Brembo GT pedal feel

[elim11]

Pad compound plays the biggest role. Also Brake Fluid and pad thickness.
When switching from street pads to race pads, it feels completely different with the race pads being so touchy and sensitive.

[ashtaron14]

Originally Posted by buddalun

But, but, Porsche brakes are Brembo!

You know it!

[slonik]

sorry for offtopic, but

Originally Posted by roastbeef

it was a half-hearted joke.

vw owns porsche. porsche is better than vw. sup?

incorrect.
porsche owns vw.
https://en.wikipedia.org/wiki/Volkswagen_Group

The holding company Porsche SE owns 31 percent shares of Volkswagen AG while maintaining its 50.7 percent of voting rights in the company.

[roastbeef]

Ok ok, i was 1/2 joking.

[BAMFM3]

Originally Posted by swhat

When I first installed my GT kit, I felt the same way. It didn't bit as hard as the stock brakes, but now I have come to love the pedal feel because you get so much more feel for brake modulation.

Same here. Brembo initial bite (with light pedal pressure) with supplied Brembo pads not nearly as strong as OEM setup.

Brembo has a much more linear braking effect than stock.

[azndrunk74]

Strange. My supplied Brembo pads had awesome initial bite compared to my OEM setup. After the front pads wore out I replaced them with Ferodo DS2500 pads and now they are even better (dustier too but I don't care).

I do have to add that my friend's Brembo GT setup with Brembo pads (also 380/380) initial bite did not feel as good as mine, even after re-bleeding all 4 calipers. We still can't figure it out. We both run Michelin PSS tires but I'm on a meaty 18" (275/295) setup versus his 19" (255/295) setup.

[DavidZ]

Originally Posted by Redd

I recently tried a friend's car with AP Racing bbk and the pedal feels much firmer than my M3 with Brembo GT bbk. Is this normal?

Sounds like someone just did a better job at bleeding the brakes. Or maybe your master cylinder is on the way out.

[Redd]

Master cylinder, brake booster all less than one year old. Tons of meat left on discs and pads. Steel hoses done. Brake fluid is fresh.

[DavidZ]

Fluid may be fresh but you still might have some air in there. Took me a couple bleeds to get a rock solid pedal on my GTs.

[Redd]

I've bled the fluid in my car probably 8-9 times in the last 2 years from fixing various brake issues and trying to figure out this pedal feel thing. The last 3 times included cycling the ABS/DSC pump.

[DavidZ]

Oh, sorry, I was under the impression you had just installed them.

[ixat]

Long shot trying to get some answers here. My issue is similar with OP but mainly on the travel distance before pedal firms.

When it hits firm it remains firms. It’s been bled twice by different shops , gone thru 4 bottles of RBF650. Pedal feel firms but only after about 1” of travel.

Is this just the nature of Brembo GT6? I have GT4 in rear too.

Thanks!

[Redd]

After many years of trying different solutions, I recently fixed my Brembo pedal feel issues with brake residual pressure valves.

Here's my story. I have Brembo GT kit front rear and have been experiencing knockback as well as spongy pedal since Day 1. On every brake press, there is some initial dead travel before I feel the pads contact the discs. And then when I apply more pressure, there is a lot of travel before I get full braking. It's even worse at track. I had to get used to double-pumping the brake pedal each and every time just to get somewhat predictable brake performance. And even then I could not lock up the brakes.

I tried all solutions - Endless RF650 fluid, bled so many times my brake lines are shiny inside. Steel brake hoses, new master cylinder, replaced the DSC pump (it was leaking), Project Mu HC+ pads (which I know give good pedal feel). I tried to look for anti-knockback springs but Brembo did not make them for the GT calipers which were also not designed to accept springs. I had given up and just learned to drive around it, but I never fully trusted the brakes.

Then I found this thing called the brake residual pressure valve (RPV). It's a small valve which allows pressure to bleed out of the calipers when you release the brake pedal, but maintains a small amount of residual pressure so that the pistons can't retract all the way. It's used mainly in custom hotrods to prevent all the fluid from back flowing to the fluid reservoir when the reservoir is mounted lower than the calipers. A lesser known function is to prevent knockback. By keeping a small amount of pressure (2psi) within the calipers, it stops the pistons from retracting too much and prevents caliper/pad movement from pushing the pistons further in (knockback). Best of all it's cheap! The ones I used are from McGill Motorsport but you can get them from all kinds of motorsport shops and even on Amazon (I don't trust the cheap China ones though). I went with McGill for the metric fitting.

https://www.mcgillmotorsport.com/bra...psi-c-70-p-364

I mounted them at the end of the hard line before each brake caliper and had to get custom brake hoses made from the RPV to the caliper. So if you have only front bbk then you need 2 RPV only.

The difference was amazing. With the RPVs installed, there was near zero dead pedal travel, the moment you step on the brakes you can feel it contact the disc immediately. There is no more spongy feeling either. The brake pedal is nice and firm and consistent every brake press. Best of all, it somehow feels as if the pressure in the entire brake system is increased. I can now lockup the tires at 60-70% pedal travel, the braking is now tire limited and not pad/caliper limited. Modulation is still easy and it is not as on/off as the AP Racing Pro5000R kits I've tried.

As for downsides, I did not find any. There is no pad drag, the pistons still retract far enough to let the pads clear the discs. Shortly after I installed the RPVs I got new pads and discs and even at their thickest there was no problem. However, I have only tested this on Brembo GT. Ymmv. I think the RPV only works for fixed calipers, it may not work properly with sliding calipers like our stock brakes. I have also not tested it at track but I have done dozens of balls to the wall hill runs with tons of hard braking and zero issues.

Anyway thought I'd share this as it's taken me 7 years to find a solution to finally allow me to trust my brakes fully. I've had the RPVs for over a year / 10k kms now and would highly recommend them to any Brembo bbk owner with pedal feel issues.

P/s: Had the work done by a local race shop and that's how they cable tie their brake lines. If you want you can custom fab a bracket but they said it was not necessary.

[Redd]

SPBR coding will also help a bit. With SPBR and RPV my Brembo GT now rivals the AP bbks I've tried in terms of pedal feel.

https://www.m3post.com/forums/showthread.php?t=2022199

[wyatth]

Weird... My pedal has no dead space, and feels firm and consistent immediately. No lag, no spongey feel, no irregular bite. GT6/4 380 kit with Brembo/Ferodo FM1000 pads, Brembo LCF600 fluid ...

[ixat]

Originally Posted by Redd

SPBR coding will also help a bit. With SPBR and RPV my Brembo GT now rivals the AP bbks I've tried in terms of pedal feel.

https://www.m3post.com/forums/showthread.php?t=2022199

Thank you very much Redd for the sharing. I also have PMU HC+ installed to eliminate pad feel. Will look at RPV.

On the AP BBKs you mentioned, was it tried in a E92 M3 too? Shops had told me the AP had a firmer feel and “less progressive” which results in a strong feel. I’m half hearted looking to make a switch.

Side note the brake pedal firms when it’s level with the gas pedal. Wonder if it’s a design?

[Redd]

Originally Posted by wyatth

Weird... My pedal has no dead space, and feels firm and consistent immediately. No lag, no spongey feel, no irregular bite. GT6/4 380 kit with Brembo/Ferodo FM1000 pads, Brembo LCF600 fluid ...

Yeah. Many of my other M3 friends are on Brembo GT/GTS kits and report firm pedal. I was never able to get a firm pedal until I added RPVs.

I think this is a quality issue with Brembo and clearly I'm not the only one. For this reason, along with the price of discs, I normally will not recommend Brembo GT. Maybe their GTS kit is more consistent.

[Redd]

Originally Posted by ixat

On the AP BBKs you mentioned, was it tried in a E92 M3 too? Shops had told me the AP had a firmer feel and “less progressive” which results in a strong feel. I’m half hearted looking to make a switch.

I've tried AP Pro 5000R bbks on a couple cars, including E9x M3. The Pro 5000R comes with anti-knockback springs which sort of mimics what the RPV does. Bite is very immediate and very consistent.

However what you have heard is true, the APs bite very hard and are not very progressive. They feel very on/off and the travel between brakes off and max brakes is very short. They are not as easy to modulate as other bbk. One of my friends hated the Pro 5000R for street driving for that reason. On the track they are superb.

My Brembo GT + RPV still does not have the hard initial bite as AP Pro 5000R, but it's close. And it is a lot more progressive and easier to modulate. Max braking is comparable because it is tire limited. If I brake hard enough I can lock up the tires.

[ixat]

Originally Posted by Redd

I've tried AP Pro 5000R bbks on a couple cars, including E9x M3. The Pro 5000R comes with anti-knockback springs which sort of mimics what the RPV does. Bite is very immediate and very consistent.

However what you have heard is true, the APs bite very hard and are not very progressive. They feel very on/off and the travel between brakes off and max brakes is very short. They are not as easy to modulate as other bbk. One of my friends hated the Pro 5000R for street driving for that reason. On the track they are superb.

My Brembo GT + RPV still does not have the hard initial bite as AP Pro 5000R, but it's close. And it is a lot more progressive and easier to modulate. Max braking is comparable because it is tire limited. If I brake hard enough I can lock up the tires.

Thanks the 5000r is what I’m lookin at.


Side note the brake pedal firms when it’s level with the gas pedal. Wonder if it’s a design?

[wyatth]

Originally Posted by Redd

Yeah. Many of my other M3 friends are on Brembo GT/GTS kits and report firm pedal. I was never able to get a firm pedal until I added RPVs.

I think this is a quality issue with Brembo and clearly I'm not the only one. For this reason, along with the price of discs, I normally will not recommend Brembo GT. Maybe their GTS kit is more consistent.

Interesting for sure. I'm not sure how it's a Brembo QC issue, personally. That said, I agree there are better value kits out there if one is buying new (though Girodisk rotors are available for our kits).

[Redd]

Originally Posted by wyatth

Interesting for sure. I'm not sure how it's a Brembo QC issue, personally. That said, I agree there are better value kits out there if one is buying new (though Girodisk rotors are available for our kits).

I'm curious, can you lock your tires or get ABS to activate under hard braking with your Brembo GT? Cos before RPVs I could not.

[wyatth]

Absolutely (255 PS4s up front).