Your thoughts on the rebuild after the de-build; trackable daily

[CamasM3e93]

I have an '11 e90 M3 with 6MT, currently outfitted with a Harrop supercharger and CSF radiator. 130k miles, fresh BE rod bearings, car is on its second set of throttle actuators, original clutch working fine. Car has an ultimate clutch pedal and Autosolutions short-shift kit.

Original stock non-EDC suspension but every control arm on the front of the car was replaced with OEM at about 110k miles. The suspension is at the point where it needs to be addressed but still ok for the road.

I'm running the stock brake kits front and back with streetable track pads and Motul 660 fluid. Braking into corners at the tracks in my area at my current skill set is not a limiter to my performance in events - but I've never driven a car with a big brake kit so it's possible I don't know what I am missing. I have figured that my next step is to move into a proper track pad before spending the big bucks on a big brake kit but I'm open to being wrong on that idea.

I recently added a 911 996 twin turbo to the stable and that car is hella fast stock, such that I am considering pulling off my supercharger kit and going back to the S65's NA roots. The sound a car makes is a big part of my enjoyment and I miss the induction note of a NA S65. I'd like to manage things such that what I put back into the car $$$ is roughly what I get out of selling the Harrop kit.

Belts, pulleys, radiator hoses, water pump, thermostat, VANOS covers, valve cover gaskets - all replaced in the last 2 years


Basics I'm already planning for:
Carbon fiber plenum
Carbon fiber airbox lid
New fuel injectors (fuel pump and fuel sender done in '23)
Spark plugs
BPM stage 1 or 2 tune
Fuel breather valve


That leaves 4-6k US for me to spend on other items that might benefit me at the track in this dual use track and daily car. Not on the table: interior mods, track seats, etc


Things I'm considering and would like your thoughts. Obviously some of these are big ticket items and I won't be able to do it all, so your idea on prioritization for those who track their m3's is appreciated:
in-line fuel filter
Power steering reservoir upgrade
Low temp thermostat
coil-overs v OEM refresh of struts / springs
New diff
Big brake kit(s)
Other items I'm not considering

[spammysammich]

I’d say unless you’re really out driving your braking capacity, just keep throwing pads rotors and good fluid at it. I priced out rotors and pads for my car with the 365 mm GT kit and it was around 5 grand in parts. I don’t track the car at all so far and while yeah it is great that I could just drive it straight to the ridge and probably not need to dial in anything on it, the maintenance costs are prohibitively high. All depends on your needs. I much prefer the stock brembo kit on the STI as it doesn’t require removing the calipers to change the pads.

[mikerunt]

APs or nothing at all

[kolosy]

i get that the cf plenum amps up the sound you're after, but i'd save the $3K you'd spend there and throw more track parts at it. i ran into significant cooling issues with mine (though you won't have the DCT cooling concerns, but still), so budget for an oil cooler since you already have the rad. i went the coilovers and BBK route on mine, and find the ride comparable if not better than the original EDC setup, but that's a diff conversation. Also look at a schroth quickfit harness. Easy way to get a snugger fit without going with race seats / other interior mods..

[M3SQRD]

I agree with kolosy on the CF plenum and especially on a CF airbox cover. Save the $2-3k for other performance mods and/or upgraded coolers, etc.

I’d do the following if your starting to track (in no particular order):

1. Camber plates. If you don’t already have them, get a set of camber plates that work with the stock fronts struts. These pay for themselves by increasing tire life and improving grip/performance.

2. Pads and Fluid. What streetable track pads are you using? Regardless, I’d recommend switching to a race/track pad. Streetable track pads really don’t exist and prevent you from fully using all of the braking performance. A race/track pad will eliminate one failure mode from the brake system. As for a brake kit, it shouldn’t reduce your braking distance, which is dominated by tire grip, it should allow you to go lap after lap after lap…without loss of any braking performance. Basically, it’s increasing your thermal capacity as well as reduce brake component wear (pads and rotors), improve modulation and improve pad release characteristics (both are also influenced by pad choice). So hold off on a brake kit and instead spend the plenum and brake kit money on a good suspension! If you need new rear suspension components , invest that money instead in a new suspension setup Your brake fluid is fine but make sure it’s fresh for the track. You don’t want dirty, worn out fluid in the calipers to boil quickly the first time you go out onto the track.

3. Tires. Unless I missed it, I didn’t notice any mention of tires. Depending on your skill level, I’d recommend max performance if you’re just getting started or extreme performance (200 TW) if you’re more experienced but stay away from r-comp and slick tires. Build up skills before advancing to the next step up in tire grip level. You’ll develop bad habits if you jump straight into the grippiest tires available. Start with lower grip tires and work up to higher grip tires, building driving skills and smoothness as you progress thru tire grip levels.

4. LCA monoball. This is a relatively inexpensive upgrade that is worth it. It will improve steering feel a bit, slight improvement in turn-in and improved stability under braking.

5. Maintenance. Stay on top of maintenance items and replace hubs, etc. that get abused on track and/or are subjected to high temps.

6. Seat time. The driver mod is one area to invest! Seat time, seat time and more seat time to build and hone your driving skills. One area that can always be improved.

7. DSC/MDM. Free mod! Turn this off sooner rather than later. Leaving it on for too long will allow you to develop bad habits without even knowing it and think you’re more skill than you actually are. Then when you finally turn it off, you find yourself in over your head. You’ll develop better skills if you start with DSC off and go slow (6/10) than you will if you drove with it on and went fast (9/10) because you’re the one always in charge of control and corrections. So when you finally reach 9/10 you have the appropriate driving skills/car control to match the 9/10 speed.

8. Power. I know you have the Harrop SC but starting out with stock power level allows you to build car control skills and learn how to carry the most momentum thru a corner without relying on power to make up for your mistakes. Learn car control, being smooth and maximizing momentum before unleashing the power.

[OmairK]

Interested in that Harrop lol.

[CamasM3e93]

Originally Posted by M3SQRD

I’d do the following if your starting to track (in no particular order):

1. Camber plates. If you don’t already have them, get a set of camber plates that work with the stock fronts struts. These pay for themselves by increasing tire life and improving grip/performance.

Definitely plan camber plates along with coilovers.


2. Pads and Fluid. What streetable track pads are you using? Regardless, I’d recommend switching to a race/track pad. Streetable track pads really don’t exist and prevent you from fully using all of the braking performance. A race/track pad will eliminate one failure mode from the brake system. As for a brake kit, it shouldn’t reduce your braking distance, which is dominated by tire grip, it should allow you to go lap after lap after lap…without loss of any braking performance. Basically, it’s increasing your thermal capacity as well as reduce brake component wear (pads and rotors), improve modulation and improve pad release characteristics (both are also influenced by pad choice). So hold off on a brake kit and instead spend the plenum and brake kit money on a good suspension! If you need new rear suspension components , invest that money instead in a new suspension setup Your brake fluid is fine but make sure it’s fresh for the track. You don’t want dirty, worn out fluid in the calipers to boil quickly the first time you go out onto the track.

Appreciate this and spammysammich input. But looks like we have another season where the Hawk blue compound is challenging to source.


3. Tires. Unless I missed it, I didn’t notice any mention of tires. Depending on your skill level, I’d recommend max performance if you’re just getting started or extreme performance (200 TW) if you’re more experienced but stay away from r-comp and slick tires. Build up skills before advancing to the next step up in tire grip level. You’ll develop bad habits if you jump straight into the grippiest tires available. Start with lower grip tires and work up to higher grip tires, building driving skills and smoothness as you progress thru tire grip levels.

I ran Nitto NT01's 275 35 18 square last season. I chose the tire, in part, for durability. I suspect this set will get me through 2024.


4. LCA monoball. This is a relatively inexpensive upgrade that is worth it. It will improve steering feel a bit, slight improvement in turn-in and improved stability under braking.

What's the implication on street driving?


5. Maintenance. Stay on top of maintenance items and replace hubs, etc. that get abused on track and/or are subjected to high temps.

Good thought. I was thinking about the diff but hadn't given much thought to hubs - or wheel bearings themselves, if not hub/bearing.


6. Seat time. The driver mod is one area to invest! Seat time, seat time and more seat time to build and hone your driving skills. One area that can always be improved.

Roger that - hoping to hit ~10 events this season. Time conflicts are the limiter for me.


7. DSC/MDM. Free mod! Turn this off sooner rather than later. Leaving it on for too long will allow you to develop bad habits without even knowing it and think you’re more skill than you actually are. Then when you finally turn it off, you find yourself in over your head. You’ll develop better skills if you start with DSC off and go slow (6/10) than you will if you drove with it on and went fast (9/10) because you’re the one always in charge of control and corrections. So when you finally reach 9/10 you have the appropriate driving skills/car control to match the 9/10 speed.

Way ahead of you. Took a skip pad course in the fall to prepare for this practice. I typically run with euro MDM settings with new goal to run traction control off.



8. Power. I know you have the Harrop SC but starting out with stock power level allows you to build car control skills and learn how to carry the most momentum thru a corner without relying on power to make up for your mistakes. Learn car control, being smooth and maximizing momentum before unleashing the power.

Check. Although will admit tracking the Harrop can be grin-inducing as it covers over early intermediate mistakes. Will also admit I have been passed by miatas and at least one Honda Civic. So your point is well taken.

Appreciate it!

[M3SQRD]

CamasM3e93

If you decide to stick with the stock suspension, buy a set of camber plates that can be converted from stock spring to a linear race spring and a different shaft size so they can be reused on your coilovers.

I’d consider Cobalt XR4, preferably XR3, pads or PFC 08 or 11 pads. You could also try their z-rated pad compound , if available, which is a street pad that works ok on track. Ferodo DS2500 is another street pad that does ok on track that aren’t tough on pads

NT01 is a solid track tire and, because you’ve been running them, no need to switch to something else.

Monoball. No downside at all to running them on the street. I have them on four cars, including my wife’s car, and we haven’t noticed any increase in NVH. Make sure it’s a sealed bearing. I’ve had a set on my ‘09 e92 M3 for 13 years and they’ve still working perfectly without noise.

M variable diffs have lost a huge portion of their locking capabilities after 50-60k street miles. The diffsonline 3.62 FD (DCT) diff is the best mod I’ve done by far. Even if you stick with the stock FD, a clutch type diff makes a huge difference!

I bet the Harrop SC is a blast but it does make your learning curve more challenging than a stock power learning curve which is already challenging to extract 100% of its performance. I learned to drive on track in an ‘88 CRX and a ‘92 Civic Si so I had to learn to keep the speed up thru corners otherwise I was a slow moving road block

[CamasM3e93]

Originally Posted by M3SQRD

CamasM3e93

If you decide to stick with the stock suspension, buy a set of camber plates that can be converted from stock spring to a linear race spring and a different shaft size so they can be reused on your coilovers.

I’d consider Cobalt XR4, preferably XR3, pads or PFC 08 or 11 pads. You could also try their z-rated pad compound , if available, which is a street pad that works ok on track. Ferodo DS2500 is another street pad that does ok on track that aren’t tough on pads

NT01 is a solid track tire and, because you’ve been running them, no need to switch to something else.

Monoball. No downside at all to running them on the street. I have them on four cars, including my wife’s car, and we haven’t noticed any increase in NVH. Make sure it’s a sealed bearing. I’ve had a set on my ‘09 e92 M3 for 13 years and they’ve still working perfectly without noise.

M variable diffs have lost a huge portion of their locking capabilities after 50-60k street miles. The diffsonline 3.62 FD (DCT) diff is the best mod I’ve done by far. Even if you stick with the stock FD, a clutch type diff makes a huge difference!

I bet the Harrop SC is a blast but it does make your learning curve more challenging than a stock power learning curve which is already challenging to extract 100% of its performance. I learned to drive on track in an ‘88 CRX and a ‘92 Civic Si so I had to learn to keep the speed up thru corners otherwise I was a slow moving road block

Very helpful input, giving me some critical things to think about and exactly what I was hoping for. Thank you!

Are you running a 3.62 FD on a manual car? Would you do solid (or poly) rear subframe mounts if I upgraded the diff?

[M3SQRD]

Originally Posted by CamasM3e93

Very helpful input, giving me some critical things to think about and exactly what I was hoping for. Thank you!

Are you running a 3.62 FD on a manual car? Would you do solid (or poly) rear subframe mounts if I upgraded the diff?

You’re welcome

I have DCT. I believe MT stock FD is 3.85. I’d go with at least a 4.10 FD with a MT. Definitely solid Al subframe bushings. Poly diff bushings. Solid diff bushings will introduce diff whine at various road speed ranges.

[kolosy]

Originally Posted by M3SQRD

You’re welcome

I have DCT. I believe MT stock FD is 3.85. I’d go with at least a 4.10 FD with a MT. Definitely solid Al subframe bushings. Poly diff bushings. Solid diff bushings will introduce diff whine at various road speed ranges.

fwiw, i just installed powerflex black diff bushings and now do get a touch of diff whine.

[M3SQRD]

Originally Posted by kolosy

fwiw, i just installed powerflex black diff bushings and now do get a touch of diff whine.

Not surprised you’re hearing faint diff whine with black diff bushings. However, the diff whine I’m talking about is loud, not full race car loud, but loud enough to be annoying. Bringing back fond memories of my track prep’ed e46 M3 with 4.10 FD LSD which I regret selling

[amrazM]

Not sure if I would go back to NA, while the sound of a cf plenum is good (s54 is better), the s65 is gonna feel a bit boring without the power adder. S65 with boost kinda fits into a unique category other cars dont, people who havent experienced wouldnt really understand but the power of this car with just 8psi in it makes it very entertaining to drive.

[RocketyMan]

CamasM3e93

Before you take off your Harrop, can you take me for a ride around the block so I can experience this 8 psi boost on an S65?

[omgzirra_exe]

BBK = better consistency = better track times = more fun :")

also... cheaper to replace rotor rings than it is to replace oem floaters or girodisc.

$800 all in cost to replace rings vs $1200? unless FCP i guess,