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Discussion Starter · #101 ·
Aluminum flywheel and clutch replacement

In my last update I mentioned how the clutch was slipping badly during my last track day. The car has 120k miles on the original clutch so it is time for a replacement. Instead of replacing everything with OEM parts I am taking the opportunity to upgrade as well. I ordered the Bimmerworld Lightweight Clutch Kit. This kit gives you a JB Racing 10lb aluminum flywheel (15 lb lighter than OEM!), a Sachs spring hub disc and pressure place, and a new Sachs throw out bearing all for a reasonable price.




While I have the transmission out I am going to do a few “while I’m in there” repairs as well. This includes: Clutch pivot pin, shifter detents, rear main seal, shift shaft seal, transmission fluid, and pilot bearing.




I have done a dozen or more clutch jobs in my life and they are not hard but never fun. Maybe someday I’ll have a lift so I won’t dread the crawling-out-from-under-the-car-100X-to-grab-a-tool-I-forgot that this job always entails. The transmission removal process is best described by the FCP Euro guys here:

And the transmission is out for the first time since this car was in Germany!




Everything came apart smoothly other than the starter dowel which was STUCK. I had to fashion a 3 foot long punch to drive it out from the rear. Once the transmission was out I cleaned it up a bit to make the detent and seal work a little less messy. Additionally clean parts show where any future leaks are coming from much better.

I then removed the old pressure plate, disc, and flywheel. The full OEM assembly weighs in at 39lb. I was surprised to see that the flywheel and pressure plate surfaces looked pretty good with minimal checking and scoring. The disc is worn down to the bottom of the grooves though. I was just losing clamping force due to the thinner friction lining.






The back of the engine was spotless so I decided to not replace the rear main seal. I have found that the best way to create a leak is to fix a leak that isn’t leaking. So I just went ahead replaced the pilot bearing and bolted up the new flywheel and clutch. The Sachs clutch went on perfectly using the provided instructions. I weighed the new clutch assembly before bolting it in and it weighs 26.5lb, a total reduction of 12.5 lbs.




I then replaced the shift shaft seal. The original was leaking slowly and making a big mess all over the back of the transmission. This process involves digging the old seal out of the housing with a pick and small screw driver. The new one just taps into place using a deep well socket to drive it over the shaft.






Replacing the shifter detents is next. Again I used the tutorial provided by FCP Euro:

I rented the detent drifts from a fellow E46Fanatics member. I won’t say who because the transaction wasn’t as smooth as I would have liked. In the end it worked out fine. The remainder of the detent job went as described in the video. I then did a drain & refill of the ‘box with fresh Red Line MT-LV.

The last step was to replace the clutch release pivot pin. I will never understand why BMW puts a plastic pivot on this critical part of the clutch. I design plastic parts every day for a living and I know there are good polymer materials out there that are capable of replacing many types of metal components. This is not the correct application, in my opinion. I replaced the heavily worn OEM part with a brass one sourced from Bimmerworld.




The transmission went back in easy enough, I guess. I really do wish that the sadistic German engineers who designed the starter interface and bellhousing bolt locations gave us just a little bit more access under there! Finally I bolted the shifter, driveshaft, heat shield and exhaust back up under the car. Job done. A test fire and run through the gears while still on jack stands revealed no unusual noises or leaks.


First impressions of the new lightweight flywheel and clutch setup are very positive! The Sachs clutch feels about 25% heavier than the OEM clutch, not too firm but definitely more effort. Initial take up feels stock but you can tell that the engine bogs a little easier and responds a little faster to throttle tip in. Revs build MUCH faster with the clutch in or transmission in neutral. Shifting is where the real magic is! On up shifts the RPMs drop much quicker. If you release the clutch without a perfect RPM match you don’t get nearly the same jolt as with the heavy OEM flywheel. Shift “wait” time between 1-2, and 2-3 is now non-existent. Down shifts are equally improved by the faster free-rev blip and less shock due to mismatched RPM. The whole driveline feels much more connected and telepathic. Just how it should be. This might be the single best modification I have made to the car from a driving enjoyment perspective.

Negatives? Not many. There is no rattle at idle or clutch in like you hear about on the non-spring hub disks. The engine starts and idles normally, even with the AC blasting. The only downsides I see are- 1) it is slightly easier to stall from a stop. Not really though. And 2) between 1200 and 1500 rpm, in gear, while accelerating, there is a slight rattling in the driveline. This is only noticeable in 1st or 2nd gear during slow parking lot scenarios. Totally livable for my situation but maybe annoying if this is your only mod to an otherwise stock car.

I can’t wait to get back out on the track now. I don’t expect a massive improvement in lap time due to this mod. It should be easier to drive though, which might make me faster and more confident. We’ll see soon enough.
 

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This is a great write up. I have a 330ci that is slowly changing into a track car as I become a better driver. Biggest concern over lighter flywheels is I've heard horror stories about vibration and drivability. Sounds like the direction you took is very livable.
 

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Discussion Starter · #103 ·
This is a great write up. I have a 330ci that is slowly changing into a track car as I become a better driver. Biggest concern over lighter flywheels is I've heard horror stories about vibration and drivability. Sounds like the direction you took is very livable.
Yeah that's half the reason I waited so long to make the change too. I can honestly say that these parts, on my car, exhibit none of the behavior I was worried about. I have less than 100 miles on it so far though. I'll report back if my feelings change.
 

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Great to hear from a fellow ex-FSAE-er, just read through the whole thread and boy what an epic journey. I'm pretty much fresh out of school so not much funds plus my E46 is my first and only car, so my mods won't be nearly as hardcore as I want to keep it as a dual-duty car for now. But I've started open lapping and as I have access to the student machine shop have started making my own stuff on the side (such as toe jigs that mount to the car).

On another note frankly I'm quite surprised your 2003 Formula car stayed together in one piece - as the lead of my team for the last 2 years of my undergrad I had the opportunity to bring the chassis home for free, but it'd just be the bare spaceframe since the car gets parted out. I've always thought about it but living in the suburbs without my own workshop and machining tools I know it'll just sit in the corner collecting dust.

Subscribed, looking forward to seeing what you do next!
 

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Discussion Starter · #106 ·
Great to hear from a fellow ex-FSAE-er, just read through the whole thread and boy what an epic journey. I'm pretty much fresh out of school so not much funds plus my E46 is my first and only car, so my mods won't be nearly as hardcore as I want to keep it as a dual-duty car for now. But I've started open lapping and as I have access to the student machine shop have started making my own stuff on the side (such as toe jigs that mount to the car).

On another note frankly I'm quite surprised your 2003 Formula car stayed together in one piece - as the lead of my team for the last 2 years of my undergrad I had the opportunity to bring the chassis home for free, but it'd just be the bare spaceframe since the car gets parted out. I've always thought about it but living in the suburbs without my own workshop and machining tools I know it'll just sit in the corner collecting dust.

Subscribed, looking forward to seeing what you do next!
Thanks! I've been really happy with my E46 and plan to keep tinkering with it. Stay tuned!

My FSAE team decided back in the 90's to stop cannibalizing previous cars to finish the new one. We liked to keep recent cars functioning for driver training and promotional events. We also wanted to keep evolving our design and not be locked into using the same components every year. My car is mostly collecting dust but I love having it there to look at and show off.
 

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Discussion Starter · #107 ·
Headlight blanks

I have been on a mission to reduce weight in my car from the beginning of this journey. At this point I’m pretty close to maxed out (minned out?) other than fully gutting the interior and removing the air conditioning. One area that got me thinking though was the headlights. My car is equipped with the excellent, but heavy, Xenon headlights.




As you can see, each headlight assembly tips in at about 6.5lb. This isn’t a lot, but when you consider their position- way up front and relatively high- it’s worth considering alternatives. Those alternatives are: OEM halogen headlights, carbon blanks, or some sort of DIY. The halogens are out because they are only 1-2lb lighter and not nearly as good at actually lighting the road. Carbon blanks are out because nobody makes carbon blanks for a sedan and if they did they would probably be $500+. That leads me to another DIY project! I’m sure if you’ve followed along this far then you knew that’s where this was going.

To start the DIY I picked up a set of complete E46 halogen headlamp assemblies from the junkyard. One of the units I bought had a severely faded lens and a melted bulb housing. No matter though, as it is all getting cut up and then painted. First I dismantled the headlight assemblies and threw away everything except the lenses and main mounting buckets (sorry no pic). Then I cut away all unnecessary material from the mounting buckets- everything except the lens snap features and the mounting tabs.






I then cleaned, scuffed, and painted the clear lenses with a satin black spray paint.




Finally I reassembled the blanks and threw them on the scale. Final weight came in at just 1.4lb each for a total savings of 10.2lb.




The blanks will not live on the car permanently because I still drive it regularly on the street. I’ll only swap the lights out for TT races where my race weight is critical. It takes me less than 10 minutes to switch to these blanks.

For the sake of testing I mounted up the blanks before an open lapping day just to make sure everything fit and functioned correctly.






November 2020 Track Day

2020 has been very light for me with track time due to COVID closures and welcoming a new baby into our home back in April. My second and final chance to drive for the year came at High Plains Raceway in mid-November. Upon arriving at the track I attached the splitter and grabbed a couple pics of Heidi in full race mode.






A couple friends joined me for the day and they brought some serious Porsche hardware.



That’s a GT3 RS and a GT2 RS. Yes, I did get a stint in each. More on them later…



My car ran amazing all day. I did three full stints and was nearly able to match my previous best time from a race day last year on fresh Toyo RR’s. This day I kept to my two year old street driven Hankook RS4’s so I could focus on tuning adjustments rather than ultimate lap time. All the aero, power, and handling mods over the last year have absolutely made an impact. My concerns from the previous track outing back in July are erased. Weather this day was much kinder apart from a tremendous headwind on the main straight. It just goes to show what the impact weather can have day-to-day.

I spent the morning tweaking swaybars, dampers, and wing settings to get the car dialed in. After that I let my two friends each take a stint in my car and they both came back just gleaming. They raved about the brakes, the grip, and balance. They said it was just super easy and forgiving to drive on the limit. Of course they wanted more power but coming from cars with 300-500hp more, I’m not surprised.


Now about them Porsches. I have previously driven that GT3RS at another track in Pueblo, CO. It is probably the best combination of power, handling, and balance ever put into a production car. At nearly $200k, it should be! It’s hard to believe there’s any way to improve upon it. The GT2RS does just that with an extra dose of 200 turbocharged horsepowers. 700hp in any car is an extreme number. In this car it is just nuts, but somehow still manageable. I did one stint in each car and managed a 1:56.8 in the GT2 and a 1:57.8 in the GT3. My best lap in the GT2 was hindered by traffic. I was on pace for a 1:55.2 before getting held up in the last sector. Here is onboard video of my 1:56 lap (pardon the shaky camera).


What surprises me about watching this video back again is how calm and composed it looks. I certainly could have taken more chances with it, but I can’t imagine the emotional and financial ruin that would potentially follow. To put the speed into perspective, at 0:36 in the video I pass a black car as we enter the main straight. That is my car, Heidi, being driven by a very competent friend. I catch and pass him at a nearly frightening pace.

So what do you do when you finish thrashing a car on track that costs as much as your house? Double thumbs up!

 

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Have you looked at the impact bumpers? I haven’t had a chance to pull and weigh them yet but they’re likely pretty heavy. My plan is to replace them with an aluminum post that has the same mounting point. No need for 5 mph bumpers on a track car.
 

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Jesus you have some really nice friends. I need to find friends willing to let me hoon their GT2s and GT3s around a racetrack haha
 

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Discussion Starter · #111 ·
Have you looked at the impact bumpers? I haven’t had a chance to pull and weigh them yet but they’re likely pretty heavy. My plan is to replace them with an aluminum post that has the same mounting point. No need for 5 mph bumpers on a track car.
When I was messing around with the splitter I pulled a bumper shock for investigative purposes. I can't remember the weight of it but I definitely think it's worth building a lightweight replacement some day.
 

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Discussion Starter · #113 ·
Is the kevlar bumper beam from the M3 a viable option for shedding weight?
I think so but I could never figure out if the M3 beams fit the non-m bumpers. I keep my eye out for M3 part outs so I can hopefully pick up a set for cheap and try. In the mean time I went to town with a hole saw on my aluminum front beam to the tune of a 4lb weight loss.
 

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I think so but I could never figure out if the M3 beams fit the non-m bumpers. I keep my eye out for M3 part outs so I can hopefully pick up a set for cheap and try. In the mean time I went to town with a hole saw on my aluminum front beam to the tune of a 4lb weight loss.
I'm in the same boat, and haven't jumped on an M3 crash bar. The carbon kevlar M3 bar doesn't use the bumper support bars, but the bumper covers have plastic clips that mate with clips on the CF crash bar. Might be able to rig up a way to mount a non-M bumper cover or put the same clips from the M3 cover onto the non-M, but haven't gotten this far. Or copious amounts of zipties...
 

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[QUOTE="Strebor, post: 18642995, member: 1036918"


I collected all of it in a 5 gallon bucket again and weighed the result – 12 lbs.

[/QUOTE]


You are a mad man scraping all that tar off, when I was stripping mine and came across all that I was like ok that's staying
 

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There was a guy parting out a M3 in Charlotte on FB marketplace. He had 2 carbon fiber crash bars for $100 each. Maybe it's time to reach out? @ZHPizza
 

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Discussion Starter · #118 ·
Revised Air dam

One thing that bothered me about the splitter and air dam system I built was the fact that so much of the front tire was sticking out into the oncoming airflow. Something like two inches worth of tire was exposed.




Spinning tires and concentrated airflow atop the splitter has got to be causing some significant drag, right? This got my mental gears turning and I decided to revise the air dam to shroud the front tires more. To do so I also needed to extend the plastic air dam upwards. This meant the air dam now must rise up to cover nearly the entire front bumper as it wraps around towards the wheel openings.




The newly crafted upper air dam extensions were too floppy on their own. To combat that I added some mounting points using a couple ¼-28 mil spec nut plates inside the bumper and attached them with oversize-flange head rivets. This way I can still remove the slitter assembly for street driving and then just run a couple bolts in to lock down the splitter/air dam at the track.




I had to make a large access hole in the inner plastic bumper brackets to gain access to the nutplate mounting location.




The final effect is a much more shrouded front tire. It’s not perfect but I imagine there will be a little more efficiency of the splitter and some reduction in drag too.






To finish out the installation I turned a couple little conical washers on my lathe. These spread out the clamping loads between the air dam and my bumper and smooth the airflow over the screw head.






Hub Stands

I have been wanting to upgrade my home alignment setup for some time. I never felt that I was getting the accurate and repeatable results I was looking for. My ideal solution is to buy a set of Paco Motorsports Hub Stands.




These devices bolt to the wheel hubs and give you the ability to measure camber/caster/toe/thrust angle easily. Because the wheels aren’t in the way you also have unobstructed access to the adjustments. They have really nice ball transfers on the feet that reduce sliding friction against the ground. Overall it’s just a really well thought out system.

Unfortunately, I’m cheap and I can’t bring myself cough up $1100 for an alignment rig. The other problem I have is my floor is very unlevel. I would have to compensate each stand’s mounting height so the car is measured relative to a level plane.

My solution was to design and build my own!




The most significant departure for my design is using slip plates instead of ball transfers. I made my plates out of melamine panel with some light lube between the hard surfaces. There are two main advantages to the slip plate method- 1) Cost. I built all four slip plates for the cost of 2 (two!) ball transfers. 2) Leveling. Using extra layers of melamine panel and stick on vinyl floor tiles I was able to level all four pads to within 1/16 inch.

Otherwise my design is very similar to the Paco’s. Once I was happy with things I sent my files out for laser cutting. A few days later they arrived.




The individual parts are designed to key together and hold each other in alignment while being welded. Simply clamping them to my welding table was enough to hold everything flat and square. I TIG welded the entire assemblies.






The bases are made of some 5/16” aluminum plate and machined pieces of angle iron.




All assembled.






Installed on the car.






My first pass at an alignment revealed some interesting facts about my old methods. My camber was uneven on the front axle and too high on the rear axle. My front toe was actually ‘in’ 1/16” when I thought it was ‘out’ 1/8”. I made all the necessary adjustments and corrections. Repeatedly lifting and setting the car back on stands showed that my repeatability was much better now. I was getting camber measurements within .1 degree and toe within 1/32” on each iteration.

Next up is a corner balance at my local race shop. Then I’ll head back to the track and see how the new setup feels. I’m expecting more initial turn in bite on the front end due to the toe correction, and a little freer rear end mid corner due to the camber corrections.


2021 Race Season Updates


2021 should see me return to NASA TT competition. In preparation for that I have decided to ditch the Toyo RR’s and go to Hoosier R7’s. All the fast guys run Hoosiers and I want to be one of the fast guys. I ordered a set of 245/40-R17 R7 tires from TrackDayTire.com and they showed up a few days later.




I also ordered another set of Apex ARC-8 17x9 ET42 wheels to mount the Hoosiers on. I ultimately want two full set of wheels and tires so I can swap them between sessions as needed.




The final bit of preparation will be to finally remove the AC system. To get to my maximized Weight/Power ratio I need to lose about 40 more pounds. There is no more easy or inexpensive weight to lose on my car, so the AC has to go. #becauseracecar This should put my final race weight at 2935lb with me in the car and an 1/8 tank of fuel.

‘Till next time!
 

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amazing work on those alignement hub stands, they look awesome and look like could take quite a beating hahah

and that you could correct the alignement on the first try it was the cherry on top.

Looking forward for more updates :D
 

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Funny you make this post now...having just gotten a mill in my garage, I've been planning to build some of these setup wheels too. I like your combination of sliding and pivoting to get the necessary DOF. Do you have to grease your pivot bolts, or do any special prep to minimize stiction there? When is the string alignment setup coming?
 
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