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IRRAź chassis main rail construction clarification


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#1 IRRAź Retro Racing

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Posted 22 February 2017 - 06:15 AM

A question has been raised about the legality of the top chassis show below. The answer is that it is not legal per the IRRA chassis rule cited below:
 
"3i. Wire or tubing rails must connect the front and rear sections of the chassis. Using metal strip for this purpose is not permitted. A rail is defined as that which connects the motor bracket to the front of the chassis."
 
To be considered as main rails, whether center or outer rails, they must solidly connect the motor bracket and the front of the chassis (nosepiece). For example, center rails that are inserted into tubes in the nosepiece (but are not soldered into the tubes) do not qualify as main rails.

Main rails are there to support the frame. In the top picture below there are no main rails connecting the nosepiece to the motor bracket so the main rails cannot support the frame.
 
Note that main rails do not have to be one-piece, but multiple pieces of wire or brass tubing, or rod, must be connected with solder joint lengths of at least .250 inches to be considered permissible main rails.
 
chassis.1.jpg
 
This chassis does not have complete main rails connecting the motor bracket to the front of the chassis.
 
chassis.2.jpg
 
By adding additional wire with at least .250" long solder joints, this chassis does have a complete main rail structure.

 

Further clarification of the main rail issue...

 

The IRRA® wishes to show how to construct this new chassis so it complies with the long-standing IRRA® chassis rules, rather than have racers purchase something they believe is legal and later find out at tech it is not.
 
An additional restriction being imposed is that bracing or partial rails soldered atop brass plate to "complete" a main rail structure can be no smaller than .047" diameter.
 
Clarification of main rails on the original chassis design:
 
chassis.a.jpg
 
Here are illustrations showing a few ways how this new chassis kit can be built to comply with the IRRA® chassis rules for main rails.
 
chassis.b.jpg

 

chassis.c.jpg

 

chassis.d.jpg
 

(Posted for the IRRA® BoD by Tony Przybylowicz)


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#2 Rick Moore

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Posted 22 February 2017 - 02:09 PM

On the picture of the “legal” correction of the chassis in question, the added wire sections appear to be soldered atop the brass plate motor box. There is no bottom view, so I am assuming the chassis appears the same from the bottom before and after modification of the main rail structure; as such, the brass plate of the motor box is underneath that portion of the main rail wire structure. Is this correct?

 

For some reason I was operating under the assumption the “main rail(s)” had to be visible from the bottom, and that no brass plate/sheet could be below the main rails (even when still conforming to the bottom plane of the chassis).

 

The reason I ask is that in the past I have tinkered with chassis designs and construction that were 0.010” brass sheet on the bottom, but were backed/topped with piano wire that still met the “main rail” rule. Obviously the 0.010” brass sheet is not strong enough to support the chassis, but with a wire “skeleton” on top it certainly was. A very old example is pictured below.

 

Not trying to be contentious here, just want some clarification because I’m curious and, who knows, I might consider revisiting some of my newer designs using the wire-backed brass sheet construction method, admittedly for no better reason than I like to build weird stuff…

 

Thanks.

 

Rick / CMF3

 

1109-bottom-e.jpg

 

1109-top-e.jpg



#3 Noose

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Posted 22 February 2017 - 03:15 PM

I cannot tell from this picture if the outer rail is connected to the motor bracket. The tuning fork is not that's for sure.


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#4 raisin27

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Posted 22 February 2017 - 04:13 PM

I don't know if its legal or not, but it sure looks cool!


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#5 Rick Moore

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Posted 22 February 2017 - 04:18 PM

Please note, the legality of this specific chassis is not my question, but was posted as an example of brass plate/sheet being used under the main rail structures.

 

But, since you asked... Yes, the main rail structure attaches at the motor bracket sides, forward and rearward of the rear axle tube. The center-guide section ("iso-guide", as some have called it, but which I believe you are referring to as the "tuning fork" in this case) also attaches to the main rails; the rear aspect of the motor box stiffeners (running parallel with the motor bracket sides) on this particular chassis design are also attached to the main rail structure, but do not extend forward to attach with the center-guide section wire framing (this portion of the chassis is self supporting, but these were added to the design solely to restrict flex and twisting in this portion of the chassis; on subsequent designs they do attach). All of the wire framing components are legal IRRA® IRRA rules, however...

 

Technically, this chassis was built many years ago before the 1-piece motor bracket rule was instated, as back then I used home-made three-piece motor brackets, and that is what makes this specific chassis non-compliant with IRRA® rules.

 

No hurry on this one. As I said, just curious regarding chassis construction using brass plate/sheet below any or all of the main rail structure(s), and at the same time thought it might be beneficial for others to know as well.

 

Rick / CMF3



#6 MSwiss

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Posted 22 February 2017 - 05:11 PM

Rick,
Originally, the point of the main rails, was to have them as the lowest point of the chassis.

When Warmack started building chassis with the outer rails in tubing, it was questioned whether that violated the rules, as these rails were raised up by the wall thickness of the tubing.

IMO, they did violate the rules.

After much BOD discussion, we determined it did not violate the intent of the rules, because nothing was hanging below the clearance plane of the chassis.

Also, it could be argued as soon as a chassis got bent, it violated the rules.

Thus,IIRC (it was many years ago) either we never wrote in that the main rails must be the lowest part of the chassis, or possibly "wrote it out".

That style of chassis, with all the rails, not being the lowest part of the chassis became more common place with the advent of the GVP tuning fork.

As far as your chassis, while you are not inquiring about it in particular, AFAICT, you have brass strip connecting the front and back, so at some point you would have to split the front and back, to make it at least 2 separate pieces.
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#7 Rick Moore

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Posted 22 February 2017 - 06:52 PM

Thanks Mike.

 

Good starting point to clarify this. Since the brass sheet (in this case only 0.010” thick, but regardless of any thickness) is continuous front to back, it would not be deemed within the rule; the “front” brass plate/sheet must be a separate piece from the “rear” brass plate/sheet. Hypothetically that demarcation could be a slice the width of my dremel cutting wheel and it would in essence create two pieces, front and back, and thus be within the rule. Got it.

 

Now for some additional clarification, the rule states:

 

“3i. Wire or tubing rails must connect the front and rear sections of the chassis. Using metal strip for this purpose is not permitted. A rail is defined as that which connects the motor bracket to the front of the chassis.”

 

Now for some additional clarification:

 

The “rear” section is easy enough as this is simply the mandatory motor bracket as stated (and rear axle tube if used).

 

What defines the “front” of the chassis? Is it:

 

a) That portion of the chassis that connects to the front axle support;

 

b) That portion of the chassis that connects to the guide tongue; or,

 

c) That portion of the chassis that connects to the front axle support AND the guide tongue.

 

Still using the above chassis as an example, while all connecting to the chassis “rear”, the rails that connect to the guide tongue (“center-guide” or “iso-guide” section) are separate from the rails that connect to the front axle support (and the “side pans”).

 

For example, if the answer is “c” above, there would have to be a demarcation of the brass sheet between the left & right sections that attach to the front axle uprights, AS WELL AS a demarcation of the brass sheet somewhere between the chassis “rear” and the guide tongue mount.

 

I am only pursuing these questions because way-back-when I found these wire-backed 0.010” brass sheet chassis exhibited some very promising handling characteristics, but most of my efforts then were with no-rules anglewinders, and I only adapted a couple of those designs to inlines for retro racing, as opposed designing dedicated inline chassis. But it was always something that was worth consideration and additional exploration… well… at least to me, but that’s not saying much… and on the odd chance someone else taking leave of their senses might try building like this…

 

No doubt y’all would prefer I just keep building all-wire chassis and shut up…

 

Thanks guys.

 

Rick / CMF3


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#8 911GT3

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Posted 25 February 2017 - 11:39 AM

From the pictures in post #1, it appears the it is legal to build a chassis that has round or tubular rails of one diameter connected to a brass strip that connects to the motor bracket.  The solder another diameter of tubing or rod on top of the brass strip to make the chassis legal.  From the picture, I can come up with a few ideas that makes the chassis legal according to the picture.  Will there be a written specification that defines what is legal and not legal?  A picture may be worth 1000 words but there is so much left to interpretation.


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#9 Cap Henry

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Posted 25 February 2017 - 12:04 PM

The brass strip doesn't count as a rail. You have a rail/tube round or square made from steel or brass going from front to back. If the rail is more then one piece it has to have a minimum of .25" overlap and if soldered on top of brace plate a minimum diameter of .047"

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#10 JHMerriman

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Posted 25 February 2017 - 12:46 PM

I am still interested in the answers to Rick's questions regarding what makes a "front end" a front end.


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#11 MSwiss

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Posted 25 February 2017 - 01:04 PM

James,

 

From RETRO rules;

Chassis Main Rails must connect the front of the chassis to the rear motor bracket.

 

What is considered the "front of the chassis"?


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#12 JHMerriman

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Posted 25 February 2017 - 01:16 PM

Why are you quoting RETRO rules, Mike?

 

My local series uses IRRA® rules, that's why I'm asking.


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#13 MSwiss

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Posted 25 February 2017 - 01:19 PM

Because, I'm curious what's the RETRO officials take is on that vague passage.

Mike Swiss
 
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#14 JHMerriman

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Posted 25 February 2017 - 01:30 PM

Then you should probably pose that question to them, just as I have asked the IRRA® here.


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#15 MSwiss

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Posted 25 February 2017 - 01:37 PM

Last time I posted on SCRT, on Jim Crider's FB handle, but clearly identifying myself, that account was terminated.

Since a number of Retro racers participate in both series, don't you think it would be important that the rules coincide?

It's not like you can easily change a rail, like someone can change a .007" body to a .010" one.


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#16 JHMerriman

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Posted 25 February 2017 - 01:45 PM

I give up! I had a question and you keep wanting to talk about the other org. When is it going to stop? How about you as a BoD member focus on what your org does and a little less about what they do?
 


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#17 The Number of

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Posted 25 February 2017 - 01:47 PM

The brass strip doesn't count as a rail. You have a rail/tube round or square made from steel or brass and a minimum of .047" going from front to back. If the rail is more then one piece it has to have a minimum of .25" overlap.


I don't think the rule says the dia. of the rail needs to be .047" front to back just the connecting piece need to be at least .047". I still do not see any min. dia. listed for a main rail. Maybe I am reading this wrong?


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#18 Cheater

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Posted 25 February 2017 - 01:57 PM

You have it right, Bill.


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#19 Cap Henry

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Posted 25 February 2017 - 02:06 PM

OK, I stand corrected on that part.


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#20 MSwiss

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Posted 25 February 2017 - 02:16 PM

I give up! I had a question and you keep wanting to talk about the other org. When is it going to stop? How about you as a BoD member focus on what your org does and a little less about what they do?

 

Since a number of Retro racers participate in both series, don't you think it would be important that the rules coincide?


Mike Swiss
 
IRRA® Components Committee Chairman
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Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#21 MSwiss

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Posted 25 February 2017 - 02:29 PM

How about you as a BoD member focus on what your org does and a little less about what they do?

 

But somehow, it doesn't bother you when the head of RETRO continually brings up IRRA® issues on SCRT.

Sorry, James, but you are a hypocrite.
 
Along with the above example, you are interested in what the IRRA® interprets is the front end, but don't seem to care what RETRO interprets it as.
 
Or aren't you planning to participate in any more RETRO races in your lifetime?


Mike Swiss
 
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Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
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#22 JHMerriman

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Posted 25 February 2017 - 02:41 PM

I'm not a hypocrite at all. I had a question for the IRRA® BoD since the majority of my racing will probably be under IRRA® rules. Two people had an honest question and it turns into this BS. No ulterior motives for the question, not trying to get the BoD into a gotcha moment. Just a plain and simple question. Not everything needs to turn into a us vs them mentality/argument/bashing, etc.

I'll await the answer to the simple question Rick asked. I understand it'll take time, as you and the rest of the BoD have a life.


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#23 JHMerriman

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Posted 25 February 2017 - 02:44 PM

I didn't see the additional question you asked above before I posted.

Things have changed in my life (unforeseen) that will probably limit my racing to a local level. Maybe one or two races a year outside the state.


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