Hydraulic steering conversion - N52-engined Z4 models

[rosskins]

I does depend how you drive the car. I agree, the steering was a little bit heavy at lower speeds but it became nimble the faster you went and then you got that feeling that man and beast became connected. Sorry, slightly off topic but my first BMW was a 120d (great car) which had electronic steering (this failed me but thankfully it was under warranty - the repair bill was nearly £800) but the the replacement car, an older 325ti was my first straight six and I have never looked back since. I do miss that car - it was bullet proof, fast and produced a great noise and it rejected everything I threw at it even after 165,000 miles when i traded it. Nothing went wrong! The e85s steering is just different, it is great but i would love to feel what hydraulic steering would feel in my e85 now.

[ionofchios]

Great how-to - simply excellent.

[ionofchios]

Anyways, my main question is - how well would you rate the steering of your car now you’ve done this, meaning generally, not just compared to how it was before? I think you commented previously that all twitchiness is gone, right? But is the overall feel of the steering now what you would call good? As good as any other hydraulic BMW?

I’m gonna try to source a LHD yellow rack or new OEM equivalent. I’ve been able to find several used with part number 7852974712, but I can’t find that number on RealOEM. Is this a BMW part number? Do you know if it’s possible to buy a new OEM steering rack built to the same spec and do you know what part number that might be?

[Hydro_Z4]

Anyways, my main question is - how well would you rate the steering of your car now you’ve done this, meaning generally, not just compared to how it was before? I think you commented previously that all twitchiness is gone, right? But is the overall feel of the steering now what you would call good? As good as any other hydraulic BMW?

We run an E91 330iT as daily next to the Z4 3.0Si and E46 M-Sport before that.
The steering is quite similar in feel, although the Z4 is of course more nimble.
Nice and solid. No twitchiness.
Basically the conversion is the same setup as an E46 M-Sport so not surprising it feels similar.

I've also owned several Z4M Coupes and the Z4 3.0Si feels identical to that... which isn't surprising as it's essentially the exact same setup. There's a reason that BMW choose to spec the Z4M with hydraulic steering in 2006, when they had been building Z4 with electric steering for several years.

I’m gonna try to source a LHD yellow rack or new OEM equivalent. I’ve been able to find several used with part number 7852974712, but I can’t find that number on RealOEM. Is this a BMW part number? Do you know if it’s possible to buy a new OEM steering rack built to the same spec and do you know what part number that might be?

I believe it's a ZF part number. Not really an issue - it just helps to identify the correct used rack.
Haven't spent much time trying to figure out the BMW part number, maybe you could obtain it by running VIN from a 330i ZHP against realoem.
There are various suppliers of re-manufactured racks which would essentially be comparable to a new rack.
In my opinion steering racks don't really wear much on regular 3-series doing lots of highway mileage.
If you were unlucky enough to source one with a bit of play, it's pretty straightforward to swap to another used rack after doing the conversion.

[ionofchios]

OP, thanks for the useful replies. I have ordered second-hand yellow rack and new intermediate shaft. Will wait for those to arrive before doing the rest. Having some trouble at moment finding a decent used pump with brackets. Again, I would just go new OEM, but those don’t seem to come with brackets, and BMW don’t seem to list the prt number for brackets separately, so can’t source them new.

[Hydro_Z4]

OP, thanks for the useful replies. I have ordered second-hand yellow rack and new intermediate shaft. Will wait for those to arrive before doing the rest. Having some trouble at moment finding a decent used pump with brackets. Again, I would just go new OEM, but those don’t seem to come with brackets, and BMW don’t seem to list the prt number for brackets separately, so can’t source them new.

Correct on the brackets - they don't seem to have a separate BMW partnr

If it helps - I believe any N52 engined E90, E60 or E65 should have the same pump.

[ionofchios]

If it helps - I believe any N52 engined E90, E60 or E65 should have the same pump.

Yeah, that's probably what I will end up with. Infuriatingly, I have found a few pics of the brackets with the BMW numbers stamped on them, but it is just that BMW don't recognise these numbers.

BTW., does anyone know if it is a bad idea to omit the cooling loop from the system?

[Hydro_Z4]

My guess is unless you're doing long stints on trackdays that it shouldn't be a problem.

Question is why you would want to omit the cooling loop - the parts are relatively cheap.
There's a reason that it's installed on all BMWs of that era.

Worst case you could end up with air bubbles in the fluid and unexpected reduction in power steering.

[Joycey]

Brilliant article, I'll likely be doing just this at some point.

[ionofchios]

My guess is unless you're doing long stints on trackdays that it shouldn't be a problem.

Question is why you would want to omit the cooling loop - the parts are relatively cheap.
There's a reason that it's installed on all BMWs of that era.

Worst case you could end up with air bubbles in the fluid and unexpected reduction in power steering.

Wondered if it was one of those things that is overkill and can be deleted, saving me trouble of mounting it somewhere. I’ve sourced one anyways, and will be installing it.

[ionofchios]

Right, I’ve hit a problem and would really appreciate some advice or knowledge that would help!

I sourced all the bits, and ended up with yellow tag rack and LF30 pump from an N52 e90 (32416769887), with a new Meyle HP hose (32416764725). The problem is the hose fitting to the pump, which is integrated to a hard line on one end of the hose, is screw-in (not banjo) and does not fit properly to the pump, plus the angle of the hard line is totally wrong for the inlet of the pump - when installed on the engine, the inlet of the pump is basically point down, but the hose seems to expect the inlet to be on the back of the pump, or something.

From what I gather (may be false), there are 2 versions of LF30: one that was used on, at least, e46s (32411094965), and one that was used on, at least, N52 e90s (32416769887). It seems I have the HP hose for the former, but the latter pump.

The integrated screw-in fitting on my hose does fit in the pump, but when I screw it all the way in, the screw collar part is not deep enough to push the end of the pipe with the o-ring up against the internal receptor of the pump, so it has room to slide up and down. This, presumably, cannot work.

The LF30 I have was off an e90, and it came with a banjo bolt and washers screwed into the inlet, so that seems to be at least the type of fitting for the HP hose it had on the car it came off.

So, I’ve buggered up somewhere, but I don’t know what to do next.

1) Do I keep this e90 LF30 pump, which has the right brackets and fits on my n52 nicely? What hose do I need then? I looked at the one for e90, and the banjo end will fit in the pump, but the banjo hard line at the other end that goes to the rack seems to be a different shape and the e90 rack seems to have connectors in different locations compared to e46, which may mean this hose won’t fit at the rack end.

2) Does the e90 LF30 pump I have have to be connected using banjo bolt, or is there some inline screw-in connector, like the in one my current hose, that will also work? Which hose do I need for that? Funnily, the LF20 hose looks like it would fit - the hard line at the pump end seems to be orientated in a way that it would line up with the pump inlet, and pics seem to show that the screw-in collar is deeper than the one I have, so it may seal up.

3) Do I have the wrong pump? Should I get the older LF30 and use my current hose? If I do that, will the brackets I have fit that pump as well?

Hollow are some pics my current hose and pump.

[Hydro_Z4]

I guess your options are:

1) have a custom hose made up with the correct connectors

2) use the LF20 hose - which is what I believe was probably used with my conversion

[ionofchios]

2) use the LF20 hose - which is what I believe was probably used with my conversion

Okay, thanks! Can you, or anyone else, confirm that it is OK to connect a HP line to a newer LF30 (32416769887) using an inline screw-in connector as found on LF20 hose, and not banjo? I’d like to make sure that actually something these connectors are designed to do, else I may end up damaging both my 2nd new hose and my pump, and still end up with a system that does not hold pressure.

[ionofchios]

So, LF20 hose would be 32416774215, I think. And the reason I think the connector might fit, is in many pictures I’ve seen, it looks longer (the number of threads on the screw-In collar is greater).

Here’s one such picture - as you can see, that distance, X, looks greater here than on my hose.

[ionofchios]

And, for anyone that's interested, I now have everything installed, but still have couple of brackets to build and some tidying to do.

The 32416774215 high-pressure hose seems to fit, and I've run the engine for a couple of minutes and there don't appear to be any leaks. The hard line on the pump end is not at a great angle, and it makes it hard to route the line around the sump without touching it, keeping it away from the belt, but it's workable. I need to make a nice bracket that will make sure it can't touch either of the previously mentioned components. I wonder if an e90 high-pressure line would fit better, since it is designed for this pump and N52, so it should fit nicely on the pump end. But, the hard line on the rack end of that hose looks a bit different, as I think e90 racks are different than e46 racks, but it might fit, since the connection like to be in a very similar place - don't want to spend another hundred quid to find out, though.

I decided to mount the reservoir up next to the fuse box, as I don't want to modify anything to do with the air intake and risk upsetting some delicately balanced airflow calculations done by BMW engineers. I removed the fuse box from the plastic bracket and removed the bracket totally, to create more room, and they both fit in that space nicely. There is actually not much need to secure them in place, as everything fits so snuggly there, but I will make a bracket or something at some point.

I installed the cooler in front of the radiator, behind the bumper, but did not need to remove the bumper to do so. It is just cable-tied at the moment, but is quite secure - brackets will, though, be fabricated. It strikes me that the e90 cooler would fit better, since the e46 cooler goes up before it goes horizontal, in front of the radiator, meaning it interferes with coolant expansion tank plastic housing. The e90 cooler just runs straight horizontal, which would fit the space better and stays out of the way for aforementioned plastic bits. Don't take my word for this, but that's what it looks like from looking at pictures on RealOEM.

My steering wheel is now 180 degrees off. I assume this is as the rack has a different ratio, but can someone confirm that makes sense? I don't see any other way to orientate the intermediate shaft, as there is a plastic flange on the rack end that has to fit in the split in the yoke (meaning it only goes on one way) and its the same at the steering column end, where the column has a sort or metal key that needs to go in the same.