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Old 07-08-2021, 03:28 PM   #29
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The FRS springs have a ~15% split, [/url]
Wow, great point among several good points. Maybe I should just throw the frs springs I have on to B6 dampers and call it a day. And if I end up on the bump stops in corners upgrade the sway bars slightly.

Thanks for this.
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Old 07-08-2021, 05:51 PM   #30
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@itschris Thanks for posting the link to the article. Looking at the parent site there is a wealth if information there. Wow. A lot of reading material - a lot of food for thought. Thanks again.
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Old 07-08-2021, 05:59 PM   #31
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If looking for a plug-and-play option for the GT feel on a daily driver. Both of these DFV style setups will do the trick.

Ohlins Road and Track
https://www.ohlins.com/product/road-...2012-2017-zn6/

Showa Tuning Evolution (non-U.S.)
https://showa-tuning.com/line-up/toyota-86/
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Old 07-08-2021, 06:50 PM   #32
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OptimumG is good stuff!

We did a very basic primer on suspension frequencies on our instagram here:
https://www.instagram.com/p/B6TKG6Un..._web_copy_link

Stock springs do work nicely with Bilstein B6 and actually BRZ front with FRS rear is pretty good. That would indeed ride better than Bilstein + Yellows (performance was important when designing those springs).

IMO if you're designing from the ground up (which means you're also starting from scratch on the dampers and bumpstops and swaybars etc) then flat ride is the ticket for comfort. But as an example, a BRZ with 200 lbs/in springs front and rear will likely be more comfortable than a car with 200 lbs/in springs front and 250 lbs/in springs rear, (with the same dampers and/or same damping ratio). I encourage you to think about the bumps you encounter, which are most noticeable, and if/when flat ride would help.

One note since it sort of came up...don't go above recommend ride heights with a coilover like KW V3, SS1, or Bilstein B16 for comfort reasons. You do get tons of bump travel which is nice but you also limit your extension/droop travel. I've gone beyond in testing and it isn't great. There are a lot of "drop off" type bumps where I drive and they become a little annoying.

- Andrew
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Old 07-08-2021, 07:20 PM   #33
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OptimumG is good stuff!

We did a very basic primer on suspension frequencies on our instagram here:
https://www.instagram.com/p/B6TKG6Un..._web_copy_link

Stock springs do work nicely with Bilstein B6 and actually BRZ front with FRS rear is pretty good. That would indeed ride better than Bilstein + Yellows (performance was important when designing those springs).

IMO if you're designing from the ground up (which means you're also starting from scratch on the dampers and bumpstops and swaybars etc) then flat ride is the ticket for comfort. But as an example, a BRZ with 200 lbs/in springs front and rear will likely be more comfortable than a car with 200 lbs/in springs front and 250 lbs/in springs rear, (with the same dampers and/or same damping ratio). I encourage you to think about the bumps you encounter, which are most noticeable, and if/when flat ride would help.

One note since it sort of came up...don't go above recommend ride heights with a coilover like KW V3, SS1, or Bilstein B16 for comfort reasons. You do get tons of bump travel which is nice but you also limit your extension/droop travel. I've gone beyond in testing and it isn't great. There are a lot of "drop off" type bumps where I drive and they become a little annoying.

- Andrew
Thanks Andrew. My reading and arithmetic so far had suggested just that. B6s - BRZ front/rear or BRZ front - FRS rear.

Edit: quick question. How does the motion ration built in to the rear affect the calculations?
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Old 07-08-2021, 08:05 PM   #34
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OptimumG is good stuff!

We did a very basic primer on suspension frequencies on our instagram here:
https://www.instagram.com/p/B6TKG6Un..._web_copy_link

Stock springs do work nicely with Bilstein B6 and actually BRZ front with FRS rear is pretty good. That would indeed ride better than Bilstein + Yellows (performance was important when designing those springs).

IMO if you're designing from the ground up (which means you're also starting from scratch on the dampers and bumpstops and swaybars etc) then flat ride is the ticket for comfort. But as an example, a BRZ with 200 lbs/in springs front and rear will likely be more comfortable than a car with 200 lbs/in springs front and 250 lbs/in springs rear, (with the same dampers and/or same damping ratio). I encourage you to think about the bumps you encounter, which are most noticeable, and if/when flat ride would help.

- Andrew
I saw the math and my mind went a little numb, but then I remembered there's smart people put there that's done the math already. So it's just a matter of understanding the concept and using it to help me try to pick parts. So yeah. I found their tech tips and read through all of them, despite having no need or ability to add a third spring to my inboard suspension...

I actually found your Instagram post last night while digging around for more info.

Yeah, I'm pretty set on trying the B6 with what I have now and then playing with factory springs to tune as required. Maybe I'll play with ARBs later as well.
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Old 07-08-2021, 08:08 PM   #35
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Talk to me about the MCA traction mod, please. It looks fantastic and like something I would really benefit from as I've encountered oversteer several times when I didn't intend to. Surprisingly, that is a large part of why I started down the road of modifying my suspension. I started by trying to gain feedback from the rear, then to increasing spring rate to increase ride frequency, then to coilovers for better damping... When I started I'd be feeding a little throttle into the car to maintain a corner line, nothing intended to accelerate, just maintaining balance front and rear at what should have been about 8/10s, and then I'd hit a bump and would end up thanking the traction control programmers. It seems like the MCA kit would help with the predictability there. Is there any down side? Aside from possibly increased wear on the trailing arm bushings I can't see where a down side would be.

Comfort is a priority, but predictability and competence in a corner are still priorities as well and unless I'm misunderstanding something, this shouldn't negatively effect any of those.
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Old 07-08-2021, 10:25 PM   #36
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If your in SoCal I have 2017 dampers, yellows, and peddler top hats for camber I am selling

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Old 07-09-2021, 04:01 AM   #37
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Originally Posted by Calum View Post
Talk to me about the MCA traction mod, please. It looks fantastic and like something I would really benefit from as I've encountered oversteer several times when I didn't intend to. Surprisingly, that is a large part of why I started down the road of modifying my suspension. I started by trying to gain feedback from the rear, then to increasing spring rate to increase ride frequency, then to coilovers for better damping... When I started I'd be feeding a little throttle into the car to maintain a corner line, nothing intended to accelerate, just maintaining balance front and rear at what should have been about 8/10s, and then I'd hit a bump and would end up thanking the traction control programmers. It seems like the MCA kit would help with the predictability there. Is there any down side? Aside from possibly increased wear on the trailing arm bushings I can't see where a down side would be.

Comfort is a priority, but predictability and competence in a corner are still priorities as well and unless I'm misunderstanding something, this shouldn't negatively effect any of those.

I had been debating about this for sometime. I tried the white line subframe inserts and didnt like the noise it generated ( there was no vibration or harshness).

And the car would under steer a lot and this change in character of the car didnt make it fun anymore.
Then i removed them and fitted STI subframe stoppers coupled with STI subframe bolts. ( Any restriction of subframe movement in form of bushings or braces will give the feel of the rear being very planted)

The amount of play you decrease in the rear subframe determines the degree of under/over steer you induce at the limit of grip.

This, in my opinion, is a much better compromise in keeping the subframe in check, not promoting under steer, giving predictable/controllable oversteer at the limit and with very minimal noise ( I have sensitive ears, lol).

As for the GT suspension set up, the B6 with the yellows seem to be a very good compromise. I have not heard any negative reviews yet from anyone considering them from a DD perspective.

Will be following this thread. I like the discussion so far.
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Old 07-09-2021, 06:22 AM   #38
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Pardon my ignorance, my education on this is only read and not practical experience, but what is the general opinion on air suspension? It sounds like the thing modern GT cars often do from the factory for comfort.
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Old 07-09-2021, 06:54 AM   #39
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General opinion on air suspension on twins is that for money it costs, better return is from high end classic coilovers for same money. I guess, only "use" for air suspension on twins is for those very few/rare that are into overdone lowering/hardpark and so on, to at least have it somewhat driveable at all via onthefly height adjustment. For 100x more owners that don't do that, paying half the cost for comparable suspension performance/comfort or getting higher performance for same money, is better choice.
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Old 07-09-2021, 06:55 AM   #40
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Quote:
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I had been debating about this for sometime. I tried the white line subframe inserts and didnt like the noise it generated ( there was no vibration or harshness).

And the car would under steer a lot and this change in character of the car didnt make it fun anymore.
Then i removed them and fitted STI subframe stoppers coupled with STI subframe bolts. ( Any restriction of subframe movement in form of bushings or braces will give the feel of the rear being very planted)

The amount of play you decrease in the rear subframe determines the degree of under/over steer you induce at the limit of grip.

This, in my opinion, is a much better compromise in keeping the subframe in check, not promoting under steer, giving predictable/controllable oversteer at the limit and with very minimal noise ( I have sensitive ears, lol).

As for the GT suspension set up, the B6 with the yellows seem to be a very good compromise. I have not heard any negative reviews yet from anyone considering them from a DD perspective.

Will be following this thread. I like the discussion so far.
The MCA traction mod doesn't do anything to subframe, it has nothing at all do with the controlling movement of the subframe. They move the position of the trailing arms body side mount. They don't even reduce compliance of the trailing arms bushings.
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Old 07-09-2021, 08:04 AM   #41
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If your in SoCal I have 2017 dampers, yellows, and peddler top hats for camber I am selling

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According to Google maps I'm 2830miles from SoCal. Give or take a few. Thanks anyway.
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Old 07-09-2021, 04:49 PM   #42
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Talk to me about the MCA traction mod, please. It looks fantastic and like something I would really benefit from as I've encountered oversteer several times when I didn't intend to. Surprisingly, that is a large part of why I started down the road of modifying my suspension. I started by trying to gain feedback from the rear, then to increasing spring rate to increase ride frequency, then to coilovers for better damping... When I started I'd be feeding a little throttle into the car to maintain a corner line, nothing intended to accelerate, just maintaining balance front and rear at what should have been about 8/10s, and then I'd hit a bump and would end up thanking the traction control programmers. It seems like the MCA kit would help with the predictability there. Is there any down side? Aside from possibly increased wear on the trailing arm bushings I can't see where a down side would be.

Comfort is a priority, but predictability and competence in a corner are still priorities as well and unless I'm misunderstanding something, this shouldn't negatively effect any of those.
We can see by diagraming the suspension (or just reading the part description) that MCA’s traction mod reduces anti-squat. Anti-squat geometry loads forces through the suspension linkages and bushings and ultimately to the chassis. The traction mod alters the characteristics of how these forces get loaded via modifying the trailing arm pickup. Let’s visualize this.



This diagram is simplified, but notice that the acceleration force transfers through the trailing arm (black line), into the chassis. Negative anti-squat tries to push the chassis down, lifting the rear wheel up and resulting in less traction. Positive anti-squat tries to lift the chassis, and there’s a corresponding downward force on the tire providing additional grip. Neutral anti-squat would result in no downward or lift forces, instead the acceleration force is just transferred forward into the chassis. Maximum acceleration is tuned using this geometry to determine how much of the engine’s power pushes the tires into the ground, and how much pushes the chassis forward. This is well documented in drag communities.

Next let’s look at the effects at equilibrium. When neither accelerating nor decelerating, the amount of force in the trailing arm is greatly reduced - until we hit a bump. The instant we hit that bump the tire momentarily gains a ton of traction. The wheel wants to move up and back. ‘Up’ should be handled by our spring/shock, so let’s focus on the ‘back’ right now. We can visualize this by reversing the acceleration force, which in turn reverses the other forces as well.

In the negative anti-squat scenario, we’re now lifting the chassis up, pushing the rear wheel down. The amount of ‘up’ force our spring/shock deals with is also reduced since part is transmitted directly to the chassis.

In the positive anti-squat scenario, we’re now pulling the chassis down and lifting the rear wheel up. This jacking force means we have less traction at the rear tire in a bumpy scenario. This increases the ‘up’ force our spring/shock deals with and we are dependent on the resistance given by it for tire grip.

We can surmise that maximum grip over bumps happens when a neutral range, as the least amount of force gets transmitted through the trailing arm to the chassis. Therefore by reducing positive anti-squat, reduced jacking forces mean traction should be increased on the rear tire in a bumpy scenario (lots of mini deceleration forces).

So that’s the theory as I understand it. There’s a lot of implications here, and keep in mind geometry is ever changing as the suspension works. In reality the MCA mod is a relatively mild change. Corner exit on rough surfaces is improved and it’s a little harder to kick the tail out when I want to. There’s probably a loss of performance from a dig and during corner exit on smooth surfaces, but I don’t see too many of those.
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Last edited by itschris; 07-09-2021 at 06:58 PM. Reason: accuracy
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