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Old 01-03-2018, 04:31 AM   #1
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Rear GT3 control arms and sway bar, worth it?

What is the general thought on rear GT3 arms and sway bar, Iíve been running with front GT3 control arms, front GT3 sway bar, and rear toe links but havenít spent the money on the rear sway and arms. Is it worth it, are you guys using the adjustability and seeing lap time improvements?

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Old 01-03-2018, 05:00 AM   #2
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I'd say no on the rear gt3 arms as I haven't seen people need too much extra negative camber in back on a lowered car.

Adjustable rear sway bar (gt3 one won't fit as far as i know) seems to be a good mod.
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Old 01-03-2018, 05:28 AM   #3
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Originally Posted by truegearhead View Post
What is the general thought on rear GT3 arms and sway bar, I’ve been running with front GT3 control arms, front GT3 sway bar, and rear toe links but haven’t spent the money on the rear sway and arms. Is it worth it, are you guys using the adjustability and seeing lap time improvements?

What rear bar do you have and what struts/springs are you running?

I've heard that the front GT3 bar on the softest settings, even though it is stiffer than the stock bars, can actually provide more grip in the front because it keeps the car from leaning over so much in the front. Then I have also heard that it is a fine line, and too much stiffness in the front can increase the understeer. How is it working for you? (And how easy was it to install, I haven't replaced a front sway bar yet)


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What is the general thought on rear GT3 arms
Do you need more neg camber in the back, or are you wanting to go to monoballs in the lower control arms? If you have enough neg camber back there and you just want to go monoballs, several places have press in monoball cartridges, rennline has some for $250, and elephant has some for $390 that are offset and can give you an extra -.36 of neg camber to boot.

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Is it worth it, are you guys using the adjustability and seeing lap time improvements?

Is the car doing things now that are holding you back?

For example, I am on the stock M030 sport suspension, running 225/45/17 front and 255/40/17 rear. It is much more balanced that when using 205/50/17 front, but I am still biased towards understeer (which I like, and which may go away as I get more skills... ) but I still have the following issues:
  • I am losing time on late mid-corner and track exit on long sweepers due to understeer
  • On tighter corners I am also losing time due to understeer
  • My rear tires are stuck like glue, the only time I can break them loose is if I get too aggressive trail braking or lift when the car is highly loaded up. Which makes me feel very safe, but I am losing time...
  • My car is really leaning in the turns, and I am also wearing the edges of my tires too much still, even with -2.5 in front and -1.9 in back.

I have recently gotten both the front and rear Tarett GT bars (GT3 front and their adjustable matched rear bar) and I hope to solve those problems and see what happens. I'm not installing them until later in February where I am going to a private/open track day where I will have plenty of time to get it dialed in without having to worry about sessions or missing my runs.

If it solves these issues for me than to me it would be worth it If not, I guess it would be an educational experience and that would be worth it too...

Last edited by steved0x; 01-03-2018 at 05:33 AM.
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Old 01-03-2018, 05:49 AM   #4
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Stiffening the front sway bar induces understeer!
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Old 01-03-2018, 06:43 AM   #5
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Stiffening the front bar definitely adds understeer. Iím running it on the second setting. As far as whatís holing me back Iím not sure, I experience a little understeer at low speeds and oversteer at high speeds. Overall itís pretty balanced.

Steve, I used to run M030 with a front GT3 bar and I think itís a stronger setup than my KW2s. Itís hard to beat a factory setup I guess
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Old 01-03-2018, 07:52 AM   #6
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Stiffening the front bar definitely adds understeer. Iím running it on the second setting. As far as whatís holing me back Iím not sure, I experience a little understeer at low speeds and oversteer at high speeds. Overall itís pretty balanced.

Steve, I used to run M030 with a front GT3 bar and I think itís a stronger setup than my KW2s. Itís hard to beat a factory setup I guess
Sounds like you have a balanced setup, going to the adjustable rear Tarett GT bar would increase oversteer I think since it would be stiffer than stock or M030.

If you got the rear bar and got too much oversteer I guess you could go 1 hole stiffer in the front and experiment until you got it balanced again, at which point you possibly may have less body roll and lean?

I'm trying to think about when I get oversteer and earlier I gave a couple of examples of trail braking on corner entry and lifting mid corner, I forgot to say, I also get oversteer when powering out of very tight/slow turns when I'm in 2nd gear.

Do you have an LSD? I have heard that an LSD can increase understeer in slower turns (due to locking the rears?) and also tend more toward oversteer in faster corners (both rear wheels spinning instead of just the unloaded inner wheel?) I don't have an LSD so I don't know
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Old 01-03-2018, 09:34 AM   #7
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I have not added the GT3 LCA's to the rear of my SPB as I have plenty of camber adjustment available. I do run the tarett gt3 bars front (2nd from full hard) and rear (softest) with 450F/500R springs (PSS9s).
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Old 01-03-2018, 09:17 PM   #8
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As Quadcammer said, the major reason to add rear adj control arms is to get additional negative camber in the rear. Most Spec Boxster's can get sufficient rear camber on the stock arms so there may not be much advantage in adding those.

An adjustable rear sway bar adds another way to tune the handling. Typically, engineers recommend adjusting the end of the car that is causing the problem. For example, if you have understeer, loosen up the front end. If you have oversteer, tighten up the rear end. If you run out of adjustability at one end of the car, then go to the other end of the car to move the dial further in the preferred direction.

In terms of adjustability, generally the car should be mostly neutral but can lean towards understeer or oversteer depending on your comfort and skill.

If the handling is mostly neutral and the tires are wearing evenly and have good temps across the width of the tire, then your setup is probably pretty good.

The key is to find a setup that creates handling characteristics that complement your driving style and makes you feel confident in the car. Sometimes you have to adjust your driving technique to better match the inherent characteristics of the car and sometimes the car can be adjusted to better match your individual driving style. This is the art of car setup.

To answer your question directly, no I don't need rear adj lower control arms to get enough rear camber and yes, I use the Tarrett adj rear sway bar to help balance the handling to my preference.

Beyond that, the car should be at minimum weight and the engine should be dyno tested to make sure that it has the expected power.

After that, concentrate your efforts on the person behind the wheel.

I say that because once the car is pretty good, then the driver becomes (by far) the biggest variable. And this is why I focus a lot of my energy, time, and money on improving my driving skills. In my case, I know that I am the weakest link!
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Last edited by thstone; 01-03-2018 at 09:20 PM.
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Old 01-04-2018, 04:03 AM   #9
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I have not added the GT3 LCA's to the rear of my SPB as I have plenty of camber adjustment available. I do run the tarett gt3 bars front (2nd from full hard) and rear (softest) with 450F/500R springs (PSS9s).
Youíre running much stiffer springs than me, I think this is another problem with my setup. Iím running 400F/285R (swift springs on KW2 coilovers), Iím a little lighter than spec Boxster minimum weight at 2500lbs w/driver. Iíve always thought a little softer setup works best for me but maybe Iíve gone too far
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Old 01-04-2018, 04:04 AM   #10
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As Quadcammer said, the major reason to add rear adj control arms is to get additional negative camber in the rear. Most Spec Boxster's can get sufficient rear camber on the stock arms so there may not be much advantage in adding those.

An adjustable rear sway bar adds another way to tune the handling. Typically, engineers recommend adjusting the end of the car that is causing the problem. For example, if you have understeer, loosen up the front end. If you have oversteer, tighten up the rear end. If you run out of adjustability at one end of the car, then go to the other end of the car to move the dial further in the preferred direction.

In terms of adjustability, generally the car should be mostly neutral but can lean towards understeer or oversteer depending on your comfort and skill.

If the handling is mostly neutral and the tires are wearing evenly and have good temps across the width of the tire, then your setup is probably pretty good.

The key is to find a setup that creates handling characteristics that complement your driving style and makes you feel confident in the car. Sometimes you have to adjust your driving technique to better match the inherent characteristics of the car and sometimes the car can be adjusted to better match your individual driving style. This is the art of car setup.

To answer your question directly, no I don't need rear adj lower control arms to get enough rear camber and yes, I use the Tarrett adj rear sway bar to help balance the handling to my preference.

Beyond that, the car should be at minimum weight and the engine should be dyno tested to make sure that it has the expected power.

After that, concentrate your efforts on the person behind the wheel.

I say that because once the car is pretty good, then the driver becomes (by far) the biggest variable. And this is why I focus a lot of my energy, time, and money on improving my driving skills. In my case, I know that I am the weakest link!
Stone thanks for the detailed reply! This helps!
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