Electric Hydraulic Steering upgrade.
Been meaning to do a video on this, but stuff keeps getting in the way, so here is a quick write-up.
Posted in the BMW Z4 Track Day and Race Car Group
This removes the EPS and replaces it with an electric hydraulic quick rack system from an E46.
Positives are: not driven by the engine, so no power-sapping pump; and, as it's not driven by the motor and therefore spun at engine-dependent speeds, you don't need extra cooling/lines. Oh....and you get much better feel/steering with less nervousness at speed!!
Things you'll need:
Fitting is fairly straightforward. Swap the rack, connect the steering shaft, and technically you have steering, although it is very, very heavy. I purchased a mount for the pump from eBay and screwed/bolted it to the rear left of the engine bay and ran the AN6 lines.
The only issue I found during fitting is that because of the change in ratio and possibly other things, the alignment piece of plastic on the rack puts the steering wheel 100 degrees out when mated up. So I removed the plastic centring piece, centred the rack manually with the wheel and refitted the shaft.
Connecting the power is easy. Main feed from the distribution block in the engine bay, with an 80amp fuse on a circuit breaker so I can switch the pump off if I need just the ignition on (60amp is not big enough; ask me how I know....steering is mega heavy with no power assistance), negative is close by. The two trigger wires, I took to the fuse board in the glovebox, but you could easily use the one in the engine bay. If you put the two trigger wires to the same fuse the pump takes about 15 seconds to spool; if you separate them and have them on circuits that switch on at different times, it spools instantly. The 15 second spool is no biggie for me. I believe if you use the Volvo/Merc pump, it spools instantly but isn't as powerful as the TRW pump. Plus, I use my car on track....if it's good enough for a factory Porsche racecar......
Remove the EPS motor from the steering column by folding yourself like origami, getting multiple cuts/bruises and swearing like a trooper. Oh, and it helps massively to push the brake pedal down whilst removing the motor....whilst in the footwell...upside down. Don't ask me to do it again, I'm fairly sure I had to dislocate my shoulder to do it!!!
Code out the EPS to remove the warning light using NCSExpert and you are good to go.
And that's it. It's been on for a few months now with zero issues; I've completed 2 track days in that time, and it's bloody brilliant. No more nervousness at speed, tonnes more feedback, the car is easier to place, and it's easier to catch when the back moves too. Steering is a little heavier whilst parking, but it's no biggie. Sport button still works for throttle if that's your thing. Overall very very happy.
Oh yeah, make sure you use the correct fluid for the pump; otherwise it bubbles and spills out of the cap.
I will try to put a video together when I get chance
Been meaning to do a video on this, but stuff keeps getting in the way, so here is a quick write-up.
Posted in the BMW Z4 Track Day and Race Car Group
This removes the EPS and replaces it with an electric hydraulic quick rack system from an E46.
Positives are: not driven by the engine, so no power-sapping pump; and, as it's not driven by the motor and therefore spun at engine-dependent speeds, you don't need extra cooling/lines. Oh....and you get much better feel/steering with less nervousness at speed!!
Things you'll need:
- E46 Purple Tag Rack (yellow in the states I think) This has the same ratio as the Z4MR - from £50
- Electric power steering pump. I went for a TRW pump that is used in the Porsche Cup race cars... also comes as stock in the Vauxhall Zafira, so it's fairly cheap to acquire £80 Some use Volvo or Merc pumps
- Z4M steering shaft or butcher 2 Z4 shafts by moving the top yoke of one onto the bottom of another. The issue is the splines on the E46 rack match the Z4M shaft but not the stock Z4 shaft. You can't use an E46 shaft safely as the yoke isn't long enough. You could probably extend an E46 shaft too but I don't have the ability to do that, so i bought a Z4M shaft for £150
- AN6 lines with connectors on PTFE hose for the high pressure and pushlock for the low pressure. You need 2xM16x1.5 and 1 M14x1.4 plus some 150-degree and straight adaptors c£110
- Power steering fluid
- Cage to mount the pump £20 ebay
Fitting is fairly straightforward. Swap the rack, connect the steering shaft, and technically you have steering, although it is very, very heavy. I purchased a mount for the pump from eBay and screwed/bolted it to the rear left of the engine bay and ran the AN6 lines.
The only issue I found during fitting is that because of the change in ratio and possibly other things, the alignment piece of plastic on the rack puts the steering wheel 100 degrees out when mated up. So I removed the plastic centring piece, centred the rack manually with the wheel and refitted the shaft.
Connecting the power is easy. Main feed from the distribution block in the engine bay, with an 80amp fuse on a circuit breaker so I can switch the pump off if I need just the ignition on (60amp is not big enough; ask me how I know....steering is mega heavy with no power assistance), negative is close by. The two trigger wires, I took to the fuse board in the glovebox, but you could easily use the one in the engine bay. If you put the two trigger wires to the same fuse the pump takes about 15 seconds to spool; if you separate them and have them on circuits that switch on at different times, it spools instantly. The 15 second spool is no biggie for me. I believe if you use the Volvo/Merc pump, it spools instantly but isn't as powerful as the TRW pump. Plus, I use my car on track....if it's good enough for a factory Porsche racecar......
Remove the EPS motor from the steering column by folding yourself like origami, getting multiple cuts/bruises and swearing like a trooper. Oh, and it helps massively to push the brake pedal down whilst removing the motor....whilst in the footwell...upside down. Don't ask me to do it again, I'm fairly sure I had to dislocate my shoulder to do it!!!
Code out the EPS to remove the warning light using NCSExpert and you are good to go.
And that's it. It's been on for a few months now with zero issues; I've completed 2 track days in that time, and it's bloody brilliant. No more nervousness at speed, tonnes more feedback, the car is easier to place, and it's easier to catch when the back moves too. Steering is a little heavier whilst parking, but it's no biggie. Sport button still works for throttle if that's your thing. Overall very very happy.
Oh yeah, make sure you use the correct fluid for the pump; otherwise it bubbles and spills out of the cap.
I will try to put a video together when I get chance
Ware, East Hertfordshire