Hydraulic steering conversion - how much better is it?

Thanks for the input guys. I have driven an M coupe and the steering definitely felt meatier, but it did tramline a bit too. I think the key difference was that it felt a lot better around centre and just off centre, where the epas feels quite vague. There wasn’t from memory masses more feel when cornering on the M vs Si though - a bit more but I wouldn’t say you could feel understeer through the wheel unlike in eg an Elise.

Could increasing castor on the epas set up help with centre/off centre feel?
 
I don’t think so. It’s pretty inert around the middle - on my si I had totally shot lollipop bushes and you could hold the wheel dead straight while the car wandered slightly from left to right!

In theory you’d get better handling with more castor, regardless of feel, because of the increase in negative camber while cornering. Switching to the Z4M rear control arm bushes might be a relatively cheap experiment compared to castor plates etc.
 
It's interesting what folks are saying re the difference between an M and standard. Before this thread and from reading previous threads I thought it was night and day. I wonder how much effect the heavier/larger 45 profile m tyres play in this. I remember thinking when I made the switch it felt a tad meatier, not alot but a definite difference. I still have a second set of wheels with some standard profile non runflats Bridgestones on, I may well bang them on for a quick comparison. Although then I'll still be wondering how much is Goodyear f1 vs Bridgestone
 
MACK said:
It's interesting what folks are saying re the difference between an M and standard. Before this thread and from reading previous threads I thought it was night and day. I wonder how much effect the heavier/larger 45 profile m tyres play in this. I remember thinking when I made the switch it felt a tad meatier, not alot but a definite difference. I still have a second set of wheels with some standard profile non runflats Bridgestones on, I may well bang them on for a quick comparison. Although then I'll still be wondering how much is Goodyear f1 vs Bridgestone
Click to expand...

I think going from the run flats to a normal tyre helps a lot with the feel of the steering. Because the "EPAS" is known to suffer from "sticking" , this makes the steering feel sluggish and number, when compared to the hydraulic systems. When I got a chance to drive a normal 3.0 (only for about 10-15 mins), I didn't find the steering to be a negative, but at the same time, I can see why people lust for a traditional system instead.

With my Z4Mr , I run the Michelin Sport 3's on the standard wheels and I have found the steering to really feel responsive. The one thing I will say is the weight of the wheel actually feels really spot on and is able to balance out and out Hooning, but also be so nice when doing a longer run on a motorway. I do wonder how big an impact the steering racks are between the E85 and E86? With the E86 having a quicker rack than the E85, it could be the E86's setup will sharpen the steering up and give a nicer feel with the feedback off the road.
 
Felix79 said:
MACK said:
It's interesting what folks are saying re the difference between an M and standard. Before this thread and from reading previous threads I thought it was night and day. I wonder how much effect the heavier/larger 45 profile m tyres play in this. I remember thinking when I made the switch it felt a tad meatier, not alot but a definite difference. I still have a second set of wheels with some standard profile non runflats Bridgestones on, I may well bang them on for a quick comparison. Although then I'll still be wondering how much is Goodyear f1 vs Bridgestone
Click to expand...

I think going from the run flats to a normal tyre helps a lot with the feel of the steering. Because the "EPAS" is known to suffer from "sticking" , this makes the steering feel sluggish and number, when compared to the hydraulic systems. When I got a chance to drive a normal 3.0 (only for about 10-15 mins), I didn't find the steering to be a negative, but at the same time, I can see why people lust for a traditional system instead.

With my Z4Mr , I run the Michelin Sport 3's on the standard wheels and I have found the steering to really feel responsive. The one thing I will say is the weight of the wheel actually feels really spot on and is able to balance out and out Hooning, but also be so nice when doing a longer run on a motorway. I do wonder how big an impact the steering racks are between the E85 and E86? With the E86 having a quicker rack than the E85, it could be the E86's setup will sharpen the steering up and give a nicer feel with the feedback off the road.
Click to expand...

I'm always a bit confused by this "the E86 has a quicker rack" thing. The parts on realoem for both the rack and the column are the same for all non Ms E85/6
 
MACK said:
Felix79 said:
MACK said:
It's interesting what folks are saying re the difference between an M and standard. Before this thread and from reading previous threads I thought it was night and day. I wonder how much effect the heavier/larger 45 profile m tyres play in this. I remember thinking when I made the switch it felt a tad meatier, not alot but a definite difference. I still have a second set of wheels with some standard profile non runflats Bridgestones on, I may well bang them on for a quick comparison. Although then I'll still be wondering how much is Goodyear f1 vs Bridgestone
Click to expand...

I think going from the run flats to a normal tyre helps a lot with the feel of the steering. Because the "EPAS" is known to suffer from "sticking" , this makes the steering feel sluggish and number, when compared to the hydraulic systems. When I got a chance to drive a normal 3.0 (only for about 10-15 mins), I didn't find the steering to be a negative, but at the same time, I can see why people lust for a traditional system instead.

With my Z4Mr , I run the Michelin Sport 3's on the standard wheels and I have found the steering to really feel responsive. The one thing I will say is the weight of the wheel actually feels really spot on and is able to balance out and out Hooning, but also be so nice when doing a longer run on a motorway. I do wonder how big an impact the steering racks are between the E85 and E86? With the E86 having a quicker rack than the E85, it could be the E86's setup will sharpen the steering up and give a nicer feel with the feedback off the road.
Click to expand...

I'm always a bit confused by this "the E86 has a quicker rack" thing. The parts on realoem for both the rack and the column are the same for all non Ms E85/6
Click to expand...

From what I have read from various sites, is that the rack they used with the E86 M is a quicker rack. They used the one from the E46 M3 CSL for the E86M, where the E85M has the same rack that the E46 M3 used? The turn to turn figure quoted for the two cars is different, which I have seen on various websites.

(I just realised the confusion) I was meaning the E86M , rather than the standard E86. I apologise if it seemed I was talking about the normal E86, because I am Dyslexic and I have the bad habit of missing bits of a sentence when I am typing my comments, which ends up with me saying stupid things.
 
Yes, it’s just the M roadster and Coupe that are different (steering ratios of 13.7:1 and 12.8:1, respectively). Maybe the CSL rack has a lot of shared components, but it can’t be exactly the same because the part number is different and it has a slower ratio than either Z4M.

Any differences between non-Ms might be down to the components changed between pre and post facelift (just a guess).
 
Felix79 said:
MACK said:
Felix79 said:
I think going from the run flats to a normal tyre helps a lot with the feel of the steering. Because the "EPAS" is known to suffer from "sticking" , this makes the steering feel sluggish and number, when compared to the hydraulic systems. When I got a chance to drive a normal 3.0 (only for about 10-15 mins), I didn't find the steering to be a negative, but at the same time, I can see why people lust for a traditional system instead.

With my Z4Mr , I run the Michelin Sport 3's on the standard wheels and I have found the steering to really feel responsive. The one thing I will say is the weight of the wheel actually feels really spot on and is able to balance out and out Hooning, but also be so nice when doing a longer run on a motorway. I do wonder how big an impact the steering racks are between the E85 and E86? With the E86 having a quicker rack than the E85, it could be the E86's setup will sharpen the steering up and give a nicer feel with the feedback off the road.
Click to expand...

I'm always a bit confused by this "the E86 has a quicker rack" thing. The parts on realoem for both the rack and the column are the same for all non Ms E85/6
Click to expand...

From what I have read from various sites, is that the rack they used with the E86 M is a quicker rack. They used the one from the E46 M3 CSL for the E86M, where the E85M has the same rack that the E46 M3 used? The turn to turn figure quoted for the two cars is different, which I have seen on various websites.

(I just realised the confusion) I was meaning the E86M , rather than the standard E86. I apologise if it seemed I was talking about the normal E86, because I am Dyslexic and I have the bad habit of missing bits of a sentence when I am typing my comments, which ends up with me saying stupid things.
Click to expand...
Thanks for clearing that up
 
MACK said:
It's interesting what folks are saying re the difference between an M and standard. Before this thread and from reading previous threads I thought it was night and day.
Click to expand...

That might be because people have a lot of issues with the feel of the EPS where there is play in the spigot ring etc, particularly in the non-facelift cars. This undoubtedly makes it feel pretty crap compared to a hydraulic rack. I think on a fresh, tight fully working EPS though, the difference is quite marginal.

I guess the real dilemma comes at the point where you have to repair / replace a knackered EPS. At the point, the hydraulic system becomes somewhat more attractive if you are going to have to shell out £2k anyway (although most EPS can be sorted for way less than that if it's just an adjustment / ECU issue).
 
ph001 said:
MACK said:
It's interesting what folks are saying re the difference between an M and standard. Before this thread and from reading previous threads I thought it was night and day.
Click to expand...

That might be because people have a lot of issues with the feel of the EPS where there is play in the spigot ring etc, particularly in the non-facelift cars. This undoubtedly makes it feel pretty crap compared to a hydraulic rack. I think on a fresh, tight fully working EPS though, the difference is quite marginal.

I guess the real dilemma comes at the point where you have to repair / replace a knackered EPS. At the point, the hydraulic system becomes somewhat more attractive if you are going to have to shell out £2k anyway (although most EPS can be sorted for way less than that if it's just an adjustment / ECU issue).
Click to expand...
ph001 said:
MACK said:
It's interesting what folks are saying re the difference between an M and standard. Before this thread and from reading previous threads I thought it was night and day.
Click to expand...

That might be because people have a lot of issues with the feel of the EPS where there is play in the spigot ring etc, particularly in the non-facelift cars. This undoubtedly makes it feel pretty crap compared to a hydraulic rack. I think on a fresh, tight fully working EPS though, the difference is quite marginal.

I guess the real dilemma comes at the point where you have to repair / replace a knackered EPS. At the point, the hydraulic system becomes somewhat more attractive if you are going to have to shell out £2k anyway (although most EPS can be sorted for way less than that if it's just an adjustment / ECU issue).
Click to expand...
You could well be on to something there, I've never really felt there's too much of an issue with the EPS on mine but that said even though its a pre its had a post EPS setup from early in the cars life.
I did honestly think they may have put a quicker rack on the coupe over the roadster to make it a bit more aggressive. They did something similar by fitting a 3.46 diff instead of the 3.23 one on the roadie
 
Felix79 said:
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?
Click to expand...

That's a really kind offer - thanks. :thumbsup:

I'll PM you about it!
 
Mr Tidy said:
Felix79 said:
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?
Click to expand...

That's a really kind offer - thanks. :thumbsup:

I'll PM you about it!
Click to expand...

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.
 
Felix79 said:
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.
Click to expand...

Interested in your feedback on this Gents. Is the M steering markedly better than the standard Si?
 
DaveD said:
Felix79 said:
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.
Click to expand...

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

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.
 
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
 
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.
 
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.
 
[ref]DaveD[/ref] 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.
 
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).
 
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
 
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