Hydraulic steering conversion - N52-engined Z4 models
- Thread starter Hydro_Z4
- Start date
Mine is currently running with no cooler (the push in end on one hose was broken) interestingly I can dip my finger in the ATF fluid after running around the NC500 for 5 hours and I would say its slightly above body temp. I do intend on adding the hoses back to the cooling loop but it appears it doesnt really need it?
Special Kay
Active member
I know this is quite an old thread, but kudos to Hydro Z4 for a very comprehensive write up. I will definitely keep this thread in mind if I start to have problems with my steering. Thank you for such a great write up 
portculisz4
Member
Scanning through the forum I came across your informative description on the hydraulic steering conversion. I am now seriously considering doing this to my 2005 E85 2.5i Z4 so I am going through the various steps to make sure I have thought about all the detail. I have a number of questions which I would like to ask (I will start with one now and add further questions later as I progress through the list)
The first is the intermediate shaft - I take onboard the different size splined fitting of the Z4 shaft going to the racks splined input shaft and the solution to use the Z4M intermediate shaft, but is it possible to swap the lower splined knuckle joint on the Z4 shaft with the lower knuckle joint used on the E46 intermediate shaft by removing the hardy spicer joint at the lower end. Would the length of the modified Z4 shaft be adequate to connect the end of the steering column shaft to the steering rack input ??
The first is the intermediate shaft - I take onboard the different size splined fitting of the Z4 shaft going to the racks splined input shaft and the solution to use the Z4M intermediate shaft, but is it possible to swap the lower splined knuckle joint on the Z4 shaft with the lower knuckle joint used on the E46 intermediate shaft by removing the hardy spicer joint at the lower end. Would the length of the modified Z4 shaft be adequate to connect the end of the steering column shaft to the steering rack input ??
portculisz4 said:
No worries. Happy to help.
If I'm not mistaken your Z4 2.5i isn't N52 engined but M54 engined.
As mentioned in my initial post that actually simplifies the conversion...
This guide should map quite well to M54-engined cars, with adjustments to take into account LF-20 instead of LF-30 steering pump. This should be limited to high-pressure line from pump to rack (specific to LF-20 steering pump - there are LHD and RHD versions), V-belt 6PK 1538 (11287636379) and mounting screw M8x22 (07119905739). There is a M54 mounting bracket for the reservoir (32411092940) with screw (7119904524) and 2x screw (7119905529).
portculisz4 said:
As mentioned in my initial post, that's it's exactly what BMW did for the Z4M intermediate shaft. Any decent machine shop should be able to perform this step. However, considering new price from BMW of around €/£/$ 200-300, there would be little to no financial incentive to undertake this in my opinion though. In terms of length there is no notable difference between Z4, E46 or hybrid (Z4M) intermediate shaft...
After doing this conversion I think it’s peace of mind just buying the z4m intermediate shaft rather than machine shop or any modifications … I’m a tight Yorkshireman and always go for the cheap option but realised if this fails your doomed … plus your already saving £2500 on electric rack replacement … might make you feel better about handing over 250 quid for a bit of metal with a couple of universal joints 
portculisz4
Member
Thanks for your reply, will almost certainly go the Z4M way but interested to know whether others have looked at this. Also, very interested to hear of others experience in doing this conversion, did you go for the E46 purple rack, I have read threads on suggestions to use the Z3-E36 rack which has a lower turns ratio (2.7) but not sure if this swap is directly compatible with the E46 rack swap.
portculisz4
Member
hydro-Z4
I have now got a E46 purple rack (which I will service with a new seal set) and an LF-20 pump (which I have just serviced and it looks to be in excellent condition) so this will be my hydraulic conversion base for the steering. Can you confirm on the pulley diameter you are using since the pulley P/N listed above seems to list a whole generic set of items and I cannot see the pulley listed amongst them so will buy seperately. I have seen sizes referenced from 119 - 135mm, the size will obviously affect the pressure output so would like to get the most appropriate for my setup
I have now got a E46 purple rack (which I will service with a new seal set) and an LF-20 pump (which I have just serviced and it looks to be in excellent condition) so this will be my hydraulic conversion base for the steering. Can you confirm on the pulley diameter you are using since the pulley P/N listed above seems to list a whole generic set of items and I cannot see the pulley listed amongst them so will buy seperately. I have seen sizes referenced from 119 - 135mm, the size will obviously affect the pressure output so would like to get the most appropriate for my setup
Hello,
I made my account just to share my experience related to the conversion of electrical to hydraulic steering. With no using new shaft from Z4M.
1/ The conversation was done on M46 engine, on the car which I converted from right-hand drive to left. Only a hydraulic pump is needed, not any additional pulley, belts, etc. The hydraulic pump is behind water on the same shaft.
2/ I did not buy a middle shaft from Z4 M, just exchanged the top part E46 to Z4 one in my leaving room. It is not hard, I used dremmel tool to "unlock" small bearings and pull them out.
3/ To turn off the steering dash light I used Scanner 1.4. Very easy just put out the tick for the steering light from the dash menu. Also the same tool to adjust the steering sensor.
I made my account just to share my experience related to the conversion of electrical to hydraulic steering. With no using new shaft from Z4M.
1/ The conversation was done on M46 engine, on the car which I converted from right-hand drive to left. Only a hydraulic pump is needed, not any additional pulley, belts, etc. The hydraulic pump is behind water on the same shaft.
2/ I did not buy a middle shaft from Z4 M, just exchanged the top part E46 to Z4 one in my leaving room. It is not hard, I used dremmel tool to "unlock" small bearings and pull them out.
3/ To turn off the steering dash light I used Scanner 1.4. Very easy just put out the tick for the steering light from the dash menu. Also the same tool to adjust the steering sensor.
