[Z06] suspension advice
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
I had my Koni's custom made to be an inch shorter, so shock length and bottoming was never an issue for me. Since you plan on eventually tracking the car you should corner weight it when you lower it. It costs little and it will handle better if you have it done right.
Lowering, corner weighting and an aggressive alignment actually wake up the car a lot.
Racer
Joined: Sep 2003
Posts: 360
Likes: 2
From: DFW Texas
I can use any shocks, and my double adjustable Koni's are not as expensive as Penske's, so I could have spent a lot more. For autocrossing, if I were doing it again I would probably have just gone with the single adjustable Koni's. I recommended that setup to a friend in Colorado who is doing track days as well as autocrosses with it and he is turning times that are nationally competitive in just a few events with the car and he is very happy with it on the street, track and autocross course. The best price I've seen for a complete set of Koni's is right at $1200. That is very close to a lot of other shocks that aren't nearly as good. Shocks are one area where you generally get what you pay for in that shocks with big price tags are really good, But at the mid and lower end there's a lot of junk out there that is way overpriced. I haven't seen anybody who is really seriously autocrossing winning on anything but Koni's, Penske's or Moton's. As Dennis Grant say's the others are junk. He likes Bilsteins, but I want to be able to fine tune my car between runs and I can't do that with Bilsteins so I didn't go there. Also being able to soften the car on the street and crank in some additional stiffness on the track is a good thing.
I am not a fan of coilovers, most of the kits are overpriced and don't provide any real performance advantage. If you are racing the ability to change spring rates at different tracks is important. If you are doing track days and autocross, and driving the car on the street, the stock springs are plenty stiff, and putting a more money into better shocks has a lot better payoff than coilovers. If I were to go to coilovers I'd look seriously at the Penske's that Gary Hoffman has at Hardbar, they are $550 per corner (+springs) and that's a good price for Penske shocks. I trust LG to be able to provide a good product also, but they don't tell you whose shocks they are using, and that bothers me. Also look at the mounting hardware for the coilovers, many of them are metal joints which work great on the track but clunk like crazy on the street.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
I think that you really do want an adjuster. Shocks are like spicy food... You want it seasoned to your taste. Everybody has their opinion as to where the sweet spot is, and while some setups hit the sweet spot quite nicely (my son's stock VR6 GTI is very nicely damped), others will be too harsh or too mushy for your particular taste. Having a **** to get it dialed in is just a nice thing to have.
Team Owner
Joined: Dec 2008
Posts: 35,874
Likes: 1,600
From: Honolulu HI
Just lower it on the stock bolts, use the frame jacking points as a reference (on a flat surface) and lower it less than an inch all around. Lowering it more than that is a waste. The car won't handle as well, it will drag on driveways and is a general PITA. We have track tested different ride heights and there is no advantage lowering the car more than that. If you want a low rider look you really need to get a set of dropped spinldles, otherwise just lower it that much and don't think about it any more.
I had my Koni's custom made to be an inch shorter, so shock length and bottoming was never an issue for me. Since you plan on eventually tracking the car you should corner weight it when you lower it. It costs little and it will handle better if you have it done right.
Lowering, corner weighting and an aggressive alignment actually wake up the car a lot.
I had my Koni's custom made to be an inch shorter, so shock length and bottoming was never an issue for me. Since you plan on eventually tracking the car you should corner weight it when you lower it. It costs little and it will handle better if you have it done right.
Lowering, corner weighting and an aggressive alignment actually wake up the car a lot.
The shorter Koni's are interesting...I'm lowered on stock bolts as well, and will never go lower. I used to run Koni's on my Turbo T/A and my 5.0, and was always impressed with them.
Coilovers seem overkill for me, but I want a shock that provides adjustability and decent travel. I've been leaning towards the Pfadt inverted shocks. Any opinion on those?
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
The shorter Koni's are interesting...I'm lowered on stock bolts as well, and will never go lower. I used to run Koni's on my Turbo T/A and my 5.0, and was always impressed with them.
Coilovers seem overkill for me, but I want a shock that provides adjustability and decent travel. I've been leaning towards the Pfadt inverted shocks. Any opinion on those?
As to Pfadt shocks, I haven't used their stuff, but I have seen some shock dyno graphs and am not impressed. I am looking for optimum grip in a car set up for autocross and running on DOT racing tires, and they don't have what I am looking for, so I would pass on them. They also have a number of new products since I've looked and maybe they aren't the same now, but I'm just not into spending money to find out what might work, I tend to buy what I know works. Right now there are a lot of Corvettes autocrossing on the national level with serious suspension setups and generating huge grip and I don't see any of them using Pfadt stuff. The serious racers are all using Koni's, Penske's and Motons, so that was the short list of where I was going. Penske's were out of my price range at the time and I went with the double adjustable Koni's. Since then Gary Hoffman at Hardbar has Penske at a good price that is probably worth a look.
While Pfadt customer support appears to be very good, some of their designs have seen failures in the field, so that's another reason that I am not going there.
Team Owner
Joined: Dec 2008
Posts: 35,874
Likes: 1,600
From: Honolulu HI
I had the Koni's custom made in a shorter length because I didn't want to have a bottoming problem if I lowered the car as much as could be done on stock bolts. At the time I had not tested the car and although some of the old pro's on the autocross and racing pages has said it was a waste to lower it all the way on stock bolts I wanted to be able to test and find the right ride height for my setup and didn't want to have a bottoming issue and limit what heights I could test at. Turns out that they were correct, there was no advanage to lowering the car more and the best lap times were made with the lowered from stock, but with the ride height about 3/4 of an inch lower than stock. I spent some money that I didn't need to, but I'm ok with that because I got the piece of mind knowing where the right ride height is.
Last edited by MTPZ06; Nov 17, 2010 at 11:30 PM.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
There are only four places where you can get them rebuilt, ProParts, TrueChoice, and Performance Shocks or the Koni Service Center of Koni NA can do them. Of the four, the service center is the most expensive, although none are cheap. I had a friend who was at the time associated with ProParts so I went there. It took forever for ProParts to get all the parts and they were expensive, just be forewarned. If you like Koni's Sam Strano carries the regualr 3013's for a good price and he is a great person to deal with. Neither Koni NA or ProParts gives you a full set of damper curves, (been there, done that and was plenty PO'd at what I got from both places). That said, they are fantastic shocks so you gotta live with the few drawbacks that Koni's have.
Last edited by Solofast; Nov 18, 2010 at 01:56 PM.
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Joined: Mar 2006
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I have driven other sports cars that handle better and do not wander as much as my Z does. I have picked out my some CCW wheels and tires that will provide the lower profile tire that I want. From there: LG has a coilover and swaybar package.....how much of a difference do their sways make over our Z06 sway bars? Anyone know or have experience with them? I want this car to be planted! I still feel it floats compared to a porsche or even my old 350z that was lowered on springs/sways/19 wheels with low profile tires. I have other questions but I would like to start with the opinions on the G2 sway bars,
thanks,
thanks,
Best upgrade I made was pfadt coilovers, sway bars and 18's on all four wheels.
Also got a very good track alignment.
Handling is much better and well worth the investment for track activities. Also very streetable.
To be fair, Porsche 4s, Gt3 and turbo are all better handling and I'm an intermediate skill, solo driver at HPDE's.
HOWEVER those three Porsches are 50-100% more in cost even after the upgrades.
Not worth it in my estimation.
Team Owner
Joined: Dec 2008
Posts: 35,874
Likes: 1,600
From: Honolulu HI
Yes, the SCCA Solo rules allows shorter shocks in stock class, but only 1 inch from stock length. I had ProParts make mine up, they are 3013's that are built upside down and are double adjustable. This way you can reach the adjustments while the shocks are on the car (even though it is tough, you can adjust the rears in compression on the car but you have to dismount the fronts to adjust compression). Rebound is easy to get to while the shocks are on the car and we can adjust rebound between autocross runs with the shocks built this way.
There are only four places where you can get them rebuilt, ProParts, TrueChoice, and Performance Shocks or the Koni Service Center of Koni NA can do them. Of the four, the service center is the most expensive, although none are cheap. I had a friend who was at the time associated with ProParts so I went there. It took forever for ProParts to get all the parts and they were expensive, just be forewarned. If you like Koni's Sam Strano carries the regualr 3013's for a good price and he is a great person to deal with. Neither Koni NA or ProParts gives you a full set of damper curves, (been there, done that and was plenty PO'd at what I got from both places). That said, they are fantastic shocks so you gotta live with the few drawbacks that Koni's have.
There are only four places where you can get them rebuilt, ProParts, TrueChoice, and Performance Shocks or the Koni Service Center of Koni NA can do them. Of the four, the service center is the most expensive, although none are cheap. I had a friend who was at the time associated with ProParts so I went there. It took forever for ProParts to get all the parts and they were expensive, just be forewarned. If you like Koni's Sam Strano carries the regualr 3013's for a good price and he is a great person to deal with. Neither Koni NA or ProParts gives you a full set of damper curves, (been there, done that and was plenty PO'd at what I got from both places). That said, they are fantastic shocks so you gotta live with the few drawbacks that Koni's have.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
Been reading up on the 3013 sports for the C5/C6; and interestingly enough the specs say they are good to run on lowered vehicles as long as they are not lower than 35mm from factory ride height, which is about an inch and 3/8's. I'm only lowered about an inch (max) on stock bolts, so in theory they should work fine right out of the box. I've reached out to them for a compressed length to compare with the stockers though just for curiosity.
Team Owner
Joined: Dec 2008
Posts: 35,874
Likes: 1,600
From: Honolulu HI
Tech Contributor
Joined: Oct 1999
Posts: 41,037
Likes: 9,801
From: Charlotte, NC (formerly Endicott, NY)
I have driven other sports cars that handle better and do not wander as much as my Z does. I have picked out my some CCW wheels and tires that will provide the lower profile tire that I want. From there: LG has a coilover and swaybar package.....how much of a difference do their sways make over our Z06 sway bars? Anyone know or have experience with them? I want this car to be planted! I still feel it floats compared to a porsche or even my old 350z that was lowered on springs/sways/19 wheels with low profile tires. I have other questions but I would like to start with the opinions on the G2 sway bars,
thanks,
thanks,
Bill
Team Owner
Joined: Dec 2008
Posts: 35,874
Likes: 1,600
From: Honolulu HI
From what I've been able to find, it looks as if the stock shocks come from the factory with a 1.0625" (1-1/16") tall bumpstop (or at least the fronts do). Koni says that we can run their 3013's on our cars as long as it's not lower tham 35mm from the factory ride height; and they do recommend bumpstops as you pointed out, so that the shock doesn't bottom out and cause damage internally.Since I'm lowered somewhere around 3/4" to 1" (19-25mm), I fall into Koni's parameters. But assuming the Koni's are identical in compressed length to the stockers, and since I've lost 3/4" to 1" of travel, the only way to regain any of that travel is to go with a shorter bump stop. I've seen .500", .750", and 1" in doughnut and puck styles, and I've also seen more tapered designs which I imagine are more progressive in their compression. The tapered styles are typically too long though....sometimes longer than the stock ones. If I run the .500" stops, I should regain .5625 (9/16") of travel which is a little more than half of what I've lost. I also don't know the difference between the 50, 60, 70, and 80 "Duro".
I may just try to go the 1" shorter Koni route like you, unless the price point changes significanly by doing so. What type of Penske stops are you running (they have many) and how tall are they?
I wish LG's 1" drop spindles weren't so darn expensive.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
OK...I've done more research on bump stops than I ever thought I'd care to. From what I've been able to find, it looks as if the stock shocks come from the factory with a 1.0625" (1-1/16") tall bumpstop (or at least the fronts do). Koni says that we can run their 3013's on our cars as long as it's not lower tham 35mm from the factory ride height; and they do recommend bumpstops as you pointed out, so that the shock doesn't bottom out and cause damage internally.
Since I'm lowered somewhere around 3/4" to 1" (19-25mm), I fall into Koni's parameters. But assuming the Koni's are identical in compressed length to the stockers, and since I've lost 3/4" to 1" of travel, the only way to regain any of that travel is to go with a shorter bump stop. I've seen .500", .750", and 1" in doughnut and puck styles, and I've also seen more tapered designs which I imagine are more progressive in their compression. The tapered styles are typically too long though....sometimes longer than the stock ones. If I run the .500" stops, I should regain .5625 (9/16") of travel which is a little more than half of what I've lost. I also don't know the difference between the 50, 60, 70, and 80 "Duro".
I may just try to go the 1" shorter Koni route like you, unless the price point changes significanly by doing so. What type of Penske stops are you running (they have many) and how tall are they?
I wish LG's 1" drop spindles weren't so darn expensive.
From what I've been able to find, it looks as if the stock shocks come from the factory with a 1.0625" (1-1/16") tall bumpstop (or at least the fronts do). Koni says that we can run their 3013's on our cars as long as it's not lower tham 35mm from the factory ride height; and they do recommend bumpstops as you pointed out, so that the shock doesn't bottom out and cause damage internally.Since I'm lowered somewhere around 3/4" to 1" (19-25mm), I fall into Koni's parameters. But assuming the Koni's are identical in compressed length to the stockers, and since I've lost 3/4" to 1" of travel, the only way to regain any of that travel is to go with a shorter bump stop. I've seen .500", .750", and 1" in doughnut and puck styles, and I've also seen more tapered designs which I imagine are more progressive in their compression. The tapered styles are typically too long though....sometimes longer than the stock ones. If I run the .500" stops, I should regain .5625 (9/16") of travel which is a little more than half of what I've lost. I also don't know the difference between the 50, 60, 70, and 80 "Duro".
I may just try to go the 1" shorter Koni route like you, unless the price point changes significanly by doing so. What type of Penske stops are you running (they have many) and how tall are they?
I wish LG's 1" drop spindles weren't so darn expensive.
Talk to Gary Hoffman at Hardbar. He can set you up with the Penske bump stops, they are cheap and pretty easy to put on, but I'd try the Koni bump stops that come on the 3013's first. He did say that the Penske bump stops are very progressive and don't upset the car if you get into them.
I used some modeing clay and put it on the bottom of the shocks and when I was set at the best ride height for performance I didn't bottom them out without bump stops, but I put bump stops on because it's just dumb to run without them. I tried height settings all the way down to the limit of the stock bolts, and with the shortened shocks I could get real close to bottoming them out (deformed the clay blob on the shock, but didn't crush it. The testing showed that the ride height needed to be higher anyway, but with the shorter shocks I doubt that I will ever hit them very hard at the height setting I have right now.
Team Owner
Joined: Dec 2008
Posts: 35,874
Likes: 1,600
From: Honolulu HI
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
Mine didn't but to the best of my knowledge, the 3013's come with them. Mine didn't because ProParts didn't put them on. I don't know if they simply didn't bother or maybe I should have specified bump stops? Not sure, I wasn't as knowledgeable about buying custom shocks then as I am now. At the time I bought shocks over the phone and they came in the mail. I know a lot more about what to ask and how to do things now...
Burning Brakes
Joined: Aug 2007
Posts: 880
Likes: 0
From: Bath PA
I do have experience with aftermarket suspension if you consider the GM T1 suspension system "aftermarket".
I have the T1 springs, shocks and sways. All were done at the same time so I can't attribute the change in handling to any one of them, but there's a tremendous difference/improvement in the handling "feel" of the car. I think it's important to note these components were engineered to work as a complete system, and whatever you decide to do, changing only one component may not provide optimal results regardless of whose product you buy.
Greatly reduced body roll, increased responsiveness to steering input on turn-in, and improved steering feedback/feel through the wheel resulted from the upgrade with no noticeable trade-off in ride comfort. The bars do make quite a bit of noise though due to the hard links. The car corners flat right up to the limit of traction and is much more confidence inspiring than when stock. I've been very pleased with the results both on track as well as on the street.
I've also found that a more agressive alignment can also drastically change the handling feel of the car. You may want to experiment with this a little prior to spending money on new parts if you haven't already.
BTW, I also own a Porsche and you could spend a lot of money trying to equal the steering precision of the Porsche and might never get there. As I tell my PCA buddies looking to get a Z06 track car, they're just different animals and as much as I love the precise handling of the P-car it will never replace my Z as the total sports care package.
So there is definitley room for improving the handling characterisitics of the Z, but changing just the sway bar may not give you the results you're looking for.
I have the T1 springs, shocks and sways. All were done at the same time so I can't attribute the change in handling to any one of them, but there's a tremendous difference/improvement in the handling "feel" of the car. I think it's important to note these components were engineered to work as a complete system, and whatever you decide to do, changing only one component may not provide optimal results regardless of whose product you buy.
Greatly reduced body roll, increased responsiveness to steering input on turn-in, and improved steering feedback/feel through the wheel resulted from the upgrade with no noticeable trade-off in ride comfort. The bars do make quite a bit of noise though due to the hard links. The car corners flat right up to the limit of traction and is much more confidence inspiring than when stock. I've been very pleased with the results both on track as well as on the street.
I've also found that a more agressive alignment can also drastically change the handling feel of the car. You may want to experiment with this a little prior to spending money on new parts if you haven't already.
BTW, I also own a Porsche and you could spend a lot of money trying to equal the steering precision of the Porsche and might never get there. As I tell my PCA buddies looking to get a Z06 track car, they're just different animals and as much as I love the precise handling of the P-car it will never replace my Z as the total sports care package.
So there is definitley room for improving the handling characterisitics of the Z, but changing just the sway bar may not give you the results you're looking for.
