Hydraulic steering conversion - how much better is it?

[AlpinaZ4]

I've been following this thread with interest.

Over the past 5 years I've driven around 70k km in 3.0Si Coupes and around 50k km in Z4M Coupes. Suspension varieties ranging from bone-stock, Bilstein B12, H&R Monotube and KW V3. Now back in a 3.0Si Coupe as daily driver and general fun car.

DaveD captures the essence of issues with Z4 EPAS quite well. The Z4M just feels "meatier" and linear. As family car we currently have an E90 3-series and in the same manner it just feels "right" when driven back to back with the Z4 3.0Si. It's exactly why I'm considering a hydraulic steering conversion.

My consideration would be this... why would BMW go through the effort of hydraulic steering for the Z4M if there weren't concrete benefits in doing so?

 

[Machine monkey]

I've been following this thread with interest.

Over the past 5 years I've driven around 70k km in 3.0Si Coupes and around 50k km in Z4M Coupes. Suspension varieties ranging from bone-stock, Bilstein B12, H&R Monotube and KW V3. Now back in a 3.0Si Coupe as daily driver and general fun car.

DaveD captures the essence of issues with Z4 EPAS quite well. The Z4M just feels "meatier" and linear. As family car we currently have an E90 3-series and in the same manner it just feels "right" when driven back to back with the Z4 3.0Si. It's exactly why I'm considering a hydraulic steering conversion.

My consideration would be this... why would BMW go through the effort of hydraulic steering for the Z4M if there weren't concrete benefits in doing so?

I think mostly due to timing. The m cars that had the s54 all had hydraulic and the Z4 was BMWs first electric system. To be fair for a first attempt it ain’t bad! But the hydraulic system I have added as said. Just feels right. It’s very had to say just what it is? But it’s something and very noticeable!

 

[Mr Tidy]

I think mostly due to timing. The m cars that had the s54 all had hydraulic and the Z4 was BMWs first electric system. To be fair for a first attempt it ain’t bad! But the hydraulic system I have added as said. Just feels right. It’s very had to say just what it is? But it’s something and very noticeable!

Well it isn't exactly good.

I had a facelift (57 plate) E87 1 Series with EPAS and it was pretty unobtrusive - way better than the EPAS on my E86.

It just seems a shame BMW decided to try it out on what was supposed to be their sports car! Why not try it on the 1,3, or 5 Series first?

Just a thought but although all E46 components should be OK for a pre-facelift conversion, I would imagine any facelift with the N52 engine would need a pump from an E9* 3 Series?

 

[DaveD]

Yes, it’s the LF30 pump that would need to be used. The link below apparently has the right parts identified for the N52 block. Would be nice if someone has already tried this though to confirm it all works!!!

 

[MACK]

The thing that worries me with doing this, whether its a on a pre or a post is how it interfaces with the on board safety/stability systems and also not having the eps warning lights on etc.
I have to say I've never suffered with sticky steering fortunately (I think due to the rack etc being replaced at BMW when the car was a year or so old) but if the steering system did fail instead of getting it fixed I would be tempted to source the bits and try a hydraulic conversion. The one thing that worries me parts wise is the extortionate new cost of the Z4M column to rack shaft. They're rare as hens teeth used.