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I supported Toymods
Location:
Perth, Western Australia
Registered:
December 2002
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Torque Splits on AWD Cars
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Mon, 03 November 2003 06:18
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When distributing power to four wheels at different percentages (ie 40% front, 60% rear), how do they stop the rears from pushing against the front, as they have more power directed to them and will work more effectively, and would this put a stress through the diff assemblies? When considering a AWD setup for a custom car, what factors need to be addressed in terms of torque splitting?
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Location:
Colac, Victoria
Registered:
May 2002
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Re: Torque Splits on AWD Cars
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Mon, 03 November 2003 06:53
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As far as i know - its all computer controlled - ie the GTR nissan uses some fancuy pants computer to adjust on the run how much power is delivered to front or rear bias
Ie on accelleration - its 50 50 - then the power rto fronts reduces as speed increases to rear bias ..
On my gt4 - its straight 50 50 - no change
On a AWD corolla tercel thing - i think its the opposite 70 or 80 to the fronts , and a weeny amount to the rear to aid in grip ..
youd probably need to lok at something with a computer controlled bias ..
Sorry i cant be super cluey on it - im only learning this stuff myself
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Torque Splits on AWD Cars
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Mon, 03 November 2003 07:02
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What you'll find is generally the GTR will put at most something like 5% of its torque to the front normally, and as the computers detect slip they shuffle torque forwards.
The Porsche 911 Turbo has a similar ratio and way it does things, but has mechanical diffs to control the torque split as opposed to computers.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Torque Splits on AWD Cars
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Mon, 03 November 2003 07:46
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when ya think about it, during acceleration, you want a rear bias, how much depends on how much power and weight transfer you have. just like braking, where weight transfer dictates you have 70-80% of braking force at the front..
during cornering, you would actually want a left right split.. more on the outside....
would an LSD not do the job?? you can control the torque by the allowed slip... ie 30% slip, 70% slip etc...
LSD might be more compact and reliable than computer control, but not as controllable....
hmmmm... i guess you could calculate it for different conditions... aim for an equal 5-10% tyre slip at each corner... soo what power will accepted for a given weight transfer etc...
Cya, Stewart
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I supported Toymods
Location:
Perth, Western Australia
Registered:
December 2002
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Re: Torque Splits on AWD Cars
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Mon, 03 November 2003 08:16
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Not interested in the computer controlled setups that Nissan use - they would not be a practical retrofit. My interest is more in factory mechanical transfer cases and how different torque splits would affect the car.
To give people more of an idea behind my thinking, imagine taking any AWD transfer case and placing it into a project car, then making it work and be competitive?
On a different note, can the ST185 AWD box and transfer case be made to run different torque splits other than the 50/50 Stuart mentioned? Can it be done mechanically by changing the drive gearing in the transfer case?
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Location:
Melbourne
Registered:
September 2002
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Re: Torque Splits on AWD Cars
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Mon, 03 November 2003 11:32
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Hey Stuart,
Ive actually been put under the impression that the GT4 has 40/60 tourqe distribution under accel and 60/40 under decel.
I got this information from a freind who has his ST185 dyno'ed, im yet to see the proof but the ST185 feels like it has a rear bias so im inclined to belive it.
Clint, I bet if you bought a Toyota repair manual specific to the ST185 gearbox you could find the answer to your question ;p
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I supported Toymods
Location:
Perth, Western Australia
Registered:
December 2002
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Re: Torque Splits on AWD Cars
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Mon, 03 November 2003 14:54
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Excellent, ..., you wanna buy me one?!!! 
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I supported Toymods
Location:
Perth, Western Australia
Registered:
December 2002
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Re: Torque Splits on AWD Cars
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Tue, 28 December 2004 01:46
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OK, dragging this up again for another shot at the title - it's been floating in my head of late.
my broad strokes are:
When utilising a mechanical torque splitting install, is it simply the gear ratios that determine the percentage splits, and if so, how do you stop one end from pushing or pulling from the other less powerful end?
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I supported Toymods
Toymods Club Secretary
Location:
Sydney
Registered:
May 2002
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Re: Torque Splits on AWD Cars
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Tue, 28 December 2004 02:01
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Can't add anything of value here unfortunately Clint, but I'm really interested to hear more about what you're planning on doing!! 
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I supported Toymods
Location:
Perth, Western Australia
Registered:
December 2002
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Re: Torque Splits on AWD Cars
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Tue, 28 December 2004 02:12
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Evil project number 2: revolves around mass power, minimal weight, and maximum fun   
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Club Member
Location:
sydney
Registered:
May 2002
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Re: Torque Splits on AWD Cars
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Tue, 28 December 2004 02:40
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hmm maybe go look at the early subaru type setups, like the Leone im pretty sure they werent ecu controlled, and theres still plenty of them out there. Im thinking that as you mentioned simply applying different gear ratios at the differential makes the split work, but then again.. if its a little project whats the harm in a 50/50 split? unless your specifically chasing under or oversteer as long as you have brakes good enough to induce a slide on all four wheels 50/50 is a great split
hmm imagine.... KE70 3sge with GT4 running gear.... oh wait its allready been done but in a sportivo... man why dont you contact Neil Bates Im sure if you asked the righ questions hed give you vague enough answers to get the project up and running, hes actually not to bad at sharing his knowledge if you ask the right way
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Membership Secretary
Location:
Sydney
Registered:
June 2002
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Re: Torque Splits on AWD Cars
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Tue, 28 December 2004 04:14
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Steve the wagonist kows all the gt4 splits
From what he said, I'm not sure if I remebered it right but
the
St165 60 or 70% front
st185 50/50
and st205 is 60 or 70% rear bias
Just check with steve
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