Hi guys,

Looking for some collective mind insights into front brake options for an RX8 based track car.

I have an LFX swapped RX8 (Andrew Keisler kit) that I have been tracking for a little over two years now. Recently, I have been cracking my front rotors pretty consistently to the point that I cracked a rotor the past two events. after 6 20 min sessions in a single day.

Current car info:
Keisler 4 piston Wilwood brake kit, Stock Sport rotors (12.7" diameter), 7420 pad shape
Pads: ran st43's DTC-60's, EBC SR21's and more recently Wilwood polymatrix ones.
Rotors: the recent ones were basic Centric as it's getting impossible to find the high carbon (hi temp resistant) variation anywhere now.
I have AWR brake duct cooling plates and run 2.5" hoses to the inside of the rotor vane (not blasting the face)

The car has about 290whp and I run 200TW tires @ 295/30/18
I only do HPDE and my pace is around 1:45 at Gingerman most of the time, so I would say not really pushing it much.
I like the current caliper setup as I can find 7420 pads easily and there is a lot of options for pad compound. Pad volume is pretty nice too for bang for the buck.

My goal is to have a budget-friendly but well-performing setup that is cheap on consumables. I want to maximize the miles per dollar ratio while retaining the performance of the braking system.

I am looking for feedback / recommendations / actual user experience with different brake setups:

Option 1: Keep the current calipers and invest in the high carbon rotors (DBA 400 or similar)
Pros: easy and quick
Cons: expensive rotors (not sure how much usage I could expect from a set of DBA 400's - any actual user experience here would be appreciated)

Option 2: Upgrade to Andrew Keisler Race Willwood calipers and 1.25" thick rotors
I almost pulled the trigger for the upgraded "Race" version of Andrew's 6 piston willwoods that are paired with 12.3" (slightly smaller than OR) and 1.25" thick sloating rottors
I talked to a guy locally that has this setup but he was selling it due to ... Cracked Rotors LOL ... He said he tried Willwood basic ones and the directional vane ones and they would both crack after about 3 days of HDPE. Does anybody here have experience with those?

Option 3: Gen 5 Camaro Brembo calipers and 2014 Mustang GT 14" rotors. Pros: huge rotors with a lot of thermal mass, cheap rotors available. Brembo calipers that can be had pretty cheaply.
Cons: huge rotors LOL (over 10lbs more unspung mass per wheel), Pad choices somewhat limited and more costly,
Not sure if it fits the 18" wheel, Pad volume slightly less than the 7420, caliper piston area miss-match for the RX8 Master cylinder?

Option 4: Dedicated Brembo, Alcon, or other brake kit?
Not sure how that would compare in the running consumables cost to the other 3 options, but is for sure expensive up front.

 

Hmm. Not a racer so I can’t offer any insight, but that doesn’t look like it got overheated at all.

Were both the same brand?

 

Hmmm that's a weird one. Are the rotors well aligned in the caliper? Is the Wilwood kit meant to use stock-spec rotors?
Im not familiar with Gingerman but the layout does look like your brakes don't get a break at all, so a higher temp tolerant disc could help.. but this still pretty extreme. You could get that coloured thermal paint to tell you hot how they're getting at end of session.

 

Thanks for chiming in. I ordered the rotor paint.

The issue happened with two different sets of rotors (different brand) and two separate sets of pads, and it happened on two separate sides of the car.

I am also researching the hub flex as a potential cause. I did run this setup all last season with the same pads and slightly better rotors (hi- carbon from Centric) all last season and did not have this issue.

Thank you.

 

Are those OE brake rotors or aftermarket brake rotors?
.

 

@Team, those are OE-sized aftermarket rotors. Stoptech and Centric Brands. And this rotor (Centric) has 7, 20 min sessions on it with new Ferodo DS2000 pads (7420 pad shape). The previous one that also cracked was a slotted OE-size rotor but had over 20 sessions on it with EBC SR21's and then Wilwood Polymatrix "A" Pads.

 

Your ducting might be too good. That variable is easy/quick to alter, if this were mine I'd look at that first. You have to buy new rotors anyway, maybe cut the airflow by 50% and see what happens. The lesser allow might not be as tolerant of rapid cooling. Keep them hot, you might develop other problems, but not this.

 

I made a brake kit for mine that used fk8 civic type r calipers and 14" mustang rotors. It uses a very common pad shape and you can use off the shelf aftermarket two piece mustang rotors to drop some weight if you want. The piston size on the CTR caliper matches the stock RX8 piston. The mustang rotors needs to have the center bore opened up about 1mm to fit the RX8 hub or you need to machine the RX8 hub down. Look in my build thread towards the end for more info.

 

Hey, thank you for chiming in. I did get a pair of Mustang Rotors and was looking for the Camaro SS calipers to replicate what the Youtube vid had. If I did not have to mod the OE spindles, that would be preferred. Did you run your setup through the paces on track? Did you get any pad taper at all? How many sessions would a set of pads last for you? How long would the rotors last on track?

I will DM you for some more details on how you mounted the calipers.

Thanks/

 

That is a pretty crazy failure of a rotor. I ran Centric high carbon rotors with OEM calipers and Carbotech XP12s for years without a hiccup.. did a 1:42 at Gingerman on that setup, albeit likely much less weight and 190whp...

If you want to go nuts and never have an issue ever again, but is definitely not budget friendly: https://github.com/equinox311/RX8_AP_Kit

Can get a full season (6 events and some street driving) on a set of pads, and I haven't had to replace rotors in 2 seasons... so.. maybe in a few years may price it's way back into being friendly??

My only other anecdotal advice is that Hawk pads will TEAR up rotors and destroy them. I also wouldn't trust anything Willwood has to offer, though that's just because they are poor performing as opposed to rough on anything.