2003 Z4 Hydraulic Power Steering Conversion

[10Terp]

Hello all. Haven't posted here in a while. Since my last post I've had my first kid so time has certainly been at a premium recently. I have been itching to get back to the Z4 and have been reading and researching doing a hydraulic power steering conversion upgrade. I know there are several threads on this already, so I hope this thread will add to the already collective knowledge that is out there.

A local junkyard got in a 2002 325CI earlier in the week and I decided to take a day off and go pull the power steering system out of it. Here's what I came home with:



Interestingly, I'm pretty sure this car had a remanufactured purple tag rack. It has some markings on it that indicate it's remanufactured, and it appears another tag was riveted on. It's also very clean. Originally I was concerned it was a silver tag rack, but several things point to it being a purple tag: 3 turns lock to lock, November 2001 manufacture date, and the casting numbers on the body are the same as several ebay purple tag racks I looked up. The outer tie rod on the passenger size was busted too, so I'll need to get that off (kinda nervous of breaking something; this rack is nice). Would be curious of additional thoughts, though:





The pump is an LF-30. I'm definitely missing some odds and ends and will assemble those as I have time. Not sure how long this project will take as free time as at a premium right now, but I will keep the updates and pics coming as I make progress!

 

[raymond.harper]

Congratulations on the birth of your first child! Getting a functioning, but basic system, will take about 8 hours. I spent more time on the cooling system for the rack than on any other component. The intermediate shaft can be converted to fit at a lower cost than buying one from a Z4M. The only downside is that fuel consumption will increase by about 3mpg. Good luck and keep us updated.

 

[10Terp]

Congratulations on the birth of your first child! Getting a functioning, but basic system, will take about 8 hours. I spent more time on the cooling system for the rack than on any other component. The intermediate shaft can be converted to fit at a lower cost than buying one from a Z4M. The only downside is that fuel consumption will increase by about 3mpg. Good luck and keep us updated.

Thank you! I’ll keep everybody updated. I’ll have to check out your thread for what you did for the cooling loop. I didn’t bother taking it from the donor car because I read the e46 cooling loop doesn’t fit the Z4. I’m sure I’m missing some other odds and ends as well. It was so damn hot yesterday that as soon as I got the big components off I decided to call it and get out of the heat.

 

[10Terp]

Started tearing into the car today. I made a mock-up of the system which details the power steering cooler layout I'm going to use. Here's a photo and video walkthrough:





-Note: I had to get an aftermarket banjo fitting for the bottom port because I forgot to take the original bolt with me from the wrecking yard. Doh.

Took off the front bumper cover:



Here's the stock rack. I first busted the tie rod bolts loose with an 18mm impact.



Then I unbolted the steering shaft from the rack. It uses an E10 bolt on both the column-side and rack-side yokes:




Once that's finished, undo the two 15mm bolts with 17mm nuts that hold the rack on, and pull it free:



Also, I wanted to make a video that explains why you can't use the Z4 shaft with an E46 rack, and how to adapt it for cheaper than a Z4M shaft. Note: I do not take credit for this idea; I read it somewhere else on the forum. I may try buying an E46 intermediate shaft from a 325/330 since they're half the price of a Z4 intermediate shaft ($60 vs 120). I believe the steering shaft yoke is the same and would work on the Z4 shaft.