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Ray I think you can buy a coilover conversion that eliminates the leaf spring. I will let the more expert members chime in with more definitive answers.
Indeed, your car has 117 N/mm springs, while Z06/Z07 comes with 190 N/mm springs.
Is going up to 190 N/mm from 117 N/mm the right move? We're talking about 62% increase in rate. In my opinion, if you're switching to wider and stickier tires, YES. I've learned the importance of matching the traction with spring rates the hard way last year. When I switched to 315 front tires, despite running stiffer T1 shocks, my Z51 with its 92.4 N/mm spring literally turned into a boat. When I finally switched to coilovers with the equivalent spring rate of 177 N/mm up front, the car has been transformed!
What about sway bars? Yes, you can greatly improve your corner roll stiffness with a good set of sway bars like LG G7s that I have, but what about braking? What about turn in? Higher rated spring would make the car more consistent for sure.
The reality with Magna-ride: Well, unfortunately, you can't just change your front spring rate by 62% and assume that your shocks would
be OK. You'd either need to replace them, or get them tuned. Replacing them is pretty hard, since I've heard that the simulators might fail in time, etc. Regarding tune, GM will not share the Z07 tune with you, and at least in the case of Z06, the Z06 and Z07 specs come with different shocks, and I'm not sure if yours is any one of them.
DSC? DSC might fix the valving issue , but if you ask their opinion, they will likely tell you that the softer springs up front are great, and that they allow more weight transfer in turn-in, making faster laps possible, etc., and they would advise you to keep your front spring (since this is what they've been saying). I'd imagine they would still help you if you still want the stiffer spring, since you can do a custom tune on the suspension maps with DSC, but I'm honestly not sure if the operating window of that shock is good for the much stiffer springs.
My take: I'd first try DSC controller only (+ sways?), and see if it helps enough. If not, I would either try LG's simulators + a good set of coilovers, or just go all the way with DSC and buy their $$$ tractive shocks, which hopefully can be customized with desired spring rates, so you can make it perfect.
Indeed, your car has 117 N/mm springs, while Z06/Z07 comes with 190 N/mm springs.
Is going up to 190 N/mm from 117 N/mm the right move? We're talking about 62% increase in rate. In my opinion, if you're switching to wider and stickier tires, YES. I've learned the importance of matching the traction with spring rates the hard way last year. When I switched to 315 front tires, despite running stiffer T1 shocks, my Z51 with its 92.4 N/mm spring literally turned into a boat. When I finally switched to coilovers with the equivalent spring rate of 177 N/mm up front, the car has been transformed!
What about sway bars? Yes, you can greatly improve your corner roll stiffness with a good set of sway bars like LG G7s that I have, but what about braking? What about turn in? Higher rated spring would make the car more consistent for sure.
The reality with Magna-ride: Well, unfortunately, you can't just change your front spring rate by 62% and assume that your shocks would
be OK. You'd either need to replace them, or get them tuned. Replacing them is pretty hard, since I've heard that the simulators might fail in time, etc. Regarding tune, GM will not share the Z07 tune with you, and at least in the case of Z06, the Z06 and Z07 specs come with different shocks, and I'm not sure if yours is any one of them.
DSC? DSC might fix the valving issue , but if you ask their opinion, they will likely tell you that the softer springs up front are great, and that they allow more weight transfer in turn-in, making faster laps possible, etc., and they would advise you to keep your front spring (since this is what they've been saying). I'd imagine they would still help you if you still want the stiffer spring, since you can do a custom tune on the suspension maps with DSC, but I'm honestly not sure if the operating window of that shock is good for the much stiffer springs.
My take: I'd first try DSC controller only, and see if it helps enough. If not, I would either try LG's simulators + a good set of coilovers, or just go all the way with DSC and buy their $$$ tractive shocks, which hopefully can be customized with desired spring rates, so you can make it perfect.
Guys this is exactly the kind of info I’m looking for ! Thank you for taking the time to write this
The car is amazing with the stock sticky tires, I’m just worried it will become a boat with Hoosiers .
A 62% increase in rate does seem excessive. And my driving style does favor softer springs -
The sway bar may be the first mod then - and I think I may have to consider a coil over set up. I am excited to hear your coil overs transformed the car. Is there anything that needs to be done structuraly to the shock mounting points to handle coil overs? What brand coil over did you use ?
I still may try the Z06/Z07 front spring if I can find one relatively cheap - that seems like something I can get tested in a weekend
Also what is your opinion on the stock sway bar bushings? I feel the stock rubber is a large cause of bind and creates artificial spring - did you notice a big difference with the LG bar?
Last edited by Ray7374; Dec 26, 2017 at 08:00 PM.
Reason: No spacing
The sway bar mounts are too small for the car, and instead of changing its design, GM goes with ever stiffer and smaller bushings to tune their suspension. I honestly don't think they are doing it the best way, but rather the cheaper way.
LG bars are much stiffer than stock. They do transition to a narrower OD where it mounts to fit into the OEM mount location, and have the larger OD, elsewhere. I personally like my car's balance, but have not tried them without coilovers.
Speaking of coilovers, I first tried LG G2s, and they worked pretty well. My problem with that kit is that car has to be lowered substantially (more than 1" for sure, my car was about 1.2"-1.4" or so lower). I have recently switched to a set of Penskes, and will see what I can do with them. Penskes allowed me to keep the ride height at 0.6" below stock, which is the perfect compromise in my opinion : )
You can check out my build thread for more info on my tests and fails : )
There is no need to structurally enforce the mounts. They look even better than C6 mounts, and Lou @ LG has very nicely demonstrated that they do survive hard impacts.
The sway bar mounts are too small for the car, and instead of changing its design, GM goes with ever stiffer and smaller bushings to tune their suspension. I honestly don't think they are doing it the best way, but rather the cheaper way.
LG bars are much stiffer than stock. They do transition to a narrower OD where it mounts to fit into the OEM mount location, and have the larger OD, elsewhere. I personally like my car's balance, but have not tried them without coilovers.
Speaking of coilovers, I first tried LG G2s, and they worked pretty well. My problem with that kit is that car has to be lowered substantially (more than 1" for sure, my car was about 1.2"-1.4" or so lower). I have recently switched to a set of Penskes, and will see what I can do with them. Penskes allowed me to keep the ride height at 0.6" below stock, which is the perfect compromise in my opinion : )
You can check out my build thread for more info on my tests and fails : )
There is no need to structurally enforce the mounts. They look even better than C6 mounts, and Lou @ LG has very nicely demonstrated that they do survive hard impacts.
Guys this is exactly the kind of info I’m looking for ! Thank you for taking the time to write this
The car is amazing with the stock sticky tires, I’m just worried it will become a boat with Hoosiers .
A 62% increase in rate does seem excessive. And my driving style does favor softer springs -
The sway bar may be the first mod then - and I think I may have to consider a coil over set up. I am excited to hear your coil overs transformed the car. Is there anything that needs to be done structuraly to the shock mounting points to handle coil overs? What brand coil over did you use ?
I still may try the Z06/Z07 front spring if I can find one relatively cheap - that seems like something I can get tested in a weekend
Also what is your opinion on the stock sway bar bushings? I feel the stock rubber is a large cause of bind and creates artificial spring - did you notice a big difference with the LG bar?
I have a 18 Z06 taken apart for a complete track build so I put the OEM and our sway bars side by side for comparison. LG Front 1 9/16" LG Rear 1 1/8" OEM Front 1 1/8" OEM Rear 1 1/16"
My measurements on the OEM cold be slightly off, I did it in about 5 seconds with a tape measure.
Our sway bars aren't only larger/stronger but the over-all design is what we found worked best on the race track.
I have a 18 Z06 taken apart for a complete track build so I put the OEM and our sway bars side by side for comparison. LG Front 1 9/16" LG Rear 1 1/8" OEM Front 1 1/8" OEM Rear 1 1/16"
My measurements on the OEM cold be slightly off, I did it in about 5 seconds with a tape measure.
Our sway bars aren't only larger/stronger but the over-all design is what we found worked best on the race track.
What type bushing do you use on the LG bar. I know you guys have lots of track experience and I’m looking for a sway bar system that’s proven not to bind up . ( some I’ve seen use questionable bushings)
Last edited by Ray7374; Dec 27, 2017 at 03:17 PM.
Reason: Bad grammar
Based on what X25 wrote it sounds like your GS/Z07 front spring is the same as Z06 non-Z07 (FE6). I didn't realize that.
I had a lot of track time on my FE6 car on slicks with just the DSC controller and Tractive shocks. The car worked really well but it would wear out the spats from tire rub after a while. My current car is an FE7 car and I do think I like the stiffer spring better on track. I never felt like either car needed different sways. Of course, my Z06 were both carrying an extra ~150 lbs of weight on those front springs.
If I were you I'd just give it a try. If you're not happy then start with the DSC controller. If you go with the Tractive shocks as well I'd talk to Mike about putting a helper spring on them.
The Tractive have threading on the body for coilover spring perches and we were talking about putting a light spring in my old car to work in conjunction with the stock leaf rather than putting the full load on the shock tower. I ended up trading in my car for a 2017 instead so we never got around to trying it. We also weren't sure if they would fit in the control arms but clearly others are.
Why would the spring rates be different from a non Z07 Grand Sport to a non Z07 Z06? Not that much in weight difference.
They're not different. Per the technical details shared during that GM event, GS front spring is always the same, regardless of model, same as regular Z06.
So GM increased the spring rate on the Z07 versions regardless if it is a Z06 or a Grand Sport?
Originally Posted by X25
They're not different. Per the technical details shared during that GM event, GS front spring is always the same, regardless of model, same as regular Z06.
What type bushing do you use on the LG bar. I know you guys have lots of track experience and I’m looking for a sway bar system that’s proven not to bind up . ( some I’ve seen use questionable bushings)
Suspension question
