E34 BMW 5 Series Suspension Upgrades

Available in the US from 1989-1995, the E34 BMW 5 series is the last of the non-computer assisted design (C.A.D.) cars from BMW. Much more modern looking and driving than the E28 5 series it replaced, the E34 remains today a highly desirable car, for its durability, styling, reliability, and performance. However, even the newest E34 is over a decade old now, and chances are that unless a collector had it tucked away in storage, or was owned by the proverbial little old lady, your 525i, 525it (or 525i touring) 535i, 535it (or 535i Touring), 540i, 540i sport, or M5 has some miles on it. People are usually amazed at the difference new shocks and struts plus upgraded springs and swaybars make. Wanna make your 525i wagon dance in the twisties like an M5? Not that hard. It's all in the sway bar size, spring rates, damping rates, and quality and durometer of the bushings. E34 BMW 5 Series Shocks - Choosing the Right Shocks and Struts for Your BMW and Driving Style If you like damping rates of stock BMW 5'ers, with the consequent stock ride quality, I recommend Boge or Koni. For a firmer, more overtly sporting ride, go with Bilstein HD or Bilstein Sport, Boge Turbo Gas (which are somewhat softer) or Koni yellow. All out sporty ride, short of coilover suspension? Koni adjustable shocks or KYB's if you are on a budget (warning - KYB shocks are very stiff and not in the same league as Bilstein or Koni with regard to quality and lifespan. However, they are certainly an upgrade over anything worn out!). Some Bilstein shock experts think both the HD and Sport have the same valving, but the stroke is simply shorter on the sport models. The sports are your best bet for use with lowering springs. The stroke length is considered to be unimportant for use with lowering springs according to a few BMW experts. In the past, you were led to believe that using lowering springs with standard stroke length dampers would lead to rapid shock or strut wear, but this may not be true. The throw is shorter, and fully compressed position is the same and that is what counts. The worst thing that would happen is that some of the stroke length potential is taken up and not utilized by using a shorter spring. This comes as a relief to many BMW enthusiasts concerned that using H&R or similar springs with newer stock or Bilstein HD's would have a deleterious affect on their car's suspension components lifespans. E34 BMW 5 Series Control arms (aka aluminum wishbones) Aluminum is lighter and stiffer than steel. Aluminum control arms are available for e34 5 series BMWs. E31 8 series arms will work, but they have spherical bearings vs the E34 rubber bushing-equipped ones. If you are just looking to replace the bushings, BMW dealers do not sell them separately, but aftermarket suppliers do. Choosing Springs for your E34 BMW 5 Series If you choose to upgrade from the stock springs, you are faced with a ton of brand and model choices. The most popular spring manufacturers seem to be H&R, whose sport springs drop the car roughly 1.3" Front and 1" in the rear while providing a moderately stiff ride; Eibach, whose springs are similarly stiff with a similar drop compared to H&R; Racing Dynamics, whose springs are slightly softer, but still stiffer than stock with a mild 1" front and .75" rear drop; Bavarian Auto, whose sport springs offer close-to-stock ride quality with a 1.5" front and 1" rear drop; Dinan, whose sport springs lower the car about as much as OEM 540i Sport (sport package) springs, and OEM M5 springs, the rear s of which will not work without self-levelling suspension (the fronts work just fine). Matching Shocks and Springs for Your E34 In order of increasing stiffness: Original ride: Original springs or Bavauto springs with Boge Slightly stiffer ride: Original springs or Racing Dynamics springs with Bilsteins HD. Moderately stiff ride: H&R or Eibach or Racing Dynamics springs with Boge. Moderately stiffer ride: H&R or Eibach or Racing Dynamics springs with Bilsteins Sports/HD. If you want to lower the car and keep the OEM ride quality, go with the Bavauto springs. E34 Sway Bars (Also called anti-roll bars) Sway bars tie the lower suspension components together accross the front and the back, they affect the car oversteer and understeer. Bigger sway bars improve stability while cornering, the best setting is fully soft for the front and hard for the back. Stock E34 models usually have 23mm Front and 16mm rear bars. Cars equipped with factory sport suspension have 24mm front and 18mm rear sway bars. The M-Technic equipped cars and N. America-spec M5 models have 25mm front and 18mm rear bars. Eibach and Racing Dynamics are popular aftermarket providers for sway bars. The Eibac kit comes with a 26mm front and 13mm rear. The Racing Dynamics setup includes a 27mm and 19mm swaybar setup. The euro spec 3.8l E34 M5 had a 25mm bar, as did the rare M5 touring. 1994 and 1995 european M5's had 19mm rear swaybars, for all you Ebay and Ebay.de shoppers! Go with oem rubber bushings with larger sway bar if you want less harshness and vibration. As far as strut bars, also called strut braces or strut tower bars, they are designed to link the two strut towers together. A good strut brace reduces flex in the strut towers when the car is cornering. The tendency to flex is magnified with lowered cars. Good strut bars are a must if ever plan on taking your E34 BMW to the track. They improve chassis stiffness, making the the steering quicker and more responsive. Watch out for junk Ebay strut bars that are adjustable - they are compromised in design and useful for aesthetic purposes only haha!