Tax return...Z28 Suspension Kit Install/2010 2SS/RS

[Lonewolf583]

I finished the front end last night, just took a few hours and some elbow grease for that sway bar. I didn't need any special tools, but the sway bar did test the limits of my patience. Ended up resorting to jacking up the engine a bit.

Front end sits a very slight amount lower now. Here's a very unscientific before and after. I'm sure once the suspension is settled after driving it'll be lower. Didn't think to actually measure any of it... The rear starts tonight.

[camaro500]

looks like a sweet upgrade! Congrats

[BurntOrangeBEE]

I am considering this same upgrade for my 2010. A couple of questions for you:

1) Are the existing SS knuckle bushings the same stiffness as the Z/28's? I do not have a feel yet for how close to the Z/28 suspension set up is needed to get the full Z/28 benefit. I wonder if aftermarket knuckle/control arm bushings are necessary?

2) Have you replaced your rear cradle bushings? They appear to have a significant affect on performance (lots of posts), however stiff aftermarket bushings would promote understeer, reducing rear lateral displacement compared to stock and the front lateral displacement. I wonder if the Z/28 cradle bushings have a similar stiffness to the SS and how sensitive the whole set up is to the cradle bush stiffness. Will the cradle bushing lateral stiffness have a direct effect on over/understeer? I know the typical aftermarket set up uses stiffer roll bars and solid cradle bushes - are the stiff roll bars and bushings joined at the hip performance-wise. Hopefully the Z/28 suspension is not tuned for softer cradle bushings.

Looking forward to your posts.

[Lonewolf583]

Originally Posted by BurntOrangeBEE

I am considering this same upgrade for my 2010. A couple of questions for you:

1) Are the existing SS knuckle bushings the same stiffness as the Z/28's? I do not have a feel yet for how close to the Z/28 suspension set up is needed to get the full Z/28 benefit. I wonder if aftermarket knuckle/control arm bushings are necessary?

2) Have you replaced your rear cradle bushings? They appear to have a significant affect on performance (lots of posts), however stiff aftermarket bushings would promote understeer, reducing rear lateral displacement compared to stock and the front lateral displacement. I wonder if the Z/28 cradle bushings have a similar stiffness to the SS and how sensitive the whole set up is to the cradle bush stiffness. Will the cradle bushing lateral stiffness have a direct effect on over/understeer? I know the typical aftermarket set up uses stiffer roll bars and solid cradle bushes - are the stiff roll bars and bushings joined at the hip performance-wise. Hopefully the Z/28 suspension is not tuned for softer cradle bushings.

Looking forward to your posts.

I think I read somewhere the Z28 upright bushes are stiffer. The Z28 control arm bushes however should be stiffer. Not sure on the subframe. I'll likely upgrade those and the subframe bushes to solid when I do my driveline upgrades.

I think the critical thing is eliminating any extra degrees of freedom in the chassis, and I would argue the tendency is to understeer when the extra compliance is there..big two levers there are the motion in the lateral plane and torsional. Torsional being the bigger of the two issues when running a soft OE bush. I think there's video somewhere demonstrating how bad it is stock.

[xc_SS/RS]

Originally Posted by Lonewolf583

I think I read somewhere the Z28 upright bushes are stiffer. The Z28 control arm bushes however should be stiffer. Not sure on the subframe. I'll likely upgrade those and the subframe bushes to solid when I do my driveline upgrades.

I think the critical thing is eliminating any extra degrees of freedom in the chassis, and I would argue the tendency is to understeer when the extra compliance is there..big two levers there are the motion in the lateral plane and torsional. Torsional being the bigger of the two issues when running a soft OE bush. I think there's video somewhere demonstrating how bad it is stock.

If you haven't done anything to the rear subframe bushings you'll be pleasantly surprised when you do. Even inserts on my 2010 was a major improvement. Went from feeling like an accordion when accelerating to the whole car moving as one.

Have you installed the rear suspension yet or were you waiting for the weekend?

[Lonewolf583]

Originally Posted by xc_SS/RS

If you haven't done anything to the rear subframe bushings you'll be pleasantly surprised when you do. Even inserts on my 2010 was a major improvement. Went from feeling like an accordion when accelerating to the whole car moving as one.

Have you installed the rear suspension yet or were you waiting for the weekend?

Yep, just a few hours ago. Just went on the maiden voyage, unaligned. Holy crap. Body motion, what's that? I feel like I could toss on slicks and be set. Balance is very good. Tendency to understeer at limit, but rotates well at low speeds. I'll hold my judgement for when I'm not so misaligned, but impressions are good. Getting it in the shop Monday.

[Lonewolf583]

Before the event photo op.



Alignment settings...BigO tire, stock adjustment capability. I requested the factory Z28 settings but this is what they were able to get me.

Camber:
LF: -1.7, RF: -1.2
LR: -1.0, RR: -1.1
Caster:
L: 5.8, R: 6.3
Toe:
LF: 0.06, RF: 0.05 (out)
LR: -0.02, RR: -0.01

Overall impressions of the car on Z28 suspension are good. The car is neutral and very agile. The car will understeer at the high limit, but the car is eager to rotate at medium/low speed via throttle, aggressive wheel inputs (tossing/flicking it through tight stuff). Before I would need more throttle to get the car to dance through the cones. Slaloms...the car is better but still needs some work...at the end of the day I'm still fighting a 3800+ lb car with 340 TW street tires, stock subframe bushings, and limited alignment range. It might get better with some more bar, but the balance is good.

My next move:

- Race Rubber
- Solid subframe bushes
- Camber/Caster Plates/Bolts/Adjusters (I'd hazard a guess I'll be happy out at -2/-1.5 camber, full .5 deg of toe out in front)
- Strut tower bracing

...go from there.

Summary: If you're looking for a ready to bolt-in, warranty'd (if dealer installed) package that will transform your ride into a turn-key track car, look no further.

DIY Cost: 3657.68 - Includes shipping, kit, FE4 conversion LCA, and alignment.

[Dropspeed]

Originally Posted by Lonewolf583

Before the event photo op.

Alignment settings...BigO tire, stock adjustment capability. I requested the factory Z28 settings but this is what they were able to get me.

Camber:
LF: -1.7, RF: -1.2
LR: -1.0, RR: -1.1
Caster:
L: 5.8, R: 6.3
Toe:
LF: 0.06, RF: 0.05 (out)
LR: -0.02, RR: -0.01


My next move:

- Race Rubber
- Solid subframe bushes
- Camber/Caster Plates/Bolts/Adjusters (I'd hazard a guess I'll be happy out at -2/-1.5 camber, full .5 deg of toe out in front)
- Strut tower bracing
.

First:

Camber:
LF: -1.7, RF: -1.2 <This is a problem and they should easily be the same. Experience tells me that they didn't have the wheel straight or they moved it and it may be closer to 1.5/1.5. Either way, something is wrong with the install or the alignment tech. (I have done dozens of alignments on a Hunter machine over the years at a friends shop on my own cars. I run -2 degree on my front with only Z/28 suspension and no other adjustment mods.

LR: -1.0, RR: -1.1 < this is to be expected in the rear. Camber bolts will increase your range.

Second:

Strut bar is not needed on the coupe. The only thing that will change is on center feel, performance will not be better. Also consider this: If the car is already under steering/pushing, why would you want to stiffen the front more which would induce more under steer? Save your $$ They are needed on the convertible models, and customers like them on the coupe....

-Matt

[Lonewolf583]

Originally Posted by Dropspeed

First:

Camber:
LF: -1.7, RF: -1.2 <This is a problem and they should easily be the same. Experience tells me that they didn't have the wheel straight or they moved it and it may be closer to 1.5/1.5. Either way, something is wrong with the install or the alignment tech. (I have done dozens of alignments on a Hunter machine over the years at a friends shop on my own cars. I run -2 degree on my front with only Z/28 suspension and no other adjustment mods.

LR: -1.0, RR: -1.1 < this is to be expected in the rear. Camber bolts will increase your range.

Second:

Strut bar is not needed on the coupe. The only thing that will change is on center feel, performance will not be better. Also consider this: If the car is already under steering/pushing, why would you want to stiffen the front more which would induce more under steer? Save your $$ They are needed on the convertible models, and customers like them on the coupe....

-Matt

Thanks Matt.

Point 1. Yeah, I didn't have much choice. I'm going to invest in a longacre unit and do it myself next time.

Point 2. As you might infer the strut tower brace is not high on the list and follows solid rear subframe bushes. The list may have left room for interpretation regarding my exact sequence but as you know the bushes should stiffen up the rear. The thought is a 3 point brace evens things out after this.

[CrystalRedTintcoat]

Hi there, opening up this all thread.

For those of you who added the Z/28 Suspension Kit to your SS w/o adding the front splitter and rear spoiler for added downforce who do you feel about that decision? I’m thinking of the suspension now and may the splitter/spoiler later.

[51LE50]

Hey CRT, I can't address your question completely, as I have the full aero package (with wicker bill), brake ducts + Z/28 suspension on my 1LE.
Oh yeah, I run -2.5 degrees front camber + a track focused alignment. Vorschlag camber plates do not raise the front end ride height.
In hindsight, I think I'd have taken the next step up in the suspension department and installed something like the DSE / JRI kit, or an Ohlins, Motion Control, etc.
My 1LE is a track toy, I don't DD it and rarely take it out of the garage if not going to the track.
The Z/28 package is really good, no doubt about it, but there is no tuning of the dampers or the sway bars and you feel the mass transitioning from one side to the other. If you want a great handling package and plan to drive on the street on a regular basis the Z/28 suspension is really good (but stiff) and you will feel everything on the road. Over ~ 60 mph it smooths out though.
I think you're fine with doing the suspension first and then aero next as there are a lot of options for aero.
Hope this helps,

[cdb95z28]

I also am running the Z suspension. With Vorschlag camber plates also (with-3.4* camber). No areo mods except an Aero Sport Concepts "Z" wicker. I guess the addition of any aero mods beyond the OE 1LE package is dependent on the track. A super high speed track with lots of long high speed turns will justify the Z aero. My home track, Pitt Race, in my opinion isn't one of those super high speed tracks. There is one corner where I'm carrying tons of speed, about 120mph. But looking at how many G's I'm pulling thru it, I'm well within the tire's limit of grip. And the car is stable thru it also.

I like to let prospective Z/28 suspension owners understand the firmness of the springs and dampers. I do daily mine anytime in the summer when it is dry and warm enough. Yes, the Z setup is stiff. Our roads here in the Laurel Mountains of PA suck. That being said, The Z setup, for me, is acceptable. Ride is subjective. If you think the OE 1LE suspension is stiff, then the Z setup is not for you.

[cdb95z28]

I forgot to add, I also have a ZL1 belly pan and the ZL1 front fender deflectors. I also extended the ZL1 deflectors by adding Aero Sport Concepts deflectors. The deflectors also can help with brake cooling as they will create a low pressure area behind them which allows the air within the wheel and wheelhouse area (high pressure) to exit better.

[bkevind]

Originally Posted by cdb95z28

I also am running the Z suspension. With Vorschlag camber plates also (with-3.4* camber). No areo mods except an Aero Sport Concepts "Z" wicker. I guess the addition of any aero mods beyond the OE 1LE package is dependent on the track. A super high speed track with lots of long high speed turns will justify the Z aero. My home track, Pitt Race, in my opinion isn't one of those super high speed tracks. There is one corner where I'm carrying tons of speed, about 120mph. But looking at how many G's I'm pulling thru it, I'm well within the tire's limit of grip. And the car is stable thru it also.

I like to let prospective Z/28 suspension owners understand the firmness of the springs and dampers. I do daily mine anytime in the summer when it is dry and warm enough. Yes, the Z setup is stiff. Our roads here in the Laurel Mountains of PA suck. That being said, The Z setup, for me, is acceptable. Ride is subjective. If you think the OE 1LE suspension is stiff, then the Z setup is not for you.

I've got ridetech Hq on the car now, but I also have a z28 setup in storage I haven't used. Wondering the pros / cons of each, but especially, with 19x11 wheels and 305 track tires, I wonder if I will have fitment issues if I went to the z28 setup.

I like the theoretical adjustability of the ride tech but I don't find it much better than say....BC Racing BR single adjustable (sorry RideTech...)

It's a nice suspension but ... I think it's a miss overall. I'll know more when set some baseline lap times with it. So far have run it at my home track lightly, without timing.