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Tracking / Autocross / HPDE / Drifting What these cars were built for!


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Old 02-08-2022, 10:47 AM   #141
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And ask for what? I'm not asking to be controversial, just truly curious - the STAC won't make allowances for a single car
Oh no definitely. I am newer to scca process and thought you could bring these issues up for rulings like what comes out on the fast track newsletters

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Old 02-08-2022, 10:52 AM   #142
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I've served on the STAC and am currently on the SAC.

In general, there will never be car-specific allowances in either Street or Street Touring. So a letter asking for one will promptly get a "TYFYI" reply. It's simply not the philosophy of either category as it takes "make it simple, make it fun" out of the equation. The rulesets are already way too complex

So it really depends on what the question is. There's not really a "gray area" on this one, if the bolt holes are in a different spot they're illegal to the current rule. That leads to whether you / someone is asking for the rule to be changed. If someone was wanting to do that, it would be best to write what you'd think the rule should be, and WHY - why is it in the best interest of the general membership (not just 2022 twin owners) to change the rule THAT is why things get hard...

Does that help a little?
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Old 02-09-2022, 02:22 PM   #143
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Has anybody yet been able to measure the Konis for the first gen and compare them to the OEM dampers for the 2nd gen to confirm they're within the +-1" legal length for DS?
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Old 02-10-2022, 02:19 PM   #144
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I've served on the STAC and am currently on the SAC.

In general, there will never be car-specific allowances in either Street or Street Touring. So a letter asking for one will promptly get a "TYFYI" reply. It's simply not the philosophy of either category as it takes "make it simple, make it fun" out of the equation. The rulesets are already way too complex

So it really depends on what the question is. There's not really a "gray area" on this one, if the bolt holes are in a different spot they're illegal to the current rule. That leads to whether you / someone is asking for the rule to be changed. If someone was wanting to do that, it would be best to write what you'd think the rule should be, and WHY - why is it in the best interest of the general membership (not just 2022 twin owners) to change the rule THAT is why things get hard...

Does that help a little?
I have no input on the language because I'm not really very good at that piece, but I think something ought to be done to handle the differences in the aftermarket (it's unlikely they are going to make any new parts to address this issue with the bolt location on the new gen cars for our tiny segment of rules in comparison to their overall sales) in some fashion like how the bushing rules were recently adjusted for the 'metal content' discussion.
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Old 02-10-2022, 02:56 PM   #145
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Quote:
Originally Posted by Banannie View Post
I've served on the STAC and am currently on the SAC.

In general, there will never be car-specific allowances in either Street or Street Touring. So a letter asking for one will promptly get a "TYFYI" reply. It's simply not the philosophy of either category as it takes "make it simple, make it fun" out of the equation. The rulesets are already way too complex

So it really depends on what the question is. There's not really a "gray area" on this one, if the bolt holes are in a different spot they're illegal to the current rule. That leads to whether you / someone is asking for the rule to be changed. If someone was wanting to do that, it would be best to write what you'd think the rule should be, and WHY - why is it in the best interest of the general membership (not just 2022 twin owners) to change the rule THAT is why things get hard...

Does that help a little?
Totally understand this perspective.

Knowing how things work on the committee, and the details of the RLCA problem for gen.2 cars, can you suggest a wording that would be a good middle ground?

I think the rule that the distances between holes on a control arm should be the same as OEM is not "make it simple".
Who knows the correct OEM measurements and keeps track of what changed in which model year? Even the RLCA manufacturers that claim that their arms are STX legal don't keep track of that.
If anything, this puts people in the know at an advantage, as people not in the know will either just stay OEM out of abundance of caution, or install whatever arms they find, and will risk being disqualified later.

On top of that, it's tricky to precisely measure distances between two holes. Takes a minute even when the arm is in your hands, and gets a lot more tricky when the arm is installed on the car, and the car is not on a lift.

Is someone going to be disqualified if their car gets checked and the imprecise "in the paddock" measurement is 1 mm off OEM? 2 mm?
Is someone going to get away from disqualification if their arm was designed with the hole 1 mm off OEM just because the manufacturer didn't measure something correctly? Or it's a defective arm? How about 2 mm?
Is someone going to get away from disqualification if their arms were intentionally designed to have the holes 1 mm off? 2 mm?

As an idea: could the wording be such that disadvantageous relocation of holes is allowed? I get it that moving the hole for the spring/damper outboard (closer to the knuckle) changes the motion ratio and effectively makes the spring/damper stiffer; but moving the hole in the opposite direction should only be a disadvantage to anyone. As someone previously mentioned, changes to the effective spring rates shouldn't even matter in Street Touring classes where you can change springs and dampers, and non-OEM adjustable RLCAs aren't legal in the Street classes anyways. But maybe I'm missing something?

Can anybody suggest how could someone exploit it if moving any holes on an already-adjustable since control arm was allowed in any direction?
I get it that if multiple arms are "free to do whatever" then it's a Pandora box.
But if we're limited to changing only one arm anyways?..

Here's my idea.
Either:
- Document specific tolerances. E.g. +/- 2 mm is OK.
OR
- Allow moving any of the holes in the middle of a control arm for the control arm that's already legal for adjustments
OR
- Allow moving any of the holes in the middle of a control arm inboard for the control arm that's already legal for adjustments

Is anyone better versed at phrasing and politics willing to submit a format suggestion / proposal on my/our behalf?
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Old 02-10-2022, 04:15 PM   #146
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Before you write a letter for a line item exception to a ST class the car needs a ST class.

I donít see this effort being successful though, based on how things are handled historically. If the aftermarket doesnít make ST legal RLCAs there are other methods of camber adjustment available. Not the ideal method but upper arms, off set bushings, etc will get your allowable one camber adjustment.
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Old 02-10-2022, 04:56 PM   #147
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Before you write a letter for a line item exception to a ST class the car needs a ST class.

I donít see this effort being successful though, based on how things are handled historically. If the aftermarket doesnít make ST legal RLCAs there are other methods of camber adjustment available. Not the ideal method but upper arms, off set bushings, etc will get your allowable one camber adjustment.

This.

The RLCA method isn't going to be allowed unless you can prove that your parts are legal and for a national competition you better be prepared for that. It's on you to defend yourself.
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Old 02-10-2022, 06:06 PM   #148
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@Timurr that’s a whole can of worms. imho strike that part from 14.8.H.5 or deal with it, the rule book doesn’t need to be longer and we do not have any data to determine a nominal position to measure tolerance or allowable off of. Yes you can gum it up by saying “aha you can’t measure this accurately therefore you can’t prove my car is illegal” but that’s just bad sportsmanship in an amateur place that’s supposed to be fun.

I could see striking it as fine, aftermarket parts with different hole placements are common and not significantly advantageous nor expensive, and in the case of the 86 could allow for some cheap bump travel improvement in the back. “Intermediate mounting points (e.g., shock/spring mounts) may [s]not [/s]be moved or relocated on the arm,” but I see no need to add another knob to turn. Arguing that the rule as written is difficult if not impossible to enforce is probably the best angle, but you’ll be fighting against creating the perception of needing more parts to be competitive which is not something we should want.

Personally I ain’t protesting this one.

Edit: Above forgot to mention modifying the arm. Personally if I had a mk2 and was building for ST I’d just get the offset bushings for the upper arm, it’s technically the better solution, improves wheel clearance and keeps the track narrow. Assuming they don’t slip that is…
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Old 02-11-2022, 04:37 PM   #149
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Sounds like there's a market for a new RLCA for the gen 2... You can also always go custom made. Best way to guarantee that what you have is legal. Build it to spec.
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Old 02-11-2022, 05:55 PM   #150
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I stumbled across this RLCA discussion immediately after ordering a set of gen1 SPC RLCAs for my 22 BRZ. Good timing.

At first I thought about cancelling the order and eating the cancellation fee, but the car could really use more camber after seeing the uneven tire wear from my first track day. Who knows how long it will be before the gen2 equivalent is available. So I tried to rationalize the purchase with some math and some thought on fabrication.

Can y'all check me on this very rough math? Not a math guy or an engineer, but I was trying to estimate just how big a difference we're talking about:
From the pics in this thread it looks like roughly 440mm from the inside pivot to the hub mount. 104mm from the shock mount to the hub mount on a gen1 RLCA. 440mm-104mm=336mm from inside pivot to shock mount (not sure this matches "shock centerline" in the definition of motion ratio but it's what I've got). (336mm/440mm)^2 ~= .583 motion ratio for gen1 arm.

94mm from the shock mount to the hub mount on a gen2 RLCA. 440mm-94mm=346mm from inside pivot shock mount. (346mm/440mm)^2 ~= .618 motion ratio for gen2 arm.

I couldn't find spring rates for the new cars but for the old cars I found numbers from 185lbs/in to 210lbs/in, so I went with 200lbs/in. On a gen1 RLCA 200lbs/in * .583 motion ratio = 116.6 lbs/in wheel rate. On a gen2 RLCA 200lbs/in * .618 motion ratio = 123.6 lbs/in wheel rate. 123.6/116.6 ~= 1.06 for a 6% difference in wheel rate and I suppose "damper effectiveness" however that would be quantified. With those numbers gut feeling is more benefit from the extra camber in both grip and tire life than loss from the motion ratio change.

The other rationalization was thinking about how you could "fix" the problem. As timurrrr observed the holes are too close together gen1 vs gen2 to feel good about redrilling alone. I didn't do the math but they have to be close to touching or straight-up connected.

My thought was to grab a piece of weld steel, scribe the hole, cut and grind a round plug to weld in. Then take precise measurements from the gen2 factory piece and drill the new hole. Top it off with a coat of paint and voila. It doesn't seem too hard in theory but I always get suspicious of homebrew changes instead of relying on a known quantity with suspension parts intended for thrashing on track. For a 6% difference maybe it's better to leave it alone and sell the gen1 RLCA for a gen2-specific part in a year?
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Old 02-11-2022, 06:07 PM   #151
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alignment > motion ratio

If you don't care about competing in ST at the national level (car isn't classed in ST anyway, highly unlikely to be until next year) I wouldn't hesitate about running the gen 1 arm. btw the SPC arm isn't STX legal anyway due to the ball joint on the inboard side.

Not sure how I would 'fix' an old arm, probably weld plates on the outside and drill through that, get a longer bolt to compensate.
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Old 02-11-2022, 06:55 PM   #152
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I couldn't find spring rates for the new cars
https://www.ft86club.com/forums/showpost.php?p=3450997
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Old 02-11-2022, 06:57 PM   #153
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Before you write a letter for a line item exception to a ST class the car needs a ST class.
Just to clarify, my proposal is that the rule should be changed/removed for all cars, not just 2022's.

2015-2017 Subaru WRX and STI have the same OEM RLCA as 2022 BRZs and GR86s, so also don't have STX-legal aftermarket options available.
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Old 02-22-2022, 10:28 PM   #154
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STR.

https://www.ft86club.com/forums/showthread.php?t=148906
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