Vendor GiroDisc 370mm Rotors for GM Brembo 6-Pot Calipers

It takes a village to raise a kit. This one is TMC's very own. @Lukez pioneered the 6-piston CTS-V DIY for the Model S. Then @jesse_le prototyped a rotor with GiroDisc for the Model 3 and Y. These full-floating slotted GiroDisc rotors for the Model 3 and Y come in at 370mm x 34mm. This mirrors the rotor size on the Cadillac CTS-V, Corvette C7 Z06, and other GM performance vehicles allowing fitment of massive GM 6-piston Brembos. For comparison, the OEM Model 3 Performance 2-piece rotor measures in at 355mm x 25mm while the OEM 1-piece "Base" Rotor measures a paltry 320mm x 25mm.

The GiroDisc rotors differentiate themselves from other manufacturers with U.S. sourced iron and beautifully anodized U.S.-sourced 6061-T6 aluminum rotor hats. The hat is also 4mm thicker than OEM which helps clear the unique stepped hub of the Model 3 Performance and obfuscates the need for small wheel spacers. The GiroDisc is also a true 2-piece rotor allowing you to replace the rings without need to replace the hats.

OEM GM Brembo 6-piston Calipers​

The GiroDisc rotors allow you to mount OEM GM Brembos from a number of GM performance vehicles including the ATS-V, CTS-V, and C7 Corvette Z06. These are lightweight 6-piston monoblock aluminum calipers that are optimized for cooling, specified as "low drag", and are designed to fit under 18" wheels. They mount up to the OEM Tesla front knuckle by either drilling out your caliper mounting holes to accept M14 caliper bolts or re-threading the caliper to accept the OEM Tesla M12 hardware. The latter allows you to return the vehicle completely to stock.

Another benefit of the GM 6-piston Brembos is a wide assortment of available brake pads. If you have ever searched for brake pads for the stock Model 3 Performance calipers you know that the selection for this seemingly proprietary caliper can be somewhat limited. The GM calipers feature a standard FMSI D1405 pad shape which opens up pad options from $64 Centric OE replacement street pads up to $700+ Ferodo DSUNO race pads.

Ordering​

As these are a relatively new offering, GiroDisc requires a minimum of 5 rotor pairs to make a production batch. Pricing is $1,200 per pair with free shipping to the continental U.S. There is an approximate 4 to 6 week lead time from the batch order for fulfillment. There is already some interest in the next batch and my hope is that the demand is strong enough for these to become regular stock at Emotive Engineering.

... and introducing... The EmotiVetted GM 6-Pot Bolt-on BBK​

This is a full bolt-on affair which allows you to reuse your factory caliper mounting bolts (brake dust shield removal required).

Street Kit - $2,649

• CTS-V Calipers - Silver (or optional Yellow) - re-threaded to accept factory Tesla caliper bolts
• GiroDisc 370mm 2-Piece Rotors
• DBA SP500 Street Performance Pads - copper-free ceramic pads, low-noise, and low-dust. Everything an OE+ street pad should be.
• Spiegler Stainless Steel Brake Lines
• OE GM Caliper Hardware

Track Kit - $2,899

• C7 Corvette Z06 Calipers - Red - re-threaded to accept factory Tesla caliper bolts
• GiroDisc 370mm 2-Piece Rotors
• G-LOC R12 Track Pads - amazing pedal modulation, rotor friendly, at the expense of some noise and dust.
• Spiegler Stainless Steel Brake Lines
• OE GM Caliper Hardware

Not ready to go full on BBK? Emotive Engineering is an authorized GiroDisc dealer offering a full line of OE-replacement 2-piece rotors for your Tesla Model 3 or Y.

 

[hyp36rmax]

What’s it take to run the 394mm rotors?

Good Q! I'm curious about this also. I see the UPP BBK looks suspiciouly familiar, I wonder if the their included bracket shifts the caliper slightly to accomodate larger "394mm x 35mm 15.5″ track-proven Iron Rotors PFC V3 2 piece floating rotor technology".

Our current factory mounted GM Calipers don't leave much room to accomodate an extra 24mm from our 370mm Rotor

UP x PFC - Iron Big Brake Kit for Model 3 and Model Y

The ultimate iron-rotor big brake kit for Tesla Model 3 and Tesla Model Y. Engineered in the USA and proven at the Nurburgring!

unpluggedperformance.com

 

[Lindenwood]

Yeah I don’t think there is enough space inside the caliper for an extra 12mm of rotor radius.

But, good point on the UP kit. It looks like the caliper is physically spaced out further from the rotor hat by around 12mm compared to the 370mm kit. You don’t get any more pad area, but one would still get the benefits of greater rotor volume and more physical braking force (perhaps lighter pedal force?).

Of course, no idea of this would negatively affect brake bias, or if it would even be possible to get a bracket in there that only spaces the brakes out by 12mm…

 

[hyp36rmax]

Yeah I don’t think there is enough space inside the caliper for an extra 12mm of rotor radius.

But, good point on the UP kit. It looks like the caliper is physically spaced out further from the rotor hat by around 12mm compared to the 370mm kit. You don’t get any more pad area, but one would still get the benefits of greater rotor volume and more physical braking force (perhaps lighter pedal force?).

Of course, no idea of this would negatively affect brake bias, or if it would even be possible to get a bracket in there that only spaces the brakes out by 12mm…

I think if UPP is doing it, we may be ok with brake bias. now just that bracket haha, it could also solve having to redrill. anyone here a machinist? I wonder if UPP is willing to sell that part.

I was talking to UPP fairly recently, they wanted to know more about this custom kit. so much value in comparison. what one would get with UPP are those larger 2-piece PFC, bracket,

 

[Lindenwood]

It occurs to me that slotting the hub holes out by around 10-12mm (and filling in the inner portion of the slots) might actually work to fit the 394mm rotors……

 

[drpheta]

It occurs to me that slotting the hub holes out by around 10-12mm (and filling in the inner portion of the slots) might actually work to fit the 394mm rotors……

Not sure I'd want to make that area thinner on a crucial component. We ran into this issue with Volvos running Porsche calipers. The mounting was just too tight and slotting the mounts risked failure.

If you want a caliper to handle the 390+mm rotors you'll need a different caliper that can accept a bracket like what UPP did. The GM calipers with the mounting tabs won't allow it. 12mm is a lot.

Don't forget, we already enlarged it 1mm radius to accept these calipers. So, you're really slotting it 13mm over stock unless you retap the mounting tabs on the caliper for stock bolts.

 

[hyp36rmax]

I just watched this Unplugged Performance Plaid 6-Pot install. i'm convinced these are the same GM Brembo Calipers. Confirmed that bracket shifts the caliper to allow for larger rotors.

 

[drpheta]

I just watched this Unplugged Performance Plaid 6-Pot install. i'm convinced these are the same GM Brembo Calipers. Confirmed that bracket shifts the caliper to allow for larger rotors.

View attachment 983913

View attachment 983914

View attachment 983916

They may be close, but the mounting tabs are missing on the UPP calipers. The back side has thicker parts with a hole for the bolt to go through and mount to a bracket instead.

Keep in mind that the monoblock body could have slight variations inside, piston sizes can be different, or the wall thickness can be different. Just cause it has the same shape doesn't mean it's the same caliper.

 

[hyp36rmax]

They may be close, but the mounting tabs are missing on the UPP calipers. The back side has thicker parts with a hole for the bolt to go through and mount to a bracket instead.

Keep in mind that the monoblock body could have slight variations inside, piston sizes can be different, or the wall thickness can be different. Just cause it has the same shape doesn't mean it's the same caliper.

This is true, good call out.

 

[hyp36rmax]

I created a thread, curious if you guys know the difference between Giro-Disc rear rotors?

• M3P/MYP: SKU A2-208: Tesla Model 3, Y Performance Rear Rotors
• M3/MY: SKU A2-202: Tesla Model 3, Y Rear Rotors
• Mountain Pass Performance M3P/MYP (Made by GiroDisc): Page Mill Rear Rotors for Tesla Model 3/Y Performance
• Mountain Pass Performance M3/MY (Made by GiroDisc): Page Mill Two-Piece Rear Rotors for Tesla Model 3 and Model Y

Neither of these have specs to distinguish thickness, diameter (assuming stock size), or compatibility with 2023+ MYP Mando calipers

 

[Neil818]

How much more caliper clearance is needed compared to stock performance calipers

 

[hyp36rmax]

How much more caliper clearance is needed compared to stock performance calipers

They'll fit fine with factory wheels. Stock performance Calipers are the same as SR and LR. Factory rotors are different though. 320mmx25mm (M3 SR/LR), 335mmx20mm (M3P/MY SR/LR/P)

 

[Lindenwood]

How much more caliper clearance is needed compared to stock performance calipers

All indications are the Brembo 6-piston calipers will fit under anything that will fit the rear calipers. Stock, the rears will hit the same wheel barrels before the fronts.

 

[hyp36rmax]

Been a bit since we installed the front calipers. Amazing! Loving this setup. have since added rear girodisc 2-piece rotors via EAS. (Thanks guys! @tom @ eas ) Checking autocross and track day schedules to do a legit shakedown.

 

[kirkusss]

Trying my luck here. Had made custom hats for my Model S GM conversion and ran into some issues (seems the machine shop did the hats 1mm too thin) and the rotor is not perfectly centered. Anyone knows a place that sells 370mm rotors for the S or just a pair of hats?

 

[hyp36rmax]

Trying my luck here. Had made custom hats for my Model S GM conversion and ran into some issues (seems the machine shop did the hats 1mm too thin) and the rotor is not perfectly centered. Anyone knows a place that sells 370mm rotors for the S or just a pair of hats?

You tried Girodisc? I imagine they would combo an existing Model S Hat with a 370mm (GM) Corvette rotor. Seems rotor rings and their Girodisc hats are interchangeable.

You can see GiroDisc sells a Model S/X factory replacement kit: Tesla Model S, X 355mm Front Rotors, Ask if they can make a custom kit for you. You'll need the Hats from that kit.

GM 370mm Rotor Rings: Corvette, Camaro 370mm Front Replacement Rings

 

[Lindenwood]

You tried Girodisc? I imagine they would combo an existing Model S Hat with a 370mm (GM) Corvette rotor. Seems rotor rings and their Girodisc hats are interchangeable.

You can see GiroDisc sells a Model S/X factory replacement kit: Tesla Model S, X 355mm Front Rotors, Ask if they can make a custom kit for you. You'll need the Hats from that kit.

GM 370mm Rotor Rings: Corvette, Camaro 370mm Front Replacement Rings

View attachment 1004557

View attachment 1004561

Unfortunately I did ask about adding 394mm rings to the hats designed around our 370mm kits, and spacing the calipers out to compensate, and they said the rings are not compatible. I am not sure whether the mounting holes are different, or if the hat offset is different.

 

[hyp36rmax]

Unfortunately I did ask about adding 394mm rings to the hats designed around our 370mm kits, and spacing the calipers out to compensate, and they said the rings are not compatible. I am not sure whether the mounting holes are different, or if the hat offset is different.

in other words we’d need a 394mm ring designed specifically for our hats and a caliper bracket?

Now it has me thinking are the 370mm rotors on our existing kit designed specifically for our hat or are they using their existing GM rotor rings. (That lead me to believe their rings are intechangable)

Tesla tuning is at an early phase today there are not that many manufacturers or smaller tuners producing parts such as custom CNC caliper brackets for this niche brake setup, given time someone will. At least that’s one part we can look fwd to.

 

[Lindenwood]

in other words we’d need a 394mm ring designed specifically for our hats and a caliper bracket?

Now it has me thinking are the 370mm rotors on our existing kit designed specifically for our hat or are they using their existing GM rotor rings. (That lead me to believe their rings are intechangable)

Tesla tuning is at an early phase today there are not that many manufacturers or smaller tuners producing parts such as custom CNC caliper brackets for this niche brake setup, given time someone will. At least that’s one part we can look fwd to.

To your question, yes. My gut says these are not just GM hats or else that would have been apparent earlier (and not needed to be a group-buy for the first few batches). I figure the offset is likely different, rather than the discs themselves, because making both custom hats AND custom discs seems inefficient.

But indeed, I also do not know if the GM 394mm discs are meant to fit on hats built for GM 370mm discs either. Maybe the caliper is also different enough across the GM variants that a different hat offset is also required?

 

[kirkusss]

You tried Girodisc? I imagine they would combo an existing Model S Hat with a 370mm (GM) Corvette rotor. Seems rotor rings and their Girodisc hats are interchangeable.

You can see GiroDisc sells a Model S/X factory replacement kit: Tesla Model S, X 355mm Front Rotors, Ask if they can make a custom kit for you. You'll need the Hats from that kit.

GM 370mm Rotor Rings: Corvette, Camaro 370mm Front Replacement Rings

View attachment 1004557

View attachment 1004561

Was thinking at that, but need to confirm the 355mm hats will fit the 370mm rotors. Will also be kind of expensive when only hats are needed

 

[buckets0fun]

To your question, yes. My gut says these are not just GM hats or else that would have been apparent earlier (and not needed to be a group-buy for the first few batches). I figure the offset is likely different, rather than the discs themselves, because making both custom hats AND custom discs seems inefficient.

But indeed, I also do not know if the GM 394mm discs are meant to fit on hats built for GM 370mm discs either. Maybe the caliper is also different enough across the GM variants that a different hat offset is also required?

394mm carbons have a different caliper. An inexpensive carbon kit would be having new hats made for the carbon rotor.