'23 C8 Z51 Track Build
Thread Starter
Sr.Random input generator
Joined: Jan 2008
Posts: 7,798
Likes: 2,229
From: Sammamish, WA
Edit: pic of inside of bumper:
Last edited by X25; Jun 22, 2023 at 07:20 PM.
What’s Next
Joined: Dec 2020
Posts: 1,293
Likes: 834
From: Reality
Thread Starter
Sr.Random input generator
Joined: Jan 2008
Posts: 7,798
Likes: 2,229
From: Sammamish, WA
Some great shots of 295/345s. Seems like that's the limit:https://youtu.be/CoRHt_k1qCw
I do have 295/30 (10"-11") RRs, 315/30 (10.5"-11.5") RRs, and 315/30 (11"-12") R7s, mostly grandfathered from my C7 Z06 'program'. The values in parenthesis are their recommended ranges.
As you can see, it's either within the recommended range, or one step below. I'm sure it'd give more feedback if you can stretch it more, but oh well. I've used 315s on C7 Z51, and I think it worked great. On C8, once I get acclimated and stop trying to kill myself with left foot, I can mount 295s on one set, 315s on another, and test it back to back; would be fun to test!
Edit: People state that 295s work with 18x10 on stock suspension. This is the reason why I think I can get 18x10.5 work, since MCS should provide a lot more body control than MRC, which is designed to use a much longer stroke.
Last edited by X25; Jun 22, 2023 at 09:27 PM.
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Thread Starter
Sr.Random input generator
Joined: Jan 2008
Posts: 7,798
Likes: 2,229
From: Sammamish, WA
Changed the fluids, today!
A few remarks:
- I expected the engine oil color to be brighter since the engine oil never exceeded 180s. I've seen engine oil retaining its amber color on an over-cooled ND Miata, but I suppose this engine works different : )
- Transmission only took in ~9 quarts of oil (12 quarts capacity). I thought it would take close to 10-11 quarts, but I suppose this is normal considering the large design of tranny and diff.
- Due to an issue I've spotted, I'll add the 2 additional liters of DCT fluid the hard way (from the top), but for the next time, I'm thinking about sourcing a long 1/2" ID transparent hose (like what I think Amsoil pump uses), fish it up towards the engine bay, lower the car, and just pump when the car us on the ground, and with driver side of the car jacked to hit that needed 13 degrees. Once done, I can then lift the car back up, shut the plug, and done. Reaching from rear driver side tire wheel is still a bit annoying, and you can drop the 17mm plug bolt.
These EP16 bolts are incredibly annoying. I'm guessing this design has a torque limiting nature, and if I'm even a wee bit off angle with my impact gun, it snaps and hurts the bolt a bit. I just ordered 3 boxes of M8x25 mm Flanged Hex (same) Grade 10.9 bolts. Next time when I'm removing this shield, these bolts will be retired : )
( )
Wow, amazing design. The lifting points cover the last few 13mm bolts needed to be removed!
Before / after: The pucks have a bit of a play, and I moved them away from those bolts.
Yay, bolts are now exposed.
Oil pan plug is a beautiful design. It doesn't leak as you're loosening it, until the moment you pull it out. This way, there's no mess on you hands or worse, your arms.
From top, and then zoomed-in photo: There were traces of transmission fluid under the car and on the shield I just removed. I traced them back all the way to top. There's a breather around where the oil accumulated, and I'd like to investigate. I was going to use the easy method for the additional transmission fluid for track use, but in light of this issue, I'll do the hard way, remove everything up top, and take a deep look.
Transmission fluid looked like new, and in beautiful amber color.
...yet the transmission filter is clearly full of metal, evidenced by its full gray color. No wonder some people had issues with clogged filters (i.e. their shifting improved after dealer changed the filter). Keep in mind, this car is at 1423 miles. I'm thinking about changing the filter again after a few track days to remove any material that might be accumulated from remaining break-in of parts.
Amsoil's general purpose pump uses a very thick hose, and it's incredibly fast at pumping the fluid.
Burning Brakes
Joined: Dec 2007
Posts: 761
Likes: 335
From: Charlotte NC
Just as a data point RE: C8 vs C7Z -- In similar configuration: mechanically stock other than track alignment, aftermarket wheels and (same) tires. The Z is on avg 4 seconds quicker around a 2.28 mile course same day and driver. Granted my C8 is a heavy 3LT HTC and the Z is a 2LZ M7.
Melting Slicks
Joined: Aug 2020
Posts: 3,353
Likes: 3,739
Just as a data point RE: C8 vs C7Z -- In similar configuration: mechanically stock other than track alignment, aftermarket wheels and (same) tires. The Z is on avg 4 seconds quicker around a 2.28 mile course same day and driver. Granted my C8 is a heavy 3LT HTC and the Z is a 2LZ M7.
edit: whoops, I missed your tire size post above
Last edited by ZRacerLE; Jun 23, 2023 at 02:00 PM.
Thread Starter
Sr.Random input generator
Joined: Jan 2008
Posts: 7,798
Likes: 2,229
From: Sammamish, WA
After I saw traces of transmission oil around the engine, I've decided to add the additional 2 liters from the top fill plug to investigate the top area.
It's actually not hard to remove the airbox at all... EXCEPT when it comes to those plastic wire retainers! I'm guessing now that I've tired those plastic retainers already (and broke one already), it'll likely be easier next time.
Top plug takes a 6mm allen drive. Its thread is M14.15. I was thinking we can make an extension tool. A hose with an M14-1.5 end, and a plug at the other end of the hose routed towards the center of the engine. This way, we could easily add the additional 2 liters without having to remove anything.
I was not able to see any clear evidence of leak, besides the existence of that oil. The breather's line was completely dry, and I bet it would keep a bit of the oil if it was leaking from the breather. By the way, this is such a better design than C7's breather. Since it's a long line, any oil frothing out would have plenty of time to get back into transmission instead of leaking around.
During the test drive, I had a soft hitting noise. The rear brake ducts are hitting the wheel balance weights.
I trimmed the bottom of the ducts this much to clear them.
Done!
The car is ready except alignment for the track day, and I apparently built a dragster! I don't hear any rubbing, even at full lock, which is very promising. (This is 295/30/18 front, 345/35/18 rear RRs). Here's hoping I can get it aligned before next week!
It's actually not hard to remove the airbox at all... EXCEPT when it comes to those plastic wire retainers! I'm guessing now that I've tired those plastic retainers already (and broke one already), it'll likely be easier next time.
Top plug takes a 6mm allen drive. Its thread is M14.15. I was thinking we can make an extension tool. A hose with an M14-1.5 end, and a plug at the other end of the hose routed towards the center of the engine. This way, we could easily add the additional 2 liters without having to remove anything.
I was not able to see any clear evidence of leak, besides the existence of that oil. The breather's line was completely dry, and I bet it would keep a bit of the oil if it was leaking from the breather. By the way, this is such a better design than C7's breather. Since it's a long line, any oil frothing out would have plenty of time to get back into transmission instead of leaking around.
During the test drive, I had a soft hitting noise. The rear brake ducts are hitting the wheel balance weights.
I trimmed the bottom of the ducts this much to clear them.
Done!
The car is ready except alignment for the track day, and I apparently built a dragster! I don't hear any rubbing, even at full lock, which is very promising. (This is 295/30/18 front, 345/35/18 rear RRs). Here's hoping I can get it aligned before next week!
Last edited by X25; Jun 24, 2023 at 01:56 AM.
Heel & Toe
Joined: May 2023
Posts: 16
Likes: 13
After I saw traces of transmission oil around the engine, I've decided to add the additional 2 liters from the top fill plug to investigate the top area.
It's actually not hard to remove the airbox at all... EXCEPT when it comes to those plastic wire retainers! I'm guessing now that I've tired those plastic retainers already (and broke one already), it'll likely be easier next time.
Top plug takes a 6mm allen drive. Its thread is M14.15. I was thinking we can make an extension tool. A hose with an M14-1.5 end, and a plug at the other end of the hose routed towards the center of the engine. This way, we could easily add the additional 2 liters without having to remove anything.
I was not able to see any clear evidence of leak, besides the existence of that oil. The breather's line was completely dry, and I bet it would keep a bit of the oil if it was leaking from the breather. By the way, this is such a better design than C7's breather. Since it's a long line, any oil frothing out would have plenty of time to get back into transmission instead of leaking around.
During the test drive, I had a soft hitting noise. The rear brake ducts are hitting the wheel balance weights.
I trimmed the bottom of the ducts this much to clear them.
Done!
The car is ready except alignment for the track day, and I apparently built a dragster! I don't hear any rubbing, even at full lock, which is very promising. (This is 295/30/18 front, 345/35/18 rear RRs). Here's hoping I can get it aligned before next week!
It's actually not hard to remove the airbox at all... EXCEPT when it comes to those plastic wire retainers! I'm guessing now that I've tired those plastic retainers already (and broke one already), it'll likely be easier next time.
Top plug takes a 6mm allen drive. Its thread is M14.15. I was thinking we can make an extension tool. A hose with an M14-1.5 end, and a plug at the other end of the hose routed towards the center of the engine. This way, we could easily add the additional 2 liters without having to remove anything.
I was not able to see any clear evidence of leak, besides the existence of that oil. The breather's line was completely dry, and I bet it would keep a bit of the oil if it was leaking from the breather. By the way, this is such a better design than C7's breather. Since it's a long line, any oil frothing out would have plenty of time to get back into transmission instead of leaking around.
During the test drive, I had a soft hitting noise. The rear brake ducts are hitting the wheel balance weights.
I trimmed the bottom of the ducts this much to clear them.
Done!
The car is ready except alignment for the track day, and I apparently built a dragster! I don't hear any rubbing, even at full lock, which is very promising. (This is 295/30/18 front, 345/35/18 rear RRs). Here's hoping I can get it aligned before next week!
Thread Starter
Sr.Random input generator
Joined: Jan 2008
Posts: 7,798
Likes: 2,229
From: Sammamish, WA
Another benefit of the coilovers is that it can limit droop. APEX already mentioned the interference only happens when both wheels are in full droop for a long time. Even in this condition (the car is on the lift), as you can see, the's a few mm of clearance. I've inserted my hook pick in between the wheel and the suspension to visualize the gap:
The coilovers have slightly more limited droop, which allows the 18" wheels clear the rear suspension even when both sides are at full droop (when it is supposed to happen only).
Instructor
Joined: Jul 2019
Posts: 159
Likes: 92
for the transmission fluid leak, there must be a tiny pinhole in the casting around where you saw the fluid. I'm surprised this is still an issue on newer cars. You could ignore/monitor it and get a transmission replaced near the end of your warranty. There would be more evidence of fluid if it came out of the breather.
Racer
Joined: Nov 2021
Posts: 302
Likes: 148
From: Seattle, WA
Good to know the mcs are actually limited without special request. The cicio info kinda made it seem like they aren’t limited off the shelf, so when I installed them and saw droop that was approximately the same, I just assumed that they weren’t limited.
Also, please rig us something for simpler trans refilling to the +2 spec!! That would be awesome.
Also, please rig us something for simpler trans refilling to the +2 spec!! That would be awesome.
Heel & Toe
Joined: May 2023
Posts: 16
Likes: 13
Good to know the mcs are actually limited without special request. The cicio info kinda made it seem like they aren’t limited off the shelf, so when I installed them and saw droop that was approximately the same, I just assumed that they weren’t limited.
Also, please rig us something for simpler trans refilling to the +2 spec!! That would be awesome.
Also, please rig us something for simpler trans refilling to the +2 spec!! That would be awesome.
