Obioban's 2005 IR/IR Coupe

[Obioban]

Bought some corner balancing scales, though I haven’t used them for that yet.

I’m a bit disappointed. The truck/semi weight station had told me the car weighted 3071 lbs, but it would seem that was optimistic. 3112 lbs with a 3/4 tank. Pretty sure that means I’m not going to be able to get it under 3000 lbs with a full interior and quiet (stock weight) muffler

On the other hand, 52.6% front, 47.4% rear is better than I was expecting! 52.1% front with me in the car.





My winter projects will likely get it just under 3100 lbs.

[Obioban]

Should be useful on track (running on my head unit):



Only needs these little sensors on the valve stems:

[Obioban]

I’m very pleased with the stock look of the avin3, and all the functionality it’s enabled (not to mention the ~50 lbs of weight saving)!

[Obioban]

One of my winter projects on the M3 is brake ducting. I made some progress on that recently.

3D printed brake duct I designed. They are not cleaned up at all, because I didn't know if they'll be final.





They attach to the factory mount points, and run the air through the center of the factory brake duct/underbody mount bracket, so there won't be any hard bends in the 3" soft line.

They don't attach to the factory bumper, which means no unsightly screws visible on the bumper and taking the bumper off isn't a PITA:



They do fit with the fog light mount bracket attached.... but it's ugly.



Soooo... painful to do, after 15 years of faithful service from this bumper, but time to trim:



How it looks with the fog light mounting provisions all trimmed off:



Please excuse the Tesla like panel gaps in the bumper. Nothing was clipped in place because it was just a test fit-- still had to install the passenger side.

On the rotor side, I'm planning to use the Hard Motorsports 355mm BBK rotor duct, as it's the only solution I know of that's designed to work with 355mm rotors. It also vents into the center of the rotor, instead of the face, which is the correct way to do it (I was talking to one of Brembo's engineers, and his take was the ducting onto the rotor face on one side, but not the other, was worse than no ducting at all).

I did make an alternate version of the duct that include an intake air feed for the CSL box, similar in concept to the Evanturi bumper scoop. I'm going to monitor my IATs and install it if they're elevated vs ambient (they weren't before when above ~10mph). If they're not, I'd rather have equal brake ducting for the driver and passenger side.

I'm pretty enthused with the "look" of it, installed. That's pretty rare for me-- I almost always hate any change initially. But, I think they look "stock" if you didn't know the e46 m3 came with fogs from the factory. That's my criteria for any mods that change the look of the car-- if someone can pick out any given part as aftermarket, I don't want it on my car.

[Obioban]

Winter projects underway! The front end is getting a bunch of stuff done. Including, but not limited to...
-ZHP steering rack
-fresh inner and outer tie rods
-reduced assistance from the power steering pump
-new power steering lines and reservoir, converting the system to CHF-11S
-CSL Kingpins
-new front wheel bearings
-new spring rates
-going back to the stock oil cooler
-the previously mentioned brake ducting
-replace all fluids, everywhere in the car

I had some time on new years day and started pulling her apart.





^that's copper anti-seize, not rust :lolhit:

Lots of original parts getting replaced, which doesn't happen very often anymore

[Obioban]

Thought I should update last weekends progress before I started this weekend...

Cooked the studs out of my old hubs (getting replaced with the wheel bearings, as they're part of the same part):



Swapped the springs for 325 lb/in driver front, 300 lb/in passenger front, to try out the flat ride thing (still need to change the driver rear for a 700). Amazing how stock the Ohlins look with a black spring (as least if you're used to colors):



Swapped in the ZHP/yellow tag/712 steering rack (along with new (OEM) Lemforder inner and outer tie rods:



I'm also swapping the reservoir, since the PS fluid filter is built into it. But, I was pleased to see that the new cap is a CHF-11S cap, w which is the fluid I'll be running in this car going forward

[Obioban]

Brand new parts are so satisfying to work with. It's like having a CA car :roll:

CSL kingpins (with anti seize), Hard Motorsports 355mm brake duct backing plates (which are shitty, but I can't find an alternative), and new OEM (***) wheel bearings with OE dust caps.

[Obioban]

I've had a rethink on how I'm going to route it through the undertray.

I'm going to pass it through right below the sway bar mount bracket. But, instead of drilling a 3" hole and sticking the tube through, I'm going to print a bracket. On the far side I'll add some BMW under trim screw clips. The bracket will pass through and insert into another bracket on the other side. Screws will pass through the outside bracket, then through the underbody panel, then into the far side bracket with attached screw clips. This should minimize the hassle for any project where the undertray has to come out, or where I need the ducting out of the wheel well for car work, and make replacement hose easier (and less of it required) if something happens to the hose in the wheel well.

Inside bracket:



Outside bracket:



3 screws will take everything apart, while leaving the hose clamped onto the bracket

[Obioban]

Well, my pass through duct plan didn't work out. The flat portion of the belly tray doesn't extent far enough back to pass it through there and have the duct not interfere with the tire when at full lock. So, I just cut a 3" hole towards the front, and then made it into a U shaped slot that inserts over the duct. Not as fun as what I was hoping for, but it works :P

Anyway...

Wheel turned all the way in:




Wheel turned all the way out:




All the way out, from next to the car:




Mounted up from the front:




Unless I run into unexpected issues, I think this is complete.

[Obioban]

All buttoned up, with the bumper back on:



Side note:
ZHP steering rack, CSL Kingpins, and new wheel bearings are installed, and I'm back on the stock oil cooler.

The various projects took a couple lbs off the nose, so hopefully it's closer to an even 50:50 distro now.

I'm hoping to have time to corner balance the car this weekend (and code the MK60 for the new rack, and flush all the fluids), then take it to get aligned, then corner balance it again... and then I can finally form an opinion on this flat ride stuff

[Obioban]

I wasn't originally going to post about this, but the weight difference ended up being bigger than I expected. I noticed a while back that the CSL has a different aux coolant pump than the M3. This was probably to allow it to have more clearance to the airbox, but maybe not (since the stock on cleared). The CSL used the same one as the non M e46 (64118369805), so when I randomly stumbled upon one I grabbed it.

Dry weight between them is 1.22 lbs per realoem, but I suspect the actual weight difference is a little more since it fills with coolant.
CSL/e46 version: http://www.realoem.com/bmw/enUS/part...&q=64118369805
M3 version: http://www.realoem.com/bmw/enUS/part...&q=64118369807

Wiring was pretty easy-- the M3 version has two plugs, whereas the non M version has 1. One of the plugs from the M3 part connects to the non M version, so I used that, cut off the other and taped it into the harness, and all seems to work as expected.

Size comparison:




Installed:



I fully understand that 1.5 lbs isn't much in isolation. Just working on pushing that weight distro back to 50:50.

[Obioban]

I had the car on track this weekend with flat ride for the first time. Setup: 1.84hz front, 2.09hz rear, for a 1.13 bounce ratio, with a FRC of 68%. 3.25 front camber, 1.8 rear camber, square tire setup, square hot tire pressures.

The car DID settle down much faster, so I think I'm really going to enjoy flat ride, but... holy shit was it over steer city with that 68% FRC. It made it hard to think about anything else.

So, before my next event I'm debating the following options:
1) stock M3 rear sway. This would move me to a 69% FRC (1% change)... not overly significant change
2) remove the rear sway completely. This would give me a 76% FRC. Feels like this might be too significant of a change and make the car all understeer all the time.
3) remove the rear sway and change to stiffer rear springs. This would let me get any FRC I want, but make the rear of the car stiffer than I'd like
4) stiffer front sway. I'd rather not do this if possible.
5) increase rear bump travel/decrease rear droop travel. This will put the front into the bump stops before the rear, which should push the car into understeer more at the limit.

I'm pretty surprised how oversteery the car felt at 68%, given than the stock M3 is 68%! Maybe the oversteer/understeer limit feeling is more determined by the on bump stop FRC? In which case stock is 71.6%...

Anyway, I'm open to input as to which route to proceed with. I'm kinda sorta leaning towards stock M3 sway (moves me to 69%), but don't really want to spend another with the car wanting to spin on me every turn. I had quite a few pucker moments

Do we really think 75% is neutral? Seems like the stock M3 is biased towards understeer, and it's 68-72%...

I think I'm initially going to do a combination of 1 & 5, and see how she feels next event.

[Obioban]

I removed the rear sway (8 lbs of loss) and traded some rear droop for bump this weekend (the goal being to put the front into bump stops before the rear, putting the car into understeer if I run out of travel). The next day I took it out for some hard back roads driving. The car felt great, and I didn't remember till I got home that I had removed sway-- so it was certainly not ruined or made weird by the rear sway removal.

The limits are too high to judge the oversteer/understeer situation on the street, so I don't really have anything to report on that respect till the next event. Currently sitting at a 75.7 FRC.

The best way to describe the car now on back road bombing would be unflappable. The car was absurdly composed, no matter what I did with (to) it. Bumps were immediately absorbed, car never lost its set. I was actively driving in a style that would upset the car, and it just wasn't having it. I'm pretty sold on this flat ride concept! It also rides really well-- better than my 530i (came with not very good aftermarket springs) . IF the car ends up being too understeery with the new setup, I'll likely stiffen up the rear springs next.

Current setup:
1.84hz front, 2.09hz rear, 1.14 bounce ratio, 75.7% FRC.

Potential next setup, if the car is now too understeer biased:
1.84hz front, 2.20hz rear, 1.19 bounce ratio, 73.8% FRC

The steering is also not nearly as twitchy, with street camber/toe. I am surprised to say that the steering doesn't feel any heavier? This surprises me because I...
-reduced the power steering assist by 25%
-added caster via CSL kingpins, which should make it heavier
-add caster via camber/caster plates, which should make it heavier
-went to a faster ratio rack

This isn't really a complaint, as I didn't want it heavier-- I did the 25% less assist to reduce the pressure in the lines (make them stop sweating). Just surprising.

[Obioban]

4 track events coming up in the next 4 weeks! New tires (NT01s in 17x275 square), as well!

Just going to leave the car in track mode between events :P

Rear of the car is low because it's full of all my track stuff.

[Obioban]

Installed the SS heat shield on my section 2. That was a PITA with the section 2 on the car!