'23 BRZ Manual Track Build

[X25]

I finally got to try the SC3R tires, today; my first time ever. I think they do well, but they definitely need a bit of warm-up; they have very low traction when cold.

I could only do 3 sessions of 8 laps, and I definitely need more seat time to clean up everything, but this is what I could do today:

I'm actually happy with the result, and looking forward to future opportunities to improve on it.

At this time, I think I'm also ready to try the rear bar to see how it impacts handling. I'll install it next time I put the car on the lift, and we'll see how it impacts handling! I have pretty high hopes; especially for long sweeper turns like the carousel at Ridge.

Edit: I forgot to mention that I don't think I have the steering lockup and endlink clearance issues, anymore, now that I have endlinks at 220mm (vs 245mm stock). I'd want to try ORP as well before final verdict, though, since it has more places where that happens

[X25]

Rear sway bar and oil changes

The aftermarket sway bar holes are way off what the OEM endlink is designed for, and I'd have to severely load up the endlink in order for it to just fit. I obviously didn't like the idea, and ordered whiteline end links for $114 shipped; not bad. They arrived today!


The adjustable whitelines are about same weight as OEM; 1.8 lb vs 1.7 lb.


Whiteline end links allow you to offset the link to the left, center, or right; great! Even so, Perrin's third (softest) hole was way off the endlink. I'd have to far extend the endlink to make it not pre-loaded, which would like be beyond its intended adjustment range. Alas, I've decided to use the second hole on the bar.



With endlink offset right most, the mid hole aligns nicely.


I was feeling a bit of resistance in T2 over the weekend. The rear sway bar should also help with this a little bit, but we'll see. If I still have this issue, I might consider upping the spring rates from 450/550 to 500/600 or 550/650 lb/in.


The differential fluid was very stinky, and the plug had so much stuff on it. It was so stinky that my wife asked me to open garage doors since it "stinks the house".


It was pretty hardened sludge. I'm thinking about replacing diff fluid again in a short interval for cleaning up the rest of the sludge that I probably couldn't remove. I've used Amsoil 75W-110 Severe gear LSD, which should also work better in high temps.



I did a quick test drive, and everything feels fine for street : )
Also sent the oil for analysis to Blackstone; we'll see what they have to say.

Looking forward to the next opportunity to test it out at the track..

[X25]

Got my first oil report. It's actually the last 1150 miles of 1500 miles total, but oh well, I suppose they mis-wrote it. Anyhow:



I'll send another sample after a few thousand miles.

[nissanfanatic]

Nice build and thank for posting all the info! I will probably follow a similar path with the Brey-Krause bar. Did you order direct from them?

Would you happen to know what sustained gee's are on your fast laps? Or have an export (vbo if possible) of the data? Not sure if you've come across this thread where we have been discussing oil pressure drops during cornering, but your car would be a great candidate since it's on much higher grip tires than other cars that have posted data. Even more so since you are doing and plan to continue to do UOA.

[Pat]

How many miles and track days were on that differential fluid? CSG recommends changing the fluid, "every 10,000 miles / 16,000 Km, 10 events, or when the driver can feel degraded performance of the LSD, whichever comes first. With the factory Torsen differential, depending on the driver, tires and track, degraded performance may be experienced after only 2 events."
I plan on changing the tranny and diff fluids more frequently in my ZD8 than I did my ZD6.

[X25]

Originally Posted by Pat

How many miles and track days were on that differential fluid? CSG recommends changing the fluid, "every 10,000 miles / 16,000 Km, 10 events, or when the driver can feel degraded performance of the LSD, whichever comes first. With the factory Torsen differential, depending on the driver, tires and track, degraded performance may be experienced after only 2 events."
I plan on changing the tranny and diff fluids more frequently in my ZD8 than I did my ZD6.

Per my records, the diff fluid change was at 1526 miles. More than half of it was track miles. I have a feeling that the OEM fill is not of best quality, but might be wrong.

We have quite a bit of experience in differential fluids and overall performance in diffs on various cars. One key issue is temps and how the fluid fares in these hot temps. For instance, we were able to much improve the differential fluid life on my brother's NC Miata by adding a big cooler that never let it go above operating temps. This car was used in 2 day x 7 hour endurance races, and never missed a beat. The fluid was also still in pretty good shape when he replaced it as a precaution every 2 events, if I recall.

Going back to this car, especially a Torsen diff should keep doing well if the fluid still has the right viscosity, etc. 75W-110 is a standard that was released after 75W-90, and is WITHIN the 75W-90 (i.e. any car that recommends -90 is compatible with -110 as well per specs). That said, 75W-110 fares much better at high temps, and I see no reason why anyone using their cars at road course track would want to use the less stringent standard.

Use whatever brand you deem fit of course, but I've had good experience with the Amsoil fluids. Their 75W-110 should provide more protection at higher temps, and also degrade much slower, being optimized for higher temps and high-class synthetic.

Another example, GM recommends 24 hour track use as diff fluid change interval on their C7 Corvettes. It takes quite a few events to hit 24 hours; perhaps once a season or so is enough..

Finally, if this was a full on race car, I'd probably just put in a -140 weight fluid, as that's what most racing teams do. Oh well..

[X25]

Originally Posted by nissanfanatic

Nice build and thank for posting all the info! I will probably follow a similar path with the Brey-Krause bar. Did you order direct from them?

Would you happen to know what sustained gee's are on your fast laps? Or have an export (vbo if possible) of the data? Not sure if you've come across this thread where we have been discussing oil pressure drops during cornering, but your car would be a great candidate since it's on much higher grip tires than other cars that have posted data. Even more so since you are doing and plan to continue to do UOA.

FYI, I use 818GT BT GPS transponder - the only one I've used that doesn't mess up this data.

Took a look at data on BRZ and C7 Z06.



Top is BRZ, bottom is Z06. I presume the most important corners where you might have this issue is long sweepers where the engine doesn't get to recover from it in a long time, so that would be the carousel at this local track. Corvette is pretty consistent, topping around 1.39G, while BRZ is a bit more wavy (when graph is at same scale), topping at 1.27G or so.



Top is BRZ, bottom is Z06. This is where BRZ peaked at around 1.6G. C7 also peaks at around 1.60-1.65G actually, but it was at a different corner. I think I probably slided the rear of the BRZ, and it generated that high G for a short instance when the rear finally 'settled' : ) The average Gs look similar.


Going back to your question, I think the Gs that we should care about is at 1.4G or so in my experience, at least at this track. Focus on long sweepers, and the engines are usually more vulnerable in one direction as well (left sweeper like GM V8s, or right sweepers, or both?). EDIT: just checked on that thread, and looks like there were issues at quick sweepers? Himm perhaps we should put in a baffle (if pickup is having hard time sucking oil). That's probably oil sloshing around in the pan, and not necessarily tied as much to high Gs in a way..

[nissanfanatic]

Originally Posted by X25

Going back to your question, I think the Gs that we should care about is at 1.4G or so in my experience, at least at this track. Focus on long sweepers, and the engines are usually more vulnerable in one direction as well (left sweeper like GM V8s, or right sweepers, or both?). EDIT: just checked on that thread, and looks like there were issues at quick sweepers? Himm perhaps we should put in a baffle (if pickup is having hard time sucking oil). That's probably oil sloshing around in the pan, and not necessarily tied as much to high Gs in a way..

Thanks for grabbing that data!

This post has some follow on testing and a side by side video of a car with a baffle. tldr - baffle didn't seem to help much, and it isn't necessarily transition causing slosh. It is pretty consistent in hard right hand corners.

The lateral acceleration your car is seeing _should_ be causing orders of magnitude more starvation if it is, in fact, starvation related to lateral acceleration. I still have my doubts on that, but nothing that I could back up with a rational explanation.

A logging setup on your car would be amazing, but even that never happens my original thought with getting some data on your car is if your car is surviving, then I personally am not too worried that the drop is anything other than an observation at this point. If the car survives well enough and always returns good UOA, then w/e with the drop lol. It probably happens way more often than people are aware, but most of us don't have a sensor/gauge, or a gauge that is sampling frequently enough to spot it.

[Dzmitry]

Originally Posted by nissanfanatic

Thanks for grabbing that data!

This post has some follow on testing and a side by side video of a car with a baffle. tldr - baffle didn't seem to help much, and it isn't necessarily transition causing slosh. It is pretty consistent in hard right hand corners.

The lateral acceleration your car is seeing _should_ be causing orders of magnitude more starvation if it is, in fact, starvation related to lateral acceleration. I still have my doubts on that, but nothing that I could back up with a rational explanation.

A logging setup on your car would be amazing, but even that never happens my original thought with getting some data on your car is if your car is surviving, then I personally am not too worried that the drop is anything other than an observation at this point. If the car survives well enough and always returns good UOA, then w/e with the drop lol. It probably happens way more often than people are aware, but most of us don't have a sensor/gauge, or a gauge that is sampling frequently enough to spot it.

I'm with you there as that is my theory as well. But I feel like there's JUST enough engines blowing up out there that it brings us the concern that it could be the related issue. With a lot of stuff like this, time will tell. Need a few years of this new gen getting beat on track and various part testing to determine what's necessary, what helps, and what's to even worry about.

[X25]

The car is now sold; thanks everyone for your interest! The new owner is planning to use it at the track, and we'll see how his journey goes.

In other news, I'm hoping to get my C8 Z51 delivered around July; looking forward to seeing what we can do with that car, and how it compares to C7 Z06...