From E30 Zone Wiki
Want to go round a corner? Then you're going to need some Steering.
Every E30 came with a Rack & Pinion steering configuration, which is a simple configuration found in most cars. The pinion gear sits on the end of the steering column/shaft which has the steering wheel at the other end. As you turn the steering wheel, the pinion gear then turns which moves the rack laterally, causing the track rods to push or pull the wheels and therefore turning the car.
Simply put, the rack and pinion does two things; it converts the rotational motion of the steering wheel into the linear motion needed to turn the wheels, and it provides a gear reduction making it easier to turn the wheels.
The E30 came with either Power Assisted Steering or non-Power Assisted Steering. PAS uses a belt-driven hydraulic pump powered from the crank. This fluid drives a piston built into the rack to make it easier to turn the pinion gear.
As mentioned earlier, PAS and non-PAS racks are available for the E30. Both forms are generally very reliable.
The tie rod is what connects the rack to the wheel hub. At the rack end the tie rod simply screws into the output shafts of the rack. There is an inner and outer ball joint as you can see in the below image. The tie rod itself can be split in two, leaving you with the outer part commonly known as the track rod end. The amount this is wound back into the tie rod is what affects the front wheel alignment. The inner ball joint is protected by the rubber gaiters which fit over the end of the rack and then onto the rubber grommet, which can be seen partway down the inner section of the track rod.
The PAS pump is located on the front left hand side of the engine. It take the PAS fluid down from the reservoir and then pumps it under pressure to the rack when the steering wheel is moved. This process makes the weight of the steering much lighter for the driver. The PAS pump is driven by an auxiliary belt, so as the belt wears or become stretched the effectiveness of the pump decreases. There is on adjuster bar which allows you to take any slack out of the belt. Learn more about fitting belts.
This connects the steering wheel to the steering rack, via a steering linkage made up of a couple of universal joints. This is simply a tube with the column going through the middle of it. Each end of the column is splined for the steering wheel to grip it at the top and the linkage to grip at the bottom. The column is held in place at either end by a bearing, a bunch of washers and clips.
The only issue that can occur with the column is the wearing out of the bearings. This can be highlighted by a squeaking type noise when turning the wheel. A quick short term fix can be packing it out with more grease, although the bearing will ultimately need replacing.
If you need to, learn more about removing the steering column.
This connects the steering column to the steering rack. This is made up of two universal joints, and is joined together by a rubber coupler known as a guibo. The universal joints are required due to the steering column being at a different angle to the steering rack's pinion gear, while the rubber guibo prevents undue noise transmitting up the column and into the car.
This linkage is held together with four solid rivets, which must be replaced with BMW originals if removed. A 'normal' bolt will put a compression load on the guibo, whereas the shoulders of BMW's special bolts bear against one side of the drive flanges, and the locknuts tighten up against the other sides, thus forming rigidly mounted pins for the guibo. This way, there are no loads on the system in any direction that wasn't designed to be loaded.
If you are changing your steering rack, you will also need to know about other steering linkages.
Main article: Steering Wheels
The steering wheel is, unsurprisingly, how you steer the car. In general, two sizes of wheel were fitted to the E30; a 380mm unit, and a smaller, sportier 370mm size which is considered more desirable.
If you need to get your steering wheel off for whatever reason, there are a number of methods open to you. The easiest is to remove the steering wheel centre, unscrew the large nut, turn the key to disengage the steering lock, and take the steering wheel off. The second easiest way is to take the nut off, and kick the wheel from the outside, through the windshield opening, until it comes off. This will damage the wheel, and the windshield if it’s still intact. Alternately, you can remove the nut and go nuts with a large crowbar or similar tool. The wheel will eventually come off, but it’s not easy. You can also try prying the lock (clockwise, all the way), but this is also difficult.
Obviously with age and regular use the the rack mechanism can wear and introduce play to the steering, manifested as a delay between turning the steering wheel to the front wheels steering. However a more common issue for this feeling is the rubber guibo in the steering linkage breaking up, meaning there is play in the linkage. You can either replace the rubber guibo with an OEM part or make a custom solid spacer.
Fluid leaks are usually from underneath the fluid reservoir located on the left hand side suspension turret. The pipes crimped in place can sometimes deteriorate. To cure the issue you can either source replacement pipes or trim the end of the old pipes and recrimp using a good quality worm-drive hose clip.
It is very rare for leaks to occur elsewhere in the pipe system; however, if removing any of the high pressure hoses on the pump or rack it is important to use new crush/sealing washers to prevent future leaks. Most E30's use 4x 16mm and 4x 14mm washers.
If you've chased down a leak to the flexible rubber gaiters on the steering rack itself then it is very likely the seals in the rack have failed and you'll need to be fitting a replacement steering rack.
The steering system is relatively simple on an E30, and as such the main requirements are to keep the rack in good condition and topped up with fluids. Changing the fluid regularly will keep the rack clean, but you must also pay attention to the tie rod ends.
Changing the Steering Rack
So you've decided to tackle to job of swapping your steering rack. This could be because the old one is faulty or, as is becoming more popular, you want to fit a rack from another BMW with a quicker ratio. This guide is applicable for both scenarios as all racks fit in the same position.
You'll need to get the front of the car jacked up and the front wheels removed. Before starting work get the rear wheels chocked and the car set on axle stands for safety as you'll be working underneath the car. Use the appropriate jacking points.
First thing to do is separate the tie rod ends from the suspension struts. For better access, turn the steering to each side. A 17mm thread lock nut holds the tie rod end to the strut so get this undone and then drop the tie rod from the strut. These two simple tasks can often be fraught with hassle due to parts being seized. If the balljoint spins while undoing the nut, place your jack under the ball joint and take the weight of the strut on the jack and try again to undo the nut. Failing that, another trick is to use heat such as a blowtorch, which can also work for removing the tie rod from the strut. A hammer and block of wood is also a commonly used way of separating the parts.
The next thing to remove is the linkage that attaches the steering rack to the column. This is secured with a 13mm nut and bolt at either end which need removing. The UJ should then slide down the splines towards the rack off the column and can then be pulled off the rack. These are often seized but some penetrating fluid and a couple of knocks with a small hammer should have it moving; there is no need to attack it with a chisel or anything similarly brutal.
Now we need to disconnect the pipework. If you're just swapping between E30 racks it'll be easiest to just undo the banjo bolts (19 & 22mm) on the rack itself and drain the fluid there. Fitting a non E30 rack will require custom pipes which will be explained **HERE**.
Now all that is left is removing the rack from its mounting on the crossmember. The rack is held to the crossmember by two 15mm nuts and bolts; simply undo and remove these. Then to remove the rack the bottom tabs need to be bent out of the way which then allows the room to simply drop the steering rack off the car.
Refitting is as a well-known maintenance manual says, the reversal of removal.
Main article: Fitting a faster rack
While the steering of an E30 is a charm of feedback-response, neither too heavy or too light, many of the more spirited drivers find the standard rack too long, in the sense that it takes too many turns from one full lock to the other. Fitting a faster rack from a BMW Z3, E36 or E46 is a common and simple upgrade. Here is a guide for fitting a faster rack.
The Z3, E36 & E46 racks all bolt straight into position on the subframe like the standard rack so it's just a case of following the conversion guide. However they do need 14mm of spacers as they are thinner than a E30 rack. You can have custom ones made up, but many have simply used thick washers; three head bolt washers are perfect. You can also use Z3 and E36 track rods as well if you desire but they can cause clearance issues if you are running larger than standard brakes.
Be aware that the rest of the install isn't quite so simple due to the different angles of the pinion gear and positioning on the pinion of the PAS feed and return pipes. You can bend your existing pipes with some trial and error, and hope that you don't kink or split them, but we recommend buying custom pipes. Either message E30Zone user DanThe for these as well as his custom steering linkages, or have a local hose specialist make you some.
The other issue can be fouling of the steering linkage on the exhaust downpipes/manifold on 6 cylinder engines such as the M20, again due to the angle of the pinion gear. This is dependent on the engine and manifold you are using. You can either make a custom steering linkage like the one in this guide or one can be purchased from DanThe which involves the use of E34 steering UJs, one of which has to be stripped down and mated to an E30 UJ.