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I’ll most likely buy the 6 piston GT-S kit here in the next month or so, I’ll update once I hit a track day with them. Not going to be a solid apples to apples comparison because I haven’t ran my own car on a road course in almost 6 years and the cars going to be quite a bit different than it used to. It will have a similar power level for road course but I may put on my JRZ RS pros for its first track day, if not I’ll use the buddyclub RSD’s I’ve had on it then change to the JRZ’s later.
yes, but it is quite close. The brembo grN kit has the disc and caliper moved a bit inwards so there is no space for that OE shield behind the disc. The disc is 355mm dia, 4 piston caliper.
yes, but it is quite close. The brembo grN kit has the disc and caliper moved a bit inwards so there is no space for that OE shield behind the disc. The disc is 355mm dia, 4 piston caliper.
Dust shield? What dust shield? LOL
I have a set of X calipers... but the idea of being able to stick with 17s is intriguing. Tough I'm sure RPFs would not be an option since they have that infamous lil' barrel.
I have a set of X calipers... but the idea of being able to stick with 17s is intriguing. Tough I'm sure RPFs would not be an option since they have that infamous lil' barrel.
The kit that Dallas and I have been discussing would not work with 17s. People looking to run a 380mm disc are going to be running tires wider than anything offered in a 17" and it's pretty likely an 18" RPF1 won't fit either. The Group N kit that he posted above is certainly cool but it's in the price range of most other BBKs and it's extremely hard for us to get GrN stuff in the US.
As for you clearance question, I had about 1mm between the barrel and my stock calipers with my drag wheels which are 16" RX7 wheels. Not contact issues whatsoever but rule of thumb is you want about 2mm.
No worries. My OEM IX brakes weren't too happy scrubbing speeds from 5th gear down to a 2nd gear hairpin. They did okay, but I don't know that they could handle doing it more than once per lap. I had Brownbos before, but now they are Blackbos. Crazy. That was my deciding factor for going with the X setup. I've been bucking the idea of going to 18s for as long as I can. the brakes above gave me hope LOL.
Anyway.... at least I won't be stuck running 255s much longer. Wider tires and better cooling = all good reasons to bite the bullet and go 18s and larger brakes.
The Group N kit that he posted above is certainly cool but it's in the price range of most other BBKs and it's extremely hard for us to get GrN stuff in the US.
it is actually stupidly expensive... I scored a used set as a part of a wider deal but now I am in the process of getting the rest of the system to work with them. THey do not have a normal handbrake, so it is hydraulic handbrake for me, as well as no booster and abs..
Having said that, the rally guys told me that with the stock e9 brakes they would run trough a set of discs and pads every rally. Which is about 200 competitive km. The big brembos last a season, which is about 5x that.
I was hoping that for you track guys that run 18 inch wheels, the usual 365 mm setup with 6 pot calipers might work fine.
Ya the larger the disc the larger the wheel unfort. I've never ever been a fan of 1-2mm gap because the natural rotation and exhaust path for heat and gasses is nullified. You're adding all that weight without taking advantage of the heat sink where it counts. The ONLY reason to jump to such a large brake kit is so you don't have to run ducting. And at that you'd better have 2 ducts on each wheel or you haven't really tried solving the problem of heat. The advantages on pretty much any of the discussed kits over OEM are 100 fold, so it really gets into availability, budget, and tech. If your car weights less then 3300lbs at race weight you can use any of the 4 piston sized ones without an issue.
In terms of performance I went form 1.4g's braking to 1.65g's braking on the same tire when using the ap8350 over oem brembo.
On the topic of taper - I went from 20-25% taper on the OEM brembos to 2-3% taper on the design of the CP8350's. Going to that gravel kit or M4 or mono ones like it lend to 1-2% taper - but at the co$t of an engine, more weight, and the act of taking it off completely to change pads. LeMans or Pcar cup level, sure. For time attack/DE stuff? Hell to the no unless you just want it to have it.
On the other hand there is a pretty good argument for running 355+ disc's so that you don't have to monkey with duct ripping itself off all the bloody time. Then again ducting cost less then 10 lbs of weight and MUCH less then the extra 2k for the upgrade. To each his own of course.
Ya the larger the disc the larger the wheel unfort. I've never ever been a fan of 1-2mm gap because the natural rotation and exhaust path for heat and gasses is nullified. You're adding all that weight without taking advantage of the heat sink where it counts. The ONLY reason to jump to such a large brake kit is so you don't have to run ducting. And at that you'd better have 2 ducts on each wheel or you haven't really tried solving the problem of heat. The advantages on pretty much any of the discussed kits over OEM are 100 fold, so it really gets into availability, budget, and tech. If your car weights less then 3300lbs at race weight you can use any of the 4 piston sized ones without an issue.
In terms of performance I went form 1.4g's braking to 1.65g's braking on the same tire when using the ap8350 over oem brembo.
On the topic of taper - I went from 20-25% taper on the OEM brembos to 2-3% taper on the design of the CP8350's. Going to that gravel kit or M4 or mono ones like it lend to 1-2% taper - but at the co$t of an engine, more weight, and the act of taking it off completely to change pads. LeMans or Pcar cup level, sure. For time attack/DE stuff? Hell to the no unless you just want it to have it.
On the other hand there is a pretty good argument for running 355+ disc's so that you don't have to monkey with duct ripping itself off all the bloody time. Then again ducting cost less then 10 lbs of weight and MUCH less then the extra 2k for the upgrade. To each his own of course.
These are all great points! I know ducting is a huge issue on the 8/9. Eventually I'm going to design a 3" duct system.
You are right that running the brake so close to the wheel is going to make it harder to evacuate heat from the brake area but once a good size duct is there it should help significantly, we'll see what my 2" ducts can do for now if they're even needed since I don't do more than 20 mins at a time. And 380mm is the limit because I don't want to move up to 19s
We talked about designing for use of a 355mm disc instead but we came to the conclusion it wouldn't be worth it because X brakes are almost that big and they would cost less most likely.
I don't want to throw out numbers because this is still pre infancy phase but I would *think* that price could be kept well under $2k (not including knuckles) considering that this would be a brake option to work with SSB steering knuckles. The caliper would bolt right onto the knuckle, with a custom rotor hat that uses off the shelf rings from a well known company like Stoptech, Girodisc, DBA, etc. Beyond that all that's needed is pads and there's plenty of options for that because it's an OE caliper.
Benefits being:
- Greater heatsinkability from larger rotor and caliper
- Greater stopping power from larger dia rotor
- Minimal weight gain due to smaller caliper pistons and 2 piece rotor
- Similar or better pedal feel/firmness due to smaller piston area
- Cheaper than aftermarket brake options
- Lots of pad compound choices
Have you thought about using AP racing PRO 5000 R bbks? They're not monoblock but 2 piece forged which the newer designs I like better than cast monoblock.
Have you thought about using AP racing PRO 5000 R bbks? They're not monoblock but 2 piece forged which the newer designs I like better than cast monoblock.
Oct 14, 2018, 10:08 AM
