The Obtainable Brembo GP4-MS, GP4-RR, GP4-PR, GP4-RS, GP4-RX and Unobtainable Brembo new GP4 caliper

[BMW Alpina]

I confirmed with Brembo Factory in Italy, yep, directly from the factory, that:
a. Brembo REVISED GP4-MS will come in 2 sizes, 100mm and 108mm bolt spacing
b. BOTH the 100mm and 108mm bolt spacing will have the now "mandatory" cooling fins
c. The only issue is, both won't be available until near the end of NEXT year (2023) , meaning my 998 will not have a brake caliper until next year ...

by the way, I sold my GP4-MS (current version) caliper a few weeks ago, but my Custom Paint Brand New GP4-RR with 108mm spacing is still available for sale in case anyone needs a track-specific "Titanium Pistons" brake caliper right now

 

[Steven777]

I have the GP4 RS with the RCS 17 Corsa Corta MC and Sicom rotors and pads…it’s a good setup.

 

[BMW Alpina]

I have the GP4 RS with the RCS 17 Corsa Corta MC and Sicom rotors and pads…it’s a good setup.

Hi Steven,
From this latest picture of your setup, I believe you have the "HIGHER GRADE BILLET" GP4-MS, and not the lower grade cast GP4-RS


This is what the GP4-RS looks like (picture below): MotoGP-derived finned surfaces for the new GP4-RS one-piece caliper

 

[Steven777]

yeah sorry, I have the GP4 MS, with titanium pistons added.

it’s the best possible option while retaining the stock forks.

otherwise you need new forks that have the 108 spacing, and the RS and MS are the only calipers upgrades you can use and still use the Sicom rotors WITH the Sicom pads. I liked the RCS Corsa Corta, GP4-MS, Sicom rotors/pads so much that I didn’t upgrade the forks to the newest throughrod KTech’s that I wanted. Ended up just getting custom valved and sprung FKR 108 carts to put in the stock NIX forks.

The Sicom don’t get hot and retain heat, so no brake fade ever, and they never wear out, and stop like you drove into a mud bog.

 

[BMW Alpina]

yeah sorry, I have the GP4 MS, with titanium pistons added.

it’s the best possible option while retaining the stock forks.

otherwise you need new forks that have the 108 spacing, and the RS and MS are the only calipers upgrades you can use and still use the Sicom rotors WITH the Sicom pads. I liked the RVS Corsa Corta, GP4-MS, Sicom rotors/pads so much that I didn’t upgrade the forks to the newest throughrod KTech’s that I wanted. Ended up just getting custom valved and sprung FKR 108 carts to put in the stock NIX forks.

The Sicom don’t get hot and retain heat, so no brake fade ever, and they never wear out, and stop like you drove into a mud bog.

Well, if someday you are bored with the current looks of your stock forks,
I am selling my Brand New Unused Red Motocorse Lower Caliper Bracket for 100mm spacing at below market price link here: Motocorse "SBK style" Ohlins forks caliper mounts for Ducati Panigale V4S and Ducati Streetfighter V4S in Red Anodized color. Motocorse Part#102130145

The left picture is how it looks with a GP4-MS, and right picture is how it looks compared to stock Ohlins forks bottom:

 

[TNC]

I confirmed with Brembo Factory in Italy, yep, directly from the factory, that:
a. Brembo REVISED GP4-MS will come in 2 sizes, 100mm and 108mm bolt spacing
b. BOTH the 100mm and 108mm bolt spacing will have the now "mandatory" cooling fins
c. The only issue is, both won't be available until near the end of NEXT year (2023) , meaning my 998 will not have a brake caliper until next year ...

by the way, I sold my GP4-MS (current version) caliper a few weeks ago, but my Custom Paint Brand New GP4-RR with 108mm spacing is still available for sale in case anyone needs a track-specific "Titanium Pistons" brake caliper right now

Hi BMW Alpina,
just today I also had a phonecall with the folks at WRS.it to ask about the 2023 update of the GP4 MS.
Since the initial release in 2019, the GP4 MS was only available in the 100mm spacing (the ones that you just sold...).

I have been told that the "cooling fins" update will only come with the new release of the 108mm spacing GP4 MS.
Now I'm a bit unsure what to do... unfortunately GP4 RR is not the most optimal caliper for the SICOM discs, so it'll need to be a MS Caliper...

 

[Steven777]

Hi BMW Alpina,
just today I also had a phonecall with the folks at WRS.it to ask about the 2023 update of the GP4 MS.
Since the initial release in 2019, the GP4 MS was only available in the 100mm spacing (the ones that you just sold...).

I have been told that the "cooling fins" update will only come with the new release of the 108mm spacing GP4 MS.
Now I'm a bit unsure what to do... unfortunately GP4 RR is not the most optimal caliper for the SICOM discs, so it'll need to be a MS Caliper...

Get the RS ;-) with the RCS 17 Corsa Corta MC, goes really well with the Sicom setup. Make sure you use the Sicom pads with the Sicom rotors, and follow their transfer procedure as best you can, the brakes only work at optimum when you do a proper thermal heat cycle transfer of the pad material to the rotors.

Also with the Sicom setup you don’t need the fins on the rotors unless you want them for looks.

One of the main benefits of the Sicom setup other than trendies weight reduction is that the braking system doesn’t build up and retain heat…there’s ZERO brake fade ever with them.

I’m 250 pounds in gear and brake very hard and late, I put a trendies strain on my brakes at the track…after a 20 minute session in 105 degree ambient temps and really hard braking I can ride back to the garage and the brakes are so cool you can touch them with no discomfort

 

[TNC]

Hi Steve, thank you for your review.
Just a few months back, I was pretty convinced in using the combination of SICOM rotors together with the GP4 RR calipers (because I simply like the hard-anodized dark look of it). But after realizing that SICOM does not offer any pads that would fit the GP4 RR caliper, I started to contact the guys at SuperbikesUnlimited and asked for their pad recommendation that they were running with the SICOM rotors. So I ordered a set of SBS DS1 and SBS DS2 pads for the GP4 RR... but since the SICOM are not really Narrow-Band rotors I ended up with the GP4 MS, which probably makes many things easier... but unfortunately they're Nickel Colour What a Choice...

 

[craig bush]

… unfortunately GP4 RR is not the most optimal caliper for the SICOM discs

Why is this?

 

[craig bush]

Get the RS

I’m familiar with the RX, RR, And MS. What are the RS?

 

[BMW Alpina]

Hi BMW Alpina,
just today I also had a phonecall with the folks at WRS.it to ask about the 2023 update of the GP4 MS.
Since the initial release in 2019, the GP4 MS was only available in the 100mm spacing (the ones that you just sold...).

I have been told that the "cooling fins" update will only come with the new release of the 108mm spacing GP4 MS.
Now I'm a bit unsure what to do... unfortunately GP4 RR is not the most optimal caliper for the SICOM discs, so it'll need to be a MS Caliper...

Hi Steve, thank you for your review.
Just a few months back, I was pretty convinced in using the combination of SICOM rotors together with the GP4 RR calipers (because I simply like the hard-anodized dark look of it). But after realizing that SICOM does not offer any pads that would fit the GP4 RR caliper, I started to contact the guys at SuperbikesUnlimited and asked for their pad recommendation that they were running with the SICOM rotors. So I ordered a set of SBS DS1 and SBS DS2 pads for the GP4 RR... but since the SICOM are not really Narrow-Band rotors I ended up with the GP4 MS, which probably makes many things easier... but unfortunately they're Nickel Colour What a Choice...

Hi TNC,
I talked directly to the Brembo Factory in Italy (real Brembo Italy factory, not their distributors Race Technologies and not Motoquality) a few months ago after EICMA when they announced the new GP4 MS with cooling fins.
They told me that the "RENEWED" GP4-MS with cooling fins would also be available in the 100mm, but it will be much later after the 108mm version. Most likely end of this year for the 100mm version.

On the other hand, the GP4-MS 108mm version might be available sooner since, as you notice, WRS already posted about the 108mm on their website: GP4MS_108 BREMBO RACING GP4-MS MONOBLOCK RADIAL BRAKE CALIPERS 108MM
Although no pricing is available yet.

I am not sure why the GP4-RR is not optimal for Sicom,... Is it simply because Sicom did not sell their brake pads in GP4-RR shape?
Besides, if SICOM is not a narrow band and GP4-RR is a narrow band, wouldn't this mean there are more surfaces available on the SICOM? And since SICOM will not rust, there will be no "ring of shame" (ring of rust) that is shown when smaller brake pads are used in larger surface steel disc.

How about the latest and greatest GP4-LM? with DUAL Row cooling fins? I already paid for this GP4-LM and today being told it might be released soon as next week
I don't know what the GP4-LM brake pads will look like, though, because it seems that the GP4-LM "ENDURANCE" brake pads will not be available until the middle of this year, so I will have a GP4-LM without brake pads for a while
But maybe, just maybe, the GP4-LM brake pads shape will be compatible with some of the SICOM brake pads? You might want to check with SICOM...

I am also going to order the "RENEWED" GP4-MS 108mm with 1 row cooling fins as soon as it is available to be used on my 998 projects, while the GP4-LM with dual row cooling fins will be paired with the Panigale V4 25° Anniversario 916 project

Last @TNC , I am selling my brand new custom-painted GP4-RR with brake pads very cheap, just in case you want a GP4-RR to try with the SICOM and those pads that SBU recommended : For Sale: Brembo GP4-MS and Brembo GP4-RR Brake Calipers brand new

 

[Steven777]

At the time it was the best available option for a 100 fork bottom, also I’m married to the Sicom Brake setup, and that only works at its best while using the Sicom pads, which further limited caliper options to the Stylema’s, GP4-MS, or GP4-RS

the latter being the best of the 3 choices, and then I put the Braketech pistons in them.

MotoGP-derived finned surfaces for the new GP4-RS one-piece caliper

7 good reasons to switch to the new Brembo GP4-RS caliper, the dominant caliper on racetracks this coming spring

www.brembo.com

 

[Steven777]

Hi Steve, thank you for your review.
Just a few months back, I was pretty convinced in using the combination of SICOM rotors together with the GP4 RR calipers (because I simply like the hard-anodized dark look of it). But after realizing that SICOM does not offer any pads that would fit the GP4 RR caliper, I started to contact the guys at SuperbikesUnlimited and asked for their pad recommendation that they were running with the SICOM rotors. So I ordered a set of SBS DS1 and SBS DS2 pads for the GP4 RR... but since the SICOM are not really Narrow-Band rotors I ended up with the GP4 MS, which probably makes many things easier... but unfortunately they're Nickel Colour What a Choice...

Regardless of what SBU said only run the Sicom pads with the Sicom rotors, otherwise you loose almost all the benefit of the rotors other than weight reduction.

The pad material is specially formulated so that material continuously passes between rotor and pad with no loss of material, hence no brake dust and never having to change pads again. Also, the pad material transferring to the rotor creates the unique friction surface that makes them so good.

The rotor material is so hard that you CAN use nearly any pad material with them, but can and should are not the same thing.

SBU briefly tested the Sicom rotors with the wrong calipers so they never actually used or tested them with the Sicom pads as they were designed, so they don’t understand WHY it’s so important to use the Sicom pad with the Sicom rotors.

that transfer of material is also why it’s really important to do the bedding procedure exactly as they say for optimal performance.

 

[BMW Alpina]

yeah sorry, I have the GP4 MS, with titanium pistons added.

it’s the best possible option while retaining the stock forks.

otherwise you need new forks that have the 108 spacing, and the RS and MS are the only calipers upgrades you can use and still use the Sicom rotors WITH the Sicom pads. I liked the RCS Corsa Corta, GP4-MS, Sicom rotors/pads so much that I didn’t upgrade the forks to the newest throughrod KTech’s that I wanted. Ended up just getting custom valved and sprung FKR 108 carts to put in the stock NIX forks.

The Sicom don’t get hot and retain heat, so no brake fade ever, and they never wear out, and stop like you drove into a mud bog.

At the time it was the best available option for a 100 fork bottom, also I’m married to the Sicom Brake setup, and that only works at its best while using the Sicom pads, which further limited caliper options to the Stylema’s, GP4-MS, or GP4-RS

the latter being the best of the 3 choices, and then I put the Braketech pistons in them.

MotoGP-derived finned surfaces for the new GP4-RS one-piece caliper

7 good reasons to switch to the new Brembo GP4-RS caliper, the dominant caliper on racetracks this coming spring

www.brembo.com

Did BrakeTech now make Titanium Pistons for GP4-MS?
I thought BrakeTech only make Stainless Steel Pistons for GP4-MS.
(A few months ago, I had to purchase the Titanium Pistons for my GP4-MS from MCET Germany)

Or perhaps I misunderstood, maybe what you meant is you put BrakeTech Stainless Steel piston in your GP4-RS but put Titanium Pistons in your GP4-MS?
If that is the case, which setup you like more, GP4-RS with BrakeTech Stainless Steel Piston or GP4-MS with Titanium Pistons? and why?

 

[Steven777]

Did BrakeTech now make Titanium Pistons for GP4-MS?
I thought BrakeTech only make Stainless Steel Pistons for GP4-MS.
(A few months ago, I had to purchase the Titanium Pistons for my GP4-MS from MCET Germany)

Or perhaps I misunderstood, maybe what you meant is you put BrakeTech Stainless Steel piston in your GP4-RS but put Titanium Pistons in your GP4-MS?
If that is the case, which setup you like more, GP4-RS with BrakeTech Stainless Steel Piston or GP4-MS with Titanium Pistons? and why?

I always get the RS and MS confused, whichever is upgraded one, if I remember right they were like $1500 per caliper.

I ordered Titanium pistons from the same place you did, briefly put them on, then put the braketech on, the weight was an inconsequential difference but the braketech are better engineered with those hole in them them

 

[BMW Alpina]

The titanium pistons for my GP4-MS that I bought from MCET also have holes drilled on them.
It also came with DLC (Diamond Like Carbon) coatings.
Here is the webpage link to the MCET website: caliper piston titanium for Brembo GP4 MS calipers

The picture below is my own titanium caliper piston (MCET) that I keep for my future 108mm GP4-MS with cooling fins.


And below is the picture of the BrakeTech stainless steel piston.
The Braketech Stainless Steel Piston does have a cleverly designed backside with a scalloped area, which further help reduce the weight a bit and has a bit more volume for brake fluid.


From BrakeTech website: https://braketech.com/caliper-racing-pistons/
However, according to the webpage above, BrakeTech points out that the main advantage of the Stainless Steel Piston compared to the Aluminum Piston is thermal Conductivity.
But Braketech did not address any advantage of Stainless Steel compared to Titanium except for the small thermal conductivity advantage in this graph I screenshot from the Braketech website below:


The graph above shows Titanium has a bit more thermal conductivity compared to Stainless Steel. The difference is only 21-14.2 = 6.8, which is nothing compared to the 237 of aluminum but wait...
we need to do more research... we cannot just accept any value shown on a brochure because the devil is in the details.

Please remember the grade of Titanium used also affects the thermal conductivity, and I noticed Braketech also did not specify the grade of Stainless Steel they use. They only say their stainless steel is proprietary. But was it 316 or 304 or other grades?
Because of the number of sales for this brake caliper piston, there is not enough economy of scale for super proprietary stainless steel. So most likely, it must be some commercially available grade of stainless steel on the market.
For example, Titanium Grade 2 has a thermal conductivity of:


This means Titanium Grade 2 has basically the same Thermal conductivity as Stainless Steel (table below)


While the Titanium Grade 5 normally used for all the bolts/screws on our motorcycle (ProTi/ProBolt) (and presumably also for the titanium pistons from MCET) has an even lower thermal conductivity of just:


Yes, so from a THERMAL CONDUCTIVITY point of view, we can call Titanium and Stainless Steel evenly match, or if we use Titanium Grade 5, it could have just 40% of the 316/304 Stainless Steel thermal conductivity, which means Titanium is a BETTER material for thermal conductivity then stainless steel.

But what really jumps out from my quick research is the fact that
Titanium has a lower coefficient of thermal expansion than stainless steel.
If you heat titanium, it will expand less than stainless steel.
Since Caliper Pistons require it to be machined precisely for a TIGHT FIT (prevent leak of brake fluid that could be a catastrophe) but still loose enough to prevent stickiness of movement with friction from the caliper seal,
Then for the caliper piston, Titanium material will have an advantage because at the most extreme heat range during racing (by professional racers), the stainless steel would expand more than titanium.

The MCET Titanium piston also has another advantage in the form of DLC coating, which helps with less friction against the caliper seal.
The Brembo GP4-RR (or higher grade) uses a TIN coating just like Ohlins forks to also help reduce friction against the caliper seal and move smoother.

Don't get me wrong, the Braketech stainless steel piston is cleverly engineered and has a better price point, possibly even more bang for the buck for the nonprofessional racer.
But if you want the ultimate, Titanium Piston is still the choice.

There are reasons why the higher-end brake calipers like GP4-RR (and higher grade) use Titanium Brake Pistons (which cost more) than stainless steel.
So, if you still have the Titanium Pistons from MCET, I recommend you swap the BrakeTech Stainless Steel piston with the Titanium Pistons from MCET for your GP4-MS.

 

[TNC]

Regardless of what SBU said only run the Sicom pads with the Sicom rotors, otherwise you loose almost all the benefit of the rotors other than weight reduction.

The pad material is specially formulated so that material continuously passes between rotor and pad with no loss of material, hence no brake dust and never having to change pads again. Also, the pad material transferring to the rotor creates the unique friction surface that makes them so good.

The rotor material is so hard that you CAN use nearly any pad material with them, but can and should are not the same thing.

SBU briefly tested the Sicom rotors with the wrong calipers so they never actually used or tested them with the Sicom pads as they were designed, so they don’t understand WHY it’s so important to use the Sicom pad with the Sicom rotors.

that transfer of material is also why it’s really important to do the bedding procedure exactly as they say for optimal performance.

Yes, I received a document from my dealer stating the importance of the "bedding procedure" of the rotors.
Unless I'll ever get the chance to compare the original pads with the SBS ones, I probably will never find out if the provided SICOM pads are really a must or probably a way to simply sell their own pads. I just thought that the SBU guys are quite quick on their bikes, assuming they won't risk sacrificing anything in terms of improper braking action.

Hi TNC,
I talked directly to the Brembo Factory in Italy (real Brembo Italy factory, not their distributors Race Technologies and not Motoquality) a few months ago after EICMA when they announced the new GP4 MS with cooling fins.
They told me that the "RENEWED" GP4-MS with cooling fins would also be available in the 100mm, but it will be much later after the 108mm version. Most likely end of this year for the 100mm version.

On the other hand, the GP4-MS 108mm version might be available sooner since, as you notice, WRS already posted about the 108mm on their website: GP4MS_108 BREMBO RACING GP4-MS MONOBLOCK RADIAL BRAKE CALIPERS 108MM
Although no pricing is available yet.

I am not sure why the GP4-RR is not optimal for Sicom,... Is it simply because Sicom did not sell their brake pads in GP4-RR shape?
Besides, if SICOM is not a narrow band and GP4-RR is a narrow band, wouldn't this mean there are more surfaces available on the SICOM? And since SICOM will not rust, there will be no "ring of shame" (ring of rust) that is shown when smaller brake pads are used in larger surface steel disc.

How about the latest and greatest GP4-LM? with DUAL Row cooling fins? I already paid for this GP4-LM and today being told it might be released soon as next week
I don't know what the GP4-LM brake pads will look like, though, because it seems that the GP4-LM "ENDURANCE" brake pads will not be available until the middle of this year, so I will have a GP4-LM without brake pads for a while
But maybe, just maybe, the GP4-LM brake pads shape will be compatible with some of the SICOM brake pads? You might want to check with SICOM...

I am also going to order the "RENEWED" GP4-MS 108mm with 1 row cooling fins as soon as it is available to be used on my 998 projects, while the GP4-LM with dual row cooling fins will be paired with the Panigale V4 25° Anniversario 916 project

Last @TNC , I am selling my brand new custom-painted GP4-RR with brake pads very cheap, just in case you want a GP4-RR to try with the SICOM and those pads that SBU recommended : For Sale: Brembo GP4-MS and Brembo GP4-RR Brake Calipers brand new

108mm GP4 MS seems to be available by May'23.

As far as I understood, GP4 RR uses pads which are held in place only by the lower brackets underneath the caliper. But SICOM pads are mostly larger in size then original pads as they are extending a bit further towards the center of the disc. With the GP4 RR that unfortunately doesn't seem to be possible. So yes, the braking surface on the rotors is fine, but the surface from the pads themselves (which are available for the RR) might not be. But I don't really know the effects and consequences of that. I'm a hobby racer and most probably won't even tell the difference. Have to try out I guess.

Unfortunately I need 100mm Spacing Calipers only... so the 108mm GP4 RR won't really fit, else wise great deal and thank you.

In Germany there's mainly one reputable provider of aftermarket titanium pistons, which is:
Federleicht (Featherlight) Performance

Tom from MCET is a friend of mine and the pistons look identical. The DLC coating is also done by a friend of mine.

 

[BMW Alpina]

Yes, I received a document from my dealer stating the importance of the "bedding procedure" of the rotors.
Unless I'll ever get the chance to compare the original pads with the SBS ones, I probably will never find out if the provided SICOM pads are really a must or probably a way to simply sell their own pads. I just thought that the SBU guys are quite quick on their bikes, assuming they won't risk sacrificing anything in terms of improper braking action.



108mm GP4 MS seems to be available by May'23.

As far as I understood, GP4 RR uses pads which are held in place only by the lower brackets underneath the caliper. But SICOM pads are mostly larger in size then original pads as they are extending a bit further towards the center of the disc. With the GP4 RR that unfortunately doesn't seem to be possible. So yes, the braking surface on the rotors is fine, but the surface from the pads themselves (which are available for the RR) might not be. But I don't really know the effects and consequences of that. I'm a hobby racer and most probably won't even tell the difference. Have to try out I guess.

Unfortunately I need 100mm Spacing Calipers only... so the 108mm GP4 RR won't really fit, else wise great deal and thank you.

In Germany there's mainly one reputable provider of aftermarket titanium pistons, which is:
Federleicht (Featherlight) Performance

Tom from MCET is a friend of mine and the pistons look identical. The DLC coating is also done by a friend of mine.

Hi TNC,

You might already be aware of this but in case you haven't, there is another way of installing a 108mm GP4-RR on the stock fork by swapping out the bottom with the Motocorse 108mm fork bottom with the added side effect of "WSBK looks bling"
According to Motocorse, they design this 108mm fork bottom to be TOTALLY COMPATIBLE with everything else meaning no need to put spacer on the back of your disk rotor even though the GP4-RR has a different offset than GP4-MS. (but make sure you don't install GP4-PR because that one have odd offset, yes GP4-PR)
Here is the link: https://www.motocorsestore.com/en/accessori-in-alluminio/1068-ohlins-front-forks-108mm-caliper-radial-mounts-motocorse-sbk-style.html

 

[TNC]

Hi TNC,

You might already be aware of this but in case you haven't, there is another way of installing a 108mm GP4-RR on the stock fork by swapping out the bottom with the Motocorse 108mm fork bottom with the added side effect of "WSBK looks bling"
According to Motocorse, they design this 108mm fork bottom to be TOTALLY COMPATIBLE with everything else meaning no need to put spacer on the back of your disk rotor even though the GP4-RR has a different offset than GP4-MS. (but make sure you don't install GP4-PR because that one have odd offset, yes GP4-PR)
Here is the link: https://www.motocorsestore.com/en/accessori-in-alluminio/1068-ohlins-front-forks-108mm-caliper-radial-mounts-motocorse-sbk-style.html

Not sure if I’m going to get banned from this forum if I reveal for what bike I’m planning to use the calipers for…

 

[craig bush]

Not sure if I’m going to get banned from this forum if I reveal for what bike I’m planning to use the calipers for…

Let’s hear it.