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2003 330i ZHP "Lightweight"

26K views 47 replies 16 participants last post by  mjdarg 
#1 · (Edited)
My plans for this car is to keep it OEM feeling while shedding some weight in areas that don't take away from the driving experience for me. Sound deadening will be getting removed but I plan on keeping full interior. This car is a DD right now so I will only be taking it to autocross events in my area. As much as I want to start with HPDE, I don't want to leave myself without a car because of an off roading excursion or engine complications. I'm not too concerned with autocross classing right now because I am still having fun. The flares already put me into DSP and the sunroof delete will put me into SM. I just don't have the funds to have a competitive DSP car. Eventual goal for this car is a car that is fun and capable on the track, but also very livable on the road for ~8k miles a year. I will be keeping things like A/C and power steering and would like to keep the complete stock interior. However, for my weight goal of 3,000 lb, I may have to pull the front seats as a lot of weight can be lost here. These things may change, but ultimately I want it to still be comfortable for day to day driving, hot or cold, rain or shine.

Current (updated 30Sept2022):
Suspension and Brakes:
KW Clubsport with Eibach linear springs 12k front, 14k rear
Revshift rear poly shock mounts
OEM M3 26mm front sway bar with eBay poly bushings and adjustable endlinks
Turner Motorsports 21 mm rear ARB with adjustable endlinks
Turner Motorsports spherical FCAB
Adjustable rear lower control arm with inboard spherical rod end
Upper and lower rear spherical ball joint
Rear upper inboard Turner Motorsports spherical joint
Moog Camry RTAB spherical
Apex ARC-8 17x9et30 with Toyo RR 255/40-17 scrubs or VMR 18x9.5 et33 with Toyo RS-1 245/640-18
Centric blank rotors
G-LOC R16 front pads and R12 rear pads

Powertrain:
Bimmerbrakes Gen 3 headers
AFE cone air filter
Rogue engineering 6 speed short shifter
3.38 rear differential from LKQ
ECS tuning poly diff bushings
PartShopMax aluminum rear subframe bushings

Chassis:
6 point roll cage
Rear subframe mount reinforcement to chassis rail

Old Mods:
Suspension and Brakes:
H&R Race Springs
Bilstein B8 Rear Shocks with ECS reinforcement plates
H&R Front Struts with BMW reinforcement plates
OEM M3 26mm front sway bar with eBay poly bushings and adjustable endlinks
OEM Non-m convertible 20mm rear sway bar with modified Whiteline poly bushings
SPC rear lower control arms
Apex ARC-8 17x9et30 with Falken Azenis RT615K+ 255-40/17; 20mm spacers in rear
Powerstop drilled and slotted rotors
Cool Carbon ST brake pads

Powertrain:
Bimmerbrakes Gen 3 headers
AFE cone air filter
Rogue engineering 6 speed short shifter
3.38 rear differential from LKQ
ECS tuning rear differential bushing

Weight Loss (lbs):
Sunroof delete - 33.5
rear seat rubber mat - 8.77
Apex ARC-8 with Falken Azenis 255/40-17 - 8
Trunk hard sound deadening - 5.5
SAP delete - 5.1
Armrest delete - 3.8
HVAC housing cut - 2.5
Spare tire plastic bowl - 2
Catless headers - 2
2nd ehaust brace - 1.6
ski bag - 1.5
Foglight delete - 1.4
Navigation module bracket chop - 1.2
Spare tire sound deadening - 1.2
Third headrest - 1
Grab handles - 1
Rear shock tower deadening - 0.9
Muffler heat shield - 0.9
Headlight washer - 0.77
Hood insulation - 0.63
Drug bin seals - 0.6
DVD cubby - 0.5
Shifter insulation - 0.4
Airbox lower rubber mount - 0.26
Over engine wire cover - 0.25
Roof rear sound deadening - 0.25
A,B,C pillar sound deadening - 0.23

I purchased this ZHP about a year ago and have slowly been working on it and performing all of the neglected maintenance. 5 owners over 120k miles is a bad recipe for this! I got it from a small dealer who had the car longer than he wanted. I was able to get it for a really good price, so I couldn't pass it up. One of the previous owners had a body shop install rear fender flares to mimic an M3. This included flares over the wheels, forming the flare into the rear door, and larger rear bumper spats to complete the look. Unfortunately it came on some heinous 19" chrome TSW wheels that HAD to go, so I promptly sold those on Craigslist and picked up some E39 style 89 from LKQ to keep me going for a while.


How she looked with the junkyard wheels.


First maintenance was oil filter housing gasket along with cooling system and drive belts. I also changed the power steering fluid once I opened that cap :eek:







Rear diff bushing was also shot when I bought the car. It would clunk badly during each shift. I opted for the ECS diff bushing at the time, but I think any poly bushing here would be suitable.



Next up was suspension. I knew the front shock towers were mushroomed and one of the front sway bar links was bad. The car had H&R front shocks which didn't leak and rebounded ok, so I left them. Rear shocks were dead so I opted for Bilstein B8s here. I found a set of H&R race springs here on the classifieds as well.





Shortly after my set of Apex ARC8s came in the mail, so I dropped those off at Discount Tire to get the 255/40-17 Falken Azenis mounted.





More recently, I've installed a second hand M3 front sway bar (26mm) and a non-M convertible rear sway bar (20mm) with upgraded poly bushings. I did this to keep with the budget theme of the entire car.





I found a Rogue short shifter, also used 👏 So that also went in. The shifts are notchy now, but very direct. I also did the shifter bushings along with selector rod joint while I was there. Make sure you do this when servicing your shifter bushings!



Over the christmas break I put on a set of Bimmerbrakes Gen3 headers on the car. I picked these up second hand from the forums with ceramic coating. It was very helpful to have a friend help take turn installing the header nuts. Getting the stock manifolds off was easier than the install.



Most recently, I installed a fiberglass sunroof delete from S2R tuning. I didn't use the sunroof much and this was a significant amount of weight. I snagged a non-sunroof headliner at the junkyard and rewrapped this with new headliner material sourced from a local upholstery shop for about $20. I used 1.5 cans of 3M headliner adhesive. I used 3/16" foam which was thicker than the recommended 1/8". In the tight bends, it was a little difficult to get it to follow the headliner contour, but it turned out good overall. If I had to do it again, I would wait and find some 1/8" headliner material.







Today, I popped the car on my scales to get a baseline weight number. This is with the spare tire, jack, and trunk hardboard and carpet removed. I had about 3/4 of a tank so in the next few days I will get another measurement just to see the number. 3/4 of a tank is roughly 11-12 gallons which equates to 66-72 lbs, so I'm expecting about 3150 with a completely empty tank.





I plan on updating this thread regularly with changes and updates as they happen. Also, as autocross season ramps up, I'll be posting up photos and results from that too!
 
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#4 ·
Sorry about that! Currently car is a DD so I'm keeping it just to autocross to avoid any costly repair bills from accidental off road excursions. Down the road, I would like to move into more track driving. At this point, I don't care too much about being autocross class competitive since the flares put me in DSP and the sunroof delete will put me in SM. End goal for this car is a full interior with A/C and other creature comforts while being only 3,000 lbs. I want it to be a car that is fun on track, but also very livable on the street. I'll update the original post with this too!

What bulbs are installed as map lights?

Thread is off to a good start! Love the look of a black ZHP..
Thanks! Bulbs are this style, but I got a few of them from a friend so I'm not sure if the ones I linked will actually work. With the lens, they direct the light very well. The passenger can have their map light on without much distraction to me while I'm driving at night.

https://www.ebay.com/itm/10x-T10-501-194-W5W-5630-LED-SMD-Car-HID-Canbus-Error-Free-Wedge-Light-Bulb-Lamp/401105238464?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D55991%26meid%3Da114717335174967832f1363bce87b4f%26pid%3D100008%26rk%3D6%26rkt%3D12%26mehot%3Dpp%26sd%3D251348485050%26itm%3D401105238464&_trksid=p2047675.c100008.m2219
 
#5 ·
Last week, I spent some time cutting down my washer fluid bottle (yes, crazy I know). I was able to shed about 230g of weight and I don't like running with extra fluid. a 5L capacity is huge! I used some epoxy to glue a 1/16" sheet of ABS to replace the top. With the SAP delete, I never liked how big the washer bottle looked.





Triad Sports Car Club had their first autocross event this past weekend as a Test N Tune weekend. Two days of driving and lots of runs. I participated only on Sunday since the weather was a bit nicer. Arrived around 8:30 with some light rain that stopped around 10am. First car was off around 10:30. I got 5 runs in wet/greasy conditions. It was first event in fun, so it was exciting and a learning experience, especially with some Falken Azenis down to the wear bars! In the afternoon, I was able to get 4 runs in mostly dry weather. Finished 44th out of 88 competitors. I was hoping to finish better, but I think the rainy conditions had me driving somewhat conservatively. I also forgot my camera mount as I like to review each run to see where I can pick up some time.

I've noticed a slight clunk every so often in the rear of the car recently. Last night I found some good/bad news. I have been planning on rear subframe panel reinforcements, but now I have a legitimate reason to weld them in! From watching videos on YouTube by Redish, it seems this particular spot on the floor is usually the first spot to crack. I'm not urgently going to fix it, but most likely in the next few months I will pull everything and weld some plates in. While I'm there I will do poly subframe bushings, new outer ball joints, new front diff bushings, and new brake lines. I have't seen too many ZHPs or late model E46s with cracks, but I bet there are many out there with this small crack on the floor. It is inboard of the rear left subframe mount, directly above the left sway bar bushing.

The first crack location in this video shows where my crack is. https://www.youtube.com/watch?v=HaTYBaMpUtE
 
#7 · (Edited)
Recently I found some lightly used rotors and pads on Craigslist for a price I couldn't pass up. As you can see below, the brakes on the car were in rough shape. The rotors were grooved pretty bad. They were ok for autocross, but even when coming off the interstate, they would sometimes vibrate under hard braking. Before any track driving, I was planning on replacing these. The rotors are drilled and slotted powerstop brand, most likely from RockAuto, and the pads are Cool Carbon. They had plenty of life left on them too. I used this opportunity to also replace the rubber caliper guides on all 4 corners. As others have mentioned, these can start to wear around 100k miles, and I think they were contributing to my mushy pedal feel. After the swap, the feel is much better. Also this rotor and pad combination is slightly noisier, but no pad squeal at all and the feel from the cool carbon pads is linear and consistent.

I did run into a slight problem when removing one of the rear calipers. I seemed to have bent the anti-rattle clip just enough when prying it off that it doesn't work anymore. Under prolonged sessions of light braking, like in stop and go traffic, a low pitch hum is heard when coming to a stop. I had to run to the junkyard and grabbed a clip from an X3 that worked like a charm.





 
#10 · (Edited)
What class do you run? OOps, saw it is DSP. I have 255 Hoosiers but rolled the fenders. I'm in North Wilkesboro if you want to compare notes.
With the sunroof delete panel, it's now technically SM. I'm still on 200TW tires, but would be interested to know what you've learned with full slicks on your car too.

What cool setup and project. I have similar goals myself with my 330. When I stop spending money on house projects my daily/mountain carver will be a dedicated HPDE car.

End goal would be similar to a Spec E46 build for the street/weekend HPDE car.

How is the grip, responsiveness and road manners of the Falken RT's?

Hello from NC as well. I'm in the Hickory/Granite Falls area.
Great to hear from some fellow NCers!

The falkens wander a bit on the road during normal driving but are grippy right out of the gate. I haven't compared them to the class leader RE-71s, but I'm sure they aren't as fast. I've gotten amazing life out of them though. I got about 15k miles along with 6 autocross events on one set. I'm willing to take the 0.5-1.0s penalty to have a much more durable tire. They lack some feel at the limit too, which can become frustrating once you push them too far.

This past weekend Bimmer Performance Center in Raleigh hosted their annual sprig Dyno day. 2 runs for $40. My mods since the last run are Bimmerbrakes gen3 headers, slight VANOS tweaks, and a short tube cold air intake. I was hoping for a bit more, but I'm happy to break the 200 mark nonetheless. And then boost in torque feels great.



I also got around to finally making my adjustable endlinks up front to go with the M3 anti roll bar. I can confirm that the links bind at full steering lock. As a result, my links were slightly bent. I used my Meyle HD links which are 10mm OD to make these diy adjustable links. Materials were about 10 bucks for the two turn buckles and jam nuts.





 
#9 · (Edited)
What cool setup and project. I have similar goals myself with my 330. When I stop spending money on house projects my daily/mountain carver will be a dedicated HPDE car.

End goal would be similar to a Spec E46 build for the street/weekend HPDE car.

How is the grip, responsiveness and road manners of the Falken RT's?

Hello from NC as well. I'm in the Hickory/Granite Falls area.
 
#11 · (Edited)
Yesterday I code my ABS module using NCSexpert to simulate M track mode since my car has the Bosch MK60 unit. I used this link from zhpmafia as a guide.

http://www.zhpmafia.com/forums/archive/index.php/t-12642.html

More specifically, this is what I did.
- PRE_MSR to aktiv
- UEBERSTEUERN_MUE_0_2 wert_04 to wert_08
- UEBERSTEUERN_MUE_1_2 wert_03 to wert_09
- UNTERSTEUERN_MUE_0_2 wert_01 to wert_02
- UNTERSTEUERN_MUE_1_2 wert_01 to wert_02
- UNTERSTEUERSCHWELLE_2 wert_10 to wert_04

In NCSexpert, when you hover over a parameter, NCSdummy is able to translate some options for each value as shown below. I haven't been able to determine what the values represent, but the M track values as greater than stock. I'm not sure if it's a threshold difference in front vs. rear lateral acceleration (yaw acceleration) or what. The effect is definitely noticeable however. Rapidly steering left and right as if to warm up your tires would normally kick the DSC light on for me. Now it does not. Also, traction control is much less intrusive and the recovery time when it does come on is much quicker. Before it used to feel like hitting a brick wall, but now it is a slight cut to regain grip. I am eager to try this out in wet conditions. I have heard great things about the MK60 in damp and wet conditions.

 
#13 · (Edited)
For the past few months I have been noticing a clicking/clunking in the steering wheel when traveling over gravel roads or when wiggling the steering wheel back and forth. I had a chance to get under the car and found the u-joint lower assembly is slightly worn. I ordered a new one from FCP and my problem is fixed. I also had slight play which was quite noticeable when making adjustments cruising down the highway.

Install was pretty straightforward, I just had to be careful of the oil pan and transmission as it was still quite warm! I used blue loctite on the 2 Torx bolts.

I'm down in Georgia for summer work, so I've signed up for an HPDE at Road Atlanta on the 15th and 16th. If anyone else is planning on going, it'd be great to meet up.

https://youtu.be/32hlIvf1I-0

 
#14 ·
Since I lasted checked in, I've made it out to Road Atlanta twice. My first time was with NASA on June 15 and 16. This was my first ever track experience and I must say, the NASA SE organization runs a very good program. I leaned a lot in my two days, met some people, and enjoyed the BBQ dinner they catered on Saturday evening. There were no issues from the car either and it made it back home in one piece. Road Atlanta is a very fun track with the large elevation changes and semi-blinds corners. I think going into the esses is my favorite section.

I also had the experience of going off into 10a as a passenger in my instructor's E36. Since I have the Schroth quickfit pro, this made me invest in a Hans. I also picked up some gloves from Murray Motorsport.



This past weekend I drove at Road Atlanta with SCCA for their Track Night in America. This was really convenient for me as it was only an afternoon instead of a whole weekend. I had my phone set up for lap-timing this time around and managed a 1:49 on my only entire clean lap for the night. In hindsight, I think I should've signed up for intermediate instead of novice, but I figured it would be better to be in a group that is too slow instead of too fast.



Someone brought their Mclaren out too! I was shocked, but it was awesome to see someone using the car as intended.


This past week I also picked up a set of Brembos locally that were from the Brembo GT kit for 325s that used a 320x28mm rotor. It only came with the calipers and brackets, so I am figuring out what rotors I can run. I'm trying to avoid the Brembo rotors as they are over $200 a pop, but the alignment of the M3 rotor looks like the rotor face is spaced outward too much to fit the current bracket. I'm not sure what rotor Brembo used for the kit as the M3 rotor is only off by about 4mm. The 330 rotor will fit in the caliper but it is not centered. If I can't get these to work for cheap, I will probably clean them up and resell them.

 
#16 ·
With all this extra free time, and it been long due, there are a few things I think I should update! I haven't done as much work as I would have liked, but moving and getting engaged have put a damper on things with time and money. :cry:

Last October I went to VIR with a few friends of mine and drove with NASA for the weekend. It wasn't without drama as I noticed a slight coolant smell about halfway through my second session. The low coolant light came on and I started limping it back to the paddock. I saw the temp gauge start to creep up, but I had modified the temp gauge output as outlined on the forums about a year ago, and boy am I glad I did that. Turns out, the radiator mounting had tweaked slightly and the drive belt had worn a nice groove in the side of the expansion tank. Thank goodness for Spec E46, as I was able to grab a new one from one of the vendors at the track! Add that to the list of spares I bring to the track next time...





Oh and my Craigslist rotors developed a big crack out on track too! Luckily I was able to snag a spare blank from my instructor who was also in an E46. I've since replaced the other rotors just to not have the liability of the drilled rotors on track as I've noticed cracks forming in the other rotors. I was running GLOC R10 pads up front and R8 pads in the rear with no issues.



Between the two failures, I only missed one session on Saturday, so I'd say I got my money's worth still!

Sunday was a real fun morning as there was a chance of rain. The 3/4 worn Azenis were a bit of an issue, but driving the first half of the rain in the dry and then transitioning into rain was fun and very educational. It was cool to experience rain and wet track on one end of the circuit and then get to the other end and it be completely dry. Towards the end of the session it started pouring real hard and the front straight got a little sketchy. The rest of the day was sunny and warm, and my instructor was ok with me running some solo in the afternoon too. All in all, I am excited to go back to VIR once this corona mess dies down and continue to improve my times there!

https://www.youtube.com/watch?v=t4TG4Xkfbrk

Having taken the HVAC filter housing off many times, I started hating how heavy that piece is/was. I decided to cut out the majority of the flat surface and replace with several layers of aluminum tape to seal it up again. Total weight loss is around 2.5 lbs and its way cheaper than buying and finding a CSL piece or getting a carbon piece made.





I also picked up a set of VMRs for $400 shipped from VMR as they were closeout. They are 18x9.5 et33 and I've got some slightly harder Falken FK510 on them as my daily driving tires. They have been holding up well and seem like a budget pilot super sport. I'm very happy with them. They are 255/35-18.



Recently I had my HVAC go out completely on me. The interior lights would turn on, but the controller would not turn on. I took the module apart and found a component that "looked" blown. But when I plugged it back in, no issues with it lol! It looks like it may be part of the fan circuit that is used to measure the interior air temperature. I picked a spare unit at LKQ to install anyways.





Things to *HOPEFULLY* come this year!
- VANOS rebuild. This is long overdue and I can't wait to feel the difference! I've got the Beisan systems kit coming right now.
- 3" single exhaust. I will likely add a catalytic converter, a resonator, and a removable muffler. I want a exhaust that is tolerable for the street, but I think I can lose 20-25 lbs here with some thin wall stainless while not absolutely hating the smell at stoplights with the windows down.
Winter Task! Rear end rebuild and reinforcement plates. I've got 1 crack I know of that needs fixing. I want to use this opportunity to completely redo the rear suspension and replace all bushings/bearings back there. I've thought about buying an M3 dropout to overhaul, but I'm not keen on the 3.62 final drive ratio.
 
#17 ·
Quarantine has given me some down to work on the car while I'm not relying on it to drive to work everyday.

I got around to installing my stainless brake lines from Techna-Fit I got through FCP. The left front was a little stubborn and was leaking for a little bit, but good cleaning of the flare and tightening got it all sealed up ok. I also ordered some rotor blanks from Rockauto for $15 a piece that are just Centric blanks. They seem good so far. I installed some Akebono ceramic pads from FCP as well for the street that I will switch out for my GLOCs when tracking. I was getting some shimmy in the front when braking from highway speeds and this is now gone.

A few days after my last post, my starter was giving me problems. No clicking, nothing in the driveway one morning. I started with checking the EWS and DME were sending signal to the starter solenoid before digging into things. I then took the HVAC housing off and it provided some good access to the starter. I tapped it slightly with my breaker bar and sure enough, it fired right up! I did not want to be replacing the starter if it wasn't the problem. A few days later, my Bosch starter arrived from Rockauto to be installed. $135 for a brand new starter with lifetime warranty! Best price I could find for new. As a bonus, this starter is 170g lighter than the original BMW starter. Weight up front too! lol





I also used this time to reroute the O2 pilot mod I performed last summer.



I figured while the car was up, I might as well do some work on the other side of the engine too, so off came the valve cover and VANOS unit. My valve cover gasket had 40k miles on it, and I'm glad I replaced it. The gasket was already getting stiff. I got my seals from Beisan Systems. Shipping was superrr fast, since I'm in the same city. His installation guide was very helpful and provided all the details necessary to install the new seals. Total time was maybe 4 hours with taking my time. The most tedious part was cutting the old seals off. Stretching the teflon seals back on was a little bit of a bear, but it was warm enough in the garage to not need any warm water. I only have about 70 miles on the car with the new seals, but low end seems smoother through the RPMs and the idle is noticeably smoother as well. I plan on taking some airflow logs and performing some VANOS adjustment once I'm through the 200 mile break in period.





 
#26 · (Edited)
Work has been slow this summer with wedding planning (around COVID too) taking up lots of time. But we refuse to push that back! I had the chance to join a few friends at the Charlotte ROVAL for a track night in America hosted by SCCA. They were well organized and things went smoothly with safety a top priority. The ROVAL has always been on the list of must drive tracks, at least once. The allure of driving on a NASCAR track was appealing and I had never been on banking before. All I can say is WOW, I wasn't expecting to have as much fun as I did. From watching videos on Youtube, you don't get a feel for the steering feel and g-forces entering and during the banking. iRacing had given me some experience with the track layout, so I was pretty much able to get out strong right away. It wasn't until the third session that I was real comfortable with the banking and didn't lift all the way through. At one point, I looked down to see 127ish. Not quite what the NASCARs are doing, but it feels plenty fast. The Azenis held up well, but with some fatigue in the third session, I started over driving a bit and getting them greasy. I was also getting caught up following some people instead of driving my line and that caused some issues as well. The only injury was a busted window regulator which ended up being one of the bolts holding the window to the red clip, so a free fix is very nice! Here's a clip of the second session of the day. NASA had two weekends at VIR this year and I plan on attending at least one of them.



Here's the gang at the end of the evening before we drove back to Raleigh in the rain.


Obligatory photo going into T1.
 
#27 ·
Since last update I've been a little busy getting ready for next year.

First, found a killer deal on lots of suspension parts on Facebook I had to grab. The guy was building a 2JZ E46 and never even got it running before his orders were changed and he had to move across the country. With the subframe reinforcement looming, this was a sign from the car gods saying now is the time.

List of parts:
KW Clubsport coilovers, installed never driven
Revshift rear poly shock mounts
Front knuckles with new wheel bearings and new control arms
Turner front Monoball FCAB
Turner rear 21mm sway bar with adjustable endlinks
Turner front 30mm M3 sway bar (I sold this)
Rear upper inner spherical ball joints
New CSF non-M radiator

With all these parts, I've begun to gather the rest of the necessary parts for a complete refresh of the rear subframe while its out over Christmas break to install plates and repair cracks. Still to come are solid subframe bushings and new sphericals to replace the ball joints in the back. I will also be installing the Moog Camry RTABs. I also have some second hand adjustable lower arms with inboard sphericals to install as well. Once the parts are in it will be time for a home alignment and corner balance before I take it to be checked by an alignment shop.









A few weeks ago I was able to get down to Carolina Motorsports Park and drive with NASA SE for the Brady Memorial on the new pavement. It was my first time there, so I wasn't exactly able to connect with people who kept raving about the NEW pavement lol. I heard many stories about the rough surface before, but that's all. The track is a bit slower than VIR or Road Atlanta, but still very fun and has some challenging parts as well. Definitely can't wait to go back. No reliability drama the whole weekend which is always good! NASA weekend are also fun with all the racing to watch. Also thanks to Jim Voss with NASA SE for taking tons of great photos this weekend. Hopefully I've got updates coming this holiday break too! Happy Thanksgiving everyone.



 
#29 ·
I recently did the Moog RTABs. They are amazing, you are going to love them. What method do you plan to use for the reinforcement? I also did an X-Brace recently with help from ZHPizza. There's one left over so if you're interested contact him. I figured you'd appreciate the extra torsional rigidity it provides since you track your car.
 
#31 ·
Hah! I've been talking with him recently about the x-brace, but am going to stitch weld for now. I plan on gutting the car in the next few years and the cage will be tied into the rear points similar to how the x-brace works. I am going to use PartShopMax plates that I got from him as well and I will be spending a few days under the car looking for any popped spot welds. I'm really excited to feel the car with the Moog bearings, it seems like everyone loves how they feel.

Damn, nice pickup! I always try to buy second-hand performance parts since there are deals to be had, I got a killer deal on my GC DA coilovers as well. That was stage 1 of my build, stage 2 next summer will be a re-spring from 440F/550R to 440F/900R lb springs and a 30 mm ST suspensions front ARB for the M3 (both the rear springs and ARB I spec'd in conjunction based off some numbers I tinkered around with in the FCM ride harmony spreadsheet).

Also I notice your front bumper looks a bit tired, mine is as well. I like nice paint so it does bug me but not enough to get a respray, since hitting cones at autox or just generally getting beaten on at the track means I don't have to worry about it so much.
It's funny you mention adding a bunch of rear spring, cause I have been wondering as well. I've put my measured points into OptimumK that I have lying around from my FSAE days, but haven't figured out what spring setup I will be using. I've only briefly looked at some sensitivity of ARB diameter change and adjustment on roll stiffness distribution. But with the rear motion ratio, the rear spring does need to be higher than usually spec'd to have the "flat" ride or at least a ride frequency higher than the front. The KW kit is 400F, progressive rear, but I will drive 2021 on these springs to get a feel for the car for a bit. If you want to talk more, feel free to PM, it's always good to bounce these ideas around. As for the bumper, whoever resprayed this car didn't use the hardener or whatever it is to make the paint durable on the plastic bumpers. Its slowly flaked off from road debris, but I haven't been bothered by and the car is a beater anyways. I keep telling myself I need to paint it at a buddy's place, but never get around to it lol.
 
#30 ·
Damn, nice pickup! I always try to buy second-hand performance parts since there are deals to be had, I got a killer deal on my GC DA coilovers as well. That was stage 1 of my build, stage 2 next summer will be a re-spring from 440F/550R to 440F/900R lb springs and a 30 mm ST suspensions front ARB for the M3 (both the rear springs and ARB I spec'd in conjunction based off some numbers I tinkered around with in the FCM ride harmony spreadsheet).

Also I notice your front bumper looks a bit tired, mine is as well. I like nice paint so it does bug me but not enough to get a respray, since hitting cones at autox or just generally getting beaten on at the track means I don't have to worry about it so much.
 
#32 ·
Ok big update here as I was busy over Christmas break. I'll put this note about subframe plates up top in case people don't make it to the end lol. I didn't install plates in the car. I had a friend weld up any cracks or popped spot welds, but with load path changes I outline below, it's my belief the plates are unnecessary, extra weight.

To prep for the subframe work, I purchased a complete dropout from a 330i auto on Facebook for $200. I haven't gotten around to putting an LSD in, but with the extra 3.38, that's my plan. I got to work removing any stock parts that I was not going to use. I started with pressing in the upper inner monoballs. I used a combination of the advance auto ball joint tool and a bolt I had lying around from E90 partouts. Inline pullers seem to work much better than the c-clamp design, I assume due to reduction in side load and bending.



The next step was to remove the old subframe bushings and install the new ones. After debate between poly vs solid and what is best for stiffness but also lightweight and cost effective, I went with the Partshopmax set. ZHPizza also used these, and the large footprint seems to distribute loads better to the chassis still. I knew aluminum would be heavier than stock, but holy moly, when I picked up the box! o_O I went to drilling some speed holes in these. Cut out about 1 lb from what they were, but they are still 1 lb heavier than the OEM rubber. Hard to beat the OEM bushings though.





Removing the old bushings was a breeze with bushing tools from pizza, a little heat, and my early christmas gift from the wife; Milwaukee 1/2" impact. A little heat on the metal bushing carrier and the process took about 1 minute per bushing with the tool. Easiest removal I've done yet lol. When pressing in the new bushings, I did have to epoxy one of them in, as it was a loose fit. I scuffed up the aluminum a bit and everything seems good. The others went in with a hammer after being in the freezer. I'm not sure the freezer was even necessary.



I also swapped the diff bushings with some ECS poly's I had lying around. I never replaced the front bushings when I first bought the car, so I did these at the same time. The large rear bushing was already in the car, so I had to wait to swap that.

Subframe removal has been documented in here, but as a solo job, it was most difficult actually lowering the subframe. It was wanting to get hung up on the front studs and required going up and down and some kicking before it was finally out. I also noticed the giubo was looking a little rough and had bought one a while back, so it was a good time to replace this as well.



With the subframe out, I began the long process of thorough chassis inspection to find all the cracks and failures I could. Here are the first ones I found.

This is the crack near the left rear mount. I knew this crack was here and was monitoring it. It definitely grew since I first saw it at 125k miles when I bought the car. In hindsight, I probably should have fixed it earlier, but nothing catastrophic happened from me letting it go. I had my friend weld this is and I left the weld bead intact.


Near this spot, I noticed some rust spots on the wheel arch. There were 3 failed spot welds here that attach the RACP to the wheel well/arch sheet metal. These failed spot welds are not easy to find, but rust spots and cracked seam sealer can be a good clue. These were in the left rear wheel arch.





I continued to search for more cracks on the bottom and found two at the right front mounting point below. A bit harder to see, but I cleaned all mounting points below to check for failures at the spot welds. After welding these, I ground them down as they would be sandwiched by the subframe bushing.





Next was inspection of the tops of the mounts. I cut into the rear mounting points with a plan of tying in the tops to the chassis rail. Removing some of this sheet metal is just extra weight savings too (; Having seen lots of idea on the internet, I decided to take my own angle at this. I didn't want to pay $500 + for an off the shelf solution and knew with some fabrication it could be done. I started with a simple gusset welded from the top of the mount to the chassis rail. I didn't like this because it didn't provide access to the top of the mount, and there still could have been located fatigue due to the welds transferring loads.



Eventually planning for a cage, I decided using tubular reinforcements might be better suited. I decided to use a bolt through design welded to the chassis rail instead. I made a trip down to Charlotte to head to Pizza's garage for some threaded rod he bought along with picking up some tubing drops at Stock Car Steel. Oh and we also made a detour to IKEA ;) Here's the new design welded in.





I decided to simply sandwich the front mounts using a thick, wide washer to better distribute load into the top panel as opposed to the 2 factory mig welds used. When I cut into the sheet metal here, I found a crack on one of the mig welds on the right front mount as well. I stop drilled this and ground down all the welds in preparation for the large washer and through stud.



 
#33 ·
Upon closer inspection at the front mounts, I found several popped spot welds on either side of the car forward of the front mounts. They ran near the rear door sill. Here they are circled on the left side of the car. It's quite interesting they were failed on both sides of the car. These were drilled out and the welded up with big fat mig welds. I had my friend add a few short stiches near these as well.










The last failed spot weld was where three plates intersect near the left rear mounting point. I had noticed cracked seam sealer here and there was some plate separation as well. I also had my friend had stitch welds across the plate from left to right.



I hit all bare metal with weld thru primer and then POR15 after the welding was done. Here are the front and rear mount solutions finished.







Having some trouble with removing the axles from the spare subframe I bought, as well as finding out the axle bolt pattern was different, I decided to use my trailing arms, axles, and 3.38 diff and keep them bolted together. I replaced the upper and lower ball joints with the Lemforder spherical. I also swapped out my rubber RTABS/Limiters with the MOOG camry RTAB. I had purchased a set a while back, but these were the 12mm ones. I was really happy at first because I thought I wouldn't need to drill out the holes. But actually, these were slightly too small and were basically a clearance fit. I had a second set of the 14mm ones from Pizza's garage (I think my car is sponsored) and had to slightly sand these, but they pressed in nicely. Both parts had the same MOOG part number, but something definitely got messed up along the way.



Assembling the entire rear end might be easier with all sphericals because control arm bushing angles are no longer important, but it does move a whole lot more as you are trying to install it into the car. I had to shimmy it up about a foot so I could get my jack underneath it with a 2x6 running longitudinally. I then slowly raised it up to the body. I double nutted the studs and threaded them all the way though to the top side and then snugged them down. I didn't want to install the studs first because I think it would have constrained the subframe too much and made it very difficult to raise up to the body. The Partshopmax bushings are 12mm clearance holes all around and not slotted like OEM bushings.







With the subframe back in, finally, it was time to install the KW Clubsport kit. I ended up putting the car as low as it can go in the rear and it seems to be the same ride height as before. I think they will settle a bit, so I may have to raise it back up. Up front, I removed the helper springs to provide some more wheel clearance as the helper spring makes a longer spring stack, and the main spring is next to the tire. Here's the coilover with the spring still installed.



I also had to modify the droplinks that came with the KW kit as I am running an M3 front anti roll bar. I cut them in half and threaded them and added a set of turnbuckles I had lying around. They also seemed a bit long for the ride height I was using, so I shortened them up a bit to provide a better angle between the droplink and the ARB. My first attempt at full strings alignment took a good while, but seem to come out ok. After the first drive, the steering wheel isn't exactly straight, but I did make a change to the LF spring once I put the car on the scales. Perhaps this had a slight change in toe. I'm still running into a long standing issue with not being able to achieve toe in or even neutral toe on the LR tire. I'm not sure if the trailing arm is tweak or maybe the RTAB bracket is bent. It's something I knew about and tried to bias the MOOG bushing, but it wasn't quite enough. Right now, I'm shooting for -2.3° camber up front, -1.5° in the rear and zero toe all around.





I've only driven the car once when it was raining last night, but everything feels very tight. The front monoball FCABs and RTABs do provide some additional NVH, but it is not a crash, but simply a quick thud when going over bumps, very similar to when you go over expansion joints. There is much more noise from driveline with the solid subframe and poly diff bushings, but I am hoping that goes away once some more of the interior is installed again.
 
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