[Bee Pee]

I wonder if G8x front 6pots cw 380mm discs would be an oem pnp upgrade for front 380/4pots on F8x cars ?

[AlpinewhiteM2C]

Interested to know this too. Tire size availability for 18” wheels are better than 19” in 200tw space

[M Fifty]

the 898M wheels also looked interesting.

[jritt@essex]

It would be incredibly difficult to fit an OEM brake setup of that size inside an 18" wheel. Our AP Racing by Essex Radi-CAL Competition Brake Kit use a 372mm disc, and that's just about as large as you can go in an 18" wheel. You can see them here: https://www.essexparts.com/my-vehicl...ompetition/All

380mm discs may occasionally fit an 18", but that is very rare. It also has to do with the physical dimensions of the caliper itself. Those OEM calipers on the G8X are huge. They don't have the compact nature of a racing caliper. The large pad that is highlighted is one of the reasons for that. Tall pads and a tall disc face require a taller caliper. On a racing setup, the caliper, disc, and pad height are not as tall, and instead they use a thicker pad and/or disc to add thermal mass.

As an example, below is a pic of our AP Racing Pro5000R Radi-CAL caliper sitting next to the six piston OEM Porsche 991 GT3 caliper. You can see how much more compact our caliper is. On that car, the OEM setup is that caliper on a 380mm disc. Our caliper rides on a 394mm disc on that application, yet our overall packaging envelope is just as tight due to the shorter caliper height. In other words, we can use a considerably larger diameter disc because the caliper is so much shorter.

With brakes there's no free lunch. If you want taller pads and taller disc faces, you need a taller caliper to accommodate them. That hurts wheel fitment and also dramatically increases unsprung weight. Additional radial depth on the disc, the larger calipers, and the taller pads all add a lot of unsprung weight...all of which are counterproductive when trying to move to the lightest, smallest wheel/tire package.

Also keep in mind that any caliper like the OEM one with a fixed bridge is going to necessitate the removal of the caliper for pad changes, which is a hassle. The more you track your car, the bigger the headache it will be.

[jritt@essex]

Here are a couple more blog posts that show our AP Racing Pro5000R vs. the OEM M2 and M2 Competition brake components, that further illustrate the size differences to which I'm referring above. Our setup shaves 45 unsprung lbs. from the M2 Comp OEM brakes, and allows for 18" wheels, all while providing am ample heat capacity for proper circuit thrashings:

https://www.essexparts.com/news-blog...m2-competition

https://www.essexparts.com/news-blog...2-now-shipping

[H20neun]

there is an 18" wheel available for the new m3/4, so this may be a hint that those oem brakes could fit the f8x series with 18" wheels

[jritt@essex]

Originally Posted by H20neun

there is an 18" wheel available for the new m3/4, so this may be a hint that those oem brakes could fit the f8x series with 18" wheels

Interesting. If that is the case, I'd be surprised if the OEM front iron discs were 380mm. It is possible, but it's typically pretty tough to cram 380mm discs into 18's. I guess we'll find out! Thanks.

[FaRKle!]

Originally Posted by jritt@essex

Interesting. If that is the case, I'd be surprised if the OEM front iron discs were 380mm. It is possible, but it's typically pretty tough to cram 380mm discs into 18's. I guess we'll find out! Thanks.

F8x M3/4 has 380mm discs and 18" 513m wheels as an option.

Here's another example of 18" 513m on a Stoptech 380mm BBK. So it's within the realm of possibility.

[jritt@essex]

Originally Posted by FaRKle!

F8x M3/4 has 380mm discs and 18" 513m wheels as an option.

Here's another example of 18" 513m on a Stoptech 380mm BBK. So it's within the realm of possibility.

Man, I must be trippin' on too many Porsches and Corvettes. You're right on F80...it used a 380x30mm on the front. Thanks for the reminder!

380mm are definitely possible. They're just very tight on 18's, and can sometimes have barrel interference, the calipers can smack wheel weights, rocks get trapped between the caliper and barrel, etc. Much of it depends on design of the wheel in the area of the spoke attachment, whether there is some type of step there, etc.

[jritt@essex]

And to be clear...there's absolutely nothing wrong with 380mm discs. Our front AP Racing Radi-CAL Road Brake Kits use a 380mm disc up front. I'm just trying to warn everyone that 380's under an 18" wheel is typically a very snug fit.

[M Fifty]

The fit is snug, and the callipers are frightened you're saying?

[jritt@essex]

Originally Posted by M Fifty

The fit is snug, and the callipers are frightened you're saying?

Absolutely lol. The calipers should be afraid, be very, very afraid.

[Bee Pee]

Originally Posted by Bee Pee

I wonder if G8x front 6pots cw 380mm discs would be an oem pnp upgrade for front 380/4pots on F8x cars ?

Base rims as standard in Germany
824M Orbit Grey

18" x 9.5" et ?