'23 BRZ Manual Track Build

[X25]

Sway bar Armageddon

Well, the simplest of jobs turned into nightmare, thanks to Subaru engineering : )



First off, received the additional tabs, so I can install the race harness to passenger seat, too.


This must be where the tire was rubbing on during that sharp hard compression section of the track. The much stiffer sway bar should help with this, too.


Painted over with Rustoleum. If it rubs again, I will be able to tell...


Also sourced a second set of APEX wheels, and got them mounted with Hankook Z214s as the second set. I cloned and copied my first APEX set's TPMS onto this second set of wheels using Autel's MaxiTPMS programmable sensors. This way, I will not have to bother programming or even switching TPMS...



I installed two 4'x8' 3/4" thick sheets of cheap wood, since without them I was forced to jack the car a bit just to put the lift arms under the car.



I mark the optimum location to where the front side of the rear driver side fender is. This is the side that I can easily check on as I drive the car in.


The nightmare with the sway bar install started with the 14mm bolts on the sway bar bushing housings. These bolts are very tight, and 14mm felt a bit loose(!) on it.... and just like that, the 14mm ended up stripping the bolt! I later found more engagement with a 9/16" wrench, and used it along with a hammer to loosen one of the damage bolts. Of course, this also failed on the other bolt. In the end, my last hope, a very tightly mounted vise grip was able to move it a bit, and I was finally able to remove the second bolt, too.


This is how the bolt looked. Why is this not grade 8.8? It says "8" on it. I don't know what it means, but it's definitely not as strong as 8.8 or higher grade bolts I'm used to seeing on the Corvette. This bolt was literally identical to those that are too easy to strip on the oil pans on various cars...


But wait, Subaru keeps on giving. You're supposed to slide out the mounts after loosening those 14mm bolts a little bit. However, the mounts never wanted to slide out. It became clear why once I completely removed them; they were a tad bit too narrow to slide out. Since there's power steering arms' boots right on the way of that bolt, you almost have to install that bolt by itself first before installing the mount to clear it. To make that happen, I slightly enlarged that channel to fit the bolt it's supposed to slide over.


Here's the bolt screwed in a bit. As you can see, it's literally touching the boot at this height. FYI, I picked same height grade 8.8 flanged bolt replacement (M10-1.25 x 25mm) at Home Depot. They're definitely better grade than what Subaru installed in there.



Let's move on to Perrin sway bar fitment. This is PRETTY CLOSE to the lower control arm. I wonder if it will interfere or hit the control arm during operation.... ughh.



OEM bar with bushings: 5.2 lb
Perrin 22mm with bushings: 9.7 lb

Anyway, this was such a simple job made harder for no reason. It's over. I'll hopefully try it on November 12/13 event (if it doesn't get canceled).

[X25]

Where it rubbed last time...


The endlink is pretty close to the wheel liner, and seems to have rubbed on the wall during those heavy compression turns at the track, where I felt the steering was a bit "locked up".


.. and the other side.


Painted all damaged areas to track new rubbing now that I have 130% stiffer front sway bars further supporting the frontend.


These bolts are so easy to break. Here's one of the bolts holding the carpet-like cover under the car. Unfortunately, its other half is inside the bolt hole, so I'll have to drill it out one day when I have time..


This is the new location of the camera. I used the opportunity to raise the height a bit to get more of the road itself in view.


This is how it looks before image cropping (for image stabulization).


November 12/13 track day event is still on! 1 week to go, and I'm ready except the passenger side occupancy sensor harness (which causes persistent airbag messages popping up every few seconds; thanks Subaru for making this beyond annoying).

[___LUNK]

For future reference - you can unbolt the braces the sway bar is attached to and drop everything out the bottom of the car, easier than threading it around the engine.

[X25]

Originally Posted by ___LUNK

For future reference - you can unbolt the braces the sway bar is attached to and drop everything out the bottom of the car, easier than threading it around the engine.

Good to know! Hopefully I won't need to do this anytime soon, and with the new bolt, everything should be much easier anyway.

The occupancy sensor harness is on backorder, and I decided to take parts from my OEM passenger side seat.



You have to remove 16 mm nuts and rails to get to the sensors.


Unfortunately, the sensors are also what holds those rails attached to the seat : (


OEM seat; looted.



Verified that it would work.


The warning message is finally gone! It was very annoying, flashing back every 5 seconds. It'd make it very hard to look into the dashboard for sure..


I zip-tied stuff back on the seat so I'd not lose anything important.


The sensors are not protected well, since they're supposed to be sandwiched in between the seat base and rails. As such, they could easily get damaged if you leave the loose under the seat. I decided to fix them by the seat mount base.


Done!


.. not yet done. I seem to be rubbing on the carpet while blipping the throttle...


Sticked a piece of felt in there, so hopefully it would take the beating instead other carpet, and the race seat might help, too.

Done!

[X25]

Just finished the first day of the last event of the season, and there's been significant improvements in times : )



Started the day with a bit of a low morale, since it snowed a bit, and I wasn't sure what the track conditions would be in the morning..


I have no good records of the morning session since the mount failed. I was able to fix it here for the time being. I need a new mount that can attach to a very wide bar..

This is what I could do with the Hoosiers.. About 2 seconds improvement!


I was not able to push further on these tires, though, since they corded by the second session. I used the first session to experiment on the coilover settings with the new sway bar, so have not had much time.


The steering still gets locked a bit in high compression turns. That said, there are no more witness marks on the chassis! The black paint I put on where it rubbed is still there.


The sway bar's tip hits the control arm, though. I'm thinking about shaving the tip of the sway bar a wee bit to allow better clearance.


Hankooks Z214 245/40/17 on Dark gray (Anthracite) APEX ARC-8s

.. and another ~2 secs improvement over corded Hoosiers! This is now my new PB with this car at this track: 1:55.77.

[X25]

Fixed the GoPro mount.
From DIY thread: Mini DIY: Zip-tie (GoPro) bar mount for large bars!

Originally Posted by X25

If you're using a harness bar like BK's for our cars, you will realize that the center section of the bar is too wide for any off-the-shelf bar mount to work. I ended up making a mount with little to no cost.



The key is to find appropriately sized zip ties that you can fit within the rails of the GoPro mount. I inserted one side of the top mount piece to its rail first, and then forced the other side.


Align your zip ties before you fully insert the top mount, since you won't get to move it once it's in.


Ready to install


You probably don't need to use the adhesive bottom, but why not; it would reduce vibrations and movements at least..


Done!

In other news...



This solves the very annoying and unrelenting seat belt warning issue.


This was how the car looked Sunday morning. It did NOT snow : P


Both Z214s and A7s lasted for about 60 laps before starting to lose time and cording on the outer front tire (to the direction of the track). The rears look fine and I suppose a front swap can much-increase the life, but I'm still surprised a bit at the rate of wear. I know that ORP's surface is quite abrasive, but I was still hoping for more. This is about the same rate I get with my Corvette, too.


In other other news, ordered a set of whiteline end links in hopes of solving the interference issue. I was very happy to see that the top side of the end links are no longer rubbing on the chassis with the much stiffer sway bars, so fixing the bottom interference with the LCA should finally resolve my "steering locking" feeling in some high compression turns.

[Lincoln Logs]

Couple of notes:

1) Run a smaller Hoosier, the 245 is MASSIVE and wants a wider wheel.

2) I had a lot of issues with MCS shocks and the sway bar end link. I used a shorter link but always had witness marks on the chassis (used Feal Suspension OEM style that were shorter). I'd recommend talking to Karcepts about this, I think they have the best solution for the sway bar and those shocks.

3) Do you have a pyrometer?

[X25]

Originally Posted by Lincoln Logs

Couple of notes:

1) Run a smaller Hoosier, the 245 is MASSIVE and wants a wider wheel.

2) I had a lot of issues with MCS shocks and the sway bar end link. I used a shorter link but always had witness marks on the chassis (used Feal Suspension OEM style that were shorter). I'd recommend talking to Karcepts about this, I think they have the best solution for the sway bar and those shocks.

3) Do you have a pyrometer?

My wheels are 17"x9"; they should be fine for this size. I don't use OEM wheels

Karcepts recommended aftermarket endlinks. Their sway bar is also good, but $800 for something I'll likely not experiment much with.

I do have a pyrometer, but I need a sidekick to take "hot" measurements, or else they get way off if I need to hit paddock. I don't think pressures were off ideals.

[Pat]

Originally Posted by X25

My wheels are 17"x9"; they should be fine for this size. I don't use OEM wheels.

Fine, yes. Ideal, no. It's best not to just go by the quoted measurements of 9" and 245mm in this case.

[X25]

I'm quite surprised, of all things, you find the wheel size not being ideal. Sure, a bit more stretched tire would help I suppose, but 17"x9" is definitely not pinched by any means.

There was a back-to-back test done by emilio on different tire width and wheel width sizes, and even though wider wheels helped with the feedback, the lap times have always been better with the widest tire, even when mounted on very narrow wheels. In fact, lap times difference was very little for the same wide tire from narrow to widest wheel.

I've also used this size combination (245s on 17x9) on my NC Miata, and they worked excellent. Of course, Miata has a much more sophisticated suspension geometry, but I digress.

Judging from having no more witness marks on the chassis, the sway is contained much better with stiffer front sway bars, but I can always try adding the rear bars, too (already have 19mm bar in the garage). Rear bars might reduce rear bite a bit, but in my experience, a complementary rear bar always helped in previous cars, since it helps fight "twist" in high compression.

I am honestly waiting on experimenting more and getting very familiar with the setup before I put on the rear as well, so I'd know exactly what it gives or takes when I add it.

1:55s is a great lap time for ORP for a BRZ, so I'm pretty happy. There's a track day opportunity at RMP (Ridge Motorsports Park) this weekend, and I'll have the Goodyear S3Rs (245/40/17) and Whiteline front endlinks delivered before the event to try them out. Let's see if I can fix the interference issue; fingers crossed!

I also ordered Hankooks (2 tires to replace fronts), but they won't be here before Friday, which is a bit of a stretch to make them ready for Saturday event. Ridge's track surface is also much smoother and kinder to tires. In fact, endurance race teams for Chump Car or Lucky Dog (here in PNW) usually bring 2-3x more sets of tires for ORP vs their races at RMP, to give you an idea.

[RedReplicant]

Yeah, Hoosier tire sizing is a lie. They also vary in actual size based on the tire compound and wheel diameter. Most people putting a 245 17 onto a 9 are doing it to fit into the NASA 266mm template, otherwise they do want a wider wheel.

Originally Posted by X25

There was a back-to-back test done by emilio on different tire width and wheel width sizes, and even though wider wheels helped with the feedback, the lap times have always been better with the widest tire, even when mounted on very narrow wheels. In fact, lap times difference was very little for the same wide tire from narrow to widest wheel.

Where was that? From what I have seen he usually aims to put a tire onto a wheel that matches the section width, plus lap times > *. I also come from a Miata background where we ran 245s on a 15x10, but again, Hoosier sizing is not real and a 245 15" Hoosier is more narrow than 17/18" and fits into the 266mm template on a 10.

Andy Hollis has stated multiple times that a street tire will basically always do better on a wider wheel, Hoosiers are the exception but there are still benefits to going wider.

In either case, this is a good thread, I'll be sticking around to read.

[Lincoln Logs]

Originally Posted by X25

My wheels are 17"x9"; they should be fine for this size. I don't use OEM wheels

Karcepts recommended aftermarket endlinks. Their sway bar is also good, but $800 for something I'll likely not experiment much with.

I do have a pyrometer, but I need a sidekick to take "hot" measurements, or else they get way off if I need to hit paddock. I don't think pressures were off ideals.

I'd run a 225 or 205 on a 9 if I am using Hoosiers. 205/50/15 was the go to for a Miata running 15x9s. Hoosiers are way oversized and will last longer and give you better lap times if sized appropriately.

MCS has funky geometry for the sway bar end links, I battled it the entire time I had the shocks on my car. Karcepts built their design around the MCS and maximized clearance, you might not be able to avoid the bind without it. This is the most overlooked element of shock design on this car, everyone gets it wrong other than RCE (KW) and 949 Racing.

You totally can use one without a helper, just move fast and some data is better than none. You can record what you can and it will still tell you. Use the hot pit at a track if you can.

I know Emilio very well, I used to track with him all the time and worked in the same business. He'll relay the same info I am giving you.

[X25]

Originally Posted by RedReplicant

Yeah, Hoosier tire sizing is a lie. They also vary in actual size based on the tire compound and wheel diameter. Most people putting a 245 17 onto a 9 are doing it to fit into the NASA 266mm template, otherwise they do want a wider wheel.



Where was that? From what I have seen he usually aims to put a tire onto a wheel that matches the section width. I also come from a Miata background where we ran 245s on a 15x10, but again, Hoosier sizing is not real and a 245 15" Hoosier will measure a different width than a 17/18".

Andy Hollis has stated multiple times that a street tire will basically always do better on a wider wheel, Hoosiers are the exception but there are still benefits to going wider.

Yeah I've heard that, but that's not what I see here. Perhaps they're no longer massively wide cheater tires? They were about same as Hankooks. Sure, wider wheel helps, but for a properly setup car, wider tire still always does better lap time than the narrower tire on a wider wheel. I'll need to find that test : )



245 Z214 vs Hoosiers. They look pretty similar in width, and Hoosiers don't seem much bigger.


Depending on how you hold it, it measured around 245 to 250 mm (Hoosiers)


For reference, RT660 225/40/17s measured around 220-225 mm.

[X25]

Replaced the endlinks, and dropped off Goodyear SC3R tires for mounting; getting ready for Saturday event!




Passenger and driver side (in respective order). The track layout was clockwise, and you can clearly see more damage on the driver side during sharp (high compression) turns.


OEM end links are 245mm long from bolt center to center.

Eventually settled at 220mm length for endlinks that let me clear the LCAs.

At full droop, with steering at max left (passenger side). This is as close as it gets. I'm not sure what happens when it's not at full droop, and we'll see very soon : P I could never have the steering fully turned during at the track anyway, so I should have more clearance.


At full droop, with steering at max right (passenger side). From this to full left, the endlink never got close to the shock body, or showed any sign of binding. That said, I'm not sure of the geometry under compression.


SC3Rs on the left (not mounted), and Hoosier A7s on the right (on 17"x9" wheels); both 245/40/17. As you can see, there's not much of a difference in total width, and 9" wide wheel seems to neither pinch, nor stretch the Hoosiers...