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Bostonbq

ST5 Rules Clarification

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Bostonbq

Hi There,

I am relatively new to NASA and am beginning to plan my build for the upcoming nationals. In doing so I have some questions about the ST5 rules that are laid out. First are the aero rules, and I just want to make sure I get this right:

·       With BTM aero rules I’m allowed +.4 but have to run stock aero, (no stock wing, etc.)

·       Single Flat Splitter is -.5

·       However, I could run a wing and air dam with no modification factor either way?

Second is the A-arm or Wishbone suspension rule. Is there any way you may be able to define this for me? There isn’t much of an explanation so I’m hoping for some form of clarification. My stock e30 daily technically has rear lower A-arm control arms so in this case all e30’s have to take a -.7 hit? I’m not building an e30, I’m just trying to wrap my head around this and using it as an example. If you have an A-arm set up currently, are you allowed to somehow convert to an alternate non A-arm/wishbone design? By A-arm/Wishbone, do you mean any control arm with a curve making the shape of an A no matter how wide or narrow? Basically, two mounting points to the vehicle and a single mounting point to the hub?

I appreciate the help.  

Edited by Bostonbq

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Roman V.
On 2/6/2019 at 9:26 PM, Bostonbq said:

Hi There,

I am relatively new to NASA and am beginning to plan my build for the upcoming nationals. In doing so I have some questions about the ST5 rules that are laid out. First are the aero rules, and I just want to make sure I get this right:

·       With BTM aero rules I’m allowed +.4 but have to run stock aero, (no stock wing, etc.)

·       Single Flat Splitter is -.5

·       However, I could run a wing and air dam with no modification factor either way?

Second is the A-arm or Wishbone suspension rule. Is there any way you may be able to define this for me? There isn’t much of an explanation so I’m hoping for some form of clarification. My stock e30 daily technically has rear lower A-arm control arms so in this case all e30’s have to take a -.7 hit? I’m not building an e30, I’m just trying to wrap my head around this and using it as an example. If you have an A-arm set up currently, are you allowed to somehow convert to an alternate non A-arm/wishbone design? By A-arm/Wishbone, do you mean any control arm with a curve making the shape of an A no matter how wide or narrow? Basically, two mounting points to the vehicle and a single mounting point to the hub?

I appreciate the help.  

Welcome to the NASA family.

1. Correct, you can run air dam and wing with no modification factor in ST5.

2. The A-arm rule talks about the upper A-arm. See Section 6.1.9 in the ST5 rules:

"If the vehicle has an OEM suspension design utilizing an upper “A-arm” or “Wishbone” type control arm on either the front or rear suspension, a Modification Factor will be assessed. Conversion from an alternate design to an “A-arm” or “Wishbone” suspension design using non-OEM parts is not permitted (front or rear)."

Hope this answers your questions.

 

Roman

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Bostonbq

Hi Roman,

Thank you for the response, good note on upper suspension only, I didn’t notice that.

However, you note converting from an alternate design to A-arm is not permitted; however, I want to know if you can convert from an oem A-arm design to the alternate. In doing so can one remove the -.7 penalty?

 

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Roman V.
1 hour ago, Bostonbq said:

Hi Roman,

Thank you for the response, good note on upper suspension only, I didn’t notice that.

However, you note converting from an alternate design to A-arm is not permitted; however, I want to know if you can convert from an oem A-arm design to the alternate. In doing so can one remove the -.7 penalty?

 

The conversion will require for you to change suspension mounting points, which is also not permitted in ST5. From the rules:

"Relocation of OEM suspension mounting points is not permitted." 

You can change your stock control arms to aftermarket with a mod factor assessment. 

Roman

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Bostonbq
40 minutes ago, Roman V. said:

The conversion will require for you to change suspension mounting points, which is also not permitted in ST5. From the rules:

"Relocation of OEM suspension mounting points is not permitted." 

You can change your stock control arms to aftermarket with a mod factor assessment. 

Roman

Hi Roman,

thanks for the reply, I can convert to a non A-arm without changing my mounting points. If I interpret this correctly, I would have to take a -.5 mod factor for aftermarket control arms; however I wouldn’t have to take the -.7 for A-arm since I would no longer have an arm design?

appecriate the clarification

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Roman V.
3 minutes ago, Bostonbq said:

Hi Roman,

thanks for the reply, I can convert to a non A-arm without changing my mounting points. If I interpret this correctly, I would have to take a -.5 mod factor for aftermarket control arms; however I wouldn’t have to take the -.7 for A-arm since I would no longer have an arm design?

appecriate the clarification

Yes, you can replace your stock control arms with an aftermarket ones and take -.5 assessment. Check out the ST calculator.

https://form.jotform.com/drivenasa/st-tt-car-classification-form

If the car came factory with an upper A-arm, converting it to a non A-arm design does not remove the point assessment. 

Your E30 has a lower A-arm, so it does not take the -.7 assessment. 

Roman

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Bostonbq
7 hours ago, Roman V. said:

Yes, you can replace your stock control arms with an aftermarket ones and take -.5 assessment. Check out the ST calculator.

https://form.jotform.com/drivenasa/st-tt-car-classification-form

If the car came factory with an upper A-arm, converting it to a non A-arm design does not remove the point assessment. 

Your E30 has a lower A-arm, so it does not take the -.7 assessment. 

Roman

Hmm. That sucks. I’m not planning on running an e30 I was using that as an example of a lower a-arm design prior to the clarification that the rule is upper only. My plan is an s2000 build; however, I had the idea/there are parts on the web to convert the upper front control arms to a set up like the e36/e46s have in the rear. Extremely similar designs but just aren’t an “A”. Figured you’d allow someone to go backwards in this case. 

Appreciate the clarification 

Edited by Bostonbq

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Roman V.
13 hours ago, Bostonbq said:

Hmm. That sucks. I’m not planning on running an e30 I was using that as an example of a lower a-arm design prior to the clarification that the rule is upper only. My plan is an s2000 build; however, I had the idea/there are parts on the web to convert the upper front control arms to a set up like the e36/e46s have in the rear. Extremely similar designs but just aren’t an “A”. Figured you’d allow someone to go backwards in this case. 

Appreciate the clarification 

That is interesting. What is the benefit of converting to the e36/e46 suspension design? Does it offer a better performance than a stock upper A-arm suspension? Link to a conversion? 

Roman

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Bostonbq
4 minutes ago, Roman V. said:

That is interesting. What is the benefit of converting to the e36/e46 suspension design? Does it offer a better performance than a stock upper A-arm suspension? Link to a conversion? 

Roman

In my mind I don’t think there is or would be any differentiation in performance between either design since they are very similar. My thought was I could shave another 40-45 pounds by taking the .5 hit instead of the .7; However as you mentioned if the stock design is an A arm I can’t ever get away from it. The 140+ pound penalty seems a bit of a stretch in my mind especially when the designs are similar. 

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djqd36

I have a more basic question. 

Why is this a rule at all? Choosing an upper A-Arm as a performance differentiator seems a bit random.

What is background/foundation for this rule?

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Roman V.
8 hours ago, djqd36 said:

I have a more basic question. 

Why is this a rule at all? Choosing an upper A-Arm as a performance differentiator seems a bit random.

What is background/foundation for this rule?

There is lots of discussion on the forums regarding how the rule came to be. Do a search. 

Roman

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djqd36

10-4

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Bostonbq
21 hours ago, Roman V. said:

There is lots of discussion on the forums regarding how the rule came to be. Do a search. 

Roman

Just seems interesting that the rule is applied to only ST/TT5/6 but not ST4... which share similar rule sets, in regards to aero modification and tire allocation. 

The argument made was that cars with A-arms were able to corner better than the cars without A-arm suspensions. The argument continues to go on by saying there is lots of data on this but none of the data was specifically called out or verified to the racing public and an example used oh how it was determined was one car with A-arms went out and broke someone else's track record.. Not exactly sure how the rules officials know of this story unless they were directly involved somehow, and if so, kinda seems like the rule may be a little stiff because of that specific occurrence. 

The rule is the rule and life will go on; however, there seems to be quite a lot of solid arguments on this issue in the past that if you want to apply the rule that's fine but you should at least including "multi-link" suspension designs in this as well as they are basically the same thing (as mentioned by countless ppl in prior posts and my point above). As i look at the data and results from last year it is quite clear that this rule is impacting s2000's quite significantly. My build can it can be classed in ST/TT4 and ST/TT5, and at nationals this last year an s2000 was only a second off of TT4 national champ in an e46, while in TT5 where the a-arm rule applies the closest s2000 was 3+ seconds off the national champ in an e46. 

It's quite clear to me to push my build out into ST/TT4 so i can be more competitive I just hope in the future this rule will either be re-assessed to include multi-link or a reduction in the penalty. 

On a side note, I looked into the database and only 65% of the cars in ST5 that should be applying mod factor are actually applying it.. Not sure who is supposed to be reviewing these but looks like some have slipped through the cracks.

-B

 

 

 

Edited by Bostonbq

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rob_h
On 2/8/2019 at 6:37 PM, Roman V. said:

Welcome to the NASA family.

1. Correct, you can run air dam and wing with no modification factor in ST5.

Roman

Okay so now I'm confused too.  Please  confirm or correct:

Assuming a base 14:1

If I take no air-dam, wing, splitter, and run BTM Aero it's +.4 for 14.4:1 so there is an opportunity to remove weight.

I can take an aftermarket air dam (as defined in the rules) and rear wing and stay at 14:1

I can add a single flat splitter and the rear wing for -.5 or 13.5:1 and have to add weight to get back to 14:1

Do I have this right?

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djqd36

Correct

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Bostonbq
2 hours ago, rob_h said:

Okay so now I'm confused too.  Please  confirm or correct:

Assuming a base 14:1

If I take no air-dam, wing, splitter, and run BTM Aero it's +.4 for 14.4:1 so there is an opportunity to remove weight.

I can take an aftermarket air dam (as defined in the rules) and rear wing and stay at 14:1

I can add a single flat splitter and the rear wing for -.5 or 13.5:1 and have to add weight to get back to 14:1

Do I have this right?

No think of it in the opposite way. Even though it’s +.4 for btm it doesn’t mean you add to 14:1 you subtract so it would be 13.6:1 for btm aero. 14:1 for wing and air-dam. 14.5:1 for splitter. 

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rob_h
1 hour ago, Bostonbq said:

No think of it in the opposite way. Even though it’s +.4 for btm it doesn’t mean you add to 14:1 you subtract so it would be 13.6:1 for btm aero. 14:1 for wing and air-dam. 14.5:1 for splitter. 

That's not how the calculator seems to work:

If I'm at 2995 lbs and 214 average HP then it's 14:1.  I believe this gives me a wing and air dam, but no splitter?

If I take BTM Aero then I'm at 14.4:1 and can reduce weight to 2910 and still be at 14:1 (adjusted).  I lose the wing and air dam but I added lightness.

If I don't take BTM Aero and take the splitter then I'm at 14:1 (adjusted) if I go up to 3102 lbs and 214 average HP.

 

 

Edited by rob_h

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Roman V.
15 minutes ago, rob_h said:

That's not how the calculator seems to work:

If I'm at 2995 lbs and 214 average HP then it's 14:1.  I believe this gives me a wing and air dam, but no splitter?

If I take BTM Aero then I'm at 14.4:1 and can reduce weight to 2910 and still be at 14:1 (adjusted).  I lose the wing and air dam but I added lightness.

If I don't take BTM Aero and take the splitter then I'm at 14:1 (adjusted) if I go up to 3102 lbs and 214 average HP.

 

 

Rob, you are correct in your calculations.

Roman

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Greg G.
On 2/8/2019 at 11:34 PM, Bostonbq said:

Hmm. That sucks. I’m not planning on running an e30 I was using that as an example of a lower a-arm design prior to the clarification that the rule is upper only. My plan is an s2000 build; however, I had the idea/there are parts on the web to convert the upper front control arms to a set up like the e36/e46s have in the rear. Extremely similar designs but just aren’t an “A”. Figured you’d allow someone to go backwards in this case. 

Appreciate the clarification 

"3) If the vehicle has an OEM suspension design utilizing an upper “A-arm” or
“Wishbone” type control arm on either the front or rear suspension, a Modification
Factor will be assessed. Conversion from an alternate design to an “A-arm” or “Wishbone” suspension design using non-OEM parts is not permitted
(front or rear)."

So, changing the control arms will not change the OEM design of the suspension, although it would change the suspension design on your particular vehicle.  So, the assessment would still apply.

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