Skip to main content
news

Re: Ideological differences...

-hh
Google Google
SubjectRe: Ideological differences between big 3 german, americans and jap trash
From-hh
Date2014-02-24 15:09 (2014-02-24 06:09)
Message-ID<221d8b38-683c-43ff-b55f-d5413fef45c2@googlegroups.com>
Client
Newsgroupscomp.sys.mac.advocacy
FollowsNashton
Nashton wrote:

Nashton
Brake Dive, Acceleration Squat, Body Roll Works LLC wrote:

Brake Dive, Acceleration Squat, Body Roll Works LLC
Well, understeer is mostly obvious at low speeds cause I obviously do uturns in 2nd gear. Torque steer I think is not in issue in something moderately expensive such as fwd versions of A4. The arms are of equal length I think.

Nashton
This comment alone, disqualifies you from any serious discussion about steering dynamics in any type of vehicle.

Well, he is correct that the effect is more noticable when slow, because there's more torque available at the wheels due to transmission gearing.

Torque steer is hardly an issue with AWD/4x4 automobiles, why even mention this?

One needs to understand that torque steer is due to the differences in contact patch sizes (left vs right), on the drive wheels, as this is the source of the asymmetric forces. If any of the drive force is on the front axle, then it can be perceived thorugh feedback sent through the steeering wheel.

What this means is that torque steer can be present not only in AWD, but also in RWD-only vehicles; it simply isn't as large in magnitude due to geometry, and the perception thereof isn't through the steering wheel. Just because it is less obvious doesn't mean that it is gone, however.

In terms of engineering for mitigating FWD-based torque steering, a mainstay of the traditional approach has been "equal length", which is a figurative shortcut: the actual design objective is equality in torsional stiffness, and having identical lengths/diameters is merely one of many acceptable solutions.

Brake Dive, Acceleration Squat, Body Roll Works LLC
Any subton lotus (exige, elise) will blow doors on your Q7 in twisties.

Nashton
And the purpose of this comment is...?

Merely yet another reminder to you that there's far more to performance than merely a straight line 0-60mph time.

Brake Dive, Acceleration Squat, Body Roll Works LLC
Even underpowered bmw i120 would, given the willow glen rate of twistiness of old page mill road. And so will (gasp) claustrophobic miata.

Nashton
?

Handling.

I din't purchase a q7 to compete with subcompact girly cars. I bought it because it suits my purposes...

Which is highly ego-based, not objective requirements. Afterall, its not even rated to be able to haul your alledged "7500lb" trailer.

and for a vehicle of this size, given the outstanding torque output and sweet power band, I will leave every SUV in the dust...

No you won't. For example, the Q7 doesn't beat the Porsche version built on the same exact pan. You'll need to add some more qualifiers if you're not going to lose your Pink Slip.

... and once in dynamic mode (lowered air suspension), will not only outperform every SUV out there in the twisties, but most sedans as well.

Real world testing says otherwise:

"Audi's brand image has made it a success, but X5 drives better and Disco is far more versatile."

"Everything a modern SUV should be; ugly, massive, not very good off-road..."

<http://www.topgear.com/uk/audi/q7/road-test/3.0-tdi> <http://www.topgear.com/uk/audi/q7/verdict>

...and in 172th place with the V12 TDI motor:

<http://fastestlaps.com/tracks/top_gear_track.html>

...which means that with the 3.0L TDI, even lower (393th place):

<http://fastestlaps.com/tracks/autozeitung_test_track.html>

FYI, the latter also has the X5, X3, Q5 and others listed for you to enjoy comparing. And FYI, not yet listed are the SQ5, GLA 45 AMG and Macan, just to name a few more SUVs (qualifier "every SUV", remember?) whose pending test numbers are quite likely to cause the Q7 3.0 TDI to drop even further down on such higherarchical lists.

-hh