I'm in the middle of building a fun street car. The goal is exterior similiar to a Cup car with handling bearable for street driving but aggressive enough for lapping days. This is my daily driver and I do about 4-5 track days a year. I keep hearing about "gt3 suspension mods" but haven't really looked into it much.

Im convinced I wanna run either a set of Ohlins or AST Coilovers but need a bit more guidance on what else should be upgraded. Things like LCA's, bumpsteer kits, sway bars etc. How can I get some improvements in handling on this car? Also, if it just makes sense to stick with just the set of coilovers, that's fine with me too.

Car is a 2010 Carrera 4 with Eibach springs, Recaro bucket seats, short shifter, 18X10/12.5 wheels, NT01's, Cup flares, lip and bumpers and Getty decklid and wing.

 

I'm curious to see answers here as well because I've got similar plans for my 2009 C4S. As I understand it the GT3 suspension bits such as lower control arms allow you to get a more preferential alignment specs with additional negative camber and more positive castor as well as the stiffer bushings etc.

Side note: any pics of your car? I'm excited to see it with those flares.

 

Yeah I had plans to do some cheap coilovers or h&r springs to have the car sit lower but am now finding out that lots of the aftermarket parts can be swapped on such as those parts you mentioned. The goal is to get handling down and eventually upgrade to a turbo platform.

*Wheels in the pic are 17x8 & 10 temporarily*

 

Does AST still exist? They were hot like ten years ago, but i think they went defunct. If not for sales at least for service/support. Definitely see what MCS has to offer.

 

Hey Troy, pm me i get pretty good prices on most parts and would love to help!

 

Your PM's aren't working haha

 

lovely haha, been having some issues with PMs recently.

 

Lowering the car with Ohlin coilovers changes the center of gravity and reduces the roll rate, adding more track to the car with the adjustable LCA also reduce weight transfer across the car. Add better turnin by stiffer monoballs and a solid Red thrust puck on the Tarett Cup LCAs also help more accurate steering. You can see the Tarett Cup LCA's to push out the track and add camber to the rear. The ride height is lowered by 35mm by the Ohlin coilovers. Corner balanced and Tarett adjustable down links allow neutral swaybar settings without loading. Elephant adjustable toe links with bump steer adjustments and rear toe locker plates. Also GT 3 Cup rear cooling ducts attached to the Taratt LCA.

 

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Very nice setup! See what I'm trying to understand is what extent of suspension mods are needed for the kind of driving I do. The two tracks I frequent are either a sub 2:00 min(The Ridge in WA) and 1:25min(Vancouver Island Motorsports, BC)track. I'm always chasing laptimes haha. A 991.2 rs has done 1:48 and 1:17 on those tracks. Im using those as a benchmark but understand I don't have a gt3. However I'm aiming to shave off a few seconds anyways.

So far from what research I've done, I believe I would be fine with adjustable sways, rear toe arms, front adjustable LCA's and coilovers.

Any other suggestions? Keep in mind, I do a maximum of 5 lapping days a year and my laptimes were all done on OEM non pasm shocks, Eibachs and 17x8/10's on 255/275 NT01's.

Thanks!

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If you are indeed chasing lap times, then I would spend the money on Tarett Cup LCA's. They will benefit you with precision tracking, better turnin, and less worry about rubber bushings allowing the toe to wonder around, especially in the rear causing bump toe steering, triggering a snap oversteer. This can happen mid corner just after you put the throttle down, just before the apex. Not good. So, what do the Tarett Cup LCA's do to prevent this, The solid thrust puck allows the thrust arms to do their job very effeciently, no forward or aft motion, so when a slight bump happens in compression the toe does not radically change from toe in to toe out during the suspension arc. You can actually dial in less toe in with these in place in the rear and a few minutes of toe out in front, like 4-5 minutes to help initiate turnin. Because the inner monoball bearing and the larger outer monoball bearing do not move or flex, your feedback is more accurate. My impression is that the Tarett Cup lower control arms in the rear are just a necessary as in front due to the rubber inner and outer bearings and rubber coated thrust puck in the center.

With coilovers, you can determine the ride height. Some say that the LCA's need to be parallel with the ground in a static level ground. That means a ride height about where PASM would be from those springs. I have found that with corner balancing, starting with a 30 mm drop, I ended with about 35mm drop with the corner balancing including 200 lbs in the drivers set. This works for me. You can see on the picture of the rear end setup the angle of the LCA are not parallel with the ground. I do touch the rubber wind deflector in front of the tires some times, but not a big deal as they are a rubber type material. If you run on a very bumpy track, I would suggest not quite as much drop as your springs need some room to work. Too stiff of spring rate is a hindrance on very bumpy tracks, causing a lot of rebound to occur. Seems that every action there is a reaction. So the essence is to do suspension modification in moderation. Currently, I am living with the standard Ohlin spring rate of 400 lbs/in f and 458 lbs/in r. Some feel the f is slightly over sprung (350 lbs/in better) and the r is slightly under sprung( 515 lbs/in better) but I agree that its a good starting point. Hope my opinion that helps,

 

Good to know! I might pick up those pieces down the road then. I have a pretty numb feeling to some of these similar mods done on previous cars I've owned, just don't wanna feel like I'm wasting money. Now if I'm switching over to solid bearing everything, I'm giving up street comfort and should expect alot more noise correct? I really don't want to deal with the creaks and squeaks driving to work everyday. Is there another option like going to hardened rubber bushings that you could recommend?

 

Yes, Tarett makes a detuned CUP type of LCA with the solid Red center thrust puck and rubber outer bearing (second image).

 

I saw something similar to those but the price isn't too far off from elephant racing adj. LCA's that don't require shims and seem easier to change settings imo. What are your thoughts on those?

 

I saw something similar to those but the price isn't too far off from elephant racing adj. LCA's that don't require shims and seem easier to change settings imo. What are your thoughts on those?

 

Elephant LCA's have a single adjustment bolt with 2 locking nuts vs two bolts that pinch the shims in place. In my simple mind, the two pinch bolts are slightly a better, more stable setup. The downside is the need for various shims to push out the track and add camber with the GT3 or Tarett system. I do like Elephant equipment though I use more Tarett parts. Both are well thought out quality mods.