LOL, when the car is parked and not moving!

 

parade lap + ducts = no fan needed!

 

None of the tracks I attend allow for a cool down lap. I suppose you can keep an eye on the time and guess at when the checkered flag gets thrown, but at best I get 1/2 a lap of cooling/parade (flag is usually first show on back straight). Which I take as slow as possible with as little brake use as possible. Paddock speed limits are 10 mph so can't putz around that cooling either. Also keep in mind our front brakes have heat/dust shields on the backside of the rotors, not ideal for dissipating heat. If I was going to continually track my car removing them is one of the first things I'd do.

 

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Replaced my front caliper piston seals this weekend. They were toast after 3 track days and no shims. The rubber was falling apart even on the ones that weren’t torn. Ordered the ELIG TI shims from Lamspeed for VIR time trials in March. Will probably look into Verus Brake cooling ducts as well when the ambient temps come back up in the spring.

Before

After

 

Just ordered some Endless SSM plus pads and ACRE titanium brake shims to hopefully significantly reduce brake dust while not sacrificing much performance. Both front and rears is only $211 if ordered from Blackhawk Japan. Shipping to the states was an additional $64. They also sell the ACRE titanium GRY brake shims for $113, which is a bit pricey, but doesnt add much weight when shipped with the Endless brake pads and only added $2 to the shipping. So total shipping for the pads and shims was $66.
The price of the Endless pads even with the $65 shipping charges at $276 is a damn good deal though. If i were to order just the ACRE shims it would have been $113 + $18 for shipping, or if i were to order the other shims from lamspeed, it rould have been $80+$55 for shipping, so basically about $130 USD shipped for either set.
Really only worth getting the shims on Blackhawk if you order some pads as well to save on shipping.

 

Good to know for the pads. The ELIG titanium shims (I got front and rear shims) were $153 + $56 shipping from Australia. Let us know how the dust is with the new pads.

 

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.

 

my calipers reached the same temp with the ti shims, not sure if you mentioned it before, but are you able to do a cool down lap? even around the paddock? if i havent mentioned it here, i usually do a parade lap around the paddock. until oil temps are below 210F and hopefully that sheds heat off the rotors too. bc if they just sit after a session, the heat soak will do the most damage

 

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.

my calipers reached the same temp with the ti shims, not sure if you mentioned it before, but are you able to do a cool down lap? even around the paddock? if i havent mentioned it here, i usually do a parade lap around the paddock. until oil temps are below 210F and hopefully that sheds heat off the rotors too. bc if they just sit after a session, the heat soak will do the most damage

Yup. I did a full 60-70% cooldown lap after each session. I also would drive around the paddock till oil temps were below 220 and idled the car in my pit space until temps were below 210 and then shut the car off.

 

How long are your sessions?

 

I’ve been looking into getting some Ti brake shims for the brake heat issue, and while looking around I stumbled upon these carbon fiber shims on a GR Yaris forum. A few people got them and have said they’ve held up well. Technically carbon fiber is an even better insulator than titanium so I wonder if these would help or would it be a negligible increase in efficiency? They’re around the same price too and they’re for front and back

Hel Performance Carbon Fibre Brake Pad Shims Toyota GR Yaris 20+

HEL Performance have pulled out all the stops when developing their carbon fibre brake pad shims. They've used the finest carbon fibre, combined with an exclusive thermal-resistant resin which cures an attractive deep orange against the black fibres.

www.tegiwaimports.com

 

Carbon is a great insulator but not necessarily the best for dissipating heat. These did well for me

 

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.

 

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.

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

 

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?

 

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

Very interesting observation worth discussing more!

 

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?

 

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.

 

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.

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.

 

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.

 

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.

 

Acre said their shims are 0.8mm, ELIG hasn't replied. If anyone who got ELIG shims can let us know how think they are.

 

I was also researching this and found some interesting info:

• Acre shims are 0.8mm thick indeed (sold here)
• Yperion Titanium shim thickness range from 0.6 to 1.0mm
• Elig doesn't disclose shim width on their official website (sold here)
• 555 Engineering shims are 1.0mm thick

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).

 

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.

 

I was about to change our my brake pads in preparation for my track day and noticed one of mine was torn too 🙃. Were you able to find replacement dust boots?

 

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.