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      06-06-2021, 06:08 PM   #67
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Little sneak peek at what FINALLY came in the mail this weekend...
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      06-07-2021, 08:52 AM   #68
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Sick!
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      06-08-2021, 01:32 PM   #69
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Well I cheaped out today and paid the price. While I've been waiting and waiting for these wheels to come I began looking for stupid things to take up my time. Since I was fairly sure early on that I'd be getting PS4Ss installed, I searched Craigslist for a deal and ended up finding a pair of 235/40/19s (the exact size I was looking for in front) with 60% of their life left for $50 each. Considering that the rears will surely wear out faster than the front due to camber and slippage, this seemed to be the perfect plan! 60% used in the front, new in the rear, then they'll wear out at the same time!

Well today I went to Americas Tire to make this happen and sure enough they had issue with the fronts. They mounted but didn't have quite enough air pressure to get the bead to seat. They could have MADE them seat, but I was very specific up front that there would be hell to pay if any damage came to these rims. So after trying a number of tricks over the course of about 6 hours, I ended up just buying a new set for the front. Unfortunately they're not coming until Wednesday so now I have to wait 2 more days! Dang! Here's yet another teaser for now...
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      06-10-2021, 02:10 PM   #70
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Alright, time for a real update.

After driving a few weeks with H&R springs in the rear I decided to swap back to the Eibach's, primarily because of increased ride harshness but also because it was really a bit too low. This time however I removed the spring pads, which after measuring confirmed an extra .25" of lowering. This put her at and almost perfect 26" from ground to fender lip in the front and 26.25" in the rear. A little dark, but here's the profile shot of Eibach's all around with rear spring pads removed.


Then I got the idea to paint the two braces under the front bumper, red. Honestly it's a bit lame, but barely noticeable under normal conditions and in certain lighting helps tie the red accents into the front of the car, which has been noticeably missing. I opted to paint with plastidip for this rough draft so I can revert back to stock black if I don't like it. If I do like it however, I'll get them powder coated so they shine a bit more and match the calipers.






And for the update I've been waiting the last 6 months for- the Volks installed. As a reminder these are Volk TE37 Ultra M's in Blast Bronze in 19x8.5 +36 front and 19x10 +30 rear.










Ran a 15mm spacer in front to bring them out to flush and unfortunately the rear requires camber to fit under the fenders, but that camber was already there so it's kind of a moot point.


I'm still in processing mode for how I feel about them, and I may need to make some changes before I'm really happy. First of all the tires on them are 1.5" taller than stock (235/40/19 front and 265/35/19 rear). The 513M's were .6" taller than stock (245/40/18 front and 275/35/18 rear) and these are almost a full inch taller than those. Right now the thicker sidewalls really seem to stand out, but I think some tire shine will go a ways towards fixing some of that. I made this tire sizing choice for a few reasons:
  • Comfort- Trying to keep the same sidewall thickness as the 18's- this was a bigger deal when I was running harsher coil overs and planned to run R888R's for tires, but now that I've settled for PS4S in the tire department (R888R's were on a 6 week backorder!) and stock shocks, these things are buttery smooth
  • Wheel gap filling- A 1" taller tire will fill 0.5" of wheel gap, which has the car sitting pretty much exactly where I want it
  • Gear ratio- Even with the 1.5" taller tires, the LSD and it's 3.46 ratio will result in lower than stock ratios overall

I also wanted as much concavity as I could fit, which is why I opted for the 10" width in the rear. Unfortunately Ultra M's don't come in 9" width for the front wheels and 9.5" is simply too wide to fit (my current 9" wide fronts are very close to the spring perches. Would definitely hit with a wheel that's 0.5" inward and a tire that's 0.5" taller), so I had to settle for 8.5". Looking at the Volk website, the 8.5" wheels have a concavity rating of "Face 2" and the 10" are "Face 4". I figured this wouldn't be a huge difference but it really is. The rear wheels are MUCH more concave than the front, which the below picture does a pretty good job of demonstrating


This may grow on me over time, but for the moment it's a little bothersome. Wishing I'd gone with a 9.5" tire in the rear and then could have tried to dial out some of that excessive camber.

Lastly, I'm still very iffy on the front lip and side skirt extensions. By far my favorite picture of this car is the down low 1/4 view:


But IMO the lip and extensions absolutely ruin this perspective:


It just looks too chunky and less sleek. I'll probably remove the side skirt extensions for a couple weeks to see how I like just the front lip, and then remove the front lip for a couple weeks as well, and decide how I want to run it.

So anyways, that's where we are. Now that I've laid out my grievances I'm considering trying out another set of wheels to see which I like better. I am such a glutton for punishment and bad financial decisions! Think I want to try ESR SR07's (same wheel just knockoff) with R888R's in 235/35/19 front and 265/30/19 rear to bring the overall height back down closer to stock, and opt for a 9.5" width rear rim this time and see if I can't find a way to take some of the camber out of the rear suspension. I think the key though will be finding a way to justify this to the GF, after I just spent all this money on this setup! I doubt she'd actually say anything, but I'll have a number of extra sets of wheels (including those for the e30 which are sitting in the garage) and it's certainly excessive.

In terms of next actual steps, I've finally got all the parts together to swap in the LSD diff this weekend. Ended up getting new Meyle HD diff bushings, a new driveshaft center support bushing, and a new giubo. I'm very hopeful that these will eliminate that 6th gear heavy acceleration vibration I've been getting. Plus I might as well replace them while I'm in there.

Feel free to let me know what you think about the wheels!

Last edited by proboner; 06-10-2021 at 02:43 PM..
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      06-12-2021, 09:41 PM   #71
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Well... I have had quite an interesting day!

This afternoon I set out on the task to swap in the LSD diff. Got the car up on stands and began removing all the braces and shields that are the first line of defense.


With those out of the way I could clearly see our target, but there was still much to do before she was accessible.


As mentioned in my previous post, I had purchased replacements for the wear items in the drivetrain as "while-you're-in-there's", so this wouldn't be one of those jobs where you try to find the shortcut to get the diff out... everything had to go. While unbolting the exhaust from the downpipes, I noticed one of the bolts was missing. Surely causing some sort of exhaust leak, which I'd actually kind of been suspecting recently. Sure enough, with the exhaust removed it's clear there had been exhaust gasses slipping across the flange


I would also like to point out, I know everyone says there's no power to be gained by the mid-pipes, but that squeezed down section seriously drives me nuts. I just do not see how that doesn't cause a huge restriction and destroy HP.


With the exhaust fully removed, I could now scratch an itch that had been bugging me since I purchased the car. A rattle. I remember hearing it the first time I drove the car when out in Washington to buy it. I was 99% sure it was the valve rattling in the passenger muffler, which was actually part of the reason I ended up going aftermarket. But after moving to new mufflers the errant noise persisted. In one of my videos someone suggested they thought it was wastegate rattle, which scared me for a moment, but it just didn't sound right and the turbos are too new. Finally, several weeks ago I got under the car to inspect and find the source. I couldnt see anything that could be the culprit, but upon hitting the passenger most secondary cat, I could hear something in there rattling. With the exhaust now off, this was my time to see if my theory was right. I lifted it up from the muffler until fully vertical when a small black something came falling out the pipe inlets


I was right! The PO, who notably did a TON of performance work to this car before I got it, must have accidentally dropped a bolt down in there and either didn't realize or didn't want to deal with dropping the exhaust again to fix it. I am SO HAPPY that this was the actual reason.

It was now as easy as removing the last heat shield to have access to the driveshaft tunnel and the secrets it held. And what a secret it was! Back when I was deciding what replacement parts to buy, I was doing research to find pieces that would be upgrades from stock but wouldnt increase NVH. One of the items I did a good little bit of searching on was a metal giubo that sits between the transmission and driveshaft. I coulnd't help but think that with my now basically doubled hp/tq, that thing had taken a beating. I'd read about a metal giubo that was an upgrade for certain e90 335is', which started in about 2010 but was discontinued a few years later. There seemed to be a lot of uncertainty about this piece, but I happened upon a thread on *********** that convinced me to just buy a stock rubber replacement. Well wouldn't you know, upon pulling the heatshield, it turns out I have a metal giubo!


Now I'm not sure if this is stock, and honestly I kind of doubt it is, but it's so curious to me! I know the PO installed a 335is clutch, so maybe he went ahead and bought one of these unicorn giubo's as well?

Anyways, I decided to stop there for now, as I'm at a bit of a crossroads. I had theories that despite only having 50k miles, all the bushings were perhaps shot due to the massive increase in power. But upon close up inspection they all look totally fine. The giubo appears to be in great shape and I'm not sure if I want to replace it with a potentially less durable version. The drive shaft center support bearing rubber looks pristine, and if the giubo isn't coming off, it seems like a lot of work to replace a part that still looks new. As well, the diff bushings don't seem to be too bad either. I'll certainly replace the rear bushing, as it's easiest to get to and I had an upgraded Meyle HD version, but the 2 front bushings look fine and I believe will be noticeable harder to get access to. Choices choices. Tonight will be one of contemplation.

edit: you know what? Now that I think about it I'm willing to bet the PO already went through the drivetrain a few thousand miles ago when he did the clutch. Along with all the performance mods he performed, he was also way on top of preventative maintenance and had pretty much every possible wear item in the engine bay replaced. Seems pretty par for the course that he would have upgrade the giubo and replaced the center support bearing when the trans was out. I almost wouldn't be surprised to pull the diff and find that it was LSD already, haha!

Last edited by proboner; 06-12-2021 at 09:52 PM..
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      06-14-2021, 11:42 AM   #72
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And yesterday the work continued. Started off by cleaning the mating surfaces for the LSD diff/cover and sealing that bad boy up to prep for the fluid/install.


Also wire brushed the exhaust flanges to make sure they get a nice seal when I reinstall. You can see the gasket material that has come off on this one.


And all downpipes all cleaned up


Then it was time to get into the meat of the work. Unbolted axles and driveshaft from the diff and managed to slip it out by unbolting and turning the swaybar. For anyone wondering, I have not removed the wheels or axles during this removal. I would also note, I would HIGHLY suggest getting a Harbor Freight transmission jack or equivalent if you plan to do this job. It's just so helpful in so many places and I believe I got mine for $50 used.




While I had it all out I decided to replace the metal giubo. I've had some weird vibration issues and there have been suggestions that the metal giubos may cause issues, so I figure it couldnt hurt to just reinstall a rubber unit.


Then I moved on to the most dreaded part of the install... bushing R&R. Ended up renting a ball joint press from O'reilly but still had to go buy some all-thread, nuts, and spacers to make it work. Long story short it all worked out. To note the Z4 bushing sat different than the e46 that I ended up installing. And to be clear in case anyone else has the same question and can't find an answer (basically me for the past few weeks), E46 DIFF MOUNTS FIT. This really opens up your upgrade options, as basically nothing is available but the stock units for the Z4, but there are TONS of upgrades for the non-M e46. I was resistant to go too firm, but you've got options all the way up to solid with the e46 stuff, and there's no indication of them being cross-referenceable. Unfortunately I forgot to take a picture of the new bushing installed, but if you refer to the upcoming "installed" picture you can see how the fitment is slightly different. Same net effect, just bushing sticks out a bit farther on one side, which doesn't effect alignment, function, or install at all.


There was a moment there where I got lazy and thought about not doing the mount replacement, but I'm SUPER glad I did. Once I got that thing out I realized how much flimsier it is than the Meyle unit.






Finally the final step of the big work, moving that gigantic beast into place. Once again, I simply do not see how I would have gotten this done without the trans jack, but after about 30 minutes of struggling she was bolted into place. Thankfully I'd just done all this work on my e30 about a year ago, so it was very similar and I'd already had quite a bit of experience.




Managed to bolt up axles, driveshaft, and the sway bar before finally calling it quits for the day. To give an idea of time spent on this so far, I spent about 4 hours on Saturday and maybe 7 hours of Sunday. At this point it's mainly just buttoning things up to be completed. Final torquing of all the drivetrain bolts, reinstall heat shields, exhaust, and braces/covers... that's about it. Figure I've got another hour or two left in her. Super excited for the outcome of this! The benefits of course being:
  • No more exhaust rattle
  • Firmed up drivetrain with the stronger rear diff mount
  • Eliminated vibration witht the giubo replacement?
  • Better acceleration with the shorter final drive
  • More grip and predictability with the LSD!

Will have updates on these very soon.

Last edited by proboner; 06-14-2021 at 11:49 AM..
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      06-15-2021, 12:20 AM   #73
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And I finished her up today.

First thing I noticed, much more abrupt engagement when reversing. Honestly I was initially worried that maybe the lash on the diff was set wrong or something was loose, as the clutch engagement in reverse was so abrupt that it felt more like an on off switch. After backing her into the street and putting the car in 1st, I was able to feather the clutch and drive without an harsh engagement, so that was a relief! Definitely the engagement through the drivetrain is much more direct. My guess would be solid rubber diff bushing is causing this, which I would say isn't something I dislike, but more of a worry initially that something was wrong.

Second thing I noticed, no more exhaust rattle! Great success! So happy to be rid of that damn thing! Although now that I've had the exhaust all the way out and seen that horrendous necking down to like 1" ID in the mid-pipe, I may have convinced myself to go aftermarket with the whole thing.

After driving around for a bit and getting her up to temp, I decided to get on it. Did a WOT pull through part of 2nd and shifted early to 3rd and went WOT a bit more. I was really surprised with how different it felt. It feels... well... planted. The rear end just hunkered down and went. It was very different from the old diff, which almost felt like it skated and searched for grip. This rear end just grabs hold and takes the traction for it's own. It also feels surprisingly smoother. Under power there's no vibration at all, just smooth power delivery.

There is a bit of annoyance though. When maneuvering at slow speed, like when trying to creep up into my driveway or switching between 1st and reverse when changing directions, there's a bit of engagement weirdness. Almost like it's loaded up when it shouldn't be and pressing in the clutch releases the tension. I know that a lot of people talk about banging going into gear, and I'm definitely not getting that. But I do think that it could be the same potential culprit, which is driveshaft center support preload. I knew there needed to be some and I did push the center support towards the rear of the car to introduce that preload, but now I'm wondering if I should have maybe preloaded it in the opposite direction? I'll have to do some more driving and research to decide if it's worth digging back in there to change it.

Sorry no pictures this time around.

edit: How could I forget! The gearing change. It definitely feels quicker, especially at lower rpms off boost and especially compared to how it felt before the diff swap but with the new taller tires. Let's talk through the calculations really quickly shall we?

Stock rear tire- 255/35/18 aka 25" diameter- with the stock 3.07 final drive ratio this results in:
80mph cruise- 2880rpm
top speed- 194mph
2nd gear 7000rpm shift- 71mph
513M rear tire- 275/35/18 aka 25.6" diameter- with the stock 3.07 final drive ratio this results in:
80mph cruise- 2820rpm
top speed- 199mph
2nd gear 7000rpm shift- 72mph
Volk rear tire- 265/35/19 aka 26.3" diameter- with stock 3.07 final drive ratio this results in:
80mph cruise- 2750rpm
top speed- 204mph
2nd gear 7000rpm shift- 74mph

All in all not a huge difference, let's look at the 3.46 final drive

Stock rear tire- 255/35/18 aka 25" diameter- with the LSD 3.46 final drive ratio this results in:
80mph cruise- 3250rpm
top speed- 173mph
2nd gear 7000rpm shift- 63mph
513M rear tire- 275/35/18 aka 25.6" diameter- with the LSD 3.46 final drive ratio this results in:
80mph cruise- 3150rpm
top speed- 177mph
2nd gear 7000rpm shift- 64mph
Volk rear tire- 265/35/19 aka 26.3" diameter- with the LSD 3.46 final drive ratio this results in:
80mph cruise- 3090rpm
top speed- 182mph
2nd gear 7000rpm shift- 66mph

The 3.46 final drive obviously makes a much larger difference, which on the stock tire diameter really cuts the legs off. With the 1.3" taller tires on the Volks however, things start looking much closer to the stock tire diameter on stock diff, just a little bit quicker. We'll see how it actually works out in the real world, but I really like that it allows me to increase acceleration despite these much taller tires but not cut too much into my 80mph cruise rpm.

Last edited by proboner; 06-15-2021 at 01:07 AM..
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      06-15-2021, 01:15 PM   #74
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Did some quick searching and it seem the preload should be pushing the center support towards the front of the car, not the rear like I did. Looks like she'll be coming apart again (albiet just the bare minimum to reach the support) this weekend. Blast!!

Anyways, here she is sitting pretty (and dirty) after being pulled out of the garage yesterday. She doesn't look different at all, as the modification was obviously internal, but you can tell she feels more confident in herself, and what's sexier than confidence?
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      06-20-2021, 03:43 AM   #75
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Finally washed her for the first time since the new wheels and LSD
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      06-21-2021, 01:15 AM   #76
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Couldn't resist taking a few at the grocery store today


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      06-24-2021, 12:43 PM   #77
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Well folks, she's really coming together. Wanted to do a "look back" post here to summarize all that's been done and what's left to complete. I have the curse of just continually finding new things to do, and I'm hoping that if I set a discrete end point I can stop the madness! on to the list...
  • Gunmetal painted pieces- Sidemarker lights, kidney grilles, grille inserts, rollover hoops- A+ would recommend
  • H&R lowering springs- Great height but ride is lacking- C+
  • Android screen (no iDrive)- Missing all iDrive functionality- D+ almost useless
  • Wrapped interior pieces- Wrong color unfortunately so will be replaced- A mod if done right
  • 35is brake upgrade- bigger and better- A+ would recommend
  • Caliper powder coating- Looks fantastic- A+ would recommend
  • ST XA coilovers- Way too harsh- D- would not recommend
  • Varex mufflers- Great looks great sound- Grade A mod
  • Diamond floor covering- Easier to clean than carpet, looks pretty decent- Grade A mod
  • CX Racing coilovers- Better than STs but still harsh- C grade
  • Eibach lowering springs on stock shocks- Comfort over performance- B grade
  • LED halo bulbs- Much whiter than stock- B+ mod
  • CF lip and sideskirt extensions- look and quality leaves a bit to be desired- B- good not great
  • Cut and reinstalled valve cover cover- Looks much better than no cover!- B+
  • Volk 19" wheels- The look I've wanted since forever- A
  • 1.6" plus sized tires- Great for comfort and looks, a bit of interference- B
  • MFactory LSD- Got that traction, added a bit of weirdness to drivetrain- B
  • Meyle HD rear diff mount- Adds firmness to drivetrain but not harsh- B+
  • Painted under bumper crossbars- Meh, not a big change- B-

With all that said, there are a few things left that I will definitely be doing, and a few things that I may change (aka will almost certainly change because I cannot stop myself) in the future.

Definite list:
  • Lamin-X headlight covers- headlights currently have major pitting from rocks being thrown at them- going to sand and protect
  • Suede interior trim- To replace the cf vinyl. Already on order and will be here soon
  • Exhaust- 2.5" dual, clean up the muffler switch install (which you all have not seen yet), build muffler mounts
  • Paint correction and ceramic coating- she needs it
  • Personalized license plate- hopefully will be here soon!

Maybe list:
  • Msport rear bumper- provide capability to add a rear diffuser and hopefully bring the rear of the car in line with the front/sides
  • iDrive- the aftermarket screen is useless without actual iDrive, IMO. Don't know if I care enough to transplant an entire iDrive system, but stranger things have happened
  • Ohlins?- greatly depends on blowing out stock suspension at some point in the future
  • E92 M3 and upgraded E46 suspension pieces- as things begin to wear out, essentially OEM+ upgrades. Do not want to increase harshness.
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      07-15-2021, 04:29 PM   #78
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To continue crossing things off the list, the Lamin-X covers and Alcantara interior pieces have arrived. I've been working on and struggling to get the headlights polished, so that will likely wait another week, but I did install the Alcantara pieces yesterday.

Ordered off Aliexpress and they took about a month to get here. On the website they always seemed to be a dark grey to me, but I feel like they're trying to be black. Either way, dark grey as an accent color for the car, so they fit the scheme. The box was pretty crumpled by the time it arrived at my house, but the pieces were relatively untouched. I only ordered pieces to cover the silver accents in the interior.


If you think back (or look at the accompanying pictures) you'll remember I covered the center console and area around the HVAC controls with a grey carbon fiber vinyl. This had been a mistake from the beginning, but I gave it some time to win me over. Although the look isn't terrible, I never got around to covering the other silver interior accents, and wanted to try something new.













Don't mind the wires, it's part of hte switch install for the mufflers. They'll be cleaned up soon.

I really like what it's going for. The Alcantara looks and feels great. There is an issue however, and that is they don't cover everything 100% perfect. Honestly, now that I've installed and had experience with them, I really don't think they possibly could. I think it's an inevitability, no matter how well made, that there will be some slight showing of what's underneath, and that may kill it for me in the end. Thankfully it's actually pretty hidden from the drivers seat, but inspect any of it closely and it becomes quite glaring. I'll have to hop in the passenger seat and take a look as well.
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      07-17-2021, 12:34 AM   #79
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Wow brother. Coming along very nicely. Making me regret selling mine.
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      07-17-2021, 07:10 PM   #80
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Thanks! I've owned her for almost a year now and I'm really surprised how much money I've thrown at it. I've got to say though, with things all coming together and the end in sight, I'm pretty darn happy with it. Looking at the latest pictures, shes SO DAMN DIRTY. Thankfully she'll be getting a full thorough cleansing, paint correction, and ceramic coat soon, so that will really be the frosting, whipped, cream, and cherry on top!
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      08-11-2021, 12:24 PM   #81
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Wow mate, your Z has come a long way. You're one of the very few who are modding and experimenting with their Z. Keep it up, I enjoyed catching up on your posts!
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      10-22-2021, 07:10 PM   #82
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Wanted to do a little update since it's been a while. The car's been on jackstands in the garage for several weeks now but will hopefully be coming down this weekend, so thought I'd get things started with a small project I just completed.

As anyone who's followed this build knows, I've been running Varex mufflers on stock exhaust piping for a while now. Hilariously I originally bought these mufflers years ago for a different car, but they ended up being an absolute perfect fit for the Z4. The coolest part about them though, being that they're internally valved to be straight through or "turbo" style.


You can see in the above (dirty) picture they have a removable tip (which the included one fits the stock cutouts in the bumper perfectly) and that little box looking thing is the motor that opens and closes the valve. Now although this setup has been installed on the car for close to a year, it took me quite a while to actually run the wiring into the cabin to actuate the valves. When I finally did, I realized the closed position was so quiet as to not even be useful, which basically killed my interest in the project, so I left it in a state of half-completion.


With the car up in the air for the past few weeks however, my gaze slowly crept towards the exhaust again. It sounds great with the mufflers "open", but is almost silent with them "closed". I want something that sounds great "closed" and insane when "open", so exhaust piping has been acquired and will be going on soon. In the meantime though, I figured I'd address the unfinished switch/wiring.

I had originally purchased a rocker switch with the required polarity switching (the valve operates by switching polarity to open/close), but this style of switch proved to be much too tall. It would need to sit above the surface of the center console to fit, which obviously would work. So I went about designing a relay setup, momentary button switches, and a housing to make it fit/look better.

I'd actually done this once before on one of my old cars, but had to re-draw the diagram to remind myself of how it worked.


And then assembled it in real life


Properly sized switches were easy enough to find on Amazon


And then I hopped into tinkercad to design a housing that I could 3D print. Took a few iterations but eventually I ended up with something that looked like this:






Obviously it doesn't fit perfectly flush, and using simple screws to attach it to the cubby isn't the most elegant, but for the amount of work I was willing to put into it, I'm pretty happy. Tinkercad is a pretty flexible design application, but nowhere close to what I'd need to create something with OEM fit.

From there I installed in the car, and now she's ready for the work this weekend to commence!
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      10-25-2021, 02:08 PM   #83
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And on to the next project, which is the reason the car has been on jack stands in the garage for weeks. As you may remember, I switched to an MFactory LSD diff a few months ago. Upon first drive, I immediately noticed a harsher engagement of the drivetrain upon engagement of the clutch in 1st gear and reverse. Initially it didn't bother me all that much, but after taking a couple long drives with the GF that landed us in a bit of stop and go traffic, it started to make me insane. The harsher engagement when getting into and out of the gas, a more audible whine at highway speed under light throttle, and a noticeable whine under WOT acceleration.

I racked my head over what it could be. I'd found other reviews of people saying their LSD's "clunked", but in my mind it never really felt like a clunk. Eventually I decided it must be related to the Meyle HD diff bushing I'd installed. I figured that perhaps all the other mounts in the drivetrain being stock, with this 1 stiffer mount, it was throwing the synchronicity of the entire system off and causing issues. I also remembered a YouTube video I'd seen before installing the diff, showing how you could replace the rear diff mount on an e46 without removing the diff itself:

Given what a PITA doing the entire diff would be, I thought this could be a great option to test my bushing theory while keeping the work load low.

Well, longer story short, I discovered the hard way that removing the rear diff bushing on an e89 isn't possible with the diff installed. The ring gearis physically in the way of where the bushing would need to be pushed for removal. I'd also found when pulling the diff cover, that the fluid inside had much more metal sheen than I thought was normal. Perhaps there's something actually wrong with this unit? So, with about 1/4 of a diff removal already performed, I bit the bullet and pulled the whole thing.

With the unit now fully removed and even more concern in my mind, I made a call to Synchrotech- the guys who had done the MFactory install originally. I spoke with the BMW tech there and received some insight that eased my mind a bit.
  • The LSD will whine more under WOT- especially low mileage units which are still breaking in
  • The LSD will whine more at freeway cruising speed- especially low mileage units that are still breaking in
  • All of the LSD units are installed "tight" which causes a bit more wear in the first several thousand miles- resulting in the gear oil sheen
  • Agreed that the stiffer diff mount was probably exacerbating the problems

The one piece of assurance they could not give me however, was related to the clunk. The tech suggested there would be a bit more slack introduced to the system due to the design of the LSD, but it shouldn't be so noticeable. Again I hemmed and hawed over what to do. If I just reinstalled with a new mount and all the issues persisted, I'd be pissed at doing all that work and not covering all my bases. So I continued my search to see if I could find feedback from others on what they were experiencing with similar MFactory LSDs.

I first began with posting on N54 groups to see if anyone else had an MFactory LSD installed and if so, were they all feeling the clunk. If the clunk is par for the course and just a part of owning an aftermarket LSD, perhaps it was just the wrong thing for me. Not many responded with actual experience but there were a couple who insisted they felt no difference at all from factory. My takeaway being, clunk is likely but not guaranteed.

Next I found a guy on a forum showing a bit more clearly what his clunking visibly looked like. When I was in the throws of removing the diff, I happened upon a situation that I only vaguely noticed but now realiz I should have paid more attention to and definitely should have recorded. When I was in the process of removing the driveshaft, I found that I could turn it almost a full 1/4 of a rotation before it would engage the output shafts. This seemed to explain exactly what I was feeling. The harsh engagement in R and 1st could easily be attributed to this slack for 1/4 of a turn and then immediate harsh engagement as the output shafts would catch and engage the wheels. If you take a look through the thread, you can clearly see a similar situation going on with this guy and his Fiesta. When he engages 1st and R you can see and hear that lagging engagement: https://www.fiestastforum.com/thread...y-folks.27667/

This very much seemed to mimic my issue, so certainly others are feeling it and are annoyed. But the final piece of evidence that put me other the top, was found in an N54 forum where MFactory had provided their own take on all of this: https://www.n54tech.com/forums/showthread.php?t=29755
For those of you who don't care to visit the link, the pertinent text is thus:
"- Common Problems -

Diff Thump:
The two main causes of "thump", and both have to do with free play:

1) Worn or misaligned (during reinstallation) centre bearing of the propshaft. The only solution for this is to check the centre bearing, and replace if necessary.

2) Backlash. All LSD internals have free play in them (i.e backlash). This free play is a necessity because steel expands when heated. If there was no free play in the gears, they would end up welding themselves together due to the friction, and because of this, there is a compound effect i.e the backlash between all of the internal gears of the LSD (at least 12 of them for most Helical LSD's) plus the backlash of the Ring & Pinion.

What this means is that there is a small "lag" between turning the propshaft, and the axles locking (i.e turning), which results in the "thump" noise you are hearing. It is not noise from the diff that you are hearing, but noise due to the vibration through the chassis and the propshaft/axles locking into place. This is also why it is normally louder during hard acceleration, especially so if you've upgraded any chassis components (mounts, diff bushings, subframe bushings, braces, suspension etc) or upgraded your clutch.

There is no full solution for this, however, warming the diff up (thus reducing the overall backlash) will quieten it down slightly, as will using thicker gear oil. Baby'ing the clutch will also reduce it a lot, however, this will also increase the wear on your clutch.

When stationary and in neutral, your transmission gears are still turning, so when you put it into gear, this locks the gears together causing the propshaft to turn very slightly which causes the "thump" due to the free play between the propshaft turning and the axles turning. As the axles are basically locked into position and can't move due to not enough power being applied (i.e clutch is still disengaged), this is why the thump (i.e vibration) is more noticeable when putting it into gear from stationary, compared to changing gear when moving.

Most quality LSD's will be machined precisely to specification, based on a new set of "unworn" axle stubs i.e if new axle stubs are used, there should be very limited play between the meshing of the splines (there will be a little due to the fact that they are not press fit and just freely slide in and out). If old axle stubs are used, then there will be slightly more play due to wear/compression, and this will contribute to the overall backlash, thus the "thump".

Remember, the thump is not "noise" per se, it is vibration through the chassis.

The above is applicable to ALL LSD's, regardless of type."

So there's the answer. At this point things became pretty clear to me. If what I was feeling was normal, I had no interest in reinstalling and continuing to use this LSD. I would go back to stock diff and just be eLSD and live with it. But this then brought another question into play... what if there's something wrong with this unit? It's very low mileage, but the PO was in a wreck which is why I was able to buy it. Maybe something weird went down internal to the LSD? Based on the above writeup and my experience, it seemed clear that I needed a way to check the backlash, which I was pleasantly surprised to find in this YouTube video:

So based on this I found a way to measure the backlash, and an understanding of what the suggested tolerance is.


Backlash should be between .002" and .009", and what I measured in mine was around .007". Within spec, but definitely on the higher end. Plus, this seemed like a pretty amateur way to measure, and I wanted to know FOR SURE if anything was wrong. So I bit the bullet yet again, and sent it off to Synchrotech (which I now realized was a partner of MFactory and does all of their LSD installs) to be torn down, measured, and inspected.

While it was gone I went ahead and replaced the diff mount for stock, and awaited the results... which were very frustratingly pretty much the exact same thing I already knew. "Within spec but at the high end of tolerance". They went ahead and fully disassembled, found nothing wrong, and reassembled with at the tighter end of spec. What are you gonna do?

So, given my own reasoning, this should have been enough to decide I didn't want to use the LSD and I should install my stock diff and just moved on, right!? OF COURSE NOT! I'm still nothing if not a glutton for punishment! I don't know what to tell you folks, I really want this to work!

The reassembled diff arrived this past Friday afternoon and I was set to reinstall on Saturday. To my dismay, however, when I got under the car on Saturday I realized the stock mount I'd installed didn't go in quite right, and was actually broken. I wanted to say fuck it, and just install the bastard anyways, but cooler heads prevailed and I drove down to O'Reilly to rent tools to remove it. Sure enough it's pretty messed up, and unfortunately it's going to take a week to get a new one!






In the meantime, I've got a couple other considerations to take into account. Once again going back to the MFactory writeup, it's suggested the driveshaft center bearing can be an issue, and as luck would have it I actually have a new one sitting in my garage. Perhaps that will need to go in this week. I also have done a direct comparison between stock and LSD to see if there really is a difference in clunking due to loose fitting axle stubs, and there is! I may try putting my low mileage stock stubs into the LSD diff to see if it can clean up the tiny bit of slop.

Anyways. We shall see if these things cure what ails me, or if it's all coming back out again and the diff going up for sale!
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      10-28-2021, 12:54 PM   #84
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More updates, you ask? Well don't mind if I do!

After waiting WAY too long, I finally have a complete aftermarket exhaust in my hands. I ordered a Becker brand exhaust off of ebay, as I really didn't want to spend days laying on my back building my own, and I also didn't want to spend $3k-$4k for the usual brands. For those of you who may not have seen it, it's 304 stainless steel, dual 2.5" piping, no catalytic converters or resonators, and two dual tip mufflers in the back. I already have mufflers and don't plan on modifying my rear bumper to fit quad exhaust, so I planned not to use the ones that came with it. Even so, it's still a significant cost savings just for the piping!

I open the box and first dig into the mufflers. As mentioned, I don't plan to use them, but man are they nice quality! Welding is first rate, they just look fantastic for the price paid!


Next piece I pulled out was the flange and length of piping leading to the mid-pipe. Immediately I knew there was something wrong... this is not 2.5" piping. I stole the vernier caliper from the garage and checked to see how close it was.


52mm aka 2.047"! WTF! So I immediately looked at the piping welded to the mufflers. Now this looks like the correct size, and it is, right at 64mm.


So the first several feet of the exhaust is 2" OD, and the final portion is the correct 2.5"... where exactly does it jump up in size? I begin unwrapping the mid-pipe and immediately see the culprit.


Right at the beginning of the mid-pipe, the exhaust just randomly and without transition, grows from 2" to 2.5". What the hell are they thinking? Let's measure and confirm. Small side of transition:


55mm... a bit bigger as this is actually the slip pipe that the front section slides into. Large side of transition:


64mm. Yup. So what the hell is going on here. I head over to ebay to double check the listing and make sure I'm not going crazy. I confirm that in fact, yes, it does claim to be 2.5" piping. Then I peruse through the pictures. Now that I've actually seen it in real life, you can find it in the pictures as well. The clear jump right at the start of the midpipe in this picture.


And made even more clear in this picture of all the components separately. I mean, just look at the visible difference of flange side and muffler side exhausts as they sit next to each other. MUCH larger. I know it's only half an inch bigger, but it's obviously a pretty huge difference.


So now I'm left wondering... what the hell is happening that they'd choose to do this? It makes literally no sense! Until I see the ad for the 4cyl version of this exhaust.


2" piping, and running the exact same path as the N54 version, up until the midpipe. So pretty clearly, they designed and manufactured the 4cyl version first, and when it came time to make the N54 version they decided it woudl be easier/cheaper to just reuse the original design from flange to mid-pipe, and then just weld on a different back half to fit the dual muffler layout. I mean, you can literally see the welds where they combine the two different exhausts together. Most every section of hte exhaust is a continuous smooth pipe, but this midpipe all of a sudden has a welded on transition. Talk about a disgusting cost savings play.

Well folks, if it's not obvious by what I've written thus far, I would NOT suggest buying this system! Thankfully ebay is very good about returns when an item not matching the listing description is delivered. I don't have to deal with the seller at all, who I know would try to charge a restocking fee. Won't have to pay for return shipping either. I guess I'll end up building my own after all.

Last edited by proboner; 10-28-2021 at 01:01 PM..
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      10-31-2021, 04:36 PM   #85
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And the work continues. The new mount finally came in the mail on Wednesday and Thursday I set about trying to get it installed. I figured I'd just be very careful to make sure it wasn't going in sideways at all, and just finesse it. Try as I might however this thing simply would not go in straight. And if you did try to force it, which I had previously, you could see it ripping into two. So ended my work on Thursday with result, and headed over to O'Reilly to rent some tools for Friday.

I'd actually posted on the E89 Facebook group to see if anyone had advice to share, but it was all answers from people who obviously hadn't done the Z4 diff bushing before. Yes, I'm aware you use a threaded rod to clamp it in. No, you can't just turn harder until it's forced in. I actually ended up taking some measurements, because this thing is definitely bigger than the E46 diff bushing, which should be the same diameter. E46 is pictured below at 68mm


And the E89 bushing measuring 72mm


Anyways, I ended up with a couple O'Reilly rental tools tools that helped me piece together this little ditty.




Which was just effective enough to get the bushing in place without splitting




And with that out of the way everything went back together in a few hours. And guess what... it's basically fixed! The clunking is been reduced by about 75%, which makes me SO HAPPY. There's the odd vague clunk every one in a while when shifting into 1st from a start, but that harsh engagement is completely gone. Not sure if it was the mount or getting the diff reassembled, but either way I'm stoked!

Next update, new exhaust moves are being made. Stay tuned!

Last edited by proboner; 10-31-2021 at 11:16 PM..
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      11-29-2021, 01:38 PM   #86
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DAMMMNNN ITTT. Wrote a huge writeup for this but just lost the whole thing. Here's the cliffs notes version:
  • Traded my stock exhaust for a used Becker exhaust- straight up


  • Installed Becker exhaust piping with my current Varex mufflers






  • Bought SS mandrel bends and flanges to fix the 2" piping issue


  • Took videos of the noises


  • Stumbled across a SMOKING deal on front/rear M-sport bumpers with aftermarket CF lip/diffuser for $300


  • Took some fall glamour shots










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