I don't like electric assist stearing.

In article >,
Fred W > wrote:
> > BMW of course stuck with steering boxes on their larger cars long
> > after the rest of the world went to R&P. Something to do with our US
> > cousins not liking too positive steering on this sort of vehicle,
> > IIRC.
> >

> More like; They wanted to jam a big V8 lump in the engine compartment
> and couldn't manage to fit a steering rack in there too. A RB steering
> box is tiny by comparison and the tie rods, arms and links can be made
> to go all over the place to clear the engine.

All over the place describes the steering response, too.

Strangely I've got another make not dissimilar in size to a 5 Series which
was also available with 4, 6 and eight cylinder engines. Diesel too. But
with R&P steering and designed in the '70s. I'm not quite sure what there
is about a small V-8 that would make fitting R&P steering any more
difficult than with a six.

--
*Some people are alive only because it's illegal to kill them *

Dave Plowman London SW
To e-mail, change noise into sound.

On Mar 18, 11:16 pm, Fred W > wrote:
> JRE wrote:
> > grinder wrote:
>
> >> Next time you have dinner with Steve ask him to clear up his web site
> >> which states:
> >> "adds larger and adjustable front and rear anti-roll bars to reduce
> >> body roll for superior handling. The adjustable anti-roll bars provide
> >> the ability to fine-tune the system for closer to neutral balance
> >> reducing understeer. "
>
> >> You may also ask him to tell his engineers not to suggest roll bars to
> >> help reduce understeer.
>
> > Dinan's website is doubtless correct. It's your interpretation that's
> > wrong. Relatively stiffer front bars will increase understeer.
> > Relatively less stiff front bars will decrease it.
>
> > Since nothing comes for free, decreasing the stiffness of the front bar
> > by itself will also increase body roll.
>
> > JRE
>
> Exactly. So the premium option (after first ditching the bling-bling
> staggered tire setup) is to increase the rear stabilizer bar. That way
> you can dcrease understeer *and* reduce body roll at the same time!!
>
>

Albeit on a non-BMW, I added a larger front anti-roll bar and it
reduced the understeer. The body roll had been causing the front
end's geometry to become less than optimum and the new bar kept more
tyre in contact with the road. Whether that would work with the Z4 I
dunno but the "bigger fronts always cause more understeer" folk should
probably add an "in general" in there somewhere.

If I were the OP I'd be putting on some Eibachs and new dampers. BMW
suspension isn't always great from the factory for ride or handling.
I did that on my E36 and coupled with decent tyres would out corner
pretty much anything out there including my M3 and certainly any Mini.

Fred W wrote:
> JRE wrote:
>
>> grinder wrote:
>> <snip>
>>
>>> According to Dinan engineering:
>>>
>>> "adds larger and adjustable front and rear anti-roll bars to reduce
>>> body roll for superior handling. The adjustable anti-roll bars
>>> provide the ability to fine-tune the system for closer to neutral
>>> balance reducing understeer. "
>>>
>>
>> Yes. Stiffer front *and* rear bars will increase lateral transfer and
>> reduce body roll. The adjustability can be used to change the balance
>> of the car by making the front bar *relatively* less stiff than the
>> rear one to decrease understeer.
>>
>> JRE
>
>
> I do not think that last statement is correct. An adjustable bar allows
> you to tweak the tension from side to side on the same axle. It does
> not allow you to change the tension from front to rear because a) the
> bars are not tied together and b) nor are they fixed in position like a
> torsion bar (spring). The sway bar pivots in its bushings if the 2
> wheels on that axle travel up and down together. It only applies cross
> force when one wheel moves up or down compared to the other wheel on
> that axle.
>

Think about the end effect. If you reduce the roll stiffness at the
front through either replacement or adjustment of the front bar, you
will decrease understeer. If you increase the roll stiffness at the
rear you will also decrease understeer. But if you increase or decrease
them both in proportion it will not change the balance of the car. It's
the proportioning between the front and rear roll stiffness you're
trying to manage, right? So if one installs stiffer bars front and rear
and wants to decrease understeer, one must stiffen the rear one more
than the front one...in other words the front has to be relatively
softer than the rear at the end of the change.


JRE

"Fred W" > wrote in message
. ..
> grinder wrote:
>> "Fred W" > wrote in message
>> news >>
>>>grinder wrote:
>>>
>>>
>>>>Actually my first step will be to change tires away from run flats. The
>>>>softer sidewall will provide better traction. The second choice will be
>>>>to put a STIFFER roll bar (25mm) on the front AND a softer (22mm) on the
>>>>rear.
>>>>
>>>>http://www.dinancars.com/Series.asp?...%20Tuning#1665
>>>
>>>If you do, it will increase the understeer.
>>>
>>>--
>>>-Fred W
>>
>>
>> Not if selected and adjusted correctly.
>
> No, I'm sorry you are just wrong. Regardless of how you "select" them, if
> you increase the stiffness of the front sway bar you will increase the
> amount of understeer. If you decrease the stiffness of the rear sway bar
> you will increase the understeer. If you do both you will *really*
> increase the understeer.
>
> You have it exactly backwards to what you want to do. For what you want
> (decrease understeer or introduce oversteer) you need to stiffen the rear
> and/or soften the front.
>
> --
> -Fred W

Whatever. I will turn it over to the engineers/technicians and tell them
what I want to do.

"Fred W" > wrote in message
. ..
> grinder wrote:
>>
>>
>> Now for the last time let's say this together "it's a matter of degree!"
>> The difference between the balance of my Mini S and my Z4 allows me to
>> corner better in the Mini.
>>
>>
>>
>
> You are comparing tangerines and kumquats. The mini is a super-light
> front wheel drive car. It is a veritable go-cart compared to the Z4. The
> Z4 will NEVER handle like a mini.
>
> --
> -Fred W

Never said it would but I bet the suspension could be tuned to approach the
handling of the stock Mini. I merely pointed out the Mini's suspension is
more to the neutral side of balance than the Z4 and as a result will handle
better than the Z.

"Fred W" > wrote in message
. ..
> grinder wrote:
>>
>>
>> I don't intend on using them INCORRECTLY.
>
> Um, yes, actually you do intend to use them incorrectly. Exactly
> incorrectly to be precise.
>
> --
> -Fred W

Evidently I incorrectly assumed a larger roll bar would be stiffer than a
smaller one.

"Fred W" > wrote in message
. ..
>
> You are comparing tangerines and kumquats. The mini is a super-light
> front wheel drive car. It is a veritable go-cart compared to the Z4. The
> Z4 will NEVER handle like a mini.
>

When I still had the runflats on my Z4, I kept up with three well-driven
Minis down the Tail of the Dragon (US 129 in western NC). While it gave me
new respect for what can be done with FWD, I had no complaints about the
Z4's steering, handling or the 050 tires. However, my wife requested that I
do it solo the next time!

Tom K.

In article nk.net>,
grinder > wrote:
> Whatever. I will turn it over to the engineers/technicians and tell
> them what I want to do.

You'd be best to tell them what you *want* rather than what to do
otherwise you'll end up with even more understeer and a ride like a truck.

--
*I wonder how much deeper the ocean would be without sponges*

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" > wrote in message
...
> In article nk.net>,
> grinder > wrote:
>> Whatever. I will turn it over to the engineers/technicians and tell
>> them what I want to do.
>
> You'd be best to tell them what you *want* rather than what to do
> otherwise you'll end up with even more understeer and a ride like a truck.
>
>

Not to worry. I will tell them "I know Dave!!!!" and my problems will be
solved (or they will be bored to death). ;>)

On Mar 16, 12:39 pm, "grinder" > wrote:

> Next time you have dinner with Steve ask him to clear up his web site which
> states:
> "adds larger and adjustable front and rear anti-roll bars to reduce body
> roll for superior handling. The adjustable anti-roll bars provide the
> ability to fine-tune the system for closer to neutral balance reducing
> understeer. "

ADJUSTABLE antiroll bars. Not all bars *are* adjustable. In fact,
most AREN'T. You simply stated that you were putting on a much larger
one in front and a somewhat larger one in the rear. The net effect of
doing this with NONADJUSTABLE bars is to enhance understeer. You MAY
be able to adjust the relative balance of this with adjustable bars -
and that's what Dinan is selling. Are you comfortable with crawling
under your car to make those adjustments while testing or are you
going to have to haul it back to a tech to do it every time?

You still haven't presented the engineers with that list, have you?
Why not? Afraid to discover we aren't all idiots here?

> You may also ask him to tell his engineers not to suggest roll bars to help
> reduce understeer.

In the right circumstances, the right bars can help. But simply
slapping on a set without the slightest clue of how they work or what
effect they will have is a foolish waste of money. You will
ultimately end up with an ill-handling pig and a lot lighter wallet.
If you're going to buy Dinan's stuff, you'd better plan on buying ALL
OF IT. You aren't yet educated enough to get a satisfactory result
doing it piecemeal. You would do well to avail yourself of your local
BMW CCA chapter's experts to fill in your knowledge gaps.
--
C.R. Krieger