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TrakCar
post May 5 2014, 12:56 PM
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Posts: 37
Joined: 13-May 05
From: Louisville, Ky
Member No.: 743



Over the weekend I took the Camaro out to the Midwest Musclecar Challenge (www.midwestmusclecarchallenge.com/).

I had a blast, however I now am much more humble about my driving ability.

I have the power, I have the brakes, now I am ready to begin improving the suspension on the Z.

This, is where you guys come in.

Usage
Street - 1-2 times a month to work or cruises
Track - 3 or 4 track day events per year
Autocross - occasionally

Details about the car:
1991 Z28 hardtop

LS1/T56 Stock rear with 3.42 posi
C5 corvette front brakes, factory 91 z rear disks (HP+ pads and ATE superblue fluid)
weld in subframe connectors
Spohn tubular K-member

Suspension
boxed rear control arms
solid panhard bar
Factory 91 Z28 front and rear swaybars (not sure of size)
Eibach sportline springs (fronts cut 1 coil to level ride height after LS1 transplant)
no name shocks and struts from prior to 2003 when I bought the car.

Wheels/ tires
18X8 (245/40/18) front 18X9.5 (285/35/18) rear street tires. 200 treadwear

Be aware, I am not a rich man. changes only come slowly when I can scrape together extra cash. I need a priority list to tackle for best bang for the buck.

Questions:
1) I know I should replace the shocks/struts. should I jump straight to double adjustable or is there a less expensive option that will help?
2) Have I totally screwed myself up by cutting the coils on the Sportlines? What rates should I target?
3) Should I skip coils and struts and convert to coil overs?
4) Can I have a good setup for both track day and autocross without changes?
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RacingZ-44
post May 5 2014, 01:51 PM
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Group: Advanced Members
Posts: 30
Joined: 17-August 08
From: Calumet Region (Chicagoland)
Member No.: 2,276



QUOTE (TrakCar @ May 5 2014, 07:56 AM) *
Over the weekend I took the Camaro out to the Midwest Musclecar Challenge (www.midwestmusclecarchallenge.com/).

I had a blast, however I now am much more humble about my driving ability.

I have the power, I have the brakes, now I am ready to begin improving the suspension on the Z.

This, is where you guys come in.

Usage
Street - 1-2 times a month to work or cruises
Track - 3 or 4 track day events per year
Autocross - occasionally

Details about the car:
1991 Z28 hardtop

LS1/T56 Stock rear with 3.42 posi
C5 corvette front brakes, factory 91 z rear disks (HP+ pads and ATE superblue fluid)
weld in subframe connectors
Spohn tubular K-member

Suspension
boxed rear control arms
solid panhard bar
Factory 91 Z28 front and rear swaybars (not sure of size)
Eibach sportline springs (fronts cut 1 coil to level ride height after LS1 transplant)
no name shocks and struts from prior to 2003 when I bought the car.

Wheels/ tires
18X8 (245/40/18) front 18X9.5 (285/35/18) rear street tires. 200 treadwear

Be aware, I am not a rich man. changes only come slowly when I can scrape together extra cash. I need a priority list to tackle for best bang for the buck.

Questions:
1) I know I should replace the shocks/struts. should I jump straight to double adjustable or is there a less expensive option that will help?
2) Have I totally screwed myself up by cutting the coils on the Sportlines? What rates should I target?
3) Should I skip coils and struts and convert to coil overs?
4) Can I have a good setup for both track day and autocross without changes?


Hi,
It seems like you have plenty of power and more than enough brakes, but the cut sportlines and the no-name shocks are holding you back. As far as the shocks, unless you have reason to believe you need to dial in the shocks to within an inch of their life, there is no real need for the double adjustable shocks, again unless you are doing some serious road racing but at 3 to 4 events per year, you aren't. The best option would be Koni Single adjustables, but even needing singles is debatable depending on who you talk with. Sometimes having that adjustability only hurts you because you actually have TOO many options for damping. Plus, they are more expensive than most and if you are on a budget, there are good options. For third gens, as you know, they take a strut in front versus shocks/springs all the way around. All that being said, the full set of Konis singles are about 650 from Strano but there might be better prices out there too. A good set of Bilsteins will serve you well for what you are describing. You can buy a set of standard bilsteins, no adjustment, for 679. The thing is the Koni's have to be adjusted off the car.
I drive a fourth gen with the Strano springs in F/R, they are 550# in front and 150# in the rear. I would shoot for at LEAST that spring rate. A lot of the guys who run at top events will tell you you need 900-1000 in front and maybe 250 on the rear. I still street drive mine so that spring rqte is way too high. With the 550/150 option and Koni singles, my car drives fantastic, is very competitive at the track, and I can still drive it home.
Skip the coil over set up as it's not necessary or worth the investment for the amount of racing you do.

The other thing is if you lowered the car with the cut springs, you technically need an adjustable panhard bar (not solid) to recenter the rear diff after lowering the car. With the car sitting level, measure the fender to tire distance on the rear end. They should be identical. If not, you need the adjustable pan hard bar to recenter the rear. Especially if you lowered it more than an inch or so.

And if you don't already have a "wonder bar" for your front subframe to stiffen up the steering box issues, you need to buy one first. That by itself will make the car drive and feel different immediately.

Anyway, just my .02 cents...
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gscherer78ta
post Jun 4 2014, 12:52 PM
Post #3


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Group: Advanced Members
Posts: 40
Joined: 17-April 14
Member No.: 223,807



QUOTE (RacingZ-44 @ May 5 2014, 01:51 PM) *
And if you don't already have a "wonder bar" for your front subframe to stiffen up the steering box issues, you need to buy one first. That by itself will make the car drive and feel different immediately.

Anyway, just my .02 cents...



Curious- What is a "wonder bar"? Sorry if this is a stupid question but I've not heard that term before.
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Posts in this topic
TrakCar   Suspension Improvements   May 5 2014, 12:56 PM
RacingZ-44   QUOTE (TrakCar @ May 5 2014, 07:56 AM) Ov...   May 5 2014, 01:51 PM
TrakCar   QUOTE (RacingZ-44 @ May 5 2014, 07:5...   May 5 2014, 02:51 PM
gscherer78ta   QUOTE (RacingZ-44 @ May 5 2014, 01:5...   Jun 4 2014, 12:52 PM
Blainefab   QUOTE (gscherer78ta @ Jun 4 2014, 05:52 A...   Jun 4 2014, 09:07 PM
trackbird   Hey James! Good to see you around. That car is...   May 5 2014, 02:45 PM
TrakCar   QUOTE (trackbird @ May 5 2014, 08:45 AM) ...   May 5 2014, 02:53 PM
CrashTestDummy   Keep a close eye on that K-member. Few ever survi...   May 5 2014, 04:31 PM
TrakCar   QUOTE (CrashTestDummy @ May 5 2014, 10:31...   May 5 2014, 05:20 PM
BumpaD_Z28   Pics of the car ??? Just for reference I'm ru...   May 6 2014, 03:12 AM
TrakCar   QUOTE (BumpaD_Z28 @ May 5 2014, 09:12 PM)...   May 14 2014, 02:53 PM
nape   If you want to get serious about the street tire e...   May 6 2014, 05:41 AM
TrakCar   I thought I would update the group. I have the Me...   May 14 2014, 01:32 PM
Pablo   QUOTE (TrakCar @ May 14 2014, 05:32 AM) 2...   Jun 1 2014, 08:19 AM
slowTA   That's the same power steering cap I used on m...   Jun 1 2014, 01:26 PM
dailydriver   QUOTE (Pablo @ Jun 1 2014, 04:19 AM) QUOT...   Jun 1 2014, 08:23 PM
Pablo   QUOTE (dailydriver @ Jun 1 2014, 12:23 PM...   Jun 2 2014, 07:32 AM
Smitty2919   That's my buddies brown C2 that you have a pic...   May 15 2014, 12:45 PM
TrakCar   I took the car to the F-body event last weekend. n...   May 22 2014, 04:20 PM
trackbird   I'd run the same size tires on both ends. As y...   May 22 2014, 04:22 PM
slowTA   The cap will fit but the dipstick part is too long...   Jun 2 2014, 04:07 PM
CrashTestDummy   We got a 80's/90's Saganaw pump cap off a ...   Jun 4 2014, 06:16 PM

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