We’ve mentioned before that BMWs are really just Legos for adults. With a little bit of knowledge, you can cherry pick parts from other BMWs to upgrade yours. In our case, we improved steering feel and responsiveness with a little help from the 5 Series and the sporty e46 3 Series ZHP.
For our race car, we wanted a quicker steering ratio without going to something so quick the car felt darty. Our car’s rack was 3.2 turns lock-to-lock. Some people will swap in a Z3 non-M rack, which is 2.7 turns lock-to-lock. It may not sound like much difference, but it is. The steering is lightning quick. A little too quick in our opinion (and BMW’s), although if you are building a drift or rally car, the Z3 rack is not a bad option. We found our “just right” porridge with the e46 ZHP – a vehicle much closer in size to our vehicle than a Z3. Its rack is 3.0 turns lock-to-lock. Just right. They can usually be found used, and many BMW 330’s (not labeled ZHP) came with the yellow label -712 rack. It’s worth the hunt.
But our steering improvements didn’t stop there, we swapped our original steering coupler (that mates the steering shaft and rack) for one from the e39 5 Series. Why? The 5er’s coupler is solid metal while the stock one features a large rubber damper.
We’re not looking for luxury-car isolation, so we decided to turn off the mute button and experience a more direct connection with the tire contact patches. Our fastest speed will come through using the narrow optimal slip angle of our slicks, which were much more communicative after this mod. In the next two races we broke the track records for our class. Coincidence?
- Find a steering coupler and find a good condition ZHP rack. How do you know you’ve got one? Look for the yellow label that ends in 712. (7852974712)
- Use a turkey baster to remove as much fluid from the steering reservoir as possible. Or do nothing if you like big messes.
- Underneath the car, cut the clamps for your tie rod boot and move them out of the way.
- Use a large screwdriver to bend back the tab that holds the tie rod ends in place. Loosen the tie rod ends.
- Loosen the upper nut on the steering coupler, remove the bolt.
- Remove the 2 small bolts that hold the hard “trombone” lines to the front of the rack, loosen two bolts that attach the steering lines to the rack (and be prepared to catch the power steering fluid).
- Finally, disconnect the 2 bolts that mount the steering rack to the subframe. Carefully pull the rack out of the vehicle.
- Mount the new steering coupler to the ZHP rack before installation. The black plastic tab on the rack indexes with the gap in the coupler (Hint, this is the side of the coupler to remove later if you need to pull the rack and don’t want to re-align the steering wheel).
- Installation is the reverse of removal with one exception: the 5 Series steering shaft has a groove for the upper coupler bolt. The e36 shaft does not have this. Once you have your steering wheel and coupler aligned properly, you’ll need to use a Dremel to create this groove. There’s an arrow on the rack’s black cover that indicates dead center so you can align your steering wheel accordingly. Use the proper bit and this should take just a couple seconds.
- Note that you’ll need new crush washers for the steering line bolts, tie rod boot clamps, and power steering fluid. This is an excellent time to replace your reservoir, boots, and tie rods if worn.
Now get out there and enjoy better steering feel than any e36 had when it left the factory.
Steering coupler: 32311151454 (E28, E34, E24). These are not available new so one will have to be found used.
Steering reservoir: 32416851217
Tie rod boots: 32131096910