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Seeing you struggle with the C8 platform (Z51 and Z06) do you really believe the switch from your C7 Z06 M7 was worth it ?
I mean unless I'm wrong, you so far did not beat your C7 Z06 laps yet... Your Z06 was fast and you had the possibility of making it quite a bit faster also (you were still on leaf springs and stock power...) probably for a lot less money ?
Heyy nice to hear from you! The switch to C8 has so far not paid off, you're right! I could probably do better yet with C7 Z, especially considering I was running with PTM on and that was probably limiting my potential, etc.
That said I've never been the person who just wants to get the best laps and call it done; I rather enjoy the journey. I thought people would have sorted out this platform already, but it was far from the truth. Some of the things I've found:
Z51 running too hot (remedied by V09 mod).
Z51 competition mode way too conservative (remedied by running with everything off)
Z51 cooking its NPP valve actuators (remedied by adding spacer to its heat shield).
Z06 not working well with aftermarket brakes (partial remedy by switching to enduro pads; Pagid RSL1E).
Z06 needing aftermarket brake calipers for 18" clearance (mostly caused by ebrake caliper; remedied by using smaller AP calipers but they run hot).
Z07 suspension highly tuned to very stiff sidewall and large diameter tires (needed coilovers)
Z06 needing different coilovers than Z51, which I think is due to wheel offsets + much taller rear engine CG (Remedied by 4-way coilovers designed for Z06, where I can customize rear body motion; in progress)
Z06 shifting much harsher (no remedy; hope it doesn't brake : P)
I still have hope that I can make it 'work' very well, but C7 Z06, and C7 as a platform always had good handling and braking, regardless of what I used on it, always giving confidence, which is not something C8 provided. C8 Z07 bone stock did great lap times, but even then the rear body motions were something you needed to 'get used to and ignore a bit'.
In short, it might still be a great platform, but so far, at least in my case, I'm still working on it : ) I've learned a lot in this journey (4-ways are interesting). I hope this helps.
Heyy nice to hear from you! The switch to C8 has so far not paid off, you're right! I could probably do better yet with C7 Z, especially considering I was running with PTM on and that was probably limiting my potential, etc.
That said I've never been the person who just wants to get the best laps and call it done; I rather enjoy the journey. I thought people would have sorted out this ok platform already, but it was far from the truth. Some of things I've found:
Z51 running too hot (remedied by V09 mod).
Z51 competition mode way too conservative (remedied by running with everything off)
Z51 cooking its NPP valve actuators (remedied by adding spacer to its heat shield).
Z06 not working well with aftermarket brakes (partial remedy by switching to enduro pads; Pagid RSL1E).
Z06 needing aftermarket brake calipers for 18" clearance (mostly caused by ebrake caliper; remedied by using smaller AP calipers but they run hot).
Z07 suspension highly tuned to very stiff sidewall and large diameter tires (needed coilovers)
Z06 needing different coilovers than Z51, which I think is due to wheel offsets + much taller rear engine CG (Remedied by 4-way coilovers designed for Z06, where I can customize rear body motion; in progress)
Z06 shifting much harsher (no remedy; hope it doesn't brake : P)
I still have hope that I can make it 'work' very well, but C7 Z06, and C7 as a platform always had good handling and braking, regardless of what I used on it, always giving confidence, which is not something C8 provided. C8 Z07 bone stock did great lap times, but even then the rear body motions were something you needed to 'get used to and ignore a bit'.
In short, it might still be a great platform, but so far, at least in my case, I'm still working on it : ) I've learned a lot in this journey (4-ways are interesting). I hope this helps.
I get you, messing with the cars to make them to your liking is clearly part of the journey for me as well.
Sometimes I'm also questionning changing platform on my end ... Entertaining M3 xDrive, or waiting for M2 Xdrive... Then I'm looking at the financial aspect, and not so keen in wasting money vs amount of drive time... Lately I feel it makes more sense to save more $$ than spending into cars, I guess I'm getting older ^^
Do you think you could have gone faster with the Z51 had you put more time and development into it?
Absolutely, there's no doubt. I assumed MCS are perfect for the appliocation, and focused on other things. At the very least, I think that car could have used a stiffer rear sway bar along with the coilovers, or the 1-step stiffer springs that I've tried on the Z06.
By the way, after talking to JJ (From UpSpeed Performance), I just realized a big mistake I make: I am apparently supposed to disconnect the sway bars during corner-weight balancing!
Ordered the following to make things better:
Eibach adjustable endlinks for both front and rear: Once the balancing is done, I can then connect the endlinks with zero load with the adkjustability.
15"x15" 3 mm thick aluminum sheets: The idea is to use 2 of them on every corner with grease in between the sheets. This creates a surface where the sheets can shift to let the car settle. I've been jumping on the car to settle suspension, but this might help with the accuracy.
Trofeo 315/30/18 for front: This should add a few mm to front clearance. 295s are pretty short tires.
The scraping happened at these locations on both sides. This is the driver side. It happened hard braking + turning corners where the suspension is compressed. A bit higher spring rate or more compression damping could also help. That said, I should mention that the rears were raised 2-3 mm with the canister pressure increase, changing the front angles (rake).
This is the passenger side. Less rubbing, but same location.
I don't see cracks at the outer edges, but the front rotor is clearly getting long in the tooth. I decided to replace it, and will do so with every pad change from now on I suppose.
The rear seems to be still in good shape.
Fronts replaced; looks nice!
I added 1 turn of preload to the fronts, which restored the front height. Along with the 250 PSI canister pressure, this was enough to get the front height to 102 mm (2 mm higher than my former target). That translates to 350 mm front suspension height from wheel hub to fender line (I use wheel lip and add 248 mm offset).
The car is ready to test again. I know R7s won't rub, but now I wonder if even shorter Trofeos would be fine as well at this height. If I can get a break from weather, I'll try. I'm hitting issues here and there, but I think I'm coming close to a good setup. The rear was feeling very good with the additional +5 low speed compression. Looking forward to trying it out!
Absolutely, there's no doubt. I assumed MCS are perfect for the appliocation, and focused on other things. At the very least, I think that car could have used a stiffer rear sway bar along with the coilovers, or the 1-step stiffer springs that I've tried on the Z06.
By the way, after talking to JJ (From UpSpeed Performance), I just realized a big mistake I make: I am apparently supposed to disconnect the sway bars during corner-weight balancing!
Ordered the following to make things better:
Eibach adjustable endlinks for both front and rear: Once the balancing is done, I can then connect the endlinks with zero load with the adkjustability.
15"x15" 3 mm thick aluminum sheets: The idea is to use 2 of them on every corner with grease in between the sheets. This creates a surface where the sheets can shift to let the car settle. I've been jumping on the car to settle suspension, but this might help with the accuracy.
Trofeo 315/30/18 for front: This should add a few mm to front clearance. 295s are pretty short tires.
The scraping happened at these locations on both sides. This is the driver side. It happened hard braking + turning corners where the suspension is compressed. A bit higher spring rate or more compression damping could also help. That said, I should mention that the rears were raised 2-3 mm with the canister pressure increase, changing the front angles (rake).
This is the passenger side. Less rubbing, but same location.
I don't see cracks at the outer edges, but the front rotor is clearly getting long in the tooth. I decided to replace it, and will do so with every pad change from now on I suppose.
The rear seems to be still in good shape.
Fronts replaced; looks nice!
I added 1 turn of preload to the fronts, which restored the front height. Along with the 250 PSI canister pressure, this was enough to get the front height to 102 mm (2 mm higher than my former target). That translates to 350 mm front suspension height from wheel hub to fender line (I use wheel lip and add 248 mm offset).
The car is ready to test again. I know R7s won't rub, but now I wonder if even shorter Trofeos would be fine as well at this height. If I can get a break from weather, I'll try. I'm hitting issues here and there, but I think I'm coming close to a good setup. The rear was feeling very good with the additional +5 low speed compression. Looking forward to trying it out!
I was always wondering how you were using stock endlinks when corner balancing, that is the whole reason for the adjustable endlinks, you set them at the appropriate length at each cornee so there is zero load on the bars when balanced and re connecting them.
we have one more thing to test and that is to invert the front shock to allow me to get the adjustable endlinks back on there.
your gonna have issues getting the front endlinks to fit.
I think it goes beyond having zero load; it also falsifies the corner weight readings when they're connected. As such, even if you don't have adjustable end links, you need to disconnect them during the balancing. Anyway, I didn't know about it, and well, now I do : ))
I ordered the endlinks already. I think JJ will invert my fronts as well during winter (down) time, so I can work on this in xmas time. Until then, here's hoping I can test the shocks more, so I I'd know what needs to be done (more valving for sure, but do I need more spring?)
By the way, after talking to JJ (From UpSpeed Performance), I just realized a big mistake I make: I am apparently supposed to disconnect the sway bars during corner-weight balancing!
Ordered the following to make things better:
Eibach adjustable endlinks for both front and rear: Once the balancing is done, I can then connect the endlinks with zero load with the adkjustability.
15"x15" 3 mm thick aluminum sheets: The idea is to use 2 of them on every corner with grease in between the sheets. This creates a surface where the sheets can shift to let the car settle. I've been jumping on the car to settle suspension, but this might help with the accuracy.[size=33px]
That is a really good point. I love reading this thread as these full size cars are just like RC cars, just way bigger! lol. And yes we always disconnect the sway bars when doing corner weights on dirt oval cars (the only cars I ever did there with but they do it for on road also - off road doesn’t matter as much).
Related to setup I actually got this setup but have both yet had a chance to use it as I need a two post lift and ordered one to replace my four post, but it’s not here yet. And the season is mostly over so I will mess with it during the winter after I recover from my pending neck surgery. But since you love doing setup work maybe you would find this interesting also. Reminds me of what we use on our RC cars just way bigger
The front wheel liners are actually pretty good on the C8s, and don't seem to be suffering from rubbing issues as much as the previous gens did with wide tires. That said, the grille for the front cheek coolers' exhaust air eventually get damaged with the debris and tire rubber getting stuck in there, and slowly destroying the structure. This is most prevelant on the outer side of the grille area, and the inner side stays intact. Once enough damage is done, the fabric protective cloth behind the grille starts getting caught by the rubber, and it eventually gets ripped out of its place as well. Replacing the whole wheel liner is a solution, but I think a better solution is to replace the cloth behind the plastic grille, which would secure the internal components. I should also add, that cloth is pretty restrictive, and replacing it with metal mesh should improve the air flow.
What you need:
A pack of 3/16" split-type (tri-fold) rivets at 3/4" length to secure the new mesh in place. Example: link1, link2
A drill with a 3/16" tip for pilot holes to the rivets.
A handful of zip-ties for securing the section by the brake ducting port.
Mesh grille. I have 1/4"-gap sheet from Home depot (link).
A garden scissors or similar to cut the mesh.
Thick gloves to not get cut by sharp edges of the mesh.
Sooner or later, it looks like the plastic mesh starts failing with the rubber from the track surface getting stuck, and pulling on the ribs. This is how it looked like after I removed the dangling plastic pieces.
... and here are the pieces I've removed.
The plastic pieces are not that important besides directing air, but once they're out, the debris starts pulling on the cloth behind it that protects the fan, etc. I should also add that this cloth is very dense, and is likely reducing the air flow.
To replace that cloth, I've used the mesh cloth readily available at Home Depot. This mesh is stronger than aluminum mesh available on Amazon, etc., and should be much more resiliant to the beating. It is also galvanized, and should not easily rust. This roll should be enough for both sides..
You can start by cutting a piece large enough to cover the whole area. We'll trim it later on. It'll be about 16"x16".
You can start from the putting a rivet on the left bottom corner (this is for the passenger side), and go from there.
If you screw up with the drill and hurt the mesh while drilling your pilot hole, you can use a leftover piece from your trimming, and put it on the hole as pictured here to reinforce.
.... and done! I've used zip ties around the area by the brake cooler ducting. This area does not get beat by road debris, so zip ties here would be much more likely to survive.
@X25 how are you liking the RaceChrono app on the C8z? Are you able to pull good data from the OBDII dongle?
Any tips?
I’m currently using the Racebox Pro as a back up for the PDR (and slightly better timing) but I’m thinking of switching to a phone app with an external GPS like the 25Hz Racebox Mini.
Hoping to be able to get slightly better timing (again) and be able to overlay more data for my videos.
I'm pretty happy with Racechrono app. I also use a Racebox Mini as GPS transponder. This setup gives me freedom to display whatever data I'd like on the video, and just as important, it also allows me to fix the speed since my rear tires are often not same diameter as OEM. I use RaceRender for the overlay. I still use OBD speed instead of GPS for the gauges, but I use a correction factor depending on the tire I use.
Regarding action cam, GoPro cams pan or zoom when their image stabilization is on, making the video very weird in corners. You can stabilize it post, but it takes too much time. I use Insta360 or DJI cams, which do a better job at that.
A new season is upon us, and I'm looking forward to trying out the new valving on the coilovers!
Inverted front coilovers: JJ is working on inverting the front coilovers (it took more than 10 weeks so far; thankfully it's off-season). I'm hoping the updated coilovers will soon be shipped. With this change, I won't need to get to the wheel well to do adjustments.
Adjustable endlinks for proper corner-weight balancing:Along with revalved coilovers with much more aggressive valving, I also intend to do the corner weight balancing the proper way. For that, I need to zero the load on the sway bars, which requires adjustable endlinks. I've sourced Eibach adjustables for this.
Spherical bushings for the control arms: Well, during Black Friday, there were good discounts and I sourced a set that comes pre-installed on brand new control arms : )
Wheels: I've also sourced 2 sets of APEX 18"x11" ET28 (22.9 lb), 18x12.75" ET24 (24.9 lb) wheels in Anthracite and Satin black. These are proper 2100-lb rated wheels with no disclaimers or copouts (like Forgeline does when they say it's rated so only for 200 tw tires, or like custom wheel manufacturers do when they don't test the exact wheel spec you have, so you better trust their calculations on their design app : P )
Tires:
New Hoosier R8s are out! Got a set of 315/30/18, 345/35/18 tires. These are about the same ratio as OEM, even though they're a bit smaller in diameter.
I also realized Hankook F200s are also reasonably priced after all the price hikes on other tires, so sourced them, too, just to see how they are (300/680/18, 320/710/18). These tires are almost identical to the OEM diameters,
We did get our kitchen remodeled a bit, and our garage was turned into a workshop for sanding. I couldn't work on the car at all during this time (a month), and the work is finally getting done this week.
GSpeed spherical bushings; they come with a good seal. Here's hoping they last a long time.
As usual, the wheels look great. They're not painted in the barrell to save weight.
You can see that the spokes are pretty deep for the extra rigidity these endurance wheels promise.
I'm also going to try these Hofmann's wheel weights. These are supposedly developed for motorsports, and they come off without leaving a mark or scuff. I'm hoping they would be more tolerant to higher temps as well, and if so, this would make things a lot easier. Looking forward to trying them out.
Looking good. Yeah, I have a set of adjustable rear Eibach end-links as well. With my new adjustable rear sway, the stock end-links are too long to use the other settings.
