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Upgrading Z51 to GS/Z06 Leaf Spring?

Old 11-20-2018, 02:27 PM
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Default Upgrading Z51 to GS/Z06 Leaf Spring?

I don't think anyone has done this, I know many have pulled the leaf springs out. But I'll try anyhow:

Has anyone replaced leaf springs with another set? I'm thinking of upgrading my z51 springs with GS/Z06 springs (I have a DSC sport controller in my closet I could put back on). I'm sure I could find a used set for not much.

Do some of you more experienced folks think this is a dumb idea to improve track capability? It would be much cheaper than coilovers and still maintain mag ride.
​​​​​​
for those that have pulled the leaf springs out, is it a jack stands job ? Any details or instructions other than the GM ones theta provides ?

Last edited by BrunoTheMellow; 11-20-2018 at 05:17 PM.
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Old 11-20-2018, 03:27 PM
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I think it's a great idea, especially if you go with higher traction (and wider) tires, too. The Z51 is definitely sprung too soft for its potential.
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Old 11-20-2018, 06:25 PM
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Originally Posted by BrunoTheMellow View Post
I don't think anyone has done this, I know many have pulled the leaf springs out. But I'll try anyhow:

Has anyone replaced leaf springs with another set? I'm thinking of upgrading my z51 springs with GS/Z06 springs (I have a DSC sport controller in my closet I could put back on). I'm sure I could find a used set for not much.

Do some of you more experienced folks think this is a dumb idea to improve track capability? It would be much cheaper than coilovers and still maintain mag ride.
​​​​​​
for those that have pulled the leaf springs out, is it a jack stands job ? Any details or instructions other than the GM ones theta provides ?
I have a couple sets of take off z06 leaf springs with less than 100mi on them. Or you can sell the controller and go to coilovers
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Old 11-20-2018, 07:03 PM
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Originally Posted by [email protected] View Post
I have a couple sets of take off z06 leaf springs with less than 100mi on them. Or you can sell the controller and go to coilovers
I really like being able to make the system softer or harder since it's not a dedicated track car, PM me a price, I'm local so I can even pick them up.
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Old 11-21-2018, 12:29 PM
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Old 11-21-2018, 12:48 PM
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I have been thinking of putting in Z07 springs. But after reviewing the cost I will probably go coil overs. Iím in the same boat though. I like the ability to soften up my Monoball ride when not at the track. Please report back lap time changes once you complete.

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Old 11-21-2018, 01:31 PM
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Originally Posted by fatsport View Post
Yep. I think if I go z07 I might be oversprung for my current 255/295ish r888r size tires. Maybe someone who knows more can chime in. I can maybe go 10 mm wider but otherwise I'd need enw wheels.

For GS, you might be able to find used springs for way less than cool overs.

Last edited by BrunoTheMellow; 11-21-2018 at 01:38 PM.
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Old 11-21-2018, 02:01 PM
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For starters, I think 245/255 is very small for ANY C7 Corvette (and even C6, C5, etc.). When I started modding my C7 Z51 for better track performance, the biggest change in performance came from switching my fronts from 275s to 315s. This was in fact the reason why I switched to coilovers, since the much-increased front bite made the car feel like a boat with OEM Z51 springs and T1 sways/shocks. In other words, I'd highly recommend switching to 315 or similarly wide fronts for track use for any C7, which would necessitate much stiffer sway bars or springs for Z51 for sure.

Last edited by X25; 11-21-2018 at 02:43 PM.
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Old 11-21-2018, 02:25 PM
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Originally Posted by X25 View Post
For starters, I think 245/255 is very small for ANY C7 Corvette (and even C6, C5, etc.). When I started modding my C7 Z51 for better track performance, the biggest change in performance came from switching my fronts from 275s to 315s. This was in fact the reason why I switched to coilovers, since the much-increased front bite made the car feel like a boat with OEM Z51 springs and T1 sways/shocks. In other words, I'd highly recommend switching to 315 or similarly wide fronts for track use for any C7, which would necessitate much stiffer sway bars or springs for Z51 for sure.
How do you fit wider than 305s on the narrow rear without sticking out or rubbing? I know you just put the spats up front and use different offsets, did it not rub the top of the fender? I'll browse your thread again later. My car is fairly balanced right now on 255/295s with -2.2 camber F and -1.8 rear but I can feel it's already undersprung.

I am scared z07 springs would be too much. But maybe going to z06 springs isn't enough of a change. Hmmmm.

How do coilovers handle on the street x25? Selling my DSC controller would almost 100% offset the cost. Is it much worse? This isn't a dedicated track car.

Last edited by BrunoTheMellow; 11-21-2018 at 02:45 PM.
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Old 11-21-2018, 02:53 PM
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I did use 305/30/18 fronts, and 325/30/19 rears (NT01) at the time. I did upgrade to sway bars and coilovers at the same time. The coilovers had similar front rate to Z07 front (which I also calculated in my build thread).

Z06/GS or GS/Z07 springs are definitely good upgrades.
The following is my speculation: GM likely found the Z07 front springs to be too stiff for GS during its testing with 285 cup2s up front, but regular GS/Z06 springs are likely too soft for the optimal. However, since GM historically makes GS cars with parts available as much as possible, it went with T1 front sways and kept the regular Z06 front springs as a compromise. In our use case, we are already utilizing front tires with much more traction (e.g. 315 NT01s, or even Pirelli scrubs, R7s, etc.), and as such, I don't think Z07 front springs would be too stiff for our application, anymore. Z07 springs also help with clearance, since they don't lean as much.

Re:clearance, in your case, you should definitely try LG G7 or similar sway bars, first. Your alignment settings are aggressive enough, and hopefully they would work. 315 tires stick out up front on Z51, which is why I also ended up installing wheel spats.

EDIT: You might also need to do this for comfortable fit:
https://www.corvetteforum.com/forums...-lip-roll.html

I assume you already have a good wheel offset to clear (e.g. 19x11.5" ET83 that I've used, or 18x11 ET76-79), etc..

Last edited by X25; 11-21-2018 at 07:18 PM.
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Old 11-22-2018, 01:24 PM
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Has anyone been able to figure out the spring rates in the ZR1? It feels like it might be between the FE6 and FE7.

Also, I'm curious about doing the install without the GM spring tool.
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Old 11-22-2018, 02:56 PM
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Originally Posted by Poor-sha View Post
Has anyone been able to figure out the spring rates in the ZR1? It feels like it might be between the FE6 and FE7.

Also, I'm curious about doing the install without the GM spring tool.
I don't know about ZR1 rates, but regarding installing leaf springs: it was incredibly hard! If you don't have the spring tool, which was ~$600 for front and another ~$600 for rear (!!), I suppose you could get away with, if you have multiple transmission jacks and can control both ends, though it could get dangerous
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Old 11-22-2018, 07:57 PM
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Originally Posted by Poor-sha View Post
Has anyone been able to figure out the spring rates in the ZR1? It feels like it might be between the FE6 and FE7.

Also, I'm curious about doing the install without the GM spring tool.
i thought it was just a fe7.
​​​​​​
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Old 11-22-2018, 07:58 PM
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Originally Posted by X25 View Post
I don't know about ZR1 rates, but regarding installing leaf springs: it was incredibly hard! If you don't have the spring tool, which was ~$600 for front and another ~$600 for rear (!!), I suppose you could get away with, if you have multiple transmission jacks and can control both ends, though it could get dangerous
I figured it would be like the c5 and c6. Is it not?
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Old 11-23-2018, 11:24 AM
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Originally Posted by BrunoTheMellow View Post
i thought it was just a fe7.
​​​​​​
Well it has a different designation, FE9 I believe.

Originally Posted by BrunoTheMellow View Post
I figured it would be like the c5 and c6. Is it not?
How did you do it without the special tool on the C5/C6?
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Old 11-23-2018, 11:55 AM
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Originally Posted by Poor-sha View Post
Well it has a different designation, FE9 I believe.



How did you do it without the special tool on the C5/C6?
Haven't done it myself but read instructions.

https://www.corvetteforum.com/forums...af-spring.html
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Old 11-23-2018, 12:11 PM
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Originally Posted by Poor-sha View Post
Well it has a different designation, FE9 I believe.



How did you do it without the special tool on the C5/C6?
While supporting the lower control arm
- Remove the brake caliper from the spindle and hang off to the side with a couple bungee cords
- remove the rotor
- unbolt the upper control arm from the frame
- unbolt the front sway bar from the lower control arm
- unbolt the shock from the lower control arm
- remove the jack supporting the lower control arm slowly to release tension on the spring. Allow the lower arm to fully droop.
- repeat the above on the other side
- remove the two spring retainers
- slide the spring out

Install of the new spring takes a little patience and it helps using a block of wood and a floor jack to manipulate it.

nonetheless, it only takes about 90 minutes to do the swap.
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Old 11-24-2018, 10:08 AM
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Originally Posted by BrunoTheMellow View Post
How do you fit wider than 305s on the narrow rear without sticking out or rubbing? I know you just put the spats up front and use different offsets, did it not rub the top of the fender? I'll browse your thread again later. My car is fairly balanced right now on 255/295s with -2.2 camber F and -1.8 rear but I can feel it's already undersprung.

I am scared z07 springs would be too much. But maybe going to z06 springs isn't enough of a change. Hmmmm.

How do coilovers handle on the street x25? Selling my DSC controller would almost 100% offset the cost. Is it much worse? This isn't a dedicated track car.
X25 has some great wheels for your car in the for sale section, 18x10.5 and 18x11. The main difference between the Z51 and the GS is grip - same chassis, engine, transmission. As close as we can get comparing apples to apples, the GS Z07 ran a 2:47.1 at Car and Driver's Lightning Lap. The Z51 ran a 2:53.8, 6.7 seconds slower. Huge difference.
https://www.caranddriver.com/feature...istorical-data

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Old 11-24-2018, 11:55 AM
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Originally Posted by fatsport View Post
X25 has some great wheels for your car in the for sale section, 18x10.5 and 18x11. The main difference between the Z51 and the GS is grip - same chassis, engine, transmission. As close as we can get comparing apples to apples, the GS Z07 ran a 2:47.1 at Car and Driver's Lightning Lap. The Z51 ran a 2:53.8, 6.7 seconds slower. Huge difference.
https://www.caranddriver.com/feature...istorical-data
A few seconds of that difference was the cup2 zps. But Tires, brakes, springs, aero, shocks, (z07 different part #).

I got the aero and I got more power (just for fun). I cant use the wider wheels and tires until I upgrade my springs or else I'll rub like x25 did. I can use my dsc to work the shocks once I stiffen up the springs or sway bars.
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