Brake pedal travel issue - F80 M3 - Steel Brakes

[EGbeater]

Originally Posted by D_SheerDrivingPleasure

I installed the ss pistons + girodiscs in October and did several track days with them, including 2 days at WGI which is pretty hard on the brakes. I had complete confidence which can shave time...nothing is worse that having to stand on the pedal. It's a worthwhile upgrade for a dual duty car and/or if your taking baby steps.

Edit: A faster driver could easily overwhelm this setup. I'm kind if a granny. For reference, I'm 5 plus seconds slower that the Spanish Stig at WGI. He's 2:06 on 200tw tires.

Thanks, really appreciate your feedback. Sounds like you installed the RB stainless steel pistons at the same time as upgrading to Girodisc rotors though, which would make it impossible to discern what amount of improvement came from which change. Also, I appreciate you disclosing that you don't feel you're the reference standard for speed/driving ability... really rare in online discussion of track driving setups, be it spring rates, alignment settings, tires, brakes, tune/power output, driving at 10/10ths without nannies, whatever.

Originally Posted by D_SheerDrivingPleasure

Also, make sure you get the high temp seals and dust boots. They didn't turn to ash like the OEM ones.

Trying to decide if that's worth the extra $88 for me... I've read somewhere on bimmerpost where someone said (paraphrased) "don't bother with the RB high-temp dust boots; they'll crack and fall apart too."

https://racingbrake.com/db-40ht/

I am very hard on brakes (I tend to overbrake), and I'm at high altitude (5k feet), where all stressed vehicle systems run hotter under the same general conditions—ambient air temps, power output levels—due to the significantly lower air density in Colorado than the lucky bastards who get to play with cars much closer to sea level.

Have your front calipers fully transmogrified from pretty bright blue to an ugly dark green-brown? Looking at them in person, my front calipers actually look more gray/black than greenish-blue... they only look dark green in pictures with strong lighting (with flash).

Knowing how ugly/"Brownbo" your front calipers are would give me an idea of how much heat you've been generating with your driving/braking compared to me.

[D_SheerDrivingPleasure]

To your point, most true "race" BBKs don't have dust seals because they cannot tolerate the heat and ultimately disintegrate. Still, I figured that I'd give them a try to see how long they last. At the very least, I got some temporarily protection from road salt and grit. If I burn up these seals during this track season, I can always replace them with a fresh set for winter.

Semi Pro tip: For dust seal longevity, do not apply any lube/paste to the brake pad backing plate because it acts as frying oil when in contact with the dust seal.
My calipers are 50/50 split pea soup green and diarrhea brown. Any colored caliper will turn color if exposed to heat that’s why “true” race BBKs calipers are black.

I’ve never used those caliper temp sensor stickers…I’m lucky if I remember to refuel between sessions.

[D_SheerDrivingPleasure]

This pile of crap is why you need dust seals on a dual duty car...

[EGbeater]

Originally Posted by D_SheerDrivingPleasure

To your point, most true "race" BBKs don't have dust seals because they cannot tolerate the heat and ultimately disintegrate. Still, I figured that I'd give them a try to see how long they last. At the very least, I got some temporarily protection from road salt and grit. If I burn up these seals during this track season, I can always replace them with a fresh set for winter.

Semi Pro tip: For dust seal longevity, do not apply any lube/paste to the brake pad backing plate because it acts as frying oil when in contact with the dust seal.
My calipers are 50/50 split pea soup green and diarrhea brown. Any colored caliper will turn color if exposed to heat that’s why “true” race BBKs calipers are black.

That all makes sense. For your usage, it'd be smart to try to keep intact dust boots in place. My car is not true "dual duty"... yes, I drive it to the track and to autocross events and back, but I avoid all wet or messy conditions when I can. But, then again, my car has already experienced a ton of wet driving—with likely cracked/destroyed caliper dust boots—during One Lap 2021:

This was at Memphis:

And the pic below was at NOLA.

Originally Posted by D_SheerDrivingPleasure

I’ve never used those caliper temp sensor stickers…I’m lucky if I remember to refuel between sessions.

Regarding caliper temp stickers, I used these: https://www.amazon.com/gp/product/B07D7H1M67 and I maxxed it out (450°F/232°C) in a 12-minute session... the Wilwood stickers go to 536°F/280°C: https://www.pegasusautoracing.com/pr...sp?RecID=32053

[melanthius]

Originally Posted by EGbeater

melanthius, I'm assuming you mean the Racing Brake SS pistons for OEM F8x caliper application?

https://racingbrake.com/bb-43p/ (front, currently $266/set)
https://racingbrake.com/bb-22p/ (rear, currently $133/set)

Do you remember if you perceived a significant improvement in # of laps before the fluid started to boil, or even better brake pedal feel/firmness on the lap before a soft pedal/overheated fluid condition eventually occurred?

I asked Racing Brake today "Has Racing Brake ever conducted any controlled-condition tests regarding the difference in radiated heat over time through a RB stainless piston to brake fluid, vs a representative same-sized, flat-faced aluminum caliper piston?" and they just sent me a link to this page of marketing copy and low-res pictures of OEM brake calipers/busted-up pistons devoid of any actual testing/validation of concept and execution...

https://racingbrake.com/why-rb-stainless-steel-piston/

I found this claim of performance advantage on that page particularly amusing:

Advantage of a thin wall cut stainless steel piston vs. straight cut: weight saving - Lighter wt means quicker brake response in braking and release.



D_SheerDrivingPleasure, have you installed SS caliper pistons in your OEM brakes as planned?

If so, have you tracked the car with the new stainless pistons yet... and can you please share your experience (was there any perceived benefit)?

To be clear, I'm planning on ordering the RB stainless steel pistons anyway, because the concept seems valid and it's fairly low cost, if it even gains me an extra half hotlap (less than 60 seconds at my home track) per session before my overheated brakes fade my confidence going into the corners @ 10/10ths...

I don't think I'm boiling anything, I have fresh SRF fluid, the SS pistons, Ti shims... I tracked it yesterday and still get mushy pedal that persists well after the track session. I need to replace front pads, and I'm going to have the shop do another full bleed + ISTA DSC/ABS bleed, if that doesn't give me a firm pedal I'll try recalibration thing... then the only place left to go is full BBK.

The kit I got from racing brake included the high temp seals and dust boots.

Definitely SS is a superior material choice for the pistons, and has lower thermal conductivity than aluminum, and is less compliant, plus the little ridges reduce the contact area compared to a complete circle, which also is directly proportional to heat transfer capability. So there's lots of benefits there, it's not just marketing. The question is the OEM caliper itself, I think a lot of the compliance in the system is coming from this. That is probably one of the more noticeable things on BBK is just much higher stiffness of the caliper + overall system.

My calipers are still blue... will update if it changes though

[D_SheerDrivingPleasure]

Originally Posted by melanthius

I don't think I'm boiling anything, I have fresh SRF fluid, the SS pistons, Ti shims... I tracked it yesterday and still get mushy pedal that persists well after the track session. I need to replace front pads, and I'm going to have the shop do another full bleed + ISTA DSC/ABS bleed, if that doesn't give me a firm pedal I'll try recalibration thing... then the only place left to go is full BBK.

The kit I got from racing brake included the high temp seals and dust boots.

Definitely SS is a superior material choice for the pistons, and has lower thermal conductivity than aluminum, and is less compliant, plus the little ridges reduce the contact area compared to a complete circle, which also is directly proportional to heat transfer capability. So there's lots of benefits there, it's not just marketing. The question is the OEM caliper itself, I think a lot of the compliance in the system is coming from this. That is probably one of the more noticeable things on BBK is just much higher stiffness of the caliper + overall system.

My calipers are still blue... will update if it changes though

What rotors?

Changing to fresh pads will improve pedal firmness on its own. Maybe try that before the complete flush?

But I agree that a BBK is invitable if your fast and driving extended sessions on slick tires.

Personally, I see a lot of people buying fancy BBKs way before they have outgrown the blue boys.

[melanthius]

Originally Posted by D_SheerDrivingPleasure

What rotors?

Changing to fresh pads will improve pedal firmness on its own. Maybe try that before the complete flush?

But I agree that a BBK is invitable if your fast and driving extended sessions on slick tires.

Personally, I see a lot of people buying fancy BBKs way before they have outgrown the blue boys.

Oem rotor

[SYT_Shadow]

Originally Posted by melanthius

Oem rotor

there's a significant difference between the OEM rotor and the Girodiscs that D_Sheer is running. With the Giros, the stock system is quite capable.

[melanthius]

Originally Posted by SYT_Shadow

there's a significant difference between the OEM rotor and the Girodiscs that D_Sheer is running. With the Giros, the stock system is quite capable.

I still need to get the sponge out.

Also I do have the budget now for bbk so the question is likely more a question of when rather than if. I should probably get a bit more use out of the system and seat time in the current state then lump my next set of upgrades together (bbk, SPL parts etc)

[SYT_Shadow]

Originally Posted by melanthius

I still need to get the sponge out.

Also I do have the budget now for bbk so the question is likely more a question of when rather than if. I should probably get a bit more use out of the system and seat time in the current state then lump my next set of upgrades together (bbk, SPL parts etc)

Something like the Alcon is a big step up in capability, you'll definitely be happy with it

[ninekrpm]

Originally Posted by jfritz27

Is it analogous to what this guy is doing with ISTA to his E90?

(Buried within/part of a DSC recal routine?)

I don't (yet) have a copy of ISTA so can't confirm whether this function is present for our chassis

Man…so grateful that I found this. Solved my issue…

Was experiencing a bit of pedal travel with my AP racing BBK. What a big difference…

[Insurme]

I’m experiencing very similar issue and curious if/how you resolved the issue?

[Theruleslawyer]

I wonder if this would help on the variable pedal issue some are experiencing?
https://f87.bimmerpost.com/forums/sh....php?t=1885341

[jfritz27]

I've had that coding done, it's definitely a worthwhile endeavor given it's cheap, and David is awesome. But I think his coding is more of a solution to the variability/inconsistency issue. If the main problem is more of a long travel before it seems to bite, but is consistent, then not sure the coding would be the fix (though couldn't rule-out it helping)

[ninekrpm]

Originally Posted by Insurme

I’m experiencing very similar issue and curious if/how you resolved the issue?

The issue I here was to recalibrate the brake pedal travel. However, I did not experience any brake issues.

My car recently went through surgery and several parts (abs system, brakes, etc.) were removed/installed, etc. I also swapped out the brake calipers to a new set...

The brakes pedal had some travel before they would fully engage - this was felt by me, but more importantly, validated by a pro-driver coach. He said I am losing at least a sec or two overall because of this, and my heel/toe is off a result.

With some research I found the above video and did the ISTA process while at the track. It recalibrated the brake pedal/pistons, etc. and confirmed immediately over the next session.

[ninekrpm]

Originally Posted by Theruleslawyer

I wonder if this would help on the variable pedal issue some are experiencing?
https://f87.bimmerpost.com/forums/sh....php?t=1885341

Originally Posted by jfritz27

I've had that coding done, it's definitely a worthwhile endeavor given it's cheap, and David is awesome. But I think his coding is more of a solution to the variability/inconsistency issue. If the main problem is more of a long travel before it seems to bite, but is consistent, then not sure the coding would be the fix (though couldn't rule-out it helping)

OK, the above is very different and it effectively turns off DBC (dynamic brake control). With all the recent reading I have done on this, DBC is predictive braking control and great for the street. I was recently pointed to this by a fellow board member and local track guy.

For the track, it can overcompensate depending on your speed, pressure, etc. The coding effective does a few things, including what I believe is to turn off the DBC.

I am actually interested in getting it done, been trying to reach daap1193 to discuss this.

jfritz27 would love to learn/hear more of your experience with the daap1193 coding.

[ninekrpm]

Just had the coding done from daap1193 as already stated, very responsive, informative, and quick.

Looking forward to testing it out tomorrow at Buttonwillow and Saturday at Willow Springs.

[jfritz27]

Originally Posted by ninekrpm

Just had the coding done from daap1193 as already stated, very responsive, informative, and quick.

Looking forward to testing it out tomorrow at Buttonwillow and Saturday at Willow Springs.

Good choice I think -- my feedback so far mirrors what others have said, it improves the consistency of the travel/bite relationship. I had this done simultaneous with other changes, including a fresh set of PFC11 pads, fresh SRF bleed using ISTA, and this was also one of my first days back on track in a new car after my accident last year (with new car being DCT, previous 6MT) -- so not the easiest apples-to-apples comparison. But I'll say the first day out with all the changes the initial bite was crazy -- it actually took a bit to get the right feel for it, particularly for faster corners where just a lighter brush is needed. But overall I feel like my brakes have been very consistent and well-behaved so far, so overall I'm pleased (also have Ti shims, and stock calipers rebuilt with the RB SS pistons and high-temp boots)

[ninekrpm]

Went to Buttonwillow on Friday, it was my first time there...so no comparison, but certainly felt the braking change.

Saturday, was at Willow Springs...it is a track I have spent a lot of time at recently; so had a good comparison.

That said, I "really like" the brake coding...it is direct, does require a bit more force, however, this is what allows you to modulate the brakes better, especially when trail braking into a corner. I certainly felt more confident/in control going into corners...

daap1193 was great to deal with...very responsive, and engaging.

Highly recommend both the coding and daap1193

[SilleM3]

Originally Posted by jfritz27

Is it analogous to what this guy is doing with ISTA to his E90?

(Buried within/part of a DSC recal routine?)

I don't (yet) have a copy of ISTA so can't confirm whether this function is present for our chassis

I did this and the 1-2 cm of travel is gone. This video helps. ISTA-D re-programs the DSC. I have a consistent brake pedal again. thank you.