[SteveC]

Originally Posted by doughboy

Its clear that assistance is reduced at speed, but its the low speed assistance which is too high IMO now and results in an unstable feeling at town speeds.

So at 20mph say, turning into a t-junction, modern cars literally 'fall' into the corner with a breath on the wheel, more unpleasant than a 'problem', and any assistance numbs feedback by its very nature, more assistance = less feedback.

At town speeds, the main problem I notice with electric systems is that there is a delay in the assistance 'starting' when you begin to turn the wheel, so it feels stiff (like high speed, unassisted stiff) as you first apply pressure at straight ahead then it suddenly eases and moves as the motor starts a fraction of a second later. This results in a straight line actually being a succession of straight lines at slightly different angles as it is impossible to infinitely trim the 'straight ahead' position as it is with always-running engine driven systems.

All EPS cars I have driven have been bad it this respect, even a quick 3 point turn where you palm the wheel lock to lock in a couple of seconds or less is often faster than assistance could keep up with, resulting in yoyo-ing of the wheel back and forth as it ran out of assistance / gained assistance / ran out of assistance / gained assistance etc

I contributed my previous piece early this morning. For the rest of the day I've been out and about, driving on everything from winding country lanes, to rush hour in Durham then back home along the A1 and A19.
Due mainly to this thread, I paid particular attention to the steering to see if I could detect periods when it felt less than ideally weighted. I couldn't. As to the effects you mention, not a trace, and I would definitely notice something as intrusive as you describe. In fact I would probably take my car back to the dealer for a warranty repair if I could detect the PS switching in and out.

Take a look at the way Electronic Power Assisted Steering is implemented in a BMW and you'll immediately see why the above effects should be virtually eliminated or at least so minimized as to be unnoticable (assuming you can understand German)

http://www.kfztech.de/kfztechnik/fah...enkung/eps.htm

EPS is extremely sophisticated yet quite simple. It comprises sensitive and extremely fast photo-electric and magneto-electric sensors that capture the torque applied by the driver and the angle and speed of the steering wheel, thousands of times per second. Vehicle speed, system temperature, normal or sports settings and speed of the servo motor are all transmitted to a steering control processor. Programmable damping is applied to absorb impacts from the road surface. Signals from the control unit are transmitted to a high torque servo motor that responds far, far faster than any human muscle can. Given the types of servo motors used and the fact that the system can respond in thousandths of a second, there's absolutely no technical reason why the system should produce the see-sawing assistance you mention. That would be remarkably crude, given the speed at which the system can respond and the programming and control that can be applied.

To produce the effects you mention would require for example a situation where torque is being applied by the driver, the car is travelling slowly but the servo motor is not rotating. Should this situation ever arise, the system has the ability to correct it in microseconds, far faster than a driver could ever detect. Similarly a situation where the driver is spinning the steering wheel quickly at low speed but the servo motor is only turning slowly or not at all would constitute an out of spec situation and generate a fault message. Bear in mind that the system is able to sense all the driver and vehicle inputs, calculate and apply the assistance required and compare the actual result to its calculated requirement several hundred times a second.

I'm not saying you didn't feel these effects, merely that the effects are not inherent in BMW's EPS design, nor apparent in my vehicle, which uses it.

[jrah]

Haven't they also widened the track on LCI models to improve stability and handling?

[TMP]

Originally Posted by uke92dude

They are both "Servotronic" I think and that would seem to be confirmed by your extract from BMW's website above. What was a free option for hydraulic PAS (and standard on 335) is now a cost option.

To remove "Servotronic" from their vehicles and make you pay extra is ludicrous. It would go against the whole BMW driving experience and Ultimate Driving Machine ethos.

I shall ask BMW CS and see if they know. Watch this space...!

Err...itsnt it saying (as mentioned by someone earlier) that a hyrdraulic system actually moves the steering, but its powered by eps rather then the engine...

Yes let us know what CS say!

Originally Posted by uke92dude

PS You can add the "Servotronic" option to all coupés < 335.

Yeap, that was my point as well, Servotronic is not standard on < 335 models anymore, its an option i.e. is this why the steering feels overassisted now. Also you cannot add servotrontic to 335 models because they have the more feely hrydraulic system

[xenon]

SteveC - Using EPS the effects should be negated and there is nothing inherently wrong with the design or theory of EPS but the implementation in the E9x is dreadful because it is just too light.

[G82Dude]

Originally Posted by TMP

Err...itsnt it saying (as mentioned by someone earlier) that a hyrdraulic system actually moves the steering, but its powered by eps rather then the engine...

Yes let us know what CS say!



Yeap, that was my point as well, Servotronic is not standard on < 335 models anymore, its an option i.e. is this why the steering feels overassisted now. Also you cannot add servotrontic to 335 models because they have the more feely hrydraulic system

On this EPS system, there are NO hydraulics at all!

I am a little confused as on a previous post, you said that the "Servotronic" option could only be added to 330i. That is not the case; it can be added to any vehicle < 335. All 335 vehicles have hydraulic PAS (and Servotronic) as standard.

I still believe that the "Servotronic" option currently being offered is actually hydraulic PAS (incorporating Servotronic), which was a no cost option but now isn't. No news from CS yet, though...

[SteveC]

EPS is a dry system, with no hydraulics

Servotronic uses an electromagnetic valve to control the amount of force applied by the steering hydraulics, thereby adjusting the amount of steering assistance to suit the speed of the vehicle.

Servotronic is only available in conjunction with hydraulic power steering, is an option on some vehicles and standard on others

[TMP]

Originally Posted by uke92dude

On this EPS system, there are NO hydraulics at all!

I am a little confused as on a previous post, you said that the "Servotronic" option could only be added to 330i. That is not the case; it can be added to any vehicle < 335. All 335 vehicles have hydraulic PAS (and Servotronic) as standard.

I still believe that the "Servotronic" option currently being offered is actually hydraulic PAS (incorporating Servotronic), which was a no cost option but now isn't. No news from CS yet, though...

I was using the 330 vs 335 as a comparison - so agree it's all <335 that can have the servotronic

Originally Posted by SteveC

EPS is a dry system, with no hydraulics

Servotronic uses an electromagnetic valve to control the amount of force applied by the steering hydraulics, thereby adjusting the amount of steering assistance to suit the speed of the vehicle.

Servotronic is only available in conjunction with hydraulic power steering, is an option on some vehicles and standard on others

I am v.confused then . EPS replaces the engine in powering the hrdraulics...

My 330d spec was as follows:
Electric Power Steering (EPS) with Servotronic

[SteveC]

[QUOTE=TMP;6847793]I
I am v.confused then . EPS replaces the engine in powering the hrdraulics...

EPS is an electonics only system.....no hydraulics

In hydraulically operated power steering, Servotronic is a valve that reduces hydraulic oil pump flow as the speed of the car increases, thereby reducing the level of steering assistance at high speeds

The Servotronic concept of reducing steering power assistance as speed increases is implemented in EPS but electronically rather than by controlling oil flow.

Servotronic is very simple, comprising a valve that is opened or closed as a function of vehicle speed.

EPS is altogether more sophisticated in that it uses, amongst other things, vehicle speed, driver applied steering wheel speed, torque and angle to calculate the amount of assistance required. Through sensors, actual assistance is compared to the calculated assitance to make sure that the system always operates within very fine tolerances. The ideal level of assistance can thus be supplied, while avoiding all the old pitfalls associated with power steering. When parking an EPS equipped BMW there's lots of assistance and the steering is very light, while the car still feels stable and planted with good feedback when moving at speed or negotiating bends, due to the fact that for the vast majority of the time in active driving, no assitance is being applied.

Getting into a stationary or slow moving EPC equipped BMW and turning the wheel may create the impression that steering is overly light, however you'll also notice that all the problems usually associated with light steering like twitchy handling, lack of feedback and over sensitivity to road irregularities are noticably absent, because no assitance is being applied when those problematic situations would normally arise

[G82Dude]

Originally Posted by TMP

I was using the 330 vs 335 as a comparison - so agree it's all <335 that can have the servotronic



I am v.confused then . EPS replaces the engine in powering the hrdraulics...

My 330d spec was as follows:
Electric Power Steering (EPS) with Servotronic

Aaaarrrgghhhh!!! LOL There are no hydraulics with BMW EPS. None. Narda! It's some sensors, a control unit and a motor attached to the steering system! Take a look here at the animation. There's also an animation here of the first EPS system introduced on the Z4, where they also discuss Servotronic. You will notice that the motor has now migrated to and acts on the steering rack directly. Servotronic, such as it is on EPS, is provided for through the electric motor and its control system. "Servotronic" is strictly a trademarked system which provides variable (speed sensitive) steering assistance on a hydraulic PAS system. It's a bit like calling a Dyson a Hoover. If that makes sense.

PS Still no feedback from CS

[doughboy]

Originally Posted by SteveC

I'm not saying you didn't feel these effects, merely that the effects are not inherent in BMW's EPS design, nor apparent in my vehicle, which uses it.

I'm quite sure the BMW implementation of EPS is very good indeed. My experience is with other Makes, Audi and Honda etc.

There are some v crude systems out there. But even non-variable old hyldraulic systems 'felt' variable becaue the assistance provided was always relative to the torque applied to the steering wheel, so at high speeds you naturally don't apply large turning for to the wheel, so it 'feels' heavier.

But ultimately EPS is a designed as a CO2 saver, not a driving improvement (unless you struggle with parking) and it is therefore a compromise.

Thus why M cars don't have it as M couldn't get a decent drive out of it.

Not sure why 335x have only hydraulic, with no Servotronic listed - I'm glad though.

[TMP]

Originally Posted by uke92dude

Aaaarrrgghhhh!!! LOL There are no hydraulics with BMW EPS. None. Narda! It's some sensors, a control unit and a motor attached to the steering system! Take a look here at the animation. There's also an animation here of the first EPS system introduced on the Z4, where they also discuss Servotronic. You will notice that the motor has now migrated to and acts on the steering rack directly. Servotronic, such as it is on EPS, is provided for through the electric motor and its control system. "Servotronic" is strictly a trademarked system which provides variable (speed sensitive) steering assistance on a hydraulic PAS system. It's a bit like calling a Dyson a Hoover. If that makes sense.

PS Still no feedback from CS

ok, so EPS isnt hrydraulic.....! BUT arrggghhhh.......and lol indeed. Think it the dyson/hoover analolgy sort of makes sense - ....but hey that's still not my main issue here

BMW are now selling all <335 cars with just EPS and no servotronic (unless you tick the option). This results in the over assisted steering as per the review

[G82Dude]

Originally Posted by TMP

ok, so EPS isnt hrydraulic.....! BUT arrggghhhh.......and lol indeed. Think it the dyson/hoover analolgy sort of makes sense - ....but hey that's still not my main issue here

BMW are now selling all <335 cars with just EPS and no servotronic (unless you tick the option). This results in the over assisted steering as per the review

Nope, def not hydraulic.

I think BMW are selling their vehicles with Servotronic on EPS < 335 as standard. When they offer "Servotronic" as an option, I think you get hydraulic instead of electric PS!!!

Still nothing from CS...

[TMP]

Originally Posted by uke92dude

Nope, def not hydraulic.

I think BMW are selling their vehicles with Servotronic on EPS < 335 as standard. When they offer "Servotronic" as an option, I think you get hydraulic instead of electric PS!!!

Still nothing from CS...

Lol, we do need CS to resolve this one . My money is on EPS with servotronic, as this is what my ED car has:

Wheels and chassis
18" light alloy M Star-spoke style 193M with mixed tyres
Aluminium front and five-link rear suspension
Electric Power Steering (EPS) with Servotronic
M Sports suspension

[G82Dude]

No update from CS. Maybe they don't know either! LOL

[doughboy]

Originally Posted by uke92dude

Nope, def not hydraulic.

I think BMW are selling their vehicles with Servotronic on EPS < 335 as standard. When they offer "Servotronic" as an option, I think you get hydraulic instead of electric PS!!!

Still nothing from CS...

I think that all cars with EPS (i.e. non 335) now offer Servotronic as an option with EPS (£175). Ticking the servotronic box just seems to gives you some software controlled assistance variation on the EPS and does not give you a hydraulic system.

Interestingly the 335x just list 'hydraulic power steering' with no Servotronic as an option or otherwise, but my 335 plainly does have variable PS.....

And as a further variant the M3 comes with 'M Servotronic Steering' standard with no options.

[G82Dude]

Well, it's official.

You DO NOT get Servotronic with EPS as standard ANY MORE. What a load of shi, err, rubbish. And it would appear that you can no longer specify hydraulic PAS as an option. 335 still standard. For now. Or until the bean counters poke their noses in...

Would seem that BMW are stuck in a time warp. That's how cars came when PAS was introduced wasn't it? Non variable PAS as standard on a premium car built in 2010? And on the "Ultimate Driving Machine" too; wake up you dozey idiots!

Am pleased mine is not afflicted with this drivel (and where hydraulic was an option)! Grrr!

PS Best they change their website too, as some poor unsuspecting sucker might think this driver aid would be standard on the "Ultimate Driving Machine"...!

[TMP]

Originally Posted by uke92dude

Well, it's official.

You DO NOT get Servotronic with EPS as standard ANY MORE. What a load of shi, err, rubbish. And it would appear that you can no longer specify hydraulic PAS as an option. 335 still standard. For now. Or until the bean counters poke their noses in...

Would seem that BMW are stuck in a time warp. That's how cars came when PAS was introduced wasn't it? Non variable PAS as standard on a premium car built in 2010? And on the "Ultimate Driving Machine" too; wake up you dozey idiots!

Am pleased mine is not afflicted with this drivel (and where hydraulic was an option)! Grrr!

PS Best they change their website too, as some poor unsuspecting sucker might think this driver aid would be standard on the "Ultimate Driving Machine"...!

Thanks for clarifying mate ........ so I was right on the EPS

Yeap, I am chuffed as well this doesnt affect mine, but next time that's me excluded from a 330 AUC car - none of tem seem to have servotronic.

Maybe once car sales pick up they will add it back as standard.

[doughboy]

Originally Posted by uke92dude

Well, it's official.

You DO NOT get Servotronic with EPS as standard ANY MORE. What a load of shi, err, rubbish. And it would appear that you can no longer specify hydraulic PAS as an option. 335 still standard. For now. Or until the bean counters poke their noses in...

Would seem that BMW are stuck in a time warp. That's how cars came when PAS was introduced wasn't it? Non variable PAS as standard on a premium car built in 2010? And on the "Ultimate Driving Machine" too; wake up you dozey idiots!

Its still an option on the configurator for non 335x.....

....But 'old' Hydraulic Servotronic actually consisted of parts and equipment to add the system 'physically' to the standard car.

With EPS, any implementation of variable-assist (call it want you like) WILL ONLY be a software programming issue.

So if they are selling EPS with Servotronic as an option, it is £175 for 'enabling' the function in the software.

rip off.

[TMP]

Originally Posted by doughboy

Its still an option on the configurator for non 335x.....

....But 'old' Hydraulic Servotronic actually consisted of parts and equipment to add the system 'physically' to the standard car.

With EPS, any implementation of variable-assist (call it want you like) WILL ONLY be a software programming issue.

So if they are selling EPS with Servotronic as an option, it is £175 for 'enabling' the function in the software.

rip off.

more than just a rip off in £notes - rip off for the ultimate driving machine

[doughboy]

Originally Posted by TMP

more than just a rip off in £notes - rip off for the ultimate driving machine

Exactly, to have an EPS system without some sort of software variation seems ridiculous IMO.

I can appreciate charging extra when you are getting extra hardware - but not for software which should form part of the basic system anyway.

[DickieP]

The steering weight for me is perfect, especially after a year in a Audi A5. It's not at all light but might be because of the M sport tyres/suspension set up. i have one of the very first Lci models so i have had plenty of time (and 23k miles) to get used to it's set up, don't be put off it's so much better than Audi with it's awful tram lining issue.

[johnsonz1122]

does the servotronic makes the alignment harder? cuz i plan to install kw v1,and the suspension shop will charge me 300 bucks more if my car hv active steering for alignment. since my car only hv servotronic but no active steering will them charge me more ?