[TMP]

Good review...

http://www.evo.co.uk/carreviews/evoc.../bmw_330d.html

But this bit got me wondering....

Originally Posted by Evo

In fact, the only downside is the steering. While the 335i we drove featured mechanical assistance, here it’s electrical (aids CO2 and economy, you understand) and way too light. The manual gearshift is a touch crude compared to the auto, too.

My pre-Lci steering is very well weighted, so is this due to BMW dropping servotronic on the LCI cars (its now an option)?

[NFS]

Originally Posted by TMP

Good review...

http://www.evo.co.uk/carreviews/evoc.../bmw_330d.html

But this bit got me wondering....



My pre-Lci steering is very well weighted, so is this due to BMW dropping servotronic on the LCI cars (its now an option)?

This is the efficient dynamics electric steering, which is standard on everything except 335i and d now. It's not just on LCI models though. I believe it was introduced as long ago as 2008?

Really bad step for a driving oriented manufacturer.

[TMP]

Yeah, i think you are right, but mine is a 2008 ED.

So mine has the ED steering and Servotronic though....

[AlanQS]

It is the absence of servotronic that makes the steering too light. Mine has it and I think it's quite heavy.

Servotronic became an option after March 2009.

[TMP]

Originally Posted by AlanQS

It is the absence of servotronic that makes the steering too light. Mine has it and I think it's quite heavy.

Servotronic became an option after March 2009.

Hmmm., not good then.

Wonder how many peeps are speccing there Lci without realising this should be the first option they tick (for 'just' £170)?

Quick look at AUC shows dealers are not specifying it either

[xenon]

It makes no sense that the electrically-driven power assistance has to be so light, but it is.

[G82Dude]

Originally Posted by AlanQS

Servotronic became an option after March 2009.

Nah, if by servotronic you mean hydraulic, engine driven power steering pump, hydraulic PAS has always been an option; you just have to pay for it now. When I ordered my car for Sep 2008 build, electric PAS was (and is) standard on < 335 vehicles, with hydraulic PAS then a free option, but available. Unless that was coupés only...

[xenon]

Without splitting hairs, the electric system is hydraulic too as far as the assistance is concerned, but just has an electrically-driven hydraulic pump rather than engine-driven one. The idea is that the electric pump can be turned off at the straight-ahead and higher speeds whereas the engine-driven one is powered even when not needed.

The electric one is therefore less parasitic but it doesn't explain why it has to be so light and girly.

[TMP]

Originally Posted by xenon

Without splitting hairs, the electric system is hydraulic too as far as the assistance is concerned, but just has an electrically-driven hydraulic pump rather than engine-driven one. The idea is that the electric pump can be turned off at the straight-ahead and higher speeds whereas the engine-driven one is powered even when not needed.

The electric one is therefore less parasitic but it doesn't explain why it has to be so light and girly.

Yep...

but Servotronic adjusts the resistance/feedback hence my car has a weighted steering which does not feel overassisted at all

[G82Dude]

Originally Posted by xenon

Without splitting hairs, the electric system is hydraulic too...

I don't think you will find that their EPS is hydraulic, or more correctly, electro-hydraulic, where an electric pump takes the direct place of the engine driven one. The electric motor on their EPS system acts directly on the steering system and rack (there is no pump) and therein lies the problem. There's also no hydraulic reservoir to check/top-up anymore too! Minis use an electro-hydraulic system though (which packs up).

Engine driven hydraulic PAS has always been (until now) a no cost option on the 3 series.

According to BMW's website, Servotronic is a feature of EPS applied through the electric motor, rather than the conventional system, which acts upon the entire steering hydraulics through a valve, with a constant high pressure hydraulic pump.

This would probably explain the difference in feel and use.

[xenon]

I see. I was assuming it was the same as the Mini system. Nevertheless, if a simple electric motor delivers assistance, directly or otherwise, it should be very easy to control the amount of asisstance based on the road speed.

[doughboy]

Unfortunately liking weighted steering is a minority thing, If 90% of drivers like light steering thats what we're all gonna get.

Friends / wife all moan my 335 is too heavy (and the old 330i too) whereas I think they are/were sublime.

Another friend has a pre ED 120d and moans it makes his arms hurt driving in town- WTF (he is 6'1")

[SteveC]

Actually it doesn't

The main problem with over assisted, too light steering in that its too easy to move the wheel, so the car feels unstable, with the front end wandering around the road, especially at high speeds. And there's no feedback

Historically, performance car designers addressed this problem by varying the rate of assistance, backing it off at high speeds, where it is less necessary than for parking, so the car has lots of assistance at low speeds and gradually less as speed increases, where assistance is unneccessary

Using an electric moror instead of a permanently engaged hydraulic pump, you can tailor assistance to whatever you want. In the case of BMW, assistance is completely inactive when the car is driven straight ahead, so feels planted, quite the opposite of how an over assisted car would feel.
Similarly,for high speeds bends, little or no assistance is applied, again translating to a planted feel in corners and increased levels of feedback.

For low or no speed manoeuvres, where you're having to overcome the full friction of the tyre/road to move the wheel, maximum torque is applied, making parking very easy, However the light steering at parking speeds is not translated to light steering when driven. I have owned and driven many BMWs over the years and I can assure you that the LCI steering does not feel anything other than typical BMW

[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

[xenon]

Agreed. ^^

[creepy coupe]

I'm sure my 320d E92 with effiicient dynamics had the electric version, which was lighter than the 335i.

[xenon]

It did and it was.

[AlanQS]

At least with regard to coupes, since they came out, all but the 335i/d had electric PAS with servotronic and you couldn't specify the hydraulic version in non 335 models. Servotronic was then removed from the electric models in March 09 and made an option - the bampots!

[TMP]

Originally Posted by SteveC

I have owned and driven many BMWs over the years and I can assure you that the LCI steering does not feel anything other than typical BMW

So does yours have servotronic?

[G82Dude]

Originally Posted by AlanQS

At least with regard to coupes, since they came out, all but the 335i/d had electric PAS with servotronic and you couldn't specify the hydraulic version in non 335 models. Servotronic was then removed from the electric models in March 09 and made an option - the bampots!

Yup, you could specify hydraulic PAS on < 335! Certainly could when I ordered my 330 in August 2008 (and it was a free option)! BMW have changed how they describe it now though. When I ordered mine, the option was called "hydraulic PAS"; it's now "Servotronic". But, EPS has variable assistance, like Servotronic, although not strictly "Servotronic", as this is a trademark of Audi I think, and relates to hydraulically powered systems.

Maybe they don't know what they are selling either now (or what to call it). I can't believe they have removed the "Servotronic" element from their EPS. I think the option still is simply hydraulic in lieu of electric.

[TMP]

Originally Posted by uke92dude

Yup, you could specify hydraulic PAS on < 335! Certainly could when I ordered my 330 in August 2008 (and it was a free option)! BMW have changed how they describe it now though. When I ordered mine, the option was called "hydraulic PAS"; it's now "Servotronic". But, EPS has variable assistance, like Servotronic, although not strictly "Servotronic", as this is a trademark of Audi I think, and relates to hydraulically powered systems.

Maybe they don't know what they are selling either now (or what to call it). I can't believe they have removed the "Servotronic" element from their EPS. I think the option still is simply hydraulic in lieu of electric.

So BMW definition of Servotronic i.e its ontop of EPS

Servotronic.

Effortless agility when parking, light-footed responsiveness and stability at higher speeds: Servotronic adjusts the amount of steering assistance to suit the current speed, enhancing driver comfort by lowering the effort needed to turn the steering wheel.

The Servotronic control unit adjusts the amount of steering assistance to suit the speed of the vehicle. An electromagnetic valve accurately controls the amount of force applied by the steering hydraulics, enabling outstandingly precise steering that suits your current driving situation. Conventional power steering systems, by contrast, regulate the power steering in relation to the engine's RPM. The electromechanical steering system EPS uses an electric motor to achieve the same effect.
Thanks to Servotronic, driving along narrow streets or parking becomes easier as it requires minimum effort to turn the steering wheel. The power assist progressively decreases when the vehicle speeds up, ensuring greater stability, improved precision and smoother vehicle behaviour.

If you do a build comparison between say a 330i and 335i you get this...'Electric Power Steering (EPS)' & 'Power assisted steering, hydraulic' respectively

Only the 330i has the option to add Servotronic, as the hyrdraulic system doesnt need it

[G82Dude]

Originally Posted by TMP

So BMW definition of Servotronic i.e its ontop of EPS

Servotronic.

Effortless agility when parking, light-footed responsiveness and stability at higher speeds: Servotronic adjusts the amount of steering assistance to suit the current speed, enhancing driver comfort by lowering the effort needed to turn the steering wheel.

The Servotronic control unit adjusts the amount of steering assistance to suit the speed of the vehicle. An electromagnetic valve accurately controls the amount of force applied by the steering hydraulics, enabling outstandingly precise steering that suits your current driving situation. Conventional power steering systems, by contrast, regulate the power steering in relation to the engine's RPM. The electromechanical steering system EPS uses an electric motor to achieve the same effect.
Thanks to Servotronic, driving along narrow streets or parking becomes easier as it requires minimum effort to turn the steering wheel. The power assist progressively decreases when the vehicle speeds up, ensuring greater stability, improved precision and smoother vehicle behaviour.

If you do a build comparison between say a 330i and 335i you get this...'Electric Power Steering (EPS)' & 'Power assisted steering, hydraulic' respectively

Only the 330i has the option to add Servotronic, as the hyrdraulic system doesnt need it

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...!

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