What mods are needed for a heavily track-focused BRZ?
 

I'm waiting for delivery of my '23 Magnetite Gray Metallic BRZ Premium M6, expected in August. Since the order was placed, I've been researching what mods would be needed for a track focused car, and ordered quite a few parts. Considering most parts take a while to be delivered, I'd love to get your thoughts on what else I might need, or if you have feedback on whatever I've already ordered, good or bad : )

What's ordered so far:

• Suspension
  • Karcepts MCS 2WNR Coilover kit 450/550 lbs/in front/rear springs (link).
  • Cusco rear UCAs for fine-tuning alignment (link).
  • SPL rear toe link for fine-tuning alignment, and consistent alignment (link).
  Brakes
  • Essex AP Racing Big Brake Kit (SPRINT) - 299x32 mm (link).
  • Ferodo 3.12 front, 1.11 rear pads. Raybestos pads are out of stock.
  Wheels/Tires
  • CANCELLED
    • Enkei RPF1 17x9 5x100 ET35 Silver for fronts (link).
    • Enkei RPF1 17x9 5x100 ET45 Silver for rears (link).
  • APEX ARC-8 17x9 5x100 ET35 Black for fronts (link).
  • APEX ARC-8 17x9 5x100 ET42 Black for fronts (link).
  • Hoosier A7 245/40/17 (they run as wide as most 265s) (link)
  • T6 TPMS from Tirerack.
  • Autel MaxiTPMS TS508 for programming TPMS (link).
• Perrin transmission mount support to address 2nd gear shifting in hard-left turns (link).

Things that might be useful, or missing:

• Sway bars??
  • Karcepts highly recommended their front sway bar, and I'm in their wait list, but using aftermarket bar on only one end makes me a bit worried per my former experience.
  • I'm not sure if there are any other bars that work well with coilovers and this chassis. Karcepts bar is very expensive and not sure if I need easy adjustability. Thoughts? Any experience with Karcepts bar or others?
• Any cooling mods?
  • I will keep the engine stock. My hope is that the OEM oil cooler would do enough to keep it cool.
• Seats
  • I'm thinking about Sparco Evo L QRT, which is what I use on my Corvette. Not sure about the mounting, though; would prefer the lightest possible with no need for a slider.
  • I already have an unused pair of Scroth Profi II ASM 6-point (4+2) belts, but would need mounting locations for them..
  • Can we easily turn off error lights when stock seats are removed on these new cars, too?

Thoughts? Is there anything glaringly missing in your opinion?

As for me, if it's relevant, I'm quite experienced in track driving in various other platforms (NC Miata, Camaro SS 1LE, C6 Z06, C7 Z51, Z06, etc.), but this will be my first BRZ ever : ) I drive in advanced groups, and try my best to push the car and myself, but I'm not a racer or a pro.

Any input would be very much appreciated!!

@X25


What you don't need:

• Front UCA
  Mcpherson Strut system can be camber adjusted with a lot of flexibility with just front camber plates (in contrast to many double wishbones). If your coilover system has front camber plates, that's all you really need. If your coilovers don't have front camber plates, consider purchasing them.
• Rear toe links
  For rear camber adjustment, you want rear lower control arms. You only really need toe links if your car is significantly lowered AND you want close to zero rear camber AND simultaneously low toe. For track alignments (-2 deg or more) and close to zero camber, you don't need the toe arms.

What you might want/need

• Dedicated air-oil cooler
  The water-oil cooler from the factory is likely insufficient if you are an experienced track driver, especially in warmer climates. Gen1 cars often saw insufficient oil pressure at higher oil temperatures. Some may argue that you can get away with it as is, that oil coolers add their on risks, or simply to use heavier motor oil. But if this is your track duty car, I think oil cooler and 0W20 is the way to go.
• DOT4 or better brake fluid
  Not much to say here
• Front suspension camber plates
  See previous section
• Rear lower control arms
  See previous section
• Add Trans & Diff Oil Maintenance Interval

Things to reconsider

• Coilover Spring Stiffness
  I'm not familiar with MCS systems, but the spring rates you provided seem a little soft to run with a dedicated slick tire on the platform
• Mismatched brake compound
  It looks like you have chosen a different front vs rear braking compound. I'm not familiar with Ferodo line-up, but mismatched compounds can affect your brake bias and how the car is balanced during trail braking if their friction/character are significantly different from each other. If they are matched for each other, it shouldn't be a problem
• Sway bars
  I would say stay away from sway bars until you run out of adjustment in your coilover system. There is no swaybar panacea or universal preference on the platform. I like Eibach for sway bars, but there are many out there that do the same thing and are built well.

Thanks for your input!

Rear LCA: I should note here that I'm trying to avoid rear LCA mod, since it will revert the new wheel rate and geometry of '22+ BRZ back to the previos gen's, and the LCA camber adjustment puts more stress on the axle, etc.; UCA adjustment avoids these issues.

Toe link: Hmm, perhaps I should consider canceling the rear toe link until I really see a need. It's pretty expensive, too.

Spring rates: I don't know much about the spring rates for this platform, but the rates I picked are at the highest end of the rates the coilover manufacturer recommended. I also remember someone else mentioning rear becoming too stiff with anything above 600, so perhaps this is a good compromise. I suppose we'll have to see.

Sway bars: I'd love to wait on it as well, and perhaps use the budget for it on race seats : )

Read your original post wrong. With Rear Upper Control Arms, you might want to keep the toe link because the geometry is more closely related when adjusting from the top.

• SPL Rear Lower Control Arms have multiple holes to position the strut. I think one might correspond closely to the mounting point on the gen2. That being said, the difference in motion ratio between gen1 and gen2 is not that significant: https://www.ft86club.com/forums/show...35&postcount=4
• I think both piece parts can achieve the same camber goal. Most people go for the lower arm due to lower cost and ease-of-install

Did you communicate with the manufacturer the type of tire you would be using?

Yes, that was the first thing I mentioned : )

:w00t: I would trust them more than me on recommendations for their products. I'm sure it will work fine

I've run MCS for a couple years and am at 550 springs front and back. Very neutral handling characteristics. Not a lot of people run staggered spring rates that aren't using aero but I'm no expert in suspension dynamics so. Plus springs are relatively cheap. If you are unhappy with the rates its very easy to swap springs on the MCS damper.

The AP Sprint BBK is great, but with Hoosiers I would consider something a little bigger. Essex has some nice new AP kits that would be a better fit IMO.

I would also recommend same brake pad compound front and rear.

Yes I would use the SPL toe arm with eccentric lockout. It's worth it.

Many of the aftermarket rear lower control arms had options for rear motion ratio, and some used the WRX location anyway. You could use the Cusco upper arm and then the non-adjustable STI arm with a nice sealed pillowball for the lower. The Cusco rear LCA has 2 positions as well.

Make friends with your alignment person.

For the front swaybar...I would consider it with the spring rates that you're running, but I would also consider running stiffer front springs instead. I think that's a decision you can save for later...for now I would see what you think, collect some data, and have fun.

I would also think about replacing more bushings...at the "hoosier" level of grip that becomes more noticeable/beneficial. But something you can also do later.

- Andrew

Gen2 vehicles pads are mismatched from factory, runnig GG on front and FF on rears. The ideal brake balance may change with the hoosiers, but I would assume a similar initial setup.

I think the ideal spring rate setup has also changed in the new platform, which is why the coilover manufacturers are also revising their spring rates and valving. As far as I've heard, square setup promotes significant understeer.

.. and regarding how wide 245/40/17 Hoosiers actually are:
https://thumbnails-photos.amazon.com...Fh-iYJiH0THNlx
About 260-265mm!!! : P If I can make these fit, hopefully most other tires would also easily fit..

We'll have to see on the brakes. The AP sprint kit is very attractive from the point of weight savings, and my hope is that the little 228HP engine can't overwhelm it.

Double-check your BBK w/ 17x9 RPF1s. The backside of the x9 spokes can be an issue w/ BBKs. The x8 RPF1s are contoured differently on the backside of the spokes to better accommodate BBKs.

As an apples-to-oranges comparison, here is a list of the wheels that fit the 1st Gen PP Brembos which might be useful when looking at a different BBK kit for the 2nd Gens.

https://www.ft86club.com/forums/showthread.php?t=135328

Wow, I always assumed RPF1 17x9 +35 would clear with the extra +10mm clearance over the +45 wheels; I guess I was wrong?

Himm, now I'm thinking I should cancel the wheels order (they're in backorder anyway), and order Apex ARC-8 +35 front, +42 rears. Apex said they will come up with higher offset wheels for rear fitment late this year, and I guess I could switch to those later.

Thoughts?

The OEM pads are garbage and feel like smushing sourdough bread (extra butter) onto the rotors. I'm exaggerating, but I wouldn't worry about the factory pads. OEM design parameters are not too much of a concern here.

Coilover manufacturers do a lot of things for a lot of different reasons. Sometimes those reasons are performance related. :)

For what it's worth, the 450/550 with the karcepts front bar at the softest setting will be more front biased than a 550/550 set up with OEM swaybar. Then up from there as you make the bar stiffer. And that's not necessarily a bad thing!

Also this...the 17x9 +35 RPF1s don't have great BBK clearance and can be limiting.

- Andrew

My response was not regarding the quality of the pads, 1st thing I have done was to replace those (along with RBF600). And I assumed that it was a square setup. When, I removed the OEM pads, noticed that those were staggered, with Front bias on the apparent friction.
In other thread I mentioned that, and I am going to update my brake balance calculations based on this info (not perfect, but give some direction)
Running square setup, you’re going to move the brake bias to rear axle.