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ST5/6 Control Arm Rule Proposal for comments


Greg G.
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Proposed substitution of the current control arm rules for ST5/6 (replaces 6.1.9.4)---Mod Factor still -0.5 for the additional arms:

 

"One means of aftermarket camber adjustment per wheel by replacement of a single suspension component (in addition to camber plates) is permitted without a Modification Factor. Rear suspension link replacement or modification for toe adjustment is permitted without a Modification Factor.   Any additional non-OEM or modified control arms or links beyond the above shall be assessed a Modification factor."

Comments are welcome.

 

Here is the final version of the rule.  We made some edits for clarity:

"One means of aftermarket camber adjustability per wheel by replacement of a single suspension component not requiring modifications to the spindle or mounting points (in addition to camber plates) is permitted without a Modification Factor. Rear suspension link replacement or modification for toe adjustment is permitted without a Modification Factor.   Any additional non-OEM or modified control arms or links beyond the above shall be assessed a Modification factor."

 

So, if the part doesn't provide the ability to adjust camber (like an arm that just changes camber but doesn't give adjustability), it would take the Mod Factor for arms.

 

Edited by Greg G.
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You guys must have started Thanksgiving early. 🤣

Where are the screams of joy that ST5/6 can get "free unadulterated camber and toe" using an aftermarket camber arm or control arm and toe arm that has been requested numerous times?   Or, the howling that now you have to spend a few hundred bucks to keep up with the Jone's and their camber arms?  Or, the scowls that your supersize spec car is not allowed to do that?

Nothing?

Bueller, Bueller, Bueller......

 

Anyway, the ST Rules Committee decided that with the drop in the A-Arm penalty to -0.5, that all vehicles should be able to have the same chance to get as much negative camber and accurate toe settings as desired, and it would be beneficial since these parts are readily available and easy to install if desired.  Yet, we believe that the wording we came up with will prevent the active geometry changes that can/would occur if control arms (or more than one means of camber adjustment) were to be a no Mod Factor modification.

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So if I'm reading this correctly, I can replace my rear toe arm and one control arm per side with length adjustable units, for free?

The control arm still has to use rubber/poly/delrin bushings (no spherical), to avoid a penalty, correct?
What about the toe link bushings?

 

Additionally, do offset bushings count as "replacement of a single suspension component"

for the purposes of this rule?  Or are those still free?  If they count for this rule, then please specify that a pair of offset bushings count as a single component, and not 2 components.

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I think this is a welcome change, the mod factor for toe arms such as on an E36/E46 was too much. It would seem that this allows for different types of trailing arm adjusters to be used on cars like E30s as well, besides just eccentric bushings.

@Tansar_Motorsports the rule is worded "per wheel" so a pair of bushings, one on each side, would be fine.

I presume camber/toe links with spherical bearings would still be assessed -0.2 mod factor.

Edited by Digitalwave
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If we are allowed to replace one component per wheel the bushing type within that replacement part should not add addition penalties to the equation.  For instance the lower control arm on an E36 that is adjustable for camber is likely going to have spherical type bushings already in it off-the-shelf.  Why limit that options?

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5 hours ago, Tansar_Motorsports said:

So if I'm reading this correctly, I can replace my rear toe arm and one control arm per side with length adjustable units, for free?

The control arm still has to use rubber/poly/delrin bushings (no spherical), to avoid a penalty, correct?
What about the toe link bushings?

 

Additionally, do offset bushings count as "replacement of a single suspension component"

for the purposes of this rule?  Or are those still free?  If they count for this rule, then please specify that a pair of offset bushings count as a single component, and not 2 components.

6) Non-OEM metallic and/or spherical design replacement suspension bushing modifications on
control/camber/toe arms/links, panhard rods, watts links, and torque arms shall be assessed a
Modification Factor which is in addition to and additive to #4 & #5 above. (Includes replaced,
modified, adjustable, or altered control arm ball joints for roll-center correction or camber/caster
adjustment. Note: ball joint may be welded to the spindle for added strength).

 

So, yes, it needs to be bushing material without a spherical design to not take the above.

And, yes, offset bushings count as the replacement of a single component.  In many cases, the combination of offset bushings and a replaced control arm result in geometry changes and changes of the camber curve, not just camber.   But, yes, if you just do offset bushings, still free.  I may need to check before I speak about the "pairs" of offset bushings, but I assume you are talking about identical bushings on the two ends of an A-arm, which sounds appropriate

 

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2 hours ago, Digitalwave said:

I think this is a welcome change, the mod factor for toe arms such as on an E36/E46 was too much. It would seem that this allows for different types of trailing arm adjusters to be used on cars like E30s as well, besides just eccentric bushings.

@Tansar_Motorsports the rule is worded "per wheel" so a pair of bushings, one on each side, would be fine.

I presume camber/toe links with spherical bearings would still be assessed -0.2 mod factor.

Yes, the spherical Mod Factor did not change.

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41 minutes ago, rsotak said:

If we are allowed to replace one component per wheel the bushing type within that replacement part should not add addition penalties to the equation.  For instance the lower control arm on an E36 that is adjustable for camber is likely going to have spherical type bushings already in it off-the-shelf.  Why limit that options?

You can have the spherical type if you want--just still takes the Spherical Mod Factor.  There are off-the-shelf adjustable arms without sphericals as well.

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@Greg G. Big thanks for the much needed class attention for the 2023 season. 

Many of the TT5/ST5 class agrees that the 'a-arm' penalty should be split equally to a ''per axle (F/R) penalty" only. 

I understand the a-arm penalty was reduced to (-0.5) however, I amongst many other drivers in class are in favor of splitting the a-arm penalty to a (-0.3 per axle F / R) to bring further equality to class. It does look like the majority of TT5/ST5 would like to see this change before the 2023 rules are solidified. 

Example: (Toyota GT86) runs a front McPherson strut suspension & multi-link suspension utilizing the a-arm design in the rear only. (Honda S2000) runs a double wishbone front and rear suspension utilizing a-arms on both axles F /R. Is it just to penalize both cars equally? 

 

I would like to hear your thoughts on the matter. Thanks again Greg. 

 

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On 11/24/2022 at 8:27 PM, ZC6126 said:

@Greg G. Big thanks for the much needed class attention for the 2023 season. 

Many of the TT5/ST5 class agrees that the 'a-arm' penalty should be split equally to a ''per axle (F/R) penalty" only. 

I understand the a-arm penalty was reduced to (-0.5) however, I amongst many other drivers in class are in favor of splitting the a-arm penalty to a (-0.3 per axle F / R) to bring further equality to class. It does look like the majority of TT5/ST5 would like to see this change before the 2023 rules are solidified. 

Example: (Toyota GT86) runs a front McPherson strut suspension & multi-link suspension utilizing the a-arm design in the rear only. (Honda S2000) runs a double wishbone front and rear suspension utilizing a-arms on both axles F /R. Is it just to penalize both cars equally? 

 

I would like to hear your thoughts on the matter. Thanks again Greg. 

 

You keep trying to speak for “the majority” while also sprinkling in your own proposal (0.3/axle) as if thats what the people are clamoring for. 

-The A-Arm penalty has always been too large. People seem to agree on this
-Splitting it F/R is a good idea. People also seem to agree in this. 

However!

Leaving the total basically unchanged(at 0.6) is not what “most” drivers in 5 are looking for. Especially when the BMW contingent gains 0.1 with the TB modifier change.  
 

@Greg G.TBH the more I think about it the more 0.5 as a single A-ARM penalty makes sense.  Going to 0.3/axle, as the above post proposes, gives quite a large bump (0.4)to an already known fast chassis (frs/brz) while essentially leaving the S2000s and Miatas to rot. 
Going to 0.2/axle(the most common number I have seen) is probably even worse, giving a large bump to everyone but BMW. 
Hopefully 2023 nationals is well attended and we can get some really good data vs this year which was essentially a California Regional. 
 

 

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On 11/23/2022 at 2:29 PM, Greg G. said:

6) Non-OEM metallic and/or spherical design replacement suspension bushing modifications on
control/camber/toe arms/links, panhard rods, watts links, and torque arms shall be assessed a
Modification Factor which is in addition to and additive to #4 & #5 above. (Includes replaced,
modified, adjustable, or altered control arm ball joints for roll-center correction or camber/caster
adjustment. Note: ball joint may be welded to the spindle for added strength).

 

So, yes, it needs to be bushing material without a spherical design to not take the above.

And, yes, offset bushings count as the replacement of a single component.  In many cases, the combination of offset bushings and a replaced control arm result in geometry changes and changes of the camber curve, not just camber.   But, yes, if you just do offset bushings, still free.  I may need to check before I speak about the "pairs" of offset bushings, but I assume you are talking about identical bushings on the two ends of an A-arm, which sounds appropriate

 

Greg,

Thanks for explaining.

I was under the impression that offset bushings were already legal, under the current rules.
What I am referring to is something like this:
Superpro Bushings Kit Mazda RX8 SE17 (03-12) [Front Control Arm Upper- –  Redline360

These are installed on the inboard side of an A-arm, giving camber adjustment ability by rotating the orientation of the bushings.

There would be no need to have these plus a length adjustable arm.  They do the same thing.

 

 

So I guess to clarify:
1.  are this type of offset poly bushing currently legal?
2. if they are currently legal, then could I, in theory, have these plus one aftermarket arm per wheel?
3. if they are not currently legal, then does a matching pair of them count as a "single component" for the purposes of this rule?

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