Warped Brake Rotors and Steering Shudder/Shimmy/Vibration/Shaking

Look through any BMW message board or forum and you will hundreds of posts regarding recurring front end shimmy/shake/vibration during braking. Now, it is certainly true that older models, particularly the E24 6 series, E21 3 series, and E28 5 series had some issues related to the steering components and bushings, but I would estimate that most posts pertaining to modern BMW shaking or vibrating under braking involve an E36 3 series. Complicating matters is that the E36 cars (minus pre 6/92 build date cars and M3 models) are notorious for ball joint, control arm, and tie rod issues that make diagnosing and eliminating front end problems tricky. My 1995 325is has been experiencing progressively worse shudder under braking - and not just at speed where front end shimmy typically manifests itself. I replaced the control arm bushings a year ago, and all ball joints earlier this year. I happened to have a new set of tie rods lying around, but replacing the tie rods did not solve the problem either. Most people I spoke to felt my brake rotors, less than 1 year old and never abused or saw anything other than commuting and regular street driving, were warped. This did not make sense. How could modern steel rotors warp so quickly with seemingly no abuse? It turns out the brake pads themselves are the culprits 99% of the time. Melted brake pad deposits build up on brake rotors, and the solution is to change out the pads in favor of brake pads with a higher heat range. Rob at UUC recommends "Akebono Ceramic or Hawk Performance Ceramic. You won't get pad deposit from either of these, and as a side-benefit they have very low dust. New pads should remove the deposit, so you don't even need new rotors right away. A couple of days and your shimmy should be gone."

E30 Suspension and Tie Rod Replacement and Tips

A friend of mine recently purchased a clean 1991 BMW 318i sedan, the one year wonder with the M42 16v engine, to serve as his daily driver. Despite being well maintained by its previous owner, this rare E30 sedan did have 130k on the odometer, and was in dire need of some suspension and steering work. The car was just loose and sloppy to drive. A 2500 lb, 138 hp bare bones car like this has the potential to handle like the vaunted E30 M3, given the proper upgrades, but we were just looking to make it fun to drive on the street, without destroying any semblance of ride quality OR dropping thousands of dollars on coilovers, spherical bushings etc. This car is a commuter at this point, no a track car or autocross contender (though he intends to try his hand at autocross with the 318i) We determined that we'd replace the following items: shocks and strut inserts. A pair of used rear Bilstein HD (heavy duty's) were found on ebay, and a set of low mileage used Bilstein HD front strut inserts were found on a popular BMW E30-oriented message board. Unfortunately, it seems that the M42 318i and 318is use a larger diameter insert than the earlier four and six cylinder cars, so we ended up buying new correct-application Bilstein HDs from Bavarian Autosport. The used rear shocks fit fine, and appeared to have plenty of life remaining. The price was right, too. Tie Rods. OEM BMW style tie rods were purchased online for much less than the local dealership wanted. Again, make sure you order rods specific to the M42 E30 cars, because there are multiple E30 3 series tie rod part numbers, and others will not fit. When replacing the tie rods, tighten the inner (rack) side first, the adjust runout to approximately match the just-removed one. This way, your car's alignment won't be too far off upon completion. Make sure you get it aligned anyways, however. Control Arms, Ball Joints, and Bushings. New OEM control arms with inner and outer (aka upper and lower) ball joints, plus E30 M3 offset control arm bushings. Tip: If you are replacing control arms and don't want to deal with pressing out the old bushings from the control arm 'lollipops', find a pair of sprare lollipops (from a salvage yard, online parts source etc) and use palmolive dish soap to grease the inside of them. This enables you to use a large mallet to pound the new bushings in yourself, saving you $50 at the local machine shop (then again, it's a wash when you factor in the cost of the spare lollipops, but it does save you downtime). We ran into a nightmare on Bill's E30, when trying to remove the passenger side inner ball joint nut. There is very little clearance between the engine mount, headers, and frame crossmember. We had to remove the front sway bar (and in the process made a mental note to replace the sway bar end links and bushings in the future) to be able to get the 7/8 or 22mm wrench on the nut. Unfortunately, the nut became frozen roughly halfway, and we needed a hacksaw with High Speed Steel blade to saw through the tapered bolt, in order to get the ball joint and control arm out. Not fun lying on a cold driveway in November, sawing away with very short strokes! Rear shock mounts These are inexpensive and sort of a 'while-you-are-at-it' replacement. Springs The stock springs were tossed in favor of H&R's newer OEM-style sport springs, which do not lower the car much and do not throw ride quality away, while still offer better springs rates than stock. With daily driver status, and rough pavement around here, these were the best option. You will need a spring compressor to assemble the front strut/spring assembly. Replacing the rear springs on trailing arm suspension E30 BMWs is easy. Remove the trailing arm end links and rear shocks. Have someone stand on the brake assembly or trailing arm to push it down, and pull the old springs out. Make sure you reinstall the rubber spring 'hat' on the new springs. The performance difference this all added up to was impressive. Despite the little 318i still being handicapped by 14" steel wheels and Mastercraft Mud and Snow (M+S_ tires, there is a night and day difference not only in body roll, damping rates, and response, but the fun to drive factor is through the roof. The 16 year old car feels much tighter than it has any right to be. I anticipate that the springtime planned addition of plus one or plus two wheels and aggressive stickier tires will really transform this humble looking E30 sedan.