose piece is 3/4 wide. Made a plate to surround the MB also out of .050

[MantaRay]

Rick........I'm sure your build will be a beauty and fast

[MantaRay]

BTW..........the nose piece is actually a JK Can Am plate that was cut up to make what you see.........

[Lucky Me]

O.K., well, here is what I have so far, I guess the pan's are what is going to hold the main rail's from spreading apart at the frt ?

Will be working on the pan's tonight.

[Phil Irvin]

LOOKIN GOOD.... I like the way you have done the stops. Go FOR IT.....

OLPHRT
PHIL I

[Phil Smith]

Very nice work!

[911GT3]

Looks good, Rick.

[Rick Moore]

Rick

Some good questions you have there. As for what I like about an indirect main rail system (“Z-Rail” as commonly called here…) is that it creates a greater amount of inherent flex to a chassis that can be lessened through the use of other controlling structures as desired. (The opposite, a direct main rail system does not allow greater flex to be added.) And as for what I have learned about the successive designs, not much for my part, as all the designs/builds I have made have used the same design and materials (all of mine are 0.047” wire framed chassis) as I incorporated other design elements onto this type of main rails. Others might better be able to chime in here with their observations on various layouts and wires used. The one thing I have found is there is no difference between medial-to-lateral versus lateral-to-medial layout of the rails (other than which fits the desired design better).

As for what will “…hold the main rail's from spreading apart…”, I use one or both of two design elements. One, I always incorporate a front “spreader” wire that holds the front wing assemblies together (due to the fact all the designs have had separate center-guide assemblies). The second, on some designs the use of spanning front axle uprights on the laterally adjacent rails (ie, your side pans as you said) accomplish the same result.

Here are two pics, a CanAm and F1, showing the main rails (with the front spreader):





And the same chassis with the spanning front axle uprights:





Hope this gives you some food for thought.

CMF3 (Rick)

[Lucky Me]

Rick..........

Thank you for some insight and the pic's to digest with your concept's.

Your build's are very "busy" to say the least. but are also cool as hell !

Can you possibly elaborate on what type of "loading" you feel take's place on the race track with both the Can Am and F1 you have posted, what I mean is how do you feel forward bite on accelleration, through flat and banked turn's is gained/lost ? Do you feel with all the movement that it eat's up some H.P. ? I have witnessed more basic design's of this type be very successful on the track.

I really no nothing about the overall dynamic's of this design, as I said it is my 1st attempt at this design, and it happen's to be an F1. My experience on the "King" has pushed me to build car's (Can Am and f1) with very little movement with different pan design's whether it be a shaker, floppy, plumber ect...

Anyway's I appreciate the dialogue you have posted, and look forward to moore !

Thank you.

R.M.

[Phil Irvin]

RICK,

Glad to see ya on again. I know the learnin stuff is a killer and takes up most of your time. Are you goin to be able to take some time off this summer for some fun? Me....I'm slowin down some. Ain't got the 'gotta go racinitice' as bad as I usta BUT is still around. See ya soon,....

OLPHRT
PHIL I.

[Chris Barnes]

Is the original Z-rail theory to simulate Eurosport cars? That is what I see (sort of) as there is a lot of movement in the twisting flex direction, but a lot of stiffness up and down (like going through the bank). I don't know the correct terms to use on this - I am from the EE background and not the ME background.

[Noose]

The downside sometimes to the Z-Rail concept on sports car frames is the flex down the straight and through a bank. Why I, and some others, have seen is the frames works stupid good from the deadman to the lead on on a King but seems to go soft down the main straight and through the bank. This was partially corrected through some testing where additional points on the rails (2 in front and 2 in the rear) were "tacK' soldered to add some stiffness back in.

Have not tried a F1 built in this manner so I can't say whether the same thing happens.

[Lucky Me]

Finished this up last night.

Now that I have had a chance to hold a working "Z" Rail chassis in my hand to observe the type of movement this design has, I will say it has a unique suspension integrated to this particular type of design.

Remind's me of my Off Road R/C day's when I would set up my shock's and have the car/truck setting flat on a surface and go around and lift each wheel off the ground to ensure each tire/wheel had the same amount of travel before the 2nd wheel would come off the ground. This is what this design does. I can have the chassis on the tech block and each wheel can be lifted without any of the other 3 wheel's lifting around all 4 corner's of the frame untill the frame hit's it's stop's. I hope this is how it is suppose to be, if not, I screwed up somewhere.

Frame still has a verticle stiffness to it that feel's more traditional if the rail's were all soldered solid, but the twist is unreal. may have to adjust some of that out of it. The track will tell.

This particular build weighed in at 107 g's Race ready, no lead.

Next up is TESTING ! can't wait.

[John Miller]

Nice build Rick.

[MSwiss]

Rick.
Terrific job on the build.

Good idea going with .040 brass to keep the weight down.

My F1 Z-rail builds use .062 and they are always a bit on the heavy side without much of a way to lighten them.

It will be interesting to see what someone with lots of Tom Thumb experience can get out of it, especially with being able to test and tune it
at your leisure.

One thing I'll add is that the front axle just being supported by struts coming out of the slots in the nose pc. hasn't worked out that well.
Even with carefully cleaning out the "recast" in those slots, I think they are in a bit too far, inboard, and might get pulled out in a bad crash.
I would add additional ones as far wide out, as possible, probably at the joint where the main rail attaches to nose pc.

[ejgehrken]

After reading these posts, I'm still having trouble grasping what makes a chassis a Z-Rail.
Can someone explain what a Z-Rail is and what theories govern its performance characteristics?

[MSwiss]

The rails are not all soldered together.

They are connected back and forth in short of a flat "Z" shape.

In the theory to make three rails into one long one.

Another good example of a "Z" rail is at the below link:

http://slotblog.net/...efit-sano-dave/

[Rick Moore]

Can someone explain what a Z-Rail is and what theories govern its performance characteristics?

As Mike says, what you have is a 3-element (three wires in this case) main rail. There is:
1) A wire running forward from and only attached at its rear to the motor box / rear axle assembly;
2) A wire running rearward from and only attached at its front to the front wing assembly (which may include the front axle and guide tongue);
3) A wire in between and connecting the other two wires, attached to the front of the wire from the motor box, and attached to the rear of the wire running from the front wings.

When I first started building chassis with “z-rails” I was working under the “theory” (translation: “Gee, I wonder what happens if…”) of trying to isolate forces working on the front wings (and/or front wheels) of the chassis and minimize those forces from transferring to the motor box / rear axle assembly. Please note, in my own series of builds the guide tongue was already mounted to a separate assembly running directly to the motor box, and not attached to the front wing / front axle assembly (sort of a no-hinge/torsional iso-fulcrum drop arm, without the “drop”); others will be better suited to describing the effects with the guide tongue as a part of the front wing assembly, as I have not built any in that manner. So for the chassis I’ve built the "theoretical triangle” formed between the guide and the rear tires (which includes the motor box / bracket) remains more stable relative to the flex or twist of the rest of the chassis under running forces. This can be a “good-er” thing or a “bad-er” thing, because the amount of tension between the components will affect the chassis handling characteristics in relation to the type of track and track conditions (as well as the other usual car tuning variables). My own experience is that this inter-component tension can be controlled (and even made adjustable) through the use of “spring wires” between various chassis components.

Well, hopefully that wasn’t too confusing…

Rixk

[Tex]

The bottom view of Rick's chassis says it all. LOOK CLOSELY at the 3 rails on each side and PAY ATTENTION to how they are soldered together. The inside rail and the middle rail are soldered together at the rear. Similarly, the outside rail and the middle rail are soldered together at the front. If you can visually grasp that concept, you have the PHYSICAL makeup of a Z-rail. That's as deep as my mind can go. For the performance characteristics, refer to Rick Moore's words above; I trust him.

[SlowBeas]

I've noticed that some z-rails connect to the motor bracket from the outside of the rail configuration, while others connect on the inside. What difference does it make?

[Guy Spaulding]

If I understand it correctly the use of Z rails will promote side-to-site (twisting) flex, while minimizing forward-aft flex. This allows more equal downforce distribution while maintaining longitudinal rigidity

[SlowBeas]

Sorry, I probably didn't state my question properly...

Sometimes, the rail that connects the motor bracket connects from the outermost position, with the other two rails connecting to the inside of that first rail connected to the motor bracket. The one connecting the fore piece will be connected by the third rail, which is innermost of the three. (post #15)

Then on others z-rails, the rail connecting the motor bracket is the innermost of the three --- with the other two rails moving to the outside of the one connected to the motor bracket. (post #2)

I'm just wondering if one method is better than another, or is it six of one/half dozen of the other?

Does the question make better sense this time? (You'd never know I write for a living, would you?)

[Tex]

Question understood. Don't know the answer.