kolosy build / track journal-ish

[M3SQRD]

kolosy

The Paragon six-p fixed caliper with the quoted piston diameters is only 89% of the stock front one-piston fixed caliper with a 60 mm diameter piston. However, the forward brake bias for Paragon F/stock R and stock F/stock R are 60.1% and 62.6%, respectively.

The xp24 is a pad compound with extremely high initial bite and torque. It’s probably too much for a street car on 200-300TW tires with factory ABS software and a car that has no functional aero. It’s going to be challenging to stay out of ABS as well as modulate and release smoothly. This way help with wear rate but it’ll also potentially cause new issues.

[kolosy]

Originally Posted by M3SQRD

kolosy

The Paragon six-p fixed caliper with the quoted piston diameters is only 89% of the stock front one-piston fixed caliper with a 60 mm diameter piston. However, the forward brake bias for Paragon F/stock R and stock F/stock R are 60.1% and 62.6%, respectively.

The xp24 is a pad compound with extremely high initial bite and torque. It’s probably too much for a street car on 200-300TW tires with factory ABS software and a car that has no functional aero. It’s going to be challenging to stay out of ABS as well as modulate and release smoothly. This way help with wear rate but it’ll also potentially cause new issues.

Fair. What are your thoughts on upgrading the rear pads from XP10? Given the increased rearward bias, an undersized pad there could become even more impactful, right?

[M3SQRD]

Originally Posted by kolosy

Fair. What are your thoughts on upgrading the rear pads from XP10? Given the increased rearward bias, an undersized pad there could become even more impactful, right?

I intentionally run a pad with a higher CoF on the rear to get more out of the rear at certain tracks. If I’m not doing this I use the same (or similar depending on availability) pad compound F & R. For example, for your Paragon F and stock R if you ran a front pad with a 0.4-0.5 CoF and a rear pad with a 0.5-0.6 CoF you’ll shift your forward bias from 60.1% to 55.0-56.0% - 4-5% shift rearward. Combined with a high front spring rate, you can gain a significant time advantage in braking zones. SYT_Shadow is an expert at gaining time in braking zones

[amg6975]

Originally Posted by omgzirra_exe

it's just not using the rear brakes as much since your doing MDM off.

rears almost never wear out that fast.

MDM uses the fonts more than the rears from my understanding. I never have issues with the rears but running with MDM will absolutely destroy my front pads.

[omgzirra_exe]

Originally Posted by amg6975

MDM uses the fonts more than the rears from my understanding. I never have issues with the rears but running with MDM will absolutely destroy my front pads.

you are correct, but it still uses some rear pad. realistically rear pads shouldn't be changed much.

in terms of BBK and matching compounds... AP suggest just running similar compound to the front. (which i apply to other BBK set ups, minus the garbage "oem" bbk upgrades)

[M3SQRD]

Originally Posted by amg6975

MDM uses the fonts more than the rears from my understanding. I never have issues with the rears but running with MDM will absolutely destroy my front pads.

A few years back dogbone measured brake line pressures and on his TT setup e90 M3 showed MDM and DSC on it was close to 100% of the stability control corrections were rear brake applications, not front. However, his static handling balance and real aero means this doesn’t directly apply to stock setups with more understeer. For example, if the right rear steps out, DSC/MDM, can either use the rear left brake or the right front brake to counteract the yaw inertia about the positive vertical axis thru the CoG, keeping the car from spinning/rear sliding. A big correction like uses the front because it has more brake torque capability and, therefore, more mechanical advantage about the CoG. Corrections are based on stock brake pad CoF so with race pads the correction is higher than what’s needed. This is one reason why MDM can let things get out of control.

The f8x destroys rear pads if MDM/DSC on (no personal experience because I run with fully off DSC).

With your car do you think MDM is trying to counteract understeer or oversteer or both?

[amg6975]

Originally Posted by M3SQRD

With your car do you think MDM is trying to counteract understeer or oversteer or both?

Good question, with it off, it's extremely neutral but I would guess that the majority of the front application is trying to fight understeer. You can really notice it when you're fighting to get the car down to the apex, it'll really start to pulse the brakes with any sort of slip angle.

I never really noticed it coming up through the HPDE classes, but now after a couple years running with out and gaining a ton of pace turning it on is crippling to lap times.

[M3SQRD]

Originally Posted by amg6975

Good question, with it off, it's extremely neutral but I would guess that the majority of the front application is trying to fight understeer. You can really notice it when you're fighting to get the car down to the apex, it'll really start to pulse the brakes with any sort of slip angle.

I never really noticed it coming up through the HPDE classes, but now after a couple years running with out and gaining a ton of pace turning it on is crippling to lap times.

I wish MDM was more like Porsche’s stability control that allows you to buildup high slip angle before intervening. The Corvette and Camera ZL1/1LE have superior stability control. MDM kicks in before it lets you buildup a noticeable slip angle. Even worse is when it basically decides it’s done helping out, leaving you high and dry so sort out the mess.

[e92BMW///M3]

Originally Posted by kolosy

I’m running the 3DM dedicated track kit, with upgraded swaybars and all solid/spherical rear end and mono balls up front. -3.5 camber front, -2 rear.

If you're running the Ohlins Dedicated Track kit, would appreciate if you could confirm the spring preload measurement? I installed mine today based on their instructions (184mm) but it looks like a monster truck so wanting to trouble shoot. I will certainly adjust the independent ride height, but its so off that I think the preload has to be wrong also.

[kolosy]

Originally Posted by e92BMW///M3

If you're running the Ohlins Dedicated Track kit, would appreciate if you could confirm the spring preload measurement? I installed mine today based on their instructions (184mm) but it looks like a monster truck so wanting to trouble shoot. I will certainly adjust the independent ride height, but its so off that I think the preload has to be wrong also.

ah crap just had the car out yesterday. i'll take a look but it's stored offsite. I'd email Barry -- he's super responsive.

[kolosy]

Aaand that’s a wrap for the season. In the two years before this one, I did about 6 days total, counting the Porsche school down at Barber. I started this year with a PR of 1:24.9 on my home track (Blackhawk Farms, 2 miler). This year I did 14 days, and closed out the season with a 1:20.9 on the same track (I ran it in 1:18.9 in my G82 M4, but alas she’s in a better place now).

With the Midwest season over (or almost over, but I can’t make any of the October dates work), the car is going under the knife. She’s done remarkably well, especially considering that she’s got 151K miles on her now.

To recap, here’s where it sits now:

- WPC treated RBs, ~50K miles ago
- All new cooling (CSF Rad and oil cooler, do88 DCT cooler)
- VTT aluminum DCT pan
- Supersprint F1 catless exhaust
- CF driveshaft
- All solid/spherical rear suspension components, GC rear arms
- BW rear subframe bushings
- Powerflex Black diff bushings
- Turner front monoballs
- SPL front endlinks
- HR swaybars front/rear
- 3DM dedicated track suspension (running -3.7 front / -2 rear camber)

My plan for the winter is to focus on weight and safety. I’ve seen enough oopsies and been in one myself that I don’t want to mess around anymore. I’ll be stripping out the interior, and putting in a full cage and seats (still need to decide if I want something like a Profi SPG XL or a halo seat)

Beyond that, I think I want to keep the suspension and brakes about the same. I’m only now starting to get to the point where I can tell a difference and want to be a better driver before I really start messing around with that stuff.

Will take any advice you guys have along the way!

[Redd]

You need a proper diff.... 😁

[kolosy]

Originally Posted by Redd

You need a proper diff.... 😁

Yeah I was thinking about that. Easier than a s/c too

[M3SQRD]

I have a diffsonline 3.62 FD DCT LSD and it makes a huge difference in all performance categories. If you’re not driving to events with a full cage, I’d go with a 3.85 FD. Trip speed will still be 171 mph so no worries about running out of top speed on track. Driftflo is a great resource regarding diffs on the forum. I’ve used diffsonline for all of my LSDs (no issues but driftflo has more clutch-type options) but I’d probably go with driftflo if I was starting over. Far better than a SC and it keeps the characteristics of a NA 4.0 L V8. I’d recommend a stage II tune with a raised 8600 rpm redline and DCT software that updates the FD ratio.

I’d strongly recommend a halo seat if you’re going the full cage route. Hans + halo provides the most safety for your head and neck coming from someone who’s had 10 spine surgeries!

[kolosy]

Originally Posted by M3SQRD

I have a diffsonline 3.62 FD DCT LSD and it makes a huge difference in all performance categories. If you’re not driving to events with a full cage, I’d go with a 3.85 FD. Trip speed will still be 171 mph so no worries about running out of top speed on track. Driftflo is a great resource regarding diffs on the forum. I’ve used diffsonline for all of my LSDs (no issues but driftflo has more clutch-type options) but I’d probably go with driftflo if I was starting over. Far better than a SC and it keeps the characteristics of a NA 4.0 L V8. I’d recommend a stage II tune with a raised 8600 rpm redline and DCT software that updates the FD ratio.

I’d strongly recommend a halo seat if you’re going the full cage route. Hans + halo provides the most safety for your head and neck coming from someone who’s had 10 spine surgeries!

Why driftflo over diffsonline?

[M3SQRD]

Originally Posted by kolosy

Why driftflo over diffsonline?

Mainly because he has more diff options especially lightweight options. His pricing is better (four-five years ago) even with it coming from Europe. I have no issues with diffsonline and my two diffs have performed flawlessly. Also, if you preferred to use a US vendor then you’d be in great hands with diffsonline.

[DRLane]

Originally Posted by M3SQRD

Mainly because he has more diff options especially lightweight options. His pricing is better (four-five years ago) even with it coming from Europe. I have no issues with diffsonline and my two diffs have performed flawlessly. Also, if you preferred to use a US vendor then you’d be in great hands with diffsonline.

If you’re racing or building to this caliber, it’s worth noting stateside support is helpful! Although Dan is a proper Boston guy with accompanying personality.

Florian’s options are obviously super solid and well priced, but at the pointy end Dan’s race carrier is comparable (weight, performance, customization).

Edited to fix my spelling

[M3SQRD]

Originally Posted by DRLane

If you’re racing or building to this caliber, it’s worth noting stateside support is helpful! Although Dan is a proper Boston guy with accompanying personality.

Diflo options are obviously super solid and well priced, but at the pointy end Dan’s race carrier is comparable (weight, performance, customization).

It’s been a while since I last discussed diffs with Dan but at that time he didn’t have many different diff setups for the e9x M3 or perhaps we didn’t discuss them because I was looking for a track-street clutch-type setup biased towards track. Dan and Florian are both experts when it comes to spec’ing and building the correct diff for your needs. What’s crazy is if you buy a BMW race spec Drexler (e.g., f82 GT4, f87 CSR) diff the cost is roughly ~1/2 the cost of an equivalent diff from Dan or Florian. Only downside is the diff comes with the stock FD ratio only.

[kolosy]

maybe i just suck at the googles, but i can't find anything on diflo. what's his website?

[bipp]

Originally Posted by kolosy

maybe i just suck at the googles, but i can't find anything on diflo. what's his website?

driftflo at https://limitedslip.de

edit: i figured "diflo" was a typo

[M3SQRD]

Here’s his diff thread:
https://www.m3post.com/forums/showthread.php?t=788992

[M3SQRD]

Originally Posted by bipp

driftflo at https://limitedslip.de

edit: i figured "diflo" was a typo

I had it typed correctly