Anti-Roll Bar
| Suspension | |
The Anti-Roll Bar or ARB is an integral part of your car's suspension. Its function is to reduce body roll by locking together all the suspension components across each axle. By stiffening the entire system in this way, it's possible to dramatically reduce the wallowing, lurching motion that is often encountered otherwise.
Contents
Overview
The ARB itself mounts to the car body using two rubber bushes, held in place with steel shells. The two ends of the ARB then mount to the wishbones via drop links. These drop links operate similarly to ball joints, allowing for lateral movement in the suspension without compromising stiffness, but are actually another type of bush and need to be replaced with the same regularity.
A number of sizes of ARB were fitted to the E30, and upgrades were available from a number of manufacturers including AC Schnitzer and Racing Dynamics. The thicker the ARB, the stiffer the suspension. See the tables below to see what was fitted to your vehicle.
Standard
BMW offered an impressive range of ARBs, designed to combat the suspension niggles specific to each body style and and engine. While Front anti-roll bars were a standard feature, not every car received a rear ARB.
| Model | Front | Rear | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 17mm | 18mm | 18.5mm | 19mm | 20mm | 21mm | 12mm | 13.5mm | 14.5mm | ||
| 318i | x | |||||||||
| 318iS | x | x | ||||||||
| 320i | x | x | ||||||||
| Touring
except 325i |
x | x | ||||||||
| 325i | x | x | ||||||||
| 325i Sport | x | x | ||||||||
| 325i Convertible | x | x | ||||||||
| 325iX | x | x | ||||||||
| 325iX Touring | x | x | ||||||||
| M3 | x | x | ||||||||
| M-Technik | x | x | ||||||||
WARNING: This list is NOT comprehensive! We have not yet ascertained whether all Tourings and Cabriolets had the same suspension. If you are unsure as to the size of your ARB, try to fit a spanner onto the bar itself. For example, if you can fit a 14mm but not a 13mm spanner around your rear ARB, then it is 13.5mm.
Aftermarket
While BMW offered an impressive range of ARBs for the E30, many were simply not beefy enough for true performance driving. Because of this, a number of tuners offered much stronger versions as bolt-on upgrades.
| Manufacturer | Model | Front | Rear |
|---|---|---|---|
| AC Schnitzer | 20mm | 16mm | |
| Eibach | 20mm | 16mm | |
| H&R | Adjustable | 22mm | 18mm |
| Ireland Engineering | 22mm | 19mm | |
| Adjustable | 25mm | 22mm | |
| Racing Dynamics | Early Style (adjustable) | 22mm | 16mm |
| Late Style (adjustable) | 22mm | 19mm | |
| Suspension Techniques | 22mm | 19mm | |
| UUC Motorwerks | SwayBarbarian | 22mm | 19mm |
| Whiteline | 24mm | 16mm |
Upgrades
Fitting a Rear ARB will help tighten up body roll without stiffening the suspension to uncomfortable levels. While some E30s were fitted with these as standard, many were not. All could benefit from fitting one, so if your car is missing a coathanger on the rear subframe, learn more about fitting a Rear ARB.
