Hydraulic steering conversion - how much better is it?

Mr Tidy · Post by **Mr Tidy** » Thu May 09, 2019 7:59 pm

Felix79 wrote: ↑Thu May 09, 2019 4:20 am I'm only over in Oxford, would be happy for you to try my E85M out if you want? I'm free pretty much all the time, so can pop over to Berks as soon as "today" if you'd like?

That's a really kind offer - thanks.

I'll PM you about it!

Felix79 · Post by **Felix79** » Thu May 09, 2019 8:35 pm

Mr Tidy wrote: ↑Thu May 09, 2019 7:59 pm
Felix79 wrote: ↑Thu May 09, 2019 4:20 am I'm only over in Oxford, would be happy for you to try my E85M out if you want? I'm free pretty much all the time, so can pop over to Berks as soon as "today" if you'd like?
That's a really kind offer - thanks.

I'll PM you about it!

You're welcome dude, as you have the shape and colour I wanted my Z4M to be lol!

I'm free tomorrow and the weekend, so if the weather improves, can do some top down driving and really hear the S54.

DaveD · Post by **DaveD** » Thu May 09, 2019 9:51 pm

Felix79 wrote: ↑Thu May 09, 2019 8:35 pm You're welcome dude, as you have the shape and colour I wanted my Z4M to be lol!

I'm free tomorrow and the weekend, so if the weather improves, can do some top down driving and really hear the S54.

Interested in your feedback on this Gents. Is the M steering markedly better than the standard Si?

Felix79 · Post by **Felix79** » Thu May 09, 2019 11:08 pm

DaveD wrote: ↑Thu May 09, 2019 9:51 pm
Felix79 wrote: ↑Thu May 09, 2019 8:35 pm You're welcome dude, as you have the shape and colour I wanted my Z4M to be lol!

I'm free tomorrow and the weekend, so if the weather improves, can do some top down driving and really hear the S54.
Interested in your feedback on this Gents. Is the M steering markedly better than the standard Si?

Honestly, it's really subjective. The problem is when they EPAS starts to fail, you end up having to deal with so many problems that it makes most people steer clear of using it ever again. Because the system used on the E85/86's is actually so out dated, it's more trouble that it's worth.

DaveD · Post by **DaveD** » Mon May 13, 2019 10:37 am

Ok, so i've been out for a long drive in my coupe over the weekend - 250 odd miles over mixed terrain. I was thinking about what i still don't like about the EPAS steering, so here are some notes:
- In corners it weights up quite nicely. Not much feel, but holds the line well and doesn't kick around so actually works quite well for this purpose
- on a roads/motorways when cruising, is still a little twitchy but i don't find that much in the way of tramlining - mix of fresh bushings, deeper sidewall on tyres and a small turn on the eccentric ring on EPAS motor must help.
- when making small adjustments to keep on line, the steering itself does have an annoying trait of needing a bit of force to be applied before the wheel turns. Before anyone laughs at the obviousness of this statement (!), what i mean is you put a bit of pressure and no movement, a bit more and still no movement, and then a bit more and it finally moves. I'm not sure if this is a trait of 'sticky steering', but it does make the steering less linear than it should be. Compare to another car with better steering, and even a tiny amount of force applied to the wheel will result in movement - ie it feels smooth. It feels a bit like the epas motor needs to feel a certain amount of force before it acts, leading to this slightly uneven power assist for small movements...

Does anyone else get this? I presume hydraulic steering would fix this?

D

ph001 · Post by **ph001** » Mon May 13, 2019 10:54 am

Hydraulic steering would fix that I think but that is not how the EPS should feel. It should be perfectly linear with no 'stickiness' at all around centre.

Jakg · Post by **Jakg** » Mon May 13, 2019 10:56 am

I wonder how much the "improvement" of hydraulic over EPAS is just getting away from the rubbish system in the Z4.

I also drive a 2008 RenaultSport Megane, which also has EPAS. Steering feel is way, way better, much more confident and very reliable.

wonkydonkey · Post by **wonkydonkey** » Mon May 13, 2019 10:56 am

DaveD your comment about needing to apply a bit of breakaway torque to the wheel before it begins to turn is symptomatic of sticky steering. That said, having dialled the stickiness out of mine, I'm still not a big fan of the Z4's steering. It'll be interesting to see what you make of the Z4M.

MrPT · Post by **MrPT** » Mon May 13, 2019 11:02 am

I thought “sticky steering” was a specific issue with pre-facelift cars. Never noticed on my 2.5si, although there was a bit of a dead zone around straight ahead (which may have been intentional - not sure).

Machine monkey · Post by **Machine monkey** » Mon May 13, 2019 11:05 am

It’s night and day! Do it I love mine!
Purple tag rack
Any m54 pump and bits (some lines can be different) so be carful. Try and get a whole set up off 1 car if you can.
Take the electric motor out of the steering column as it drags!

Good luck

AlpinaZ4 · Post by **AlpinaZ4** » Mon May 13, 2019 11:09 am

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 · Post by **Machine monkey** » Mon May 13, 2019 3:24 pm

AlpinaZ4 wrote: ↑Mon May 13, 2019 11:09 am 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 · Post by **Mr Tidy** » Mon May 13, 2019 10:31 pm

Machine monkey wrote: ↑Mon May 13, 2019 3:24 pm 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 · Post by **DaveD** » Tue May 14, 2019 6:24 am

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 · Post by **MACK** » Tue May 14, 2019 6:37 am

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.

Z4-forum.com

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