II - Both Axles

• Shocks/Struts
• Springs
• Coilovers
• Wheel Bearings
• Sway Bars (Anti-Roll Bars)

III - Front Axle

• Front Axle Diagram/Overview
• Control Arms
• Lower/Front Control Arm Bushing (LCAB/FCAB)
• Strut Mounts
• Tie Rods

IV - Rear Axle

• Rear Axle Diagram/Overview
• Rear Trailing Arm Bushings (RTAB)
• Trailing Arm Bushings
• Camber Arm/Rear Lower Control Arm
• Subframe/Differential Bushings
• Rear Shock Mounts (RSM)

V - Technical Discussions

• Build for your intended application.
• Lower is not always better. Stiffer is not always better.

This FAQ was designed for anybody interested in E36 suspension. The novice can glean a large amount of information. The expert can look up part numbers, reference diagrams, and double-check failure symptoms.

Organization is by axle. Each specific item contains a description, and BMW OE part numbers. Some components also include a failure mode description. Note that only major components are covered. Small bolts, nuts, and interconnecting pieces are not referenced. I suggest www.realoem.com for locating specific things.

I use the word OBD1 M3 to describe the 1995 US model year M3 with the S50B30 engine. OBD2 M3 to describe 1996-1999 US model year M3s with the S52B32 engine. 3-Series to describe 328, 325, 323, 318 i, si, ic, and ti cars with M50, M52, and M4X series engines. This guide is focused on US spec cars, although much of this information no doubt applies to the world market as well. Also perhaps, but not necessarily, applicable to the E36-based Z3 Roadster and Coupé.

All of this information is well researched, but not cast in stone. If you run across any inaccurate information, spelling or grammatical errors, omitted information, or something you would like to see changed or added please PM or email me (evil.spoonman at gmail.com). Thank you for reading.

Universally known as 'dampers', your shocks and struts are responsible for controlling your wheel's contact with the road. There are many types: Monotube, twin tube, gas, liquid, adjustable, et cetera. For most applications the damper technology is not as important as the valving. Valving determines how your car interacts with the road, and controls your springs. If your compression or rebound damping is too aggressive, your car will not ride well. This is a very simplistic view of the role valving plays in suspension. For a further analysis see the related reads at the bottom of this thread.

It is important, when lowering the E36 chassis, to select a shock/strut combo with shortened bodies to allow proper travel. Travel is the amount a shock can compress before impacting the bump stop. In the stock setup travel is already minimal. If the vehicle is lowered on stock-height dampers bump stops will come into play far too often, and the vehicle's ride will be compromised.

The forward strut runs between the front spindle/knuckle and the strut tower/strut mount on either side of the engine bay. The 3-Series has a larger lower spring perch as part of the strut than any M3. The OBD1 M3 and 3-Series have identically sized upper spring hats (different part numbers), the OBD2 M3 has a slightly smaller hat. The M3 also has the swaybar endlink mount welded onto the strut housing, whereas the 3-Series does not. The rear mounting is identical across the E36 chassis, and across most BMWs. The rear shock attaches to the trailing arm and to the rear shock tower/shock mount on either side of the trunk. Note that the shock tower is not structural in the E36, and a true coilover cannot be placed here without very serious reinforcement. Similarly a rear shock tower bar is effectively worthless.

Generally the OE suspension will be shot after 50,000 miles, and will require replacement. The deterioration is very gradual, and is not felt by the owner. While you can drive on compromised shocks and struts, the car will handle badly, be very wallowy, and generally unpleasant. Replacing with OE again will yield fresh suspension, but a similarly short life. There are many aftermarket solutions available, and I recommend them.

Springs determine two primary things: the ride height of the vehicle, and the amount of body roll. Spring rate is generally measured in inch-pounds (in/lbs). As the spring rate increases, the harshness of the ride increases, and body roll decreases. While body roll is clearly not ideal, maintaing some semblance of comfort generally is. Usually one will not want to exceed 300 for daily driver duty. Shock valving is important in controlling the behavior, and percieved harshness, of the spring.

Rear springs are mounted inboard between the upper wishbone and the body. They are identical and interchangeable between all E36 models. Front springs are part of the strut assembly. 3-Series springs are larger than M3 springs. However, much intermixing can be done if you are willing to swap hats and struts.

On the E36 coilovers really only buy you height adjustability. Their other main (but not unique) advantage is that out of the box they are valved for the springs they are companioned to. The front is already a static coil-over so the design is not changed, the coilover simply adds a threaded adjuster. The rear geometry remains the same as well. The kit will provide an adjustable spring jack for the rear spring and an independent shock. As noted above, installing a true rear 'coilover' would entail greatly reinforcing the rear shock tower. You need a coilover kit for your E36 if: You need/want height adjustability OR you want the best out-of-box valving experience possible

Wheel bearings allow the wheel to rotate independently of its mounting. They are press-fitted into the knuckle/spindle in the front, and the trailing arm in the rear. The front bearing comes as a complete hub/bearing assembly and you must replace both if the bearing goes bad. The rear allows the bearing to be replaced independently. The hub is pressed into the bearing from the outside, and the axle half-shaft into the hub from the inside to complete the assembly.

Wheel bearings tend to be 100,000 mile wear items under normal use. Failing rear bearings can often be detected by a cyclical droning from the rear of the car. A speed-relative squeak is also a telltale sign. The only definite way to diagnose a wheel bearing is to pull the wheel and brake disc off any one hub and spin the hub independently while listening carefully. A bad wheel bearing should present itself clearly at this point. Removal and replacement of wheel bearings (rear especially) is difficult as the press-fit is very tight, usually requiring special tools. Note that OE wheel bearings appear to come from the factory with a minimal amount of grease packed into them effectively shortening their life considerably. You can install OE, attempt to pack your own with additional grease, or purchase a packed one from Road Race Tech, link here.

A sway bar is a suspension tuning tool that ties the suspension's sides together to try and reduce body roll. Often used to try to give a car with relatively soft suspension the effect of stiffer suspension when cornering. There are downsides to large sway bars, such as jacking up of inside wheels during cornering. On the whole careful sway bar selection and settings can substantially improve your car's handling.

On the 3-Series the forward sway bar attaches to the control arm via endlinks, and then bolts up to the undercarriage via bushings. The M3 (and certain 325i) uses longer links that bolt to the struts. The front bar itself is the same. Rear swaybars are the same across all E36s. They are affixed to the upper wishbone via links, and bracket to the subframe. The M3's design allows the sway bar more mechanical leverage than the control arm link design. Thus an equally sized bar on the M3 is effectively substantially stiffer.

A swaybar itself does not 'go bad' (barring some sort of accident). The bushings/brackets in the endlink and attaching the bar to the undercarriage do. It is rare to see swaybars replaced with original equipment, generally aftermarket is better and allows one to tune the handling to their liking. There is a strongly suggested reinforcement to the rear swaybar bracket points, you can make and weld in your own, or buy one from one of several manufacturers, here is a link to Turner's kit.

1. Swaybar Endlink (M3) 2. Front Spring 3. Front Shock Mount 4. Swaybar (it is positioned differently on the car) 5. Swaybar Bushing/Bracket 6. Strut 7. Control Arm Bushing/Bracket 8. Swaybar Endlink (Standard 3-Series) 9. Control Arm 10. Wheel Bearing/Hub 11. Tie Rod End

Front Suspension Overview:

The E36's front suspension is a McPherson Strut+Static Coilover design allowing only toe (via tie rod length) to be adjusted from the factory. The motion ratio for the front shock and spring is ~.94. For more information on the suspension type see here.

Control arms link attach to the spindle with the outboard ball joint, the front subframe with the inboard ball joint, and to the undercarriage with the control arm bushing end. The M3 arms lack the mounting point for the forward swaybar (if you want to use the M3 spec, you will need an M3 strut housings). It is possible to replace the outer (spindle-side) ball joint on a standard 3-Series control arm (part number below). The OBD1 and OBD2 M3s have different control arms designed to be used with different (centered vs offset) control arm bushings (see below). The OBD1 M3 arm is identical in geometry to the 3-Series arm. M3 ball joints are of higher quality than 3-Series ball joints, but none are replaceable. OBD2 M3 arms are of different geometry, having moved the spindle-side ball joint slightly towards the font of the car. Both types of M3 suspension end up with the same caster angles (if the proper control arm bushing is used).

You will usually want to simply replace these outright, and in pairs. It is the first thing to bend when you hit a curb with your wheel however, metal failures are not especially common and are not the primary reason for replacement. The ball joints in these arms will wear out and develop significant amounts of play, the inner one first usually. This will lead to an indirect front suspension. M3 control arms will last longer.

Used to attach the trailing end of the forward control arm to the undercarriage. They are pressed into brackets (lollipops) which are of unique shape right to left. 3-Series FCABs are 'webbed', and prone to rapid failure. OBD2 M3 bushings are solid and an upgrade for the standard 3-Series. OBD1 M3 bushings have an offset mount, OBD2 M3 bushings are centered.

This piece is poorly designed by BMW. There are aftermarket poly bushings available, although due to the multi-directional forces involved poly will also break down more rapidly than is ideal in this location. UUC's (non-poly) rotational bearing bushing is the ideal design for use here, but is expensive. Failure is easy to detect simply by looking at the bushings. Cracks, tears, large amounts of play... all signs that it should be replaced.

The upper mount for the strut. These should be swapped out for aftermarket camber plates for adjustable camber and caster. The OBD2 M3 mount is different left to right and can be swapped to the 'wrong' side for an increase in camber however, steering becomes more difficult (caster increase). This location benefits from reinforcement plates, and sandwiching with a strut bar.

These attach to the steering rack and to the spindle. They transmit steering action to the wheels. Tie rods are two-piece units, the primary steering rack attachment piece and a second section containing the ball joint that attaches to the spindle. The ends are most susceptible to bending, and the ball joint wears out. Play in the steering, shimmy under braking, and leaking ball joints are all signs that they need replacement.

1. Shock Mount
2. Shock
3. Swaybar Bracket
4. Swaybar Endlink
5. Upper Ball Joint
6. Rear Subframe Bushing (62.5mm)
7. Wheel Bearing
8. Lower Bushing/Ball Joint
9. Rear Trailing Arm Bushing
10. Camber Arm
11. Inner Camber Arm Bushing
12. Inner Wishbone Bushing
13. Spring
14. Swaybar
15. Diff Bushing and Bolt
16. Forward Subframe Bushing (60.5mm)

Rear Suspension Overview:

This end of the car is substantially more complicated, has propensity to fail, and deserves special attention. It is of the Independent Multilink/Trailing Arm variety. The motion ratio for the rear is ~1.05 for the shock, ~0.65 for the spring. From the factory it is possible to adjust camber (camber arm eccentric bolt) by a small amount, and toe (trailing arm carrier position). For more information see here and here.

This bushing attaches the trailing arm to the carrier and in turn to the chassis.

A frequent wear item. Replacing them with OE will maintain NVH levels but require difficult installation/removal. Several aftermarket 'limiters' are available that constrain the side-side motion this bushing is known for, I suggest these. Poly aftermarket types are available. The UUC poly RTAB has the limiters 'built-in' to the design. There is a bushing offered as 'an OE replacement' by both Pelican and Turner that apparently holds up better, realoem.com cross-reference searches can not match it to anything, but the part number is below. Failure is often characterized by a squeaking from the rear when the suspension articulates (bumps, corners). Wandering of the rear at speed and around corners is also a tell-tale sign.

There are two other bushing locations on the trailing arm. In the standard 3-Series the upper mount (for the wishbone) is occupied by a ball joint, the lower (for the camber arm) by a bushing. In the M3 both upper and lower locations use ball joints. The M3's setup is better and ball joints in all locations is an upgrade for the standard car. There are two bushings on the subframe end of the camber arm and wishbone.

These trailing arm bushings/ball joints wear out somewhat less rapidly than the OE RTAB. Standard ball joint failure modes (grease leakage, large amounts of play) apply here. Failure here will also contribute to a loose feeling rear end. The bushing should not even be considered as a replacement on any car, the price to performance ratio is very good with this upgrade. The inner wishbone bushing should be replaced along with the subframe bushings (might as well while it's out, right?). Inner camber arm bushings are generally integrated into aftermarket camber arms, which you SHOULD buy.

Camber Arm/Rear Lower Control Arm

The camber arm connects the bottom of the trailing arm to the subframe. It allows a very limited amount of camber control in stock form, and a great deal more with an adjustable aftermarket unit. Any and every E36 should replace the stock piece with an adjustable camber arm.

The subframe bolts up to the underside of the chassis by four points, each containing a large bushing. They are meant to isolate the subframe movement from the vehicle. On the 3-Series the bushings rest directly against the sheet metal of the undercarriage which is not especially strong. M3s come with reinforcement plates welded in at the mounting locations. It is suggested that ALL E36s receive this treatment, and it is absolutely necessary if more power is being pushed through the chassis. Keeping the subframe bushings in good condition will help minimize the risk of metal tearing.

There is a forward diff bushing/bolt on the lower passenger side of the carrier. It is wise to upgrade this bolt (stock is 8.8 metric grade) to a higher grade. If putting a lot of power through the chassis, upgrade further to a thicker one. There are also bushings in the ears of the differential itself.

All of the subframe bushings/diff mount+bolt should be done at once. Several aftermarket poly replacements are available and do not add too much NVH. There is apparently a different bushing (same size) for the front of the M3 subframe, I don't know what the difference is but have included it below. Have all of these bushings done at 75K miles if not beforehand. A clunk or thud under acceleration is the most common sign of something amiss with the subframe or diff mount.

RSM is part of the rear shock stack, and mounts to the shock tower.

BMW did not properly reinforce this location from the factory. Replace your OE ones with stronger reinforced aftermarket mounts. These are not a load-bearing suspension component as such. However, BMW has in the past sold reinforcement plates as well. Clunking from the trunk over bumps is a sign of bad RSMs. Inspections can reveal cracking and push-through of the shock. Worst case scenario failure can result in tearing of the rear shock mount.

Build for your intended application. This is the quintessential point everybody seems to miss. If you want a vehicle that drives to work/school and back, do not buy solid engine mounts. Do not buy all spherical bearings and run race springs. That is foolish and you will regret it. If, on the other hand, you are building an E36 race car you obviously [i]do[/i] want those things. The daily driver's more relaxing ride would do nothing but endlessly irritate and cripple you in a track situation. Consider what you want your car to do, and build to your intended application. Sounds like common sense? Well it is, you'd be amazed how many people miss this.

Lower is not always better. Stiffer is not always better. Somewhere along the line people got this preconceived notion that a harsh and low car is an excellent handler. Patently false.

If we were to take two cars: - One with low somewhat harsh race springs (H&R Race), aftermarket shocks (Bilstein Sports), big thick wheels (255/35-18), and a standard alignment (F 0 camber, 0 toe. R 0 camber, 0.1 toe in). - The other with cushy OE springs at OE ride height, properly custom valved shocks (Bilstein Sport), stock wheels (225/50/-16), and a good alignment (F -2 camber, 0 toe. R -1.5 camber, 0.1 toe in).

Well the second car would simply demolish the first in virtually every situation. Why? What's primarily important in suspension is valving, adjustably, and weight. Period.