[torsen] RE: 15mph diff lock off - torsen content
QSHIPQ at aol.com
QSHIPQ at aol.com
Sat Feb 10 12:56:02 EST 2001
In a message dated 2/9/01 2:54:46 PM Central Standard Time,
Dave.Eaton at clear.net.nz writes:
> scott, the original post was asking about the effect of maintaining the
> rear diff lock on a torsen car above the cut-off speed. the audi paper
> addresses this.
> ego to one side, this is a safety issue - not a (torsen) pissing contest.
Not at all meant to be, I just think you presented a problem that isn't
relevent to the reason folks want to cut the BL/WHT wire, nor really is the
concept a differential locking problem. Think of all the Gen 1 lockers that
*haven't* gone flying off out of control while braking, makes you think that
the test needs some scrutiny, and your warning somewhat more limited in scope
than you presented.
> if you want to tell people that it's ok to lock the rear diff under the
> conditions where, according to audi's engineers: "the driver is forced to
> correct the steering quickly and accurately. during the first second, the
> rate of increase of the steering angle exceeds the limit of
> controllability", then i would assume that you are not giving this advice
> "professionally"? if so, then i hope that you have liability insurance.
> you're not, then i will categorise this in the usual file...
Dave, please correct your *claim* here to only address *1* scenario wrt
steering input and angles. The results in fig 12 are for split u conditions
of exactly of .25 left side, .8 right side (.9 considered dry pavement, .1
solid ice). It would have been nice to see a few more results, like what is
the highest split u contrast that can be handled in fig 12. Right now, I can
share that anyone wanting to do this diff lock mod for the conditions at
Steamboat (~.1-.3) are going to find better results with rear diff locked.
HOW do I know that? Well after 7 years of watching cars come down the
straightaway at over 80mph and braking in the mixed u at the end of the
straight, I haven't seen anyone spin or lose steering input for the 90
right/left (CW/CCW respectively) with diffs unlocked or locked (I discounted
those that just went straight, a different cf problem;).
The danger of high split u exists in any car without abs engaged, and even
engaged on a 3channel abs car. Using that as a all inclusive warning call
indicates to me, that you could benefit highly from a steamboat experience.
All that said, you have laid a blanket out there that really may not apply to
many, reading this quote on page 39: "The extent to which this condition can
be controlled will of coruse depend a great deal on vehicle parameters such
as the wheelbase, track, and the height of the center of gravity, etc." So,
1 split u, 1 chassis, 1 set of results
Dave, a better report would be for you to do some of your own testing and put
forth some conclusions as to your experience in split u conditions, to help
determine what is significant to either your RS2 or your Urq. All it would
require for you to do is put a switch on the Bl/WHT wire on each car and go
test. You might find your results surprising.
Right now everyone that's been to Steamboat is smiling at this "warning" vs a
whole bunch of btdt.
Thanks for your posts.
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