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      11-28-2012, 05:41 PM   #45
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I note this debate has been raging for a while and its been a ping pong from one extreme point of view to the other...

The thing is gentlemen like most things in life it boils down to personal preference, from make, model, colour and options it is down to individual choice/taste.

If a person feels VSS makes the drive that much more beneficial in enriching the drive then so be it..either way at a cost of £250 its not going to break the bank, IMHO even if it is a slight improvement on the standard then its money well spent.

I am sure we could debate about a raft of choices/options which could be classed as gimmicks and a waste of money, but if in some way you feel that it has benefited you in some way then it was money you earned spent well.

The truth of it is we are not making an investment here for a return, its about improving the quality of life before the grim reaper comes a calling..
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      11-29-2012, 02:47 AM   #46
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Without reading all the thread again my question is has anyone said that it makes the steering worse in any way? If not then I see £250 as a reasonable punt, even if it only reduces the amount times I have to turn the wheel in car parks, which from my understanding will be its main advantage.

I am sure there must be other options that are worse value for money, as long as it doesn't spoil the steering in any way that is.
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      11-29-2012, 10:40 AM   #47
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Have to say I am very impressed with VSS and would like it on all future BMs.

The quicker, shorter rack is a joy, and does give a sportier feel when going around the twisties. Oh and it helps in car parks too!
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      11-29-2012, 10:46 AM   #48
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Quote:
Originally Posted by F30FAN View Post
I note this debate has been raging for a while and its been a ping pong from one extreme point of view to the other...

The thing is gentlemen like most things in life it boils down to personal preference, from make, model, colour and options it is down to individual choice/taste.
It certainly is down to user choice and perceptions, even if we debate the technical aspects of it all day long.

MaestroAl and I see it from totally opposite poles. I tend to assess it the same as BMW do, and as directed to similar performance as the variable steering systems fitted to their 'sporty' models like the M-cars, (albeit in hydraulic form), or the F20 M135i as the VSS version of EPS.

What I don't see from the 'loose' data which BMW are putting in the advertising blurb, that it is 100 degrees before there is any change in ratio, they simply state:

Quote:
In the case of smaller steering angles between zero and 100 degrees, the BMW 3 Series displays accurate tracking and high stability on straight stretches while conducting steering movements with impressive precision.
That statement does not definitely state the ratio is constant to 100-degrees. It doesn't even state whether it is 0 - 100 degrees in either direction, or an included angle. Can be read several ways. The typical way a variable ratio rack is geared is as set out in the graph I attach. The graph that we would need to reflect a 0 - 100 degree 'constant' ratio would be very unusual indeed, nothing like the typical form we would see for any variable steering system that is intended to make the car more agile.



I'd love to see the actual form for the variable sport racks that BMW are using, but BMW are not giving too much away, anymore than they do for the variable ratios in the M-cars. Even in their detailed technical data, they just state an overall average ratio. Plus the lock to lock figures.

For the BMW F10 M5 this is all that is stated in BMW data.

Quote:
M rack and pinion power steering gear with variable ratio, standard with Servotronic. The average overall ratio is 13.05:1 for 2.6 steering wheel turns lock-to-lock compared to 17.1:1 and 3.0 with the F10.
I doubt anyone would question the integrity of BMW in offering and fitting the 'M rack' to the M5 or M3, or even the VSS system in the F20 M135i. Saying that it isn't hardly worth having, even suggesting the reduced 'lock to lock' just helps parking.

But each to his own, not everyone sees the value in an M-car either. A lot of money for a car that is 'nearly the same' as the standard models.

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      11-29-2012, 11:05 AM   #49
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Quote:
Originally Posted by TMP View Post
Have to say I am very impressed with VSS and would like it on all future BMs.

The quicker, shorter rack is a joy, and does give a sportier feel when going around the twisties. Oh and it helps in car parks too!
+1
The F30 with VSS is certainly an improvement on the E90 with servotronic.
Together with Sport+ the F30 320D has been transformed!
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      11-29-2012, 11:25 AM   #50
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Quote:
Originally Posted by Carjack View Post
+1
The F30 with VSS is certainly an improvement on the E90 with servotronic.
Together with Sport+ the F30 320D has been transformed!
Interesting....I've got servotronic on my E90 and quite like it. I'll probably opt for VSS when it comes to replacing my car with an F30,
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      11-29-2012, 03:58 PM   #51
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Quote:
Originally Posted by NISFAN View Post
Well to compare we would need to understand the 'normal' rack first. It has a relatively small pinion gear running along a rack. Teeth on both are matched to the same pitch and tooth size. The pinion can rotate more than one revolution in either direction. Typically you can turn the wheel over 2 times lock to lock.

In a system with variable geometry, you can't just change the pitch of the rack teeth either side of centre because the pinion would run out, the gear would not mesh.

Soooo.....a variable system has a large pinion, big enough to cover the full rack movement, and has matched varying pitch. The rack and pinion are made as a matched pair. The differing ratio is machined into both the rack #and the pinion to maintain meshing. This system has to be carefully aligned to start with, etc. so quite technical and orders of magnitude more complex than a straight rack. The important feature is the pinion cannot rotate more than 360 degrees like it does on a normal system.

Coming back to what your salesman advised, as it has a similar ratio in the centre as Maestro explained it won't behave much differently, although the large pinion would require less assistance, so could 'feel' different depending on the electronic assist programming. Also in normal driving you rarely use more than 90 degree steering wheel angle where the tighter ratio kicks in, so you are unlikely to feel this action in normal driving, only low speed manoeuvres. Again as Maestro explained hardly a sporty experience on it's own, but with advanced assistance might feel significantly different to matter.
Thanks for the long explanation, but i still don't see how its £250 of a difference in manufacturing costs. To put it simply a larger pinion is used along with the steering rack, obviously the pitch between the teeth changes as you move along the rack. So the rack and pinion will just be made to different size. with different pitch between the teeth than a standard rack.. I don't know why its such a great engineering feet... after all id expect it and and standard rack to be machined to the same tolerences.. thou. Maybe a little more complex not majorly though. As both would need to be machined properly to run true anyway.
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      11-29-2012, 04:25 PM   #52
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Quote:
Originally Posted by Irnbrukid View Post
Thanks for the long explanation, but i still don't see how its £250 of a difference in manufacturing costs. To put it simply a larger pinion is used along with the steering rack, obviously the pitch between the teeth changes as you move along the rack. So the rack and pinion will just be made to different size. with different pitch between the teeth than a standard rack.. I don't know why its such a great engineering feet... after all id expect it and and standard rack to be machined to the same tolerences.. thou. Maybe a little more complex not majorly though. As both would need to be machined properly to run true anyway.
It will be a more complex engineering exercise as NISFAN has explained, maybe a little extra cost due to production run scale, but we are into added value engineering as well.

When has cost and what folks will pay been on an equal footing with sales? Just look at iPhone, iPad, etc., etc.

It is a bit like the 1300 and 1500 models cars, exact same specification, just a different engine capacity, but higher price point for the larger engine. Paying more for 'bigger holes' inside the engine. OK, that is a simplification, but additional costs are often a fraction of the selling price potential.

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      11-29-2012, 05:03 PM   #53
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Quote:
Originally Posted by HighlandPete View Post
It will be a more complex engineering exercise as NISFAN has explained, maybe a little extra cost due to production run scale, but we are into added value engineering as well.

When has cost and what folks will pay been on an equal footing with sales? Just look at iPhone, iPad, etc., etc.

It is a bit like the 1300 and 1500 models cars, exact same specification, just a different engine capacity, but higher price point for the larger engine. Paying more for 'bigger holes' inside the engine. OK, that is a simplification, but additional costs are often a fraction of the selling price potential.

HighlandPete
I did say it would be a little more complex, but not massively more. The same materials will be used in both racks, just machined to different dimension. Maybe some extra time spent in the design of it, but will just be produced in the same way as normal rack.. just set-up in a jig in cnc and machined.
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      11-29-2012, 05:04 PM   #54
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Quote:
Originally Posted by HighlandPete View Post
When has cost and what folks will pay been on an equal footing with sales?
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      11-30-2012, 12:42 PM   #55
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Is it just me or do you long for the old days when they set up a car from the factory that steered and handled well. Adjustable this, variable that, eco bore here, sport plus for the marketing execs to get to sales meets quicker.

Yawn bored. I want to drive the fucking car not play with buttons. The only reason we have electric power steering is for economy. It's not as good as hydraulic (try a new 911 even they can't get it right).

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