So, you picked up a new project car and feel like you’re ready to hit the track after a few bolt-ons and some routine maintenance. You tell your friends, “I got this thing cheap and it’s mint,” and say things like, “Yeah, it handles like it’s on rails!” Everyone has a laugh and you feel like you made it, all the while, every piece of rubber -- every mount and joint -- is worn and sloppy, resulting in your track toy feeling softer than a Yanni concert on a cool summer evening.
The biggest thing you have to understand, here, is that when you firm up parts of your suspension with new and/or upgraded parts, your weakest links only become more pronounced. Everything must work in harmony and the upgrade path has to reflect this. With this philosophy in mind, we set out to tackle Project 135i and guarantee that every piece was addressed. Of course for this, we got in touch with our buddies at BimmerWorld to figure out what we needed.
If you didn’t catch the intro of this new, smaller (way sketchier project than Project 335) project, check out that article here. Again, the goal here is: track car with a license plate, so we didn’t really hold back on firming up the ride, but we also didn’t actively seek to increase NVH (noise, vibration, harshness) without regard. Paramount to making sure every bushing and bearing was addressed, we also needed adjustability to fine-tune our alignment and give us a deeper adjustment range than what the stock eccentric bolts and suspension arms offered.
BimmerWorld President James Clay knows a thing or two about basically everything BMW related, so I asked him for his honest opinion when it comes to bushings, because there is A LOT of misinformation out there, and if there’s something you don’t want to install, uninstall, and install again, it’s press-in bushings, especially when they’re buried in your rear subframe.
“I absolutely think you need to be thoughtful in bushing selection for a car,” James said. “That being said, I put Powerflex Black Series (track) bushings on some locations of my mom's street car - and I would be replacing them if they added NVH and she seems to have a tremendous feel for it... That's the whole reason Powerflex makes bushings in 3 durometers! They focus both on the actual design of the part, as well as the material used, which has durometer differences, but is also a premium material that addresses the N and partially H part of that equation aside from durometer. Turns out a better material can take care of a lot of the noise issues.”
That was enough to sell us on running PowerFlex Black Series (Track) bushings in the 135i’s front/rear rear subframe locations, front/rear differential locations, and rear upper strut mounts. The stock bushings honestly feel like marshmallows by comparison, and with the right supporting modifications, the rear-end feels incredible, with barely an ounce of added NVH I can feel or hear. Granted, this isn’t the quietest or softest car, but these bushings are a dream compared to an E92 M3 I recently drove with solid aluminum rear subframe bushings, yet that car felt no firmer or more planted than the 1.
Quickly, before you decide to order these parts and do the installation in your driveway, I must warn you: this is probably one of the least fun installs you’ll do. Dropping the rear subframe isn’t necessarily hard, but there are many steps. I wouldn’t do it without a lift, but many people do. Getting the stock bushings out is pretty labor intensive too, but getting these new bushings in is a battle of patience, not strength. If I were you, which I’m glad I’m not, because I’m already done with the install – I’d have a capable shop do this for you! Fortunately, our friends at European Auto Source, in Anaheim, CA, have done these hundreds of times, and they handled it with ease while I tackled other parts of the car. Whether you need advice, modifications installed, maintenance or a specific part, they've got you.
With the rear bushings squared away, it was time to address some major pivot locations front and rear. The front upper control arms and rear camber arms see extremely high loads and suffer from intense deflection and stress, so together, these are some of the most critical locations on the E8X/E9X chassis cars. For a street car, you could upgrade these bits to PowerFlex bushings, but since our 1er will see a lot of track time, BimmerWorld suggested we go all out with their precision bearing kits.
While we were up front, we also opted to upgrade to the E9X M3 front lower control arms for some added negative camber and better materials. Since the front upper control arm was being modified with the new BimmerWorld bearing, and the dimensions of the non-M upper arm are the same as the M, we decided not to bother buying a new piece.
Precision Front Upper Control Arm Bearing Kit:
This location is super critical because it affects your car under braking and to a lesser degree, turn-entry and cornering. The ABS will allow you to brake until the verge of lockup, then releases pressure for the tire to roll again (or slip less), then reapplies braking force. But with the flexibility of the stock bushing in this arm, the wheel actually moves back in the wheelwell 1/4-1/2" in the braking motion, then back forward in the wheelwell when the ABS releases, then the cycle repeats - kind of like an undamped spring (or blown shock) on your suspension - except in the longitudinal direction. The BimmerWorld bearing solution keeps the tire in place so the ABS now has a much more stable system in which to look for grip - it isn't chasing a soft, moving target. Thanks to a factory sealed suspension bearing, this part is both durable and has good road manners, which I can attest to after miles of track abuse and no shortage of destroyed LA roads.
I didn’t run this kit on our E90 335i project, and I always wondered why that car felt so numb and loose under braking and turn-in. This was it… The 135i brakes straight, and QUICKLY (thanks StopTech!) and steering wheel inputs are immediate.
Rear Camber Arm Bearing Kit:
This is the most important suspension location in the rear of the car because it is the largest "soft" location that affects getting the power down. Rear grip under load is massive for the little 135i, since it makes over 400hp at the wheels and 450 lb/ft. Much like the front control arm bearing, your tire is much better at applying power and maintaining grip when it is static and not chasing a tire that is loading until it reaches the end of a bushing's travel, releasing, then reloading.
Finally, with all the bushings and bearings taken care of, we finished off this hefty upgrade day with some proper BimmerWorld adjustable rear toe arms and wishbones.
BimmerWorld Rear Toe Arm Set & Rear Wishbone Set:
The BimmerWorld E8X/E9X Adjustable Rear Toe Arm & Wishbone Set moves the adjustment from the clumsy factory eccentric bolt to a precise, fine-threaded adjustable arm. The stock arms are almost thin enough to flex by hand, and the buWith an adjustment range far greater than the standard stock adjuster, the Adjustable Arm Set allows you to achieve the correct toe setting for your specific car, tire, and use needs - anything from a lowered street car to a pro racecar with slicks.
- 100% machined and anodized, 6061-T6 lightweight aluminum
- Extremely durable Aurora professional race-quality spherical rod end
- Lighter than stock
- Extremely easy installation and adjustment
That about does it for suspension arms, save the endlinks and a few smaller bits. This car is RIGID and gives instant feedback with lightning response. It's pretty incredible to feel the difference after removing thin metal arms and mushy rubber bushings, in favor of true race-bred parts.
Stay tuned as we continue this build by addressing the motor mounts, trans mounts & shifter, some big power bolt-on parts, and a new WaveTrac LSD with shorter gearing from the less powerful 128i.
Thanks to our friends at European Auto Source for the install and BimmerWorld for the support and awesome products!