BMW Z3 Rack Swap and Install

At my two most recent BMW CCA autocross events the typical comment from my instructors (i’m still a ‘novice’) has been “wow, you’re pretty smooth even though you have to shuffle steer.” It became clear that the stock 4-turn e30 steering rack was slowing me down and needed to be swapped out.


At the outset I thought this project would take a day, maybe two at the most. It actually took 3 weekends to complete because of missing parts and tools. I also wasted a lot of time researching various steps and confirming that I was doing the right thing. Hopefully my experience will help you with your own steering rack swap. I learned some valuable lessons about this kind of work:

  1. Test fit everything “on the ground” before the day of install. This includes checking bolt fitment in new parts and final assembly. Don’t assume all parts were shipped.
  2. Check all available photos and diagrams for parts and examples of how final install should look before the day of install.

I started my research by asking for some opinions which fell into two categories:

  1. The e36 z3 rack is too twitchy, go with a 95 e36 M3 rack with a lock to lock of 3.0 turns.
  2. You can handle it, go for the e36 z3 rack with a lock to lock of 2.7 turns.

e30 rack vs z3 rack

Above: Comparison of Racks. (Photo Source)

I heard so much praise for the z3 rack, like “best mod ever for an e30″, that I decided to pursue it. Next I started researching the method: most of my web searches turned up the same DIY (posted on R3vlimited) time and again so I decided to follow it. Going with the DIY seemed like the only option but was my first and most costly, time consuming mistake.

I want to put a very fine point on this: If you are planning to do an e30 steering rack to e36 m3 or e36 z3 steering rack swap you should buy a complete kit. There may be other retailers but the kit used by people I know is available from Zionsville Autosport. The pros to buying the complete kit is substantial savings over buying the component parts and the kit is complete requiring no retrofitting or fabrication to install unlike the DIY procedure. I wasted a lot of time blocked because of missing tools, fiddling with retrofits and installing things incorrectly. Save yourself the trouble and buy the kit.

But I didn’t know about the complete kits when I started so I set about ordering the parts I’d need. Web searching led me to The Rack Doctor who I ordered from because I felt most confident that I was getting the rack I wanted. On a scale of 1-5 I’d say my experience was a 3.5.

Pros:


  • Rack was clean, painted
  • They called to confirm that I wanted e36 tie rod arms vs. e30 (there is a difference)
  • New copper crush washers were included but just for the rack, not the pump
  • Shipping was quick

Cons:


  • Paint chipped horribly during install especially on some of the plastic hoses
  • Some important nuts and lock clamps for tie rods were not included which delayed install
  • High core charge not refundable except for identical core return

The DIY I referenced listed out the following parts:

DIY Parts List (DO NOT ORDER FROM THIS LIST):


2x 7/16 Bolt 2 Inches Long
2x Bolt M10x50 26111226737
2x Self Locking Nuts 07129964672
4x Copper Seals 14×20 32411093596
4x Copper Seals 16×22 32411093597
4x Self Locking Nuts 07129922716
1x Power Steering Reservoir 32411097164
1x High Pres. PS Hose 32411141953
1x Spacer 72118119268
2x Spacer 72111847480
2x Nut 721119779250
2x LP PS Return Hoses
1x Bottle of ATF

Some of these parts are NLA or the author just didn’t list part numbers. I have crossed out the list entirely because I don’t think you should reference it. Here’s my recommended parts list:

My Updated Parts List:


4x Copper Seals 14×20 32411093596
4x Copper Seals 16×22 32411093597
1x Power Steering Reservoir 32411097164
1x High Pres. PS Hose 32411141953
1x LP PS Return Hose 32411135936
1x LP PS Return Hose 32411133401
1x e30 to e36 Steering Knuckle Kit (either RPKIT or the kit from here)
1x *e36 Left Ball Joint 32111139313
1x *e36 Right Ball Joint 32111139314
2x *Clamp Ring 32111136179
2x *Nuts 32111136494
1x Bottle ATF Fluid

*Necessary only if you get the e36 ball joints and these parts are not included. e30 tie rods require a different locking nut and may be reused from your old rack. Probably.

BMW e36 tie rod clamp ring parts
BMW e36 tie rod clamp ring parts

Above: Clamp rings and chunky nuts required but not mentioned in the DIY.

IMG_8733

Above: The tiny nut shipped with the e36 z3 rack that is not suitable for this swap.

Additional Tools:


Two 15mm wrenches (for the knuckle)
8mm and 6mm extended hex bits (for installing the knuckle kit around the parts of the knuckle – you’ll see!)
Tie Rod Puller
Bottle Jack (for flattening the rack tabs)
C-Clamps (for depressing brake cylinders)

A note about tie rod pullers: There are two styles. The most common style you’ll find at your local auto supply store features a single U shaped clamp with a bolt through the center. This bolt has a pointed tip that seats in the top of the ball joint bolt. The bolt must have a divot in the top for this tip to seat in otherwise it will not work, and it should be noted that the e36 arms do NOT have this divot. Also note that in order to use the U shaped puller you will need to take off the rotors and loosen the dust shield. It’s really loud when the bolt finally breaks loose but a little less violent than banging on it with a hammer or a pickle fork. The other kind of puller looks like a metal clothes pin and a bolt is used to close the jaws of the pin, again pushing the ball joint bolt out. This tool works by pressing down on the ball joint bolt with a flat surface and therefore works on bolts that do NOT have a divot in the top. Like e36 tie rods and ball joints. So if you have the choice get the clothes pin kind of tool since it’s more versatile.

BMW e30 e36 Two kinds of tie rod pullers

Above: Two different styles of tie rod end pullers.

BMW e30 e36 Tie rod puller in use how to

Above: The clothes pin style of tie rod puller in use.

Notes and Addendum to the DIY:


  1. Disconnecting the ball joints and tie rods was impossible for me without using a puller. A hammer and block of wood only resulted in destroying the wood. Tie rod removal also required the removal of the brake calipers and loosening the dust plate to make enough room for the puller.
  2. BMW e30 tie rod end arm puller removal

    Above: The U style puller. Notice how much room it requires next to the dust shield.
  3. I used zip ties and plastic bags to keep the hoses from dripping after disconnecting them. Keep your work space clean.
  4. Take photos of where the old hoses run so you can run the new hoses along the same pathway.
  5. Removing (and installing) hoses on the rack need to be done in order: there is not room to remove the upper banjo bolt while the lower bolt is in place.
  6. The DIY called for bending the rack tabs on the center cross member to make room to drop the rack. In retrospect lifting the motor or bending these tabs the very smallest amount required would be advisable. I spent 2 hours working the tabs back into place with a bottle jack and some folks posit that bending the tabs weakens them.
  7. Plan to soak the knuckle to rack spline in PB blaster over night. The knuckle to steering column spline slipped right off but I could not remove the knuckle from the steering rack and ended up sourcing a donor knuckle while waiting for the PB blaster to work. I finally got the knuckle off by standing on the old rack and pulling. I can deadlift 300 lb. so that says something about how seized up the splines may be. Also note that the bolt on the rack side of the knuckle must be completely removed as it passes through a slot in the spine that holds it on. You cannot remove the knuckle with the bolt merely loosened.
  8. If modifying your current knuckle i.e. not using a pre-fabricated knuckle then you need to remember that the kit or shortened spacer is used to make the knuckle shorter NOT longer. You will need to enlarge two of the holes on the knuckle to fit the bolts through. A 23/32 drill bit was the right size for me but you should use a bit gauge to measure your bolts.
  9. I needed to tap the knuckle onto the rack spline using a hammer. Actually a friend with more experience did it for me. This should not be necessary but if you simply can’t work the knuckle on by hand then be very sure that the splines are not binding and are lined up properly before gently tapping it onto the spline. Go slow, you’re not driving a nail.
  10. The rack and knuckle need to connect to the steering spline when both are centered (this is mentioned in the DIY). I used a protractor and made a measuring tool to count the number of degrees in a complete lock to lock rotation, dividing the total by 2 and then finding that middle point in the racks rotation. In my case middle was 510 degrees. This is very accurate and does not require the removal of the boots, etc. to measure the tie rod ends. I marked this middle point on the rack and spline using a white paint marker for reference during install but marked it on the side I couldn’t see: make your marks so they are visible when the spline is on your left.
  11. Using rubber bicycle inner tube to protect splines
    e30 rack swap how to center rack
    e30 rack swap how to center rack

    Above: Finding the center of the rack.
  12. Even after finding center I still had to disconnect the rack and knuckle and move it over a single spline tooth. If you put a peice of tape at dead center on your wheel and turn it all the way to the left and right you should see that the terminal position of each is the mirror image of the other. My first attempt found it to be 2″ off (about the amount of a single spline tooth).
  13. The DIY reads “if there is binding use your Dremel to grind the knuckle joint.” You should assume that the knuckle will bind and grind it down on your bench where you have maximum control NOT when it’s installed in the car like the DIY shows. I recommend using a cutting bit not a grinding bit as the amount of metal you need to remove is significant. I removed metal from the U but in hindsight grinding down the edges of the fork may have been tidier and resulted in less cutting.
  14. Dremel cutter grinder bit for shaving down steering knuckle in e30 z3 swap
    Dremel cutter grinder bit for shaving down steering knuckle in e30 z3 swap

    Above: The correct Dremel cutter bit used for shaving down the knuckle to prevent binding.
  15. The DIY calls for tapping the cross member tabs into place with a hammer. This is impossible as the tabs will bounce and absorb all the force of the hammer. Using vice grips mangled the tabs. I recommend using a bottle jack and wood blocks under the tabs to bend them into place but be careful not to lift the car by accident. Putting the rack and spacer on the tab while bending the tabs up will help make sure you don’t bend the tabs too far the other way.
  16. bmw e30 z3 rack install bending cross member tabs back into place

  17. If you use the hoses called for in the DIY you can bend the new high pressure hose into place using your hands, or a little heat and your gloved hands. Using a vice or bender should not be required. Only the pump side should require bending. Study my photos and try to match what I’ve done.
  18. BMW e30 steering rack swap high pressure hose bends
    BMW e30 steering rack swap high pressure hose bends
    BMW e30 steering rack swap high pressure hose bends

  19. The new hoses are a tight fit. The new high pressure hose will need to go over the motor mount arm. Just make sure there is a finger’s width between each hose as you tighten it down because rubbing hoses will eventually spring a leak. Two sets of hands can be helpful here.
  20. During bleeding of the steering rack do not press the brakes because you may over extend the brake piston. If you do this by accident you may be able to use a c-clamp to compress the piston back down. Otherwise a bleed and flush will be required.

BMW e30 e36 z3 rack swap tie rod arm bolt and clamp
1989 BMW e30 sedan blue on flat bed recovery vehicle

Above: Towing my e30 to Bavarian Motorsport in Milpitas, CA for an alignment.

1989 BMW e30 alignment at Bavarian Motorsport

Above: My 1989 BMW e30 on the alignment rack at Bavarian Motorsport in Milpitas.

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August 29, 2014 mechanical, repairs