[X25]

Originally Posted by seanblurr

My SRF boiled though :( I should slow down, I guess.

My take on the fluids is that my brake system should be good enough to work with a regular high-quality DOT4, like RBF 600. If it doesn't work for even the first day, and if I need something 'special' to make it work, then it means to me that I'm already stressing and overheating the whole system (rotors, calipers, lines, bushings, wheels/tires) beyond its design tolerances. I am really impressed with SRF, but I always fear that it might hide issues with the rest of the brake system.

When you use relatively cheaper fluid, you can also change it much more often, since it's expendable, and you don't care : )

Regarding boiling SRF, I think the official boiling points are determined by a certain amount of contamination (like 6% water, etc.; I don't remember anymore). In other words, sooner or later (but later than other fluids), it will also bow down to mighty water.

Back when I had a gen5 1LE, I had to add brake cooling ducting all the way to rotors, and switch to StopTech BBKs (which have superior air flow into the rotors) for it to be reliable for many track days without service. On my C7 Z51, I use same brakes as you guys (C7 Z06 iron brakes), but since the car is much lighter (3350 lbs), the system is adequate with simple air reflectors and simpler OEM cooling ducting.

[Mr. Meh]

Originally Posted by ZL1 1LE

Another potential source for Ti shims:

https://hardbrakes.com/

Giro finally got back to me. I'd been caught in a spam filter. Oh well.

They have some neat stuff coming up and did point me in a direction for the Ti shims as well as comments about the fluid boiling.

[Ryephile]

Originally Posted by seanblurr

My SRF boiled though :( I should slow down, I guess.

On the contrary, you're likely over-slowing everywhere. If you're actually boiling SRF, then you have bigger problems at hand, like decimated caliper piston o-rings, and accelerated wear.

Do you roast brakes in your Miata? If you do, it's driver error.

[glamcem]

Originally Posted by X25

My take on the fluids is that my brake system should be good enough to work with a regular high-quality DOT4, like RBF 600. If it doesn't work for even the first day, and if I need something 'special' to make it work, then it means to me that I'm already stressing and overheating the whole system (rotors, calipers, lines, bushings, wheels/tires) beyond its design tolerances. I am really impressed with SRF, but I always fear that it might hide issues with the rest of the brake system.

When you use relatively cheaper fluid, you can also change it much more often, since it's expendable, and you don't care : )

Regarding boiling SRF, I think the official boiling points are determined by a certain amount of contamination (like 6% water, etc.; I don't remember anymore). In other words, sooner or later (but later than other fluids), it will also bow down to mighty water.

Back when I had a gen5 1LE, I had to add brake cooling ducting all the way to rotors, and switch to StopTech BBKs (which have superior air flow into the rotors) for it to be reliable for many track days without service. On my C7 Z51, I use same brakes as you guys (C7 Z06 iron brakes), but since the car is much lighter (3350 lbs), the system is adequate with simple air reflectors and simpler OEM cooling ducting.

Good points. I just checked the price of the Castrol SRF, holy schnikes!! It costs $65 per bottle (1 liter) where as it's only $28 for Motul ($14 for 1/2 liter bottles). Also, I use one full bottle of Motul each time I bleed the brakes and so I am not worried about the fluid absorbing moisture from the air that degrades the quality of the brake fluid (shortened life span on an already problematic brake system)

I remember switching back to Mobil 1 engine oil from Motul V300 for this reason; changing the oil more often like every 2,000 miles vs keep using the Motul for 5,000 miles and hope the best. I can get the 5qt bottle Mobil 1 from Wally world for around $25 and even cheaper at discount at times and it looks like Motul only has a slight advantage on boiling points.

It sounds like addressing the excessive heat at the core is the ideal solution. GM uses a 15.4" BBK system on ZL1/ZL1 1LE that are only about 300 lbs heavier than the C7 Z06 (14.6" rotors/calipers) , I think that should tell us something :/

[TrackClub]

So ZL1 has bigger brakes than SS 1LE?!

[JeromeS13]

Originally Posted by TrackClub

So ZL1 has bigger brakes than SS 1LE?!

Yes.

[TrackClub]

Thx! Rotors AND calipers?

[Provoste]

Originally Posted by TrackClub

Thx! Rotors AND calipers?

Rotors and Pads. Same caliper. 390mm rotors on ZL1’s versus 370mm for SS 1LE.

[RUQWIKR]

Larger in rear, too, 365 vs. 340. Both front and rear on ZL1 (J6H) are 2mm thicker than SS 1LE (J6M). Both are aluminum hat 2-piece fronts with one piece rears. Six piston front and four piston rear calipers for both, but the calipers are machined differently for the diameter & width differences.

J6H: 390x36 front, 365x28 rear
J6M: 370x34 front, 340x26 rear

[TrackClub]

Than you! So the rotors are different offsets and won't fit a 1LE - correct?

[seanblurr]

Originally Posted by Ryephile

On the contrary, you're likely over-slowing everywhere. If you're actually boiling SRF, then you have bigger problems at hand, like decimated caliper piston o-rings, and accelerated wear.

Do you roast brakes in your Miata? If you do, it's driver error.

Negative. About 10 years ago when I first got my comp license I had some issues overheating brakes by dragging the brakes over too long of a period. Think applying 85% brake pressure from 200 meters out over 10 seconds, when I should have been applying 100% brake pressure from 125m out over 6 seconds. There tends to be confusion that the brakes will last longer if you apply less force when in reality heat is generated more by an increase in time, not pressure. But alas, it's been a few years and many test days since my rookie year, so I do not believe I am reliving past problems in this car.

I believe the problem that I was having was related to the brake pads overheating to such a degree that it fried the caliper, and in turn overheated the fluid. My thought process behind this is a comparison between the stock brake pads and G-Loc R12's at Laguna Seca, a track notoriously hard on brakes. My stock pads lasted most of a 25-minute session, while the pads (and a bit of the fluid) faded around the halfway mark, it was a linear fade that remained at a certain point once it got there. This allowed the car to be driveable through the entire session with a slight change in pace and brake points, the car would "reset" and repeat each session. At the end of the day, the brake calipers were not discolored, the pedal was firm, and the piston seals were not cracked/melted. Contrast this to a similar day with G-LOC R12's, it lasted about a session and went downhill from there. There was a bit of pad fade, but mostly fluid, as the pedal went to the floor after only a few laps, it remained this way throughout the day. Brake calipers are now discolored and the piston boots are trash. Both are "normal" things to happen when you really push these cars, but it is also an indication that the race pads allowed a much higher level of heat to accumulate. This, in addition to the pads lasting a whopping 8 sessions before they had less than 2mm of material left. Carbotech/G-Loc are known for drastic wear when used outside of their temp range.

Perhaps there were other issues at play, maybe the fluid I bled with was too old, or maybe I do, in fact, suck at driving. It was a startingly issue, especially with the pedal remaining long on the drive home. The car has sat since then, so I haven't had a chance to install new pads and flush the fluid. I certainly hope the issue doesn't remain!

Sorry for the thread derail.

[RUQWIKR]

Originally Posted by TrackClub

Than you! So the rotors are different offsets and won't fit a 1LE - correct?

They'll fit: You have to change rotors, calipers, and pads.

[Lugnutty]

And pads are the same? So the only upgrade parts are the calipers and rotors? No brackets or lines or anything? This is tempting. Anyone have part numbers for the ZL1 calipers?

[TrackClub]

I am confused...if rotors AND calipers are different then to "upgrade" one would need to do a wholesale change of the braking system - yes?
And I'd imagine the calipers are a bit of $...
I was simply wondering if I could stick ZL1 rotors on the 1LE but if offsets differ that's a no go - correct?

PS Sean, I very much share your thoughts re: more aggressive pads (and a very demanding track layout) throwing too much heat onto the system. My system fully recovered each session, hence I believe the "hero" pads faded (vs fluid boiled). But frankly I am back to stockers and liking them. They do a good job in my case at least. I will try the Hawks tho, to compare.