Girodisc Discussion

[SMGDHG]

Hi everyone,

Help me understand girodisc rotors. Some quick specs to start the discussion:

Edit: My car is a 290whp 3600lb S-197 with s550 6p brembos up front. The tracks I go to and my driving style are easy on brakes.

GIRODISC

• https://www.girodisc.com/Front-2-Piece-Rotors-for-2013-GT500_p_6701.html
• Cost: $1,000 for initial investment
• Replacement cost: $800
• Weight savings: 9.5lbs/rotor
• Service Life: (?????)

STOPTECH/CENTRIC BLANKS

• https://lmr.com/item/LRS-1102LK/mustang-front-brake-rotor-pair-15-high-carbon-steel-13-14
• Cost: $450
• Service Life: 16 Events (could be more, but my pads lasted 16 events and I like to replace pads+rotors at the same time).

To summarize, I have four questions I'd like to ask the group:

1. Other than weight savings, what advantage is there to the girodisc rotors?
2. How much longer will a girodisc rotor last compared to a high quality centric blank? Is 2x the life to be expected?
3. IF the girodisc rotor does last 2x as long as the centric blank, is it ok to put new pads on the old rotor, or will previous pad deposits ruin the rotor/new pads?
4. Does anyone have cold, hard DATA in regards to rotor temperature, rotor life and pad life comparing centric blanks to girodisc?

I can appreciate un-sprung weight reduction just as much as the next guy/gal but literally doubling my consumables cost? Nah. So unless the girodiscs last 2x longer compared to the centric blanks, and it is possible possible to put new pads on the old rotors, I have to conclude I just don't have the budget to run these beauties.

Thanks everyone

 

[honeybadger]

I don't think you're going to get an answer that satisfies you unless you could find a race team with good note keeping that has run the same analysis. Too many variables - tracks, tires, brake pads, driver skill, etc--for us normies.

Here's some data from my own experience with my GT350.

OEM: roughly 8 track days (sometimes 6, sometimes 10 - never more running 200TW or faster)
Girodisc: Minimum of 8 days, thinking I'll even out around 12 after it's said and done. But I'd like to run them another season before I swear by that.

Brake pads? they last me 6-8 track days on average depending on tires, track, and heat

The fact that you're getting 16 events out of the OEM rotors is indicative that the Giro's probably are not going to be justifiable.

For me, I like the Giro's not because they last longer (although that's nice), but because they're more durable. They take longer to crack and they allow me to replace pads and rotors around the same time (I never start a new rotor on used pads).

 

[Bill Pemberton]

Two keys I can give you having run both over the years is that the Girodisc rotors will dissipate heat better, wear better partly due to that and as you noted they weigh less. One thing you can know for sure is they are made from American Steel and that is not a given with many other rotors. That is a key, knowing you are not getting farmed out Steel from who knows where , though it likely would be Chinese.

 

[KazarS197]

Hi everyone,

Help me understand girodisc rotors. Some quick specs to start the discussion:

GIRODISC

• https://www.girodisc.com/Front-2-Piece-Rotors-for-2013-GT500_p_6701.html
• Cost: $1,000 for initial investment
• Replacement cost: $800
• Weight savings: 9.5lbs/rotor
• Service Life: (?????)

STOPTECH/CENTRIC BLANKS

• https://lmr.com/item/LRS-1102LK/mustang-front-brake-rotor-pair-15-high-carbon-steel-13-14
• Cost: $450
• Service Life: 16 Events (could be more, but my pads lasted 16 events and I like to replace pads+rotors at the same time).

To summarize, I have four questions I'd like to ask the group:

1. Other than weight savings, what advantage is there to the girodisc rotors?
2. How much longer will a girodisc rotor last compared to a high quality centric blank? Is 2x the life to be expected?
3. IF the girodisc rotor does last 2x as long as the centric blank, is it ok to put new pads on the old rotor, or will previous pad deposits ruin the rotor/new pads?
4. Does anyone have cold, hard DATA in regards to rotor temperature, rotor life and pad life comparing centric blanks to girodisc?

I can appreciate un-sprung weight reduction just as much as the next guy/gal but literally doubling my consumables cost? Nah. So unless the girodiscs last 2x longer compared to the centric blanks, and it is possible possible to put new pads on the old rotors, I have to conclude I just don't have the budget to run these beauties.

Thanks everyone

You can find the 13-14 GT500 OEM Ford rotors from $300- 340 shipped depending on availability. Ford BRRF -218 ( Ford DR3Z-1125-A)

 

[ChrisM]

It'll be tough to get a really accurate comparison considering the weight and power differences between the various platforms, all other things being equal. Comparing service life of a ~315ish hp 3v that might weigh 3400 pounds will be very different from a 500+ hp 3700ish pound GT350 (rough estimates from street cars, not race cars).

I don't really have much to add for experience, but this is relevant to my interests since I have a similar car.

 

[JAJ]

Hi everyone,

Help me understand girodisc rotors. Some quick specs to start the discussion:

GIRODISC

• https://www.girodisc.com/Front-2-Piece-Rotors-for-2013-GT500_p_6701.html
• Cost: $1,000 for initial investment
• Replacement cost: $800
• Weight savings: 9.5lbs/rotor
• Service Life: (?????)

STOPTECH/CENTRIC BLANKS

• https://lmr.com/item/LRS-1102LK/mustang-front-brake-rotor-pair-15-high-carbon-steel-13-14
• Cost: $450
• Service Life: 16 Events (could be more, but my pads lasted 16 events and I like to replace pads+rotors at the same time).

To summarize, I have four questions I'd like to ask the group:

1. Other than weight savings, what advantage is there to the girodisc rotors?
2. How much longer will a girodisc rotor last compared to a high quality centric blank? Is 2x the life to be expected?
3. IF the girodisc rotor does last 2x as long as the centric blank, is it ok to put new pads on the old rotor, or will previous pad deposits ruin the rotor/new pads?
4. Does anyone have cold, hard DATA in regards to rotor temperature, rotor life and pad life comparing centric blanks to girodisc?

I can appreciate un-sprung weight reduction just as much as the next guy/gal but literally doubling my consumables cost? Nah. So unless the girodiscs last 2x longer compared to the centric blanks, and it is possible possible to put new pads on the old rotors, I have to conclude I just don't have the budget to run these beauties.

Thanks everyone

First, I've met the folks at Girodisc and they're great people - car enthusiasts just like us. Good products, and yes, they have their rotor blanks made by a foundry in the USA.

That said, it's not clear from your post just exactly what problem you're trying to solve, nor did you say what brakes are on the car - your sig says it's a 3v S197 but the Stoptech parts are for a 2013/14 GT500. Which is it? I'm asking because it matters - slowing down a 4,000 pound GT500 from 160 MPH needs bigger brakes than slowing a 3,500 pound GT from 130 MPH.

As to the rotors themselves, there are two related advantages that come with 2-piece "floating" rotors like the Girodisc product. First, the center of the rotor - the "hat" - is aluminum. Big weight savings without giving up any thermal capacity in the friction ring (where heavier is better). Second, isolating the friction ring from the hat keeps the hat cooler and that keeps the wheel bearing cooler. Solid rotors can "cook" the wheel bearing; two piece rotors generally don't do that. The GT350 and GT500 come from the factory with two-piece rotors front and rear because two-piece rotors simply work better when there's a lot of high speed braking involved.

So, those two points are why I've run two-piece rotors on my track cars for the last 18 years. It's a cost of doing business. That said, if you're getting good performance out of solid disks, then carry on.

 

[67GTA]

I’ve been running Ford OE blanks with G-loc R16 - same setup (S197, S550 6 pot Brembos and 13-14 GT500 rotors). Just installed the 2nd set of pads on the same rotors, which look like they’ll easily survive the 2nd set of pads. Pads lasted 9 track days. As long as the replacement friction is the same and the rotor has serviceable life, no problem running a 2nd set.

I have a brand new set of Girodisc sitting on the shelf ready to go. One other consideration - several guys running the Girodisc on the S197/S550 PP package have experienced pad knock-back. In fact, I think there’s a setup for sale in the classifieds right now because of this. I have not experienced pad knock-back with the solid blanks, so I’m curious to compare with the free-floating 2 piece to see if that additional movement is causing the kick-back or not.

 

[SMGDHG]

The main advantage I'm looking to get out of the giro's is an increased service life and also the unsprung weight benefit.

I agree that it is reasonable to believe that since I am not taxing my braking system too much, the gains from the girodiscs (ie better heat dissipation) will be less than someone who puts their brakes through massive stresses.

 

[SMGDHG]

I’ve been running Ford OE blanks with G-loc R16 - same setup (S197, S550 6 pot Brembos and 13-14 GT500 rotors). Just installed the 2nd set of pads on the same rotors, which look like they’ll easily survive the 2nd set of pads. Pads lasted 9 track days. As long as the replacement friction is the same and the rotor has serviceable life, no problem running a 2nd set.

I have a brand new set of Girodisc sitting on the shelf ready to go. One other consideration - several guys running the Girodisc on the S197/S550 PP package have experienced pad knock-back. In fact, I think there’s a setup for sale in the classifieds right now because of this. I have not experienced pad knock-back with the solid blanks, so I’m curious to compare with the free-floating 2 piece to see if that additional movement is causing the kick-back or not.

Interesting. That's a bit of a bummer tbh, but great info.

Dumb question, but to measure rotor life one would just measure the original width of the rotor surface area compared to the current? Other than when a lip starts to form on the rotor where the pad meets, how do you know if the rotor is at the end of it's service life?

 

[ChrisM]

The main advantage I'm looking to get out of the giro's is an increased service life and also the unsprung weight benefit.

I agree that it is reasonable to believe that since I am not taxing my braking system too much, the gains from the girodiscs (ie better heat dissipation) will be less than someone who puts their brakes through massive stresses.

I don't think the gains would be less, but when Honeybadger says he gets 6-8 days, it just means you might get double that because of the weight and power differences. If anything, it'd mean you get more because you might get 1.5-2 times more use from them than an S550 would, but proportionally it would be the same. He wears out his OEM rotors in 8 track days, you wear yours out in 16. He wears out his Girodisc brakes in 8-12 days, which means you might get 16-24 days. Not exactly accurate, just a general wag of numbers and making a lot of assumptions. It also sounds like you might save money by not wearing out other components as quickly either.

Interesting. That's a bit of a bummer tbh, but great info.

Dumb question, but to measure rotor life one would just measure the original width of the rotor surface area compared to the current? Other than when a lip starts to form on the rotor where the pad meets, how do you know if the rotor is at the end of it's service life?

The shop my instructor works at said they toss them when they're cracked. Didn't mention measuring them.

 

[honeybadger]

The shop my instructor works at said they toss them when they're cracked. Didn't mention measuring them.

Same. My rotors crack well before I get anywhere near minimum wear/thickness.

FWIW, my solid rotors also cracked just like this - just not around the holes.

 

[Bill Pemberton]

Honeybadger posted a picture that is worth a thousand four hundred and thirteen words , " Do not get drilled rotors!!!" I think one of the things that dismayed a bunch of the early GT 350 owners when they got their cars, was to see that the rotors were drilled . Now the poseurs were happy , as they looked so pretty , but the track guys were wondering what the heck was Ford thinking? Ranks right there, in my mind, with the Boss 302 snafu , where the Engineers wanted a Tremec T6060 but the " Beano Counters " wanted to save a buck, so we got the MT-82. Apparently in the early years of the GT 350 the Marketing guys wanted rotors poseur pretty instead of serious slotted stoppers.

When do get new rotors , just pass over the " Holy Rollers " and get slotted rotors, you will glad you did.