Steering Rack Conversions

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The difference between an E30 (front) & E36 rack.

One of the best features of any E30 is the steering feel; none of this namby-pamby electric power steering, just a good old-fashioned rack-and-pinion setup, so that you can feel the road with your fingertips, via the steering wheel.

The only downside is the speed. The E30 rack is 4 turns lock-to-lock, which is far too cumbersome for enthusiastic driving.

But there's good news! You can bolt on a steering rack from newer BMWs with relative ease, giving you faster turns without losing that steering feel. Here's how to do this for RHD cars.

Overview

Racks from newer BMWs are extremely similar to the original E30 units, and are almost a direct bolt-in replacement. However, you will need to work around a few small technical issues.

For starters, the original rack is physically taller than the newer ones. This means that you need a pair of small metal spacers so that you can bolt the new rack in exactly the same location as the original rack. The pikey solution is to use a pile of washers, but a sturdier solution is to fabricate your own spacers or buy them ready-made. They need to be 14mm tall, at least 14mm wide, with an internal hole of 10mm diameter.

You also need to customise your steering linkage due to the shorter length of the new rack. We've outlined some options to fab your linkage later in this document, but you can also buy a custom linkage from Zone member DanThe.

Finally, you need to find a solution to the power steering hoses as the holes on the new rack are at a different angle to the originals. Again, you can fab your own if you're ok bending the original pipes, or DanThe can supply you with a brand new set fit for purpose.

To connect your new rack to your wheels, you need inner and outer tie rods on each side. The good news is that you can use standard E30 units, so if your current ones are in good condition then there's no need to buy new parts. However, you CAN'T use complete inner and outer rods from newer BMWs. You can use either....., but not both.


Parts

  • New Rack
  • Rack spacers (14mm)
  • Inner and outer tie rods (complete set of either E30 or E36, but not E46)
  • Steering linkage (click here for more info)
  • New aluminium crush washers (14mm and 16mm)

Tools

  • Ball-joint splitter
  • 13mm, 15mm, 17mm, 19mm and 22mm sockets or spanners
  • A hammer and crowbar or suitable drift


Which Rack?

The current choice of racks are:

Rack Part Number Turns

(lock to lock)

Comments
E30 4 Standard power steering rack for all models
E36 3.4 An adequate replacement for the E30. Nothing sporty, but certainly livelier than what the E30 left the factory with.
E36 M3 ('95) 3.0 Don't let the low lock-to-lock fool you. This rack is a variable speed unitm meaning it's ponderous in the middle and only rapid when it's close to full lock. In effect, this is the slowest of the E36 racks, and best avoided.
E36 M3 Evo ('96-) 3.2 Despite the lock-to-lock number, the E36 M3 rack isn't any faster than a standard E36 rack; it simply has massive locking plates fitted to it that limit the overall rack movements. Remove these plates, and it's a standard E36 rack.
E46 3.2 A very good compromise between the older E36 rack and the wicked-sharp Z3. Cheap and plentiful too, but try getting a Clubsport rack if you can.
E46 Clubsport 6 755 067 3 The most popular choice these days, thanks to its speed and availability. Fitted to a range of E46s - look for the purple tag.
Z3 3213 1094038

3213 1095577

2.7 The fastest rack, and no need for a custom steering linkage, makes this the perfect rack. But most are now well over 20 years old, so finding a good one is increasingly difficult.

Procedure

Removal

First off, get the car up in the air. A post-lift would be great, but most of us will have to manage with a pair of jack stands under the chassis rails. DO NOT DO THIS with just a jack. You will die.

With the front raised up, remove both front wheels and place them under the sills of the car, for added safety.

Now we can start removing the existing components.

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 good balljoint splitter will speed things up immensly, but if you don't have one then a hammer and block of wood is a common alternative:

SteeringRack004.jpg

Depending on their condition, you may want to salvage the inner and outer tie rods. If you do, then you need to remove them while the rack is still bolted to car; they're a real pain to remove otherwise.

It is very important that you do not touch the adjustment nut between the inner and outer tie rod. When you finish this swap you need to check your tracking (we'll explain later), but if you undo these adjustment nuts then you are guaranteed to bugger the steering geometry, and you'll need to set it all up for scratch. For peace of mind, leave them completely alone for now.

Instead, prise off the metal ring around the rubber boot at the steering rack end. Peel back the rubber to expose the nut on the inner tie rod, as well as the locking ring plate. The locking plate is a thin metal washer that has been bent over the tie rod nut to hold it in place. You need to bend the locking plate away from the nut, then get your spanner on the nut and give it a sharp twist. With luck, it'll start turning, allowing you to twist the entire tie rod assembly off the rack for re-use later.

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 have access due to a post-lift, then undo the banjo bolts (19 & 22mm) on the rack itself and drain the fluid there. If you don't have access, it's worth undoing the two pipes on the steering pump first. Because these are much easier to access, you can drain all the steering fluid out of the reservoir with relative ease, without it dripping all over your face while you work underneath the rack.

SteeringRack003.jpg

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 will provide the room to simply drop the steering rack off the car.

SteeringRack002.jpg

Steering Linkage

There are a number of options when it comes to linkages. The choice depends on what engine and exhaust manifold you currently have fitted, as certain combinations lead to the linkage fouling on the exhaust.

E36 hybrid

This design combines the upper universal joint (UJ) from the E30 joint, and the lower UJ from an E36 joint. You also need to make an aluminium or steel spacer to join them together. The standard E30 joint is approx 275mm long. This needs to be shortened by 25mm to 250mm long.

The E36 joint is made in 2 parts. The top half consists of the top UJ and a convoluted portion. This is connected to the lower UJ (and rubber flex joint) by a simple pinch bolt. Remove the bolt and discard the top portion. You now have the lower UJ with the rubber flex joint. You need to drill out the 2 large rivets that hold the pinch bolt section to the flex joint. If you look down the centre of the pinch bolt section, you will also see a small securing clip. Remove this with a small screwdriver. You should now have the lower UJ with the flex joint and 2 empty holes.

On the E30 joint, you need to perform a similar operation. You want just the upper UJ. You may just need to unbolt the existing flex joint if it has previously been replaced. If it is still a 'Virgin', you will need to drill the rivets out.

If you offer up the upper E30 joint to the flex joint on the E36 UJ, you will notice that the holes do not align very well. The bolt spacing on the E36 joint is 45mm, and on the E30 it is 50mm. You will also find that the overall length is only 240mm (10mm short). These 2 problems are easily overcome by making a metal (Aluminium or Steel) disc approx 10mm thick with a hole in the centre (I will come back to this hole). You need to drill 2 holes 45mm apart and another 2 holes 50mm apart. These sets of holes need to be offset by 90 degrees. This will allow you to bolt the E30 and E36 UJ's together. The overall length should now be correct. You will need to use 2 of the metal spacer tubes from the E30 flex joint and fit them in the E36 flex joint. You will see what I mean when it is in front of you. The actual thickness of the spacer should be measured on the car to allow for different tolerances between cars and parts etc. 10mm is a rough guide.

Now, back to the hole in the disc. This is for the centering bush (similar to the nylon one on the E30 joint). If you look at the pinch bolt section you removed earlier, you should see a bronze bush in the centre. This is retained by some deformations (stakes ?) in the housing. With some careful drill work, the bush can be removed. It also helps if you cut through the side of the housing and open it up with a chisel. You need to make the hole in the centre of your new metal disc the same as the O/D of the bush. It needs to be a snug fit, and can be retained with some bearing securing solution (Loctite etc).

Ready-made

DanThe's steering linkage

Forum user DanThe supplies a custom knuckle that's a simple bolt-in replacement for the existing system. These knuckles are very similar to the E36 hybrid, but use an E34 universal joint instead.

Guibo Delete

Because the original linkage needs to be shortened by 25mm, a simple solution is to remove the rubber guibo and bolt the two solid ends together.

Undo the bolts to remove the guibo and bolt the universal joints together. It's recommended to put two washers between the joints (one washer per bolt) as the flat surfaces aren't completely parallel. You may find the bolt holes are the same size in each UJ, but some do have different sized holes (either 8mm 10mm). If desired, you can drill the smaller holes to match the larger ones on the linkage.

The only issue is that it doesn't create anymore linkage to manifold clearance (which may be a problem with a 6 branch or M5x conversions), as opposed to the ready-made linkage.

Opel Corsa C

Main article: Opel Corsa C Steering linkage

One ingenious solution is to use parts from a similar-period Opel/Vauxhall Corsa. For more information, check out how to make the Opel Corsa C Steering knuckle

Fitting

Choose the appropriate steering linkage from the above options, and fit it to your steering shaft. Once it's on and secure, set the steering wheel straight and then lock the column by removing your ignition key.

Rack

Prepare the new rack. If you've bought new steel pipes, fit them to the rack now. If you haven't, then remove the ones off your old E30 rack for now.

Straighten the rack. It needs to be set to point straight ahead, which means turning it so that the rack is of equal length on both sides. Use a ruler, and turn the input nut with a 13mm spanner until both sides are the same length:

SteeringRack001.jpg
Rack mounted in the NON-PAS position

You're now ready to offer up the rack. Slide it up into the space under the subframe, and get the steering linkage onto the rack's input splines. It probably won't slide on smoothly, but some wiggling will at least make them mesh by a few millimeters, which is a good start. You can bend the lower subframe tabs back now to stop the rack dropping out of the car.

We now need to get things aligned, which is hard if the steering linkage isn't completely on because you can't line up the rack bolt-holes with the holes on the subframe. A handy tip is to use two thick screwdrivers as levers so that you can prise the rack closer to its intended location, then clout the steering linkage downwards from above (using a long crowbar or drift). Eventually, you'll get the linkage solidly onto the rack, and you can fit and tighten the linkage bolt to secure it.

With the linkage secure, we can bolt up the rack. There are two holes per side of the subframe; front for non-PAS racks, and rear for PAS racks. The holes you use will depend on which linkage you're using, but aim to fit your new rack into the rear holes - it results in a better driving feel. Wiggle the rack until you can slide a bolt up from underneath, then place your spacer (or washers) between the top of the rack and the top subframe tab. Put the nut on top, and tighten up.

Spacers placed between top of rack and subframe

Pipes

Now is a good time to get your pipes connected. If you've ordered custom pipes, you'll need to fit one hose to your PAS reservoir and the other to your PAS pump. Don't forget to use new crush washers to prevent future leaks.

If you haven't got new pipes, you need to bend your old ones to fit. This is a very delicate operation, and it may make sense to buy a few scrapyard hoses to practice on first.

Take a look at how the pipe holes on the new rack are in a different place to the originals, and plan your bends accordingly. There will be lots of trial and error here, so go slow, take your time, and be prepared to bend things multiple times. Once you can see in your head how the pipe needs to bend, you need to find a way of bending it. A handy trick is to use the wheel hub.

Using a suitable bolt and a few aluminium washers, bolt the pipe to the hole in the wheel hub where your steering tie rod usually bolts. Tighten the bolt so that the pipe end is secure. Now take a small blowtorch or heater, and warm the steel pipe, taking care not to melt the rubber hose. When the pipe is warmed, *gently* bend or twist the pipe as required. Don't try too tight a bend, or the pipe will kink, making it useless. Go slow, take your time, and repeatedly offer the pipe back to the rack to see how your bends are progressing.

When you're completely happy, connect the pipes to the rack using the correct banjo bolts and washers, and connect the other ends to the PAS reservoir and steering pump.

Track Rods

Now you just need to get your rack connected to your wheels. You'll need a set of inner and outer track rods (tie rods in Americanese) to do this.

You can use matching inner and outer rods from either an E30 or an E36, but you can't mix and match. You can't use E46 outer rods either, but inner E46 rods can be used with E36 outers if you have the parts to hand. However, if you're buying new then get proper E30 parts from a brand such as Lemforder; they're the best quality part for the cheapest price.

Modified E36 inner rod with thread venting suitable for use in E46 rack

If you're considering an E46 Clubman (purple tag) rack, keep in mind the stock inner rods use vented threads to bleed air pressure between left and right boots when the wheel is turned. Therefore, you need to pair E46 inners with E36 outers. Alternatively, you can get crafty with a bench drill and modify a pair of E36 inners to have the same thread venting. E30 outers won't work here as they connect to the inner rod using a male thread. E46 inners and outers combined are (anecdotally), too wide for the E30.

If you're using brand new parts, it's essential to get them set up to match your older rods. Place the new and old set next to eachother on a workbench, and screw the new outer to a new inner. Adjust the length until the new rod pair (inner and outer) is exactly the same length as the old rod pair. A difference of 1mm can have drastic consequences for your tracking when it comes to refitting them to the car. Once you've got this length perfect, tighten and secure the retaining clamp.

Fitting the rods to the rack is straightforward, if fiddly. With the rubber boot already squeezed onto the inner rod, offer one end up to the rack. Line up the locking plate, then screw the retaining nut down so that the inner rod is tight. Once that's done, use a small hammer to bend the locking plate tabs down over the retaining nut. It's a pain to do this upside down while fighting the rubber boot, but it's doable. When finished, use zip ties or new metal rings to tighten each end of the rubber boot.

You can now connect the outer rods to the steering hubs. Just offer them up through the hole, place on the self-locking 17mm nut, and tighten them up.

Finishing

With all the mechanicals bolted in, it's time to fill the PAS reservoir with fresh fluid. Don't overfill, and pour it in slowly. Then undo the steering lock, but don't start the car, and turn the rack lock to lock a few times. This will help bleed the rack of air, and you should notice a corresponding drop in the fluid level in the reservoir, so top it up if needed. Repeat this procedure a few times.

You can now reattach your wheels and lower the car. Start the engine to power up the steering pump, and try a few more lock to lock turns (at a gentle forward speed, if you don't want to dry-grind your tyres). Expect a graunching noise from the pump as you reach the lock point - that's normal.

Then take the car for a gentle drive, to get used to the increased steering speed and check the tracking. If the car pulls to one side, adjust the tracking using our string-based technique, or take it to a professional.

Once everything's working as it should, take the car out for a well-deserved hoon!


Complications

318iS plastic under-tray modified for rack fitment.

Some 318iS owners have reported issues with steering linkage clearance when using the Z3 rack, so pay attention to which linkage you choose before starting. In particular, the Guibo-delete linkage requires the rack to fit in the Non-PAS holes and still occasionally rubs on the manifolds (for both M42 and M44 engines).

The plastic undertray on these cars can also interrupt with the fitment of the rack, so be prepared to cut away some of the plastic to make everything fit.