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titanium brake shims

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#81 · (Edited)
I have another concern regarding the rotor itself.

After seeing multiple photos, Our rotors are "backwards." This Yaris thread claims that the rotors are backwards as a result of some study Toyota/Lexus did, and this reddit thread claims it just is what it is, they know more than you. But I'm not buying it... Ulness it was some unique system specific to a test platform race car or something. Why is every other brake system with directional vanes designed the same way, except this car that is functionally, no different?

Stoptech rotors and have grooves and vanes that are parallel, meaning the grooves swipe outware as the disc rotates forward and the vanes do the same thing. But the GR rotors are cut backards, grooves sweep outwards, but vanes pump inwards? This doesn't make sense. These photos are from Verus's brake cooling kit, LH side. You can see in the smoke flow image that the rotor vanes push the smoke forward along the bottom of the rotor, opposite the grooves. The rear image shows the vanes, and they clearly pump inward as the wheel rotates forward.

WTF is going on here?

Image

Image
 
#82 ·
wheelhaus said:
I'm not sold. It would be an interesting experiment, though. Disposable, maybe?

The carbon in those shims isn't the concern; carbon is pyrolyzed at thousands of degrees F, sometimes upwards of 6000°F. The problem with heat is always down to the resin. Hel claim the resin is thermally resistant to 752°F, which is extremely high for a laminating resin or adhesive, but that threshold is easily exceeded at the track. Once the thermal limit (Tg) is exceeded, the resin is no longer rigid. It will soften, or sort of rubberize, and deform. Any form of stress (*such as being compressed by the edge of a piston) will causes micro-delaminations within the fabric and then, well they're trash at that point.

Now exactly how much of that heat transfers from the pad face (1200°+F source) to the back of the pad I'm not sure, but I don't see that being a 500°F+ difference...

Carbon brake rotors as a comparison, are manufactured using an entirely different process than fabric lamination, so the thermal envelope is entirely different.
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That’s what I was thinking. The 750° they’re claiming the resin is good for seems way too low of a temp in my mind. But, a few people have used them and said they hold up so I guess it’s worked for them so far. I don’t think I’m willing to Guinea pig them lol
 
#83 ·
While we’re on the topic of brakes; how much brake fluid do we need for a full flush? Most cars don’t use much, like a liter at most typically, but I can’t find anywhere about a capacity on the GRC. Would a liter be enough?
 
#86 ·
wheelhaus said:
I have another concern regarding the rotor itself.

After seeing multiple photos, Our rotors are "backwards." This Yaris thread claims that the rotors are backwards as a result of some study Toyota/Lexus did, and this reddit thread claims it just is what it is, they know more than you. But I'm not buying it... Ulness it was some unique system specific to a test platform race car or something. Why is every other brake system with directional vanes designed the same way, except this car that is functionally, no different?

Stoptech rotors and have grooves and vanes that are parallel, meaning the grooves swipe outware as the disc rotates forward and the vanes do the same thing. But the GR rotors are cut backards, grooves sweep outwards, but vanes pump inwards? This doesn't make sense. These photos are from Verus's brake cooling kit, LH side. You can see in the smoke flow image that the rotor vanes push the smoke forward along the bottom of the rotor, opposite the grooves. The rear image shows the vanes, and they clearly pump inward as the wheel rotates forward.

WTF is going on here?

View attachment 23896
View attachment 23895
Click to expand...
Very interesting observation worth discussing more!
 
#87 ·
Toome said:
View attachment 23811 View attachment 23810
View attachment 23812
Update after two track days at summit point main: Still melted the dust boot seals with the TI shims. For next track day I will try installing the CE brake ducts. The brake fluid on the shim also concerns me. Going to have calipers rebuilt soon just as a precaution.
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Unless you have plans to bolt/mount cooling ducts to the back of the heat shields then you really really REALLY need to remove those heat shields on the backside of the rotors. Makes a tremendous airflow difference.
 
#88 ·
I would say these shims are bs, I have a ti camping cook pot and the only thing it is good for is boiling water as it transfers heat so well it will get hot spots and burn your food. I have also been a nasa member for 21 years and have seen a few people try them and I never saw any meaningful improvements from them.
 
#89 ·
Titanium has a much lower thermal conductivity property than most metals. It was chosen for your camping cook pot because it is extremely light weight. 5 minutes of Google research can confirm this.

Image

I've used Ti shims when tracking my AMG and they lowered the temperature of my brakes dramatically. The first event I did with that car (without shims) resulted in me boiling my fluid 3 times (was fresh for the weekend, and flushed twice during weekend), going through half my pad material, trashing a brand new set of rotors, and melting 8 of 12 front caliper piston dust boots. For the next event Ti shims weren't the only change I made, but all my problems were fixed and my temperature strips on calipers didn't top 250°F.

For less than $120 they seem like a no brainer to me. Others are welcome to disagree. :)
 
#90 ·
Sorry if I missed it, but those with the Acre and ELIG titanium shims how thick are the Acre shims and how thick are the ELIG shims? Do the stock shims fit in as well with new pads or do your titanium shims take up the available space on their own?

Does Acre offer rear titanium shims? I saw ELIG does.
 
#91 ·
I cannot address most of your questions, however I will state that you should not need shims for the rear brakes. Unless you're doing some incredibly extreme driving with highly highly modified car (that in some way shifted a significant amount of weight to the rear) the rear brakes will never approach operating temperatures necessitating the need/use of Ti shims.
 
#93 ·
I was also researching this and found some interesting info:

This video concludes there's more insulation combining OEM shims + 0.6mm Ti shims than 1.0mm Ti shims by themselves.

And this video shows the Yperion 0.6mm shims will fit the GRY (which has the same brake system as the GRC) along with the OEM ones. I like this idea because it keeps the OEM shims which have an anti vibration component (although I guess there could be vibration between the two shims anyway).
 
#94 ·
I just installed the Yperion 1mm brake shims last week and kept the OEM shims on and can confirm they fit no problem. For reference i had ~7,500 miles on my stock pads with one track day on them, so there was definitely less meat than brand new ones, but they were still pretty thick. Not sure if the 1mm Ti shims would fit with new stock pads and shims, but they had some more room to spare between the shims and pistons.

I just ran a track day this weekend with the new shims and had no issues. In hindsight, I should’ve put some temperature stickers on my calipers to test the temps after my runs on track, but I also don’t have a stock shim baseline so it wouldn’t be that helpful to see.
 
#95 ·
wheelhaus said:
But the GR rotors are cut backards, grooves sweep outwards, but vanes pump inwards?
Click to expand...

If you're talking about the blade curving, there are some benefits to having it curved "backwards".

FYI, due to the way centrifugal fans work, they always suck from the middle and exhaust outwards regardless of the spin direction. The typical centrifugal fans like the "blowers" on gaming GPUs and turbochargers just gather the air collecting on the outside of the vanes and shoots it out through a singular duct.
 
#96 ·
hatsunearu said:

If you're talking about the blade curving, there are some benefits to having it curved "backwards".

FYI, due to the way centrifugal fans work, they always suck from the middle and exhaust outwards regardless of the spin direction. The typical centrifugal fans like the "blowers" on gaming GPUs and turbochargers just gather the air collecting on the outside of the vanes and shoots it out through a singular duct.
Click to expand...
That's exactly what I was referring to. Per the diagram in that wiki page, the GR brake rotors are actually "forward" curved. Angled vanes in brake rotors are typically "backward" curved to take advantage of the centrifugal effect you mentioned.

The "backwards" I meant in my previous comment meant that the GRC rotors are opposite of typical curved vanes in brake rotors. They actually scoop air inward toward the hub, fighting the centrifugal effect.
 
#97 ·
wheelhaus said:
That's exactly what I was referring to. Per the diagram in that wiki page, the GR brake rotors are actually "forward" curved. Angled vanes in brake rotors are typically "backward" curved to take advantage of the centrifugal effect you mentioned.

The "backwards" I meant in my previous comment meant that the GRC rotors are opposite of typical curved vanes in brake rotors. They actually scoop air inward toward the hub, fighting the centrifugal effect.
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Honestly not sure about other cars’ setups so can’t comment there, but from skimming the Wikipedia article it seems like the vane directions have pros and cons for both configs and it depends on loading on which is better for which
 
#99 ·
I ran some titanium shims on the OEM pads (with the OEM shim on top) for about 4 track days this season (usually only about 4 to 5 8-minute sessions each time). Noticed that one of the brake caliper piston dust boots in the front right looked either caked with grease/dust or is a tiny bit warped from the heat cycles. I'm guessing I'll have to replace the dust boots eventually. Also the GR logos on the front brakes are yellowing too, so I think I'll need brake cooling/ducting eventually.
 
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