My E90 M3 Dedicated Track build (with pix!)

[///Mobbin]

Originally Posted by dogbone

Here's one more interesting piece of info regarding shedding weight:

I contacted Motorsport24 in Germany regarding their carbon doors. It turns out these are not just generic off the shelf items. You can influence the build of them. For instance, if maximum lightness is your goal, they can use less resin, etc.

I was curious how much weight could be lost by replacing my stock gutted doors. I weighed my front doors and they are 35lbs each. I'll guess my rear gutted doors weigh about 30lbs each.

The carbon front and rear M24 doors weigh on average about 5lbs each......!!!

So you could lose around 110lbs from the car with a door swap. Nice!!

Cost: 3950 Euro (includes VAT, but not shipping). Takes about 4 weeks.

Anyway, I always wondered about the weight savings from doors. It was more savings than I thought it would be. And Motorsport24 was very responsive. If I were to do it, I think these guys would do a nice job. Jordan Yost's car runs them. I was chatting with him on Friday. He seems happy with his set on the coupe.

I love that the modding isn't over yet. Your car is going to be one of the most highly prepped individually owned e90 m3's out there. Go go go!

[-BEASTMW-]

I saw you at Laguna on June 8! I was in a silver S2k but I didn't come and talk to you. I just remember thinking how crazy you must be to completely strip an E90 M3 haha! I specifically remember the door shutting and sounding so hollow and bare. Very cool that you did all this and must be simply awesome to drive.

[dogbone]

Originally Posted by -BEASTMW-

I saw you at Laguna on June 8! I was in a silver S2k but I didn't come and talk to you. I just remember thinking how crazy you must be to completely strip an E90 M3 haha! I specifically remember the door shutting and sounding so hollow and bare. Very cool that you did all this and must be simply awesome to drive.

Thanks! You should have come over and said hi! There was a whole group of us there. We didn't bite!----well, one of us did, but we know how to control him….

That was the first weekend I was driving the car gutted and caged. It was a mind blowing experience that weekend because I've driven the car for several years with a full stock interior. Obviously, the car was ridiculously different! There was no aero on the car and the rear was all over the place because it was so much lighter back there after the gutting. Plus, it's just SO much louder in there now. But, it is quite a blast to drive.

Now with the full aero on it, the car is very balanced and SO MUCH fun to drive. I'm dropping multiple seconds off my previous bests every track I visit. I dropped 3 seconds off my time at Chuckwalla (1:55.8), 2.4 seconds at Big Willow (1:28.4), and 5 seconds at Buttonwillow (1:49.0). And these are just my first visits to these places with the aero. I'm just starting to learn what all these changes are netting me. The car has much more in it. We'll see how much more I have in me. It will be a fun process learning to drive what is basically a whole new car.

And now, I have one more big change in the car………after 48000 miles, a part was wearing out and was making funny noises. It's been replaced with an aftermarket part upgrade. It just got installed yesterday (unfortunately, I'll have to wait until January to check it out). Anyone wanna guess what it is?

[evilspiritM3]

Originally Posted by dogbone

Thanks! You should have come over and said hi! There was a whole group of us there. We didn't bite!----well, one of us did, but we know how to control him….

That was the first weekend I was driving the car gutted and caged. It was a mind blowing experience that weekend because I've driven the car for several years with a full stock interior. Obviously, the car was ridiculously different! There was no aero on the car and the rear was all over the place because it was so much lighter back there after the gutting. Plus, it's just SO much louder in there now. But, it is quite a blast to drive.

Now with the full aero on it, the car is very balanced and SO MUCH fun to drive. I'm dropping multiple seconds off my previous bests every track I visit. I dropped 3 seconds off my time at Chuckwalla (1:55.8), 2.4 seconds at Big Willow (1:28.4), and 5 seconds at Buttonwillow (1:49.0). And these are just my first visits to these places with the aero. I'm just starting to learn what all these changes are netting me. The car has much more in it. We'll see how much more I have in me. It will be a fun process learning to drive what is basically a whole new car.

And now, I have one more big change in the car………after 48000 miles, a part was wearing out and was making funny noises. It's been replaced with an aftermarket part upgrade. It just got installed yesterday (unfortunately, I'll have to wait until January to check it out). Anyone wanna guess what it is?

New Diff???

[roastbeef]

My money is on a new diff! Did you go with solid bushings yet?

[dogbone]

Originally Posted by evilspiritM3

New Diff???

Yes!

After a lot consideration, I decided to go with the OS Giken SuperLock. This is a "Spec-X" because OS Giken did a custom setup based on the particulars of my car.

I am quite curious about how this will feel. (it won't be until January…..) A higher performance differential should reduce the lag time from when you press the gas pedal and when the weighted outside rear wheel gets the power. I have been warned to take it easy and get a feel for it. Being able to "Put down the power" means the car can go sideways more easily/quickly than with the stock LSD, so re-learning gas pedal modulation will be the top priority. Also, I keep hearing that the suspension setup may need some revisiting. The hope is that a properly setup diff allows you to get on the gas less, yet have better acceleration out of corners. Also, as this is a 1.5 differential, it should provide some degree of lockup on deceleration to give stability while braking (which the stock unit does not do), but hopefully will open back up quickly for corner entry to avoid understeer that would be caused by two rear wheels being locked together.

This thing is a work of art inside!







Once I realized I needed to do something about the diff, I had wondered how I could quantify the OS Giken's performance characteristics versus my stock diff. Honestly, this topic seems so shrouded in mystery sometimes. Finally, I realized I could analyze the new diff's performance compared to my stock diff with the AIM Solo DL since it's connected to the CAN bus and can collect individual wheel spin information (in mph), and then chart it. By comparing the rear wheel spin rates, you can at least get a sense of how fast the diff reacts to pedal input.

Below is a chart from the AIM Solo DL showing my two rear wheels at Buttonwillow with my stock diff (and DSC-off), along with the top-most chart showing gas pedal position. The numbers from 600-4000 at the bottom of the chart show how many feet down the track I am. The two lower charts, which are mostly parallel to each other, are the speeds of my rear wheels. The lower chart is the right wheel and the higher chart is the left wheel. What we will see is that the stock differential stays open for some time when you initially get on the gas, which means it is initially sending the engine's power to the unweighted inside wheel, which on a track is not really what you want. The yellow highlighted areas are the moments of interest. In a corner, if we see a spike in the unweighted wheel's chart over the weighted one, then the diff is staying open longer and not applying power to the weighted wheel, allowing the unweighted wheel to spin faster due to receiving a lot of power.

The first yellow circle highlight at the left at 825 feet is at Turn 1/Sunrise at Buttonwillow. It's a left turn. That spike in the left wheel speed occurs as I get on the gas at the apex. The right side of the car is loaded and the diff sends the initial power to the left wheel and it starts spinning at a higher rate than the right.

At 1800 feet, we are at Turn 2/Off-Ramp, a sharp right hander that goes up hill. You can see the lower line/Right wheel spins up, and it's not just a spike---it stays spun up for over 100 feet. The left side is loaded hard. I hit the gas, the power goes to the unweighted right side of the car and the unweighted wheel starts spinning. Then again at 2200 feet as I'm still going up and it gets a tad off-camber at the top, when I get hard on the gas, that same unweighted wheel spikes again.

At 3500 feet, the left wheel spikes. This is the left turn to go up the hill in Cotton Corners. The right side is loaded and the left side is unloaded. The left wheel spins because the LSD is staying open until it senses enough torque to start locking.

It's not highlighted in yellow, but it's interesting to note that at 3700 feet, the weighted wheels spin up somewhat aggressively going up the hill of Cotton Corners. In my in-car video, I can see the tail moved out a bit, but not in an unexpected way. (I have been working on trying to climb that hill as rapidly as possible. You can see the gas pedal position at 3500 feet is quite aggressive.)



So, we can see the stock differential does allow for some inside wheel spin and does take some time before it does any locking. That's not necessarily bad. It's a "safe" diff. And my car isn't' exactly slow. But if you're not worried about driving on the street, you can get a differential that is more performance and locks faster. People say that "the gas pedal is more directly connected to the weighted rear wheels".

In theory, when looking at a future chart, a more performance oriented diff should reduce these unweighted inside-wheel spin spikes. It should lock sooner and send power to the weighted wheel more quickly, thus reducing wheel spin on the unweighted side, and giving the weighted wheel with the most traction more acceleration potential and more quickly.

In reality, an aggressive differential is not good for the street. First, a diff that locks aggressively will make low speed turning on the street a nightmare. The axle will be locked and the inside tire will grind and skip and be yucky. Second, an aggressively locking differential can be unsafe for someone not expecting it. Some dude with a new car wants to show off and gases it hard in corners. If a diff is lightning quick about sending power to the weighted wheel and the car has a lot of power, he can spin the weighted wheel easily and that dude is going sideways instantly.

In my case, I've driven so much with MDM-on over the last 4 years that I could say that I haven't really fully explored what the stock diff could do, so why bother with a more performance oriented one? Honestly if my original diff had been fine, I would not have considered this piece yet. But it turns out I was forced into the position of doing something about my stock one. Now that I'm driving more with DSC-off, it seemed like a reasonable time to consider alternate options. Getting one customized for my car by OS Giken seemed like an interesting way to go. We'll see what it feels like!

[dogbone]

Originally Posted by roastbeef

Did you go with solid bushings yet?

I have purchased them, but they are not installed yet. I want to drive the new differential with everything else being the same first and try to get a feel for it.

[dogbone]

Well, 2016 has started off with a flurry of activity on my car.

First, I was able to drive the new OS Giken differential at Buttonwillow. I like it. It feels responsive to gas pedal input, but I haven't power-slammed on it yet because I like to work up to these things and there was mud on and around the track all day so it wasn't great conditions to "go for it". But I was running 1:53 laps and it felt nice. The MOST apparent thing right from the get-go is the braking. Holy cow. Initial braking so SOOO stable with the diff locking on deceleration. It's feels like a parachute is slowing the car. Quite amazing. I like that very much.

We drained the break-in fluid and put in the permanent fluid. It's an OS Giken brand fluid. It is QUITE thick--80W-250. Anyway, I'll post more detailed thoughts about the diff soon along with AIM data. I'm driving it again this Sunday so I'll post more about it after this weekend.

Ok, I know I know, nobody cares about the diff. Moving on.

Mod 1: Halo seat. This past summer, I bought a Recaro SPG but it was not a Halo seat. I have felt that the Halo feature was the last piece of the puzzle in terms of safety that I was missing. So, I bought a Recaro Pro Racer SPG Fiberglass. They call it an SPG, but it's not really the same seat. I had assumed it was an SPG with a Halo added on. Wrong. It's narrower than the SPG, you sit deeper because the sides are quite high---or at least the sides feel higher because the padding is thinner, the shoulders fit tighter. None of this is bad. It's just different. Honestly, I don't know why they gave it the "SPG" same. The one thing I like I REALLY do like about it is that the slot between your legs for the buckle/anti-sub straps sits 2 full inches further away from you than the SPG. This keeps the straps further away from your crotch which was a welcome change. Also, compared to an SPG, the Halo seat mounting holes sit you 1 inch closer to the steering wheel than my original SPG, so we had to readjust and move to different holes in the floor bracket.

Getting in and out is noticeably more difficult with the Halo feature. I don't have a removable steering wheel, and I don't have rail sliders. It's fine, but more difficult. I have tried to avoid rail sliders because I wanted everything locked down. And switching steering wheels is a bit of a pain because I want to keep access to the "M" button. Apparently, the "M" button has a special coded signature, so you can't just replace it with a generic alternative. Ultimately, we may look at moving the "M" button to the carbon fibre blank panel so a removable steering wheel is possible. That's a project for another day.

Anyway, I am very happy overall with the look, feel and safety of the new seat. I'll be on the track with it in 2 days. Looking forward to it!





Mod 2: Passenger seat. I installed the SPG over to the passenger side for now. I don't think I'll run a passenger seat all the time, but I figured I'd put there for now. It's easy to remove. The passenger seat adds about 30 lbs to the car….



Mod 3: Rear Sub-frame bushings. Ok roastbeef don't get too excited! They're in!! I went with Macht Schnell aluminum bushings. These things are SOLID chunks of aluminum---no holes, no gimmicks to make them lighter. Man, what a crazy job. I watched as the guys at minicorsa removed the subframe. Wow. That is a LOT of work. This is an expensive and very involved mod to the car. I haven't driven it yet, so i can't tell you what I think of it, but I'm curious. It's scary to see the underside of your car with nothing but heat shields….





Mod 4: Rear Toe Arms. Because we lightened the car so much with the gutting, the suspension pushed the car higher, so we had to lower the car to get back to an appropriate height. As we lowered the car, we were struggling to be able to dial in the toe we wanted. So, we put in Rogue Engineering Rear Toe Arms. They're the blue arms in the pic.



Mod 5: Exhaust. Everyone always laughs because my car is so heavily modded, but when you looked under the car, there was a stock muffler sitting under there…..hehe….I have to admit, I never really cared about exhaust much. I know that's everyone's first thing to mod. Well, in my case, it is literally the LAST item I've changed in a very long list of mods. And I didn't do it for sound or looks. I did it for weight. I decided on this first round attempt at exhaust to go as light as possible---straight out of the Akra x-pipe, to two EAS tips---no resonators, nothing. The whole exhaust, after the x-pipe, is around 14 pounds. (Stock rear section was more than 52 lbs) It's loud as hell hahahaha. And the car vibrates quite significantly at low RPMs. hehe we'll see how long I can stand it. My guess is that I will be putting some resonators in-line to smooth it out. My friend has a supercharged M3 with the same Akra x-pipe as me. He built his own muffler setup and it sounds very nice. I'll probably go that route. But it's worth hearing what this is like!



Sunday is going to be an interesting day. Lots of small changes to feel out----new halo seat, new subframe bushings, new toe arms, new exhaust. Should be fun! But I am bringing ear plugs….. I'll let you know how it goes.

[roastbeef]

Woop! Can't wait to hear the post-track review!

[redpriest]

Originally Posted by dogbone

Sunday is going to be an interesting day. Lots of small changes to feel out----new halo seat, new subframe bushings, new toe arms, new exhaust. Should be fun! But I am bringing ear plugs….. I'll let you know how it goes.

If it's as loud as the Yost Autosport E92 M3 I expect I won't even be able to hear my own induction noise over it if I happen to be following, haha. We'll see how loud it is on Sunday, if you're at Buttonwillow

Can't wait to read your detailed review as well!!

[M3 Number 86]

nice. will you be putting in a net as well?

also, way past the point of having M button. set it and forget it lol.

[dogbone]

Originally Posted by roastbeef

Woop! Can't wait to hear the post-track review!

Yeah I'm really curious how much I will feel the bushings.

[dogbone]

Originally Posted by redpriest

If it's as loud as the Yost Autosport E92 M3 I expect I won't even be able to hear my own induction noise over it if I happen to be following, haha. We'll see how loud it is on Sunday, if you're at Buttonwillow

Can't wait to read your detailed review as well!!

I'm not exactly sure, I believe the Yost car was straight pipe all the way from headers to tips.

I have an Akra Evo x-pipe that has a high flow cat and a resonator, and then it goes straight out from there. I shouldn't be as loud as the Yost car, but it'll be pretty loud.

[dogbone]

Originally Posted by M3 Number 86

nice. will you be putting in a net as well?

also, way past the point of having M button. set it and forget it lol.

No plans for a net right now.

I like my M button!!

[nicksm3]

Great thread!
Very curious myself on the solid subframe mounts. Need to to that mod myself but thinking of going with the Turner Delrin's.
Also haven't read the whole thread but you upgrade the front bushing set, monoball bearings?

[warp10]

Originally Posted by dogbone

No plans for a net right now.

I like my M button!!

I am working on a solution for this. just waiting on pieces to get here so mock it all up!

[redpriest]

dogbone, it was great meeting you today and nerding out over your new diff - the charts and data looked amazing. Was great hearing your feedback about all the mods in person!

I feel like we're unbelievably spoiled to have what is essentially a primer on building a perfect E9X race car, with detailed data to back it up.

[dogbone]

Ok, a little report from the weekend with all the mods:

1. Halo seat: I like the Recaro Pro Racer SPG, but it really is a different seat than the none-halo SPG. It's tighter in the back and shoulders, tighter around my hips, less padding on the butt, you sit deeper into it. And because the sides are so high, the lap belts can't be propped up on the sides of the seat as you're getting in. This means you need to get into the seat and then fish them out from under you, which is an enormous pain in the ass since the seat is so tight. I'm going to have to figure out how to put some velcro on the lap belt straps and then have the other piece of velcro on the seat edge or something because I'm not going on a fishing expedition for those lap belts every time I get in the car.

As far as the actual halo feature, I found that it doesn't get in my way AT ALL. The neck restraint only lets you turn so far, and the neck restraint's limit is before the halo gets in your way.

Conclusion: Thumbs up, but will require more setup.

2. Passenger seat: uh, it's fine I guess. Didn't take a passenger, so not much to comment on here. I'm probably gonna pull it out soon anyway.

Conclusion: Thumbs up. It looks cool. Adds weight.

3. Rear sub-frame bushings: I like them. My car was already pretty stiff with the cage tied into the car, so for me, there was no night-and-day difference here. I found it to be subtle. This mod added a little more predictability to the car as it starts to go sideways. Having driven it now, I'm not sure it's the best bang-for-the-buck mod for a mostly stock car. People with mostly stock cars talk about this mod all the time. This is an expensive mod. I think your money is best spent elsewhere until the car is modded more.

Conclusion: It's fine, should not be high on the list of a mostly stock car.

4. Rear Toe Arms: Fine. No drama.

5. Exhaust: ugh, this one was a thorn in my side all day. It is damned loud. And it's not really the decibel loudness. It's the resonance that is the problem. The resonance goes RIGHT THROUGH MY GOD DAMN HEAD at all different RPMs. I had ear plugs. They did nothing. The vibrations would resonate my entire skull. ugh, my ears are still ringing today. Plus, the left exhaust had a bolt that loosened and fell off, so during the middle of the session I had to pull off because I could hear it scraping. And then, I had the awesome walk of shame through the pits dragging my exhaust. I promise no one noticed my exhaust dragging on the ground through the ENTIRE paddock. Nope no one noticed at all……..

I was planning on removing the exhaust and doing something else….I think the car wanted that too and tried to shed the damn thing. So, it's back to the drawing boards.

Conclusion: Thumbs DOWN. What? I can't hear you!



Anyway, the OS Giken felt very good. The first time I drove it, all I did was think about it. Yesterday, I just drove the car and didn't worry about it. Worked great. And my fast lap was 1:50.04 on a fairly dirty/dusty track. It rained the previous day, so the track surface was not ideal to say the least.

There was a McLaren P1 there yesterday. Wow. Incredible.

[roastbeef]

good to hear you at least like the subframe bushings. i already decided i want them, i just have to make myself pull the trigger. i think the bushings will at least improve driving feel on the street and make that a little more enjoyable as well, but i know you're beyond that now. my car jerks a little bit and the traction control intervenes if i'm on it hard during a 1-2 shift (DCT), so i want a little more solidity... hehe. i'm also not ready for coilovers just yet, and i think this will help the rear suspension do its job a little better on the track.

[redpriest]

Originally Posted by roastbeef

good to hear you at least like the subframe bushings. i already decided i want them, i just have to make myself pull the trigger. i think the bushings will at least improve driving feel on the street and make that a little more enjoyable as well, but i know you're beyond that now. my car jerks a little bit and the traction control intervenes if i'm on it hard during a 1-2 shift (DCT), so i want a little more solidity... hehe. i'm also not ready for coilovers just yet, and i think this will help the rear suspension do its job a little better on the track.

Lol, my car jerked around savagely doing a 3-4 shift on the I-5 leg at Buttonwillow when it was raining

[dogbone]

Originally Posted by redpriest

dogbone, it was great meeting you today and nerding out over your new diff - the charts and data looked amazing. Was great hearing your feedback about all the mods in person!

I feel like we're unbelievably spoiled to have what is essentially a primer on building a perfect E9X race car, with detailed data to back it up.

Thanks! Glad you guys came over to say hi and chat!

I love going through the AIM data. There's quite a bit to look at, and there's quite a bit of very useful info in there.

hehe---I don't know what a perfect build would be, but I'm quite sure it would not be my car….it is fun to drive though!

[dogbone]

As I mentioned before, our first attempt at exhaust didn't quite work out……actually it was sort of a debacle. WAY too loud, WAAAYYYYYYYYY too much resonance at every RPM----every time you pressed the gas, you were punished with sound going right through your skull, the connecting pipe bolts that hang on the diff fell off, the rear part of the left exhaust fell and dragged on track, both tips were too close to the bumper and were melting it. Let's just say it was back to the drawing board….

I present to you-----Exhaust 2.0!! (cue music fanfare! Lots of horns! Very heroic!!)

So, the whole exhaust setup was re-setup, from the knuckles that fit on the Akra pipe to connect to the stock connecting pipe, to the resonators that are in line now, to the locking nuts for the connecting pipes, to the placement of the tips. It's basically a whole second try. And I have to say I'm much more hopeful for this setup.

It's still going to be fairly loud which I'm fine with, it will drone to some extent while idling which I'm also fine with, but at higher rpms I think this will be much more controlled. That's the main goal here: I want that INSANE resonance to be removed. And from what I can tell, the resonators will be able to do that. The tips are now slightly lower from the bumper than the first try, and they're in the center of the tips cutout in the bumper, whereas they were on the outer edges previously.

If this doesn't work, I'm tempted to slap the stock exhaust back on there……we'll see!