18 replies to this topic

[Shruska55]

I've been through each and every page of the the Scratchbuilt Chassis Galley thread started by Cheater those many years ago. As a new chassis builder, I'm placing this in the General Tech Forum since other new chassis builders may look here first. If it's better listed in the Scratchbuilding forum, then please feel free to move it

 

First question I have as a new racer is: What constitutes a Flat Track versus a non-Flat Track or Speed track?

 

This may seem simple when one sees the swoopy nature of some of the King track pics and an MTT, arguably, defines a flat track, but where do Hillclimbs, Englemans, Kinglemans, American styles et al fall into a track definition.

 

I've seen some interesting chassis designs specifically for Ovals as well. That's a different question for a different thread.

 

Coupled with an answer to the track definition question,  I'd like to ask the following chassis design consideration questions:

 

1) What are the main consideration for designing a chassis specifically for a flat track versus one that is built to perform better on a speed track?

 

2) I see chassis advertised with recommendations that they'll run best on King's or Hillclimbs? Why do they perform better on those tracks as opposed to a flat track?

 

3) Do flat tracks require a 'looser' design? More shakers and rattlers to move weight around?

 

4) I understand that building as light as possible allows more options for performance weight tuning on speed tracks. Does lighter the better work best for flat track designs as well?

 

Thanks in advance.

ScottH

 

 

[bbr]

Flat track chassis designing is more forgiving, a lot of different types will work, a matter of setting up the car.
High speed King car have a narrow window of performance, everything is critical because weight is the enemy, the design has to work because tuning options are limited (don't want to add weight)

You will see on the flat track all sorts of chassis performing well.
On the high speed King the chassis evolution has been refined to the point that everything almost looks the same (scrra Bpr king racing)

[crazyphysicsteacher]

A flat track has turns that have very little to no banking. If you go to The Race Place in Jersey, the big track is not a flat track but has as much bank in the corners as it can and still be flat. Speedzone has the flat track ad the jersey devil.
I find a track with banking requires a light chassis that gooks up well in the middle of the corner. It must be able to have some slide but still go forward. You will also find that you add more weight on the car and run softer tires.
A car for a banked track is light and setup for quick blips, if you have to drive it at all you are done.

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[eshorer]

On the high speed King the chassis evolution has been refined to the point that everything almost looks the same (scrra Bpr king racing)

Until someone comes up with a "Fosbury Flop" design that changes everything (again!).   :-) 

 

Eddie

[Shruska55]

A flat track has turns that have very little to no banking. If you go to The Race Place in Jersey, the big track is not a flat track but has as much bank in the corners as it can and still be flat. Speedzone has the flat track ad the jersey devil.
I find a track with banking requires a light chassis that gooks up well in the middle of the corner. It must be able to have some slide but still go forward. You will also find that you add more weight on the car and run softer tires.
A car for a banked track is light and setup for quick blips, if you have to drive it at all you are done.

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Chris,

 

Can you define "...a light chassis that gooks up well in the middle of the corner." please

 

Thanks,

Scott
 

[crazyphysicsteacher]

Sure. The lightweight mossetti chassis with the fish hook from wings and light weight steel pans is an example. It works well and only needs some lead for balance and slide. The jk aelos chassis is heavier. It works well be get beat by the lighter chassis on a bigger track.
A heavier car is easier to drive on a flat track just because it has slightly better behavior in corners and does not need to be driven as hard. Now, heavy can be only a few grams but those grams make a difference at times.
I know others will chime in but these are just what I find for me. There are always drivers that can drive a real light car on any track, but they are always faster than everybody else.

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[crazyphysicsteacher]

Until someone comes up with a "Fosbury Flop" design that changes everything (again!).   :-) 
 
Eddie

Hey, just imagine a basic hill climb with a donut but a flat bank. Wait, I have driven one and it is fun.


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[Dominator]

Chris is spot on. 

 

Weight also depends on the class.  A retro coupe for example (with a 110 gram min. weight rule) on a hillclimb style track with minimum banking will generally weigh in at 110.5-113 grams.  That same car for a flat track will come in  115-120 grams and will have softer tires.  How bodies are mounted will also vary between these tracks. 

 

If your talking about eurosport type cars then that's a hole other animal.  Gearing, chassis movement, body, weight of the motors, and RPM of the motors all play into the handling.

[Shruska55]

Chris is spot on. 

 

Weight also depends on the class.  A retro coupe for example (with a 110 gram min. weight rule) on a hillclimb style track with minimum banking will generally weigh in at 110.5-113 grams.  That same car for a flat track will come in  115-120 grams and will have softer tires.  How bodies are mounted will also vary between these tracks. 

 

If your talking about eurosport type cars then that's a hole other animal.  Gearing, chassis movement, body, weight of the motors, and RPM of the motors all play into the handling.No Eurosport in this thread. I'm only concerned with the US at this point and the non-pro Retro classes here for the purpose of scratchbuilding. My car back was a JK Cheetah 21 RTR with a NASCAR body. I've since built a Mossetti with the same body type and see the difference in handling.

 

No Eurosport for this discussion. I gotta learn the basics before I try to run advanced, eh? lol

 

I was thinking about IRRA Retro Class building for this thread.

 

Thanks,

ScottH

[crazyphysicsteacher]

The car is key. You have to decide what you want to do and how you want to drive. Start with a basic build and make changes to it. I suggest a straight rail setup to start and experiment with different types of pans and bite bars. It will take time to find what you like, but when you build your own cars you will get way more satisfaction with each win. Trust me, it is worth it.

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[Mike Patterson]

 I've had good results just copying chassis that someone else designed. If it works for them, it should work for you.

[Shruska55]

 I've had good results just copying chassis that someone else designed. If it works for them, it should work for you.

Mike,

 

Absolutely! I'm not trying to reinvent the, er, chassis.  

 

I've been busy drawing out ideas and Waaaaaaay overthinking many issues around chassis building. But that's my path to discovery.

 

The lightbulbs are coming on and it's getiing hard to wear those gimme hats.

[JerseyJohn]

Sure. The lightweight mossetti chassis with the fish hook from wings and light weight steel pans is an example. It works well and only needs some lead for balance and slide. The jk aelos chassis is heavier. It works well be get beat by the lighter chassis on a bigger track.
A heavier car is easier to drive on a flat track just because it has slightly better behavior in corners and does not need to be driven as hard. Now, heavy can be only a few grams but those grams make a difference at times.
I know others will chime in but these are just what I find for me. There are always drivers that can drive a real light car on any track, but they are always faster than everybody else.

 

MAT BRUCE !!!

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[crazyphysicsteacher]

JJ, I was thinking the green hornet.

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[team burrito]

i have one chassis for the banked track & one for the flat; two entirely different designs.

this chassis is based off a old camen wire center; the uprights are formed to fit 3/32" bearings or oilites. the rest is built with a 1/16" noseplate & 1/32" batpans. there's a fair amount of movement, controlled by 3/32" square tubing & .047" wire. the whole car with body weighs just over 100 grams. on motown's flat track, the korkscrew built by the late monty ohren, this car turned 3.8; not too bad for an old school design. the motor is an old x12 strap, popular in IMCA type racing in the 90's.

 

this design is a brass & wire version of a gt12 chassis with a center flex & floating outer rails. it's fairly stiff in length & allows for some rear steering. the front bumper keep the car from tipping in the turns & offers better handling. the car with body weighs about 89 grams & it's a blast to drive on motown's hillclimb. the motor is an old RJR super wasp.

 

 

what makes both of these cars handle are the body & the gearing. my flat track car is geared 7/44 in 72 pitch & it allows the car to rev up in & out of the turns, making it more driveable. the lightness & flex of my bank car allows me to dive deeper & corner out of the turns faster than my flexi cars. the other thing that make the cars handle are the tires; the lower the profile, the better it handles. retro inline cars aren't going to handle as well as anglewinders & the taller tires don't help either. but chassis design & some weight will overcome some of these issues. still, a day at the track is one of life's little joys. don't worry, be happy.

[Pablo]

Jay Guard makes tuneable Retro race chassis that may be of interest to you. Go to the end of this thread and start scrolling up until you find it, or send him a PM I'm sure he'll be glad to share

 

http://slotblog.net/...allery/page-124

[Jay Guard]

Although I've made several "adjustable" chassis I think Pablo is referring to my latest, Weightshifter 3.0

 

[Shruska55]

Although I've made several "adjustable" chassis I think Pablo is referring to my latest, Weightshifter 3.0

IMG_2028.JPG

 

IMG_2029.JPG
First, Pablo. T

First, Pablo

 

Thanks for the lead. Very cool build.

 

 

Second, Jay,

 

Wow! The weight shifting along the notched rail alters the CoG from what I can see with the presets?

The weight platforms appear to be independently adjustable per side as well?

The tuning fork adds flex and the weight distribution focuses/affects the angle of flex?

Does it run well on either flat or speed? Does it had a preference based on your testing?

 

Mea culpa if my explanation is simple and questions basic. I'm still working on building simple, baseline chassis, but having gone through all 124 pages of the chassis thread, there are all sorts of ideas in my head. Your chassis looks crazy versatile.

 

Thanks for sharing!

ScottH

[tonyp]

A good place to get flat track chassis ideas is check out Bryan Warmack’s race reports from the flat track at BPR.


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