Variable F/R torque split (to 50/50) idea

Lets talk clutches and everything drivetrain related

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Tue Nov 26, 2013 4:12 am

mx6er2587 wrote:The selling point for the Haldex system was always its compact size and ease of use. It made it very easy for manufactures to convert FWD into AWD platforms.
Look at the vehicles that employ this system, they are either not high performance cars, or they are factory hotrod variants of FWD vehicles.


The Haldex units are just a electronically controlled clutch packs. How you use them and how they are controlled makes the difference.
If its not working as well as you would like on your Volvo, its because Volvo set it up that way.

The Haldex clutch pack systems are used in VW/Audi and other high-end sport & super cars (Lamborghini's and the Veyron too).
Members don't see the above ad. Register now - it's free!
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Tue Nov 26, 2013 5:36 am

This is a great simple diagram of what i would achieve by making the mods:

Image
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby mx6er2587 » Tue Nov 26, 2013 12:58 pm

Check the list of vehicles that use Haldex. I"ll highlight a few for you:

VW Golf R
Audi S3
Ford Taurus
Saab 9-3 XWD
Volvo S60R
Mazdaspeed 6

Notice the pattern? Hot AWD versions of FWD cars.

The only two true performance vehicles are mid engine rwd drive cars using the system for a little front wheel traction. Do some digging around forums of haldex equipped vehicles. You'll change your mind pretty quick.

And yes I understand how the system works. but thanks anyway for the diagram.
mx6er2587
Established Member
 
Posts: 1163
Joined: Sun Jan 27, 2008 12:08 am
Location: Pittsburgh PA

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Tue Nov 26, 2013 1:25 pm

Actually, it funny you say "Hot AWD versions of FWD cars", because thats what a Celica AllTrac/GT4 is :P

So you are telling me all the Audi RSx cars aren't very good? They are all front engined 4WD haldex systems.
I would happily forget everything to do with Toyotas & Celicas (all ive ever owned) to have a Audi RS4.

Audi TT RS? I dont believe there is a FWD version of that.

Nissan GTR uses electronic clutches to move power around, as does the Mitsu EvoX and Subrau WRX STIs with DCCD.

WRC Corollas (based on ST205 drivetrain) had front & center electronically controlled clutch diffs.

Again, its not the clutches themselves that make the difference, its how they are used.
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby donk2k » Tue Nov 26, 2013 3:48 pm

I normally dont post here, but now I had to.
MWP have a look at our drivetrain and the last picture of the haldex.
The haldex system drives the driveshaft to rhe rear haldexdiff stright out of the gearbox. Here we have a open diff with a viscouse lsd added.
What will happen when you add a haldex unit in the rear is this:
When haldex is locked it will be just like the haldex was not there. A solid transfer of power between the front and rear end of the propeller shaft. Just like on our stock drivetrain.
When haldex is not engaged it will be as if you cut the propellershaft in two or just took it of the car. This would result in a overworked viscouse lsd and not much power to the front wheels. Remember our open centerdiff wich the haldex systems dont have.

If it was to work you would have to "weld/lock" the center diff somehow.

Sorry about my bad spelling.
donk2k
Newbie
 
Posts: 7
Joined: Wed May 19, 2010 2:19 pm

Re: Variable F/R torque split (to 50/50) idea

Postby underscore » Tue Nov 26, 2013 4:45 pm

MWP wrote:Actually, it funny you say "Hot AWD versions of FWD cars", because thats what a Celica AllTrac/GT4 is :P

So you are telling me all the Audi RSx cars aren't very good? They are all front engined 4WD haldex systems.
I would happily forget everything to do with Toyotas & Celicas (all ive ever owned) to have a Audi RS4.

Audi TT RS? I dont believe there is a FWD version of that.


The vehicles you're listing are worth vastly more than most Alltracs, whereas the ones mx6er2587 is listing are more at the "average" consumer end of things (ie the ones you'd be pulling hardware from). Don't tell me you plan on buying an AWD system from a Lambo and adapting it to your car because that's ludicrous (and you've got to remember that anything setup MA or RA is the opposite of our car). Just because a Haldex can be good doesn't mean they are all good.

MWP wrote:Nissan GTR uses electronic clutches to move power around, as does the Mitsu EvoX and Subrau WRX STIs with DCCD.

WRC Corollas (based on ST205 drivetrain) had front & center electronically controlled clutch diffs.

Again, its not the clutches themselves that make the difference, its how they are used.


Correct me if I'm wrong but I believe these aren't running the same style of open front diff as we are, so tossing on half of their system isn't going to make ours work the same way.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
underscore
GTFour God
 
Posts: 3821
Images: 0
Joined: Mon Apr 09, 2007 11:29 pm
Location: Kelowna, BC

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Wed Nov 27, 2013 1:03 am

donk2k wrote:If it was to work you would have to "weld/lock" the center diff somehow.


Yeah, I mentioned that in my original post :)
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Wed Nov 27, 2013 1:11 am

underscore wrote:The vehicles you're listing are worth vastly more than most Alltracs, whereas the ones mx6er2587 is listing are more at the "average" consumer end of things (ie the ones you'd be pulling hardware from). Don't tell me you plan on buying an AWD system from a Lambo and adapting it to your car because that's ludicrous (and you've got to remember that anything setup MA or RA is the opposite of our car). Just because a Haldex can be good doesn't mean they are all good.


Yup, thats very true.
I was just trying to prove that all Haldex coupling equipped cars are not "bad", and its not the fault of the Haldex coupling units, but how they are implemented.

They are really quite simple devices.
They simply control how much of the power on the input shaft appears on the output shaft in response to an electronic signal.
How you use the coupling units in/around the gearbox and diffs is what is important.

Of course using one in a GT4 would be a very very simple implementation, controlling only how much power is sent from the front to the rear with a max of 50:50 split.
I believe it'll still have quite large advantages over the viscous center.
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Wed Nov 27, 2013 1:18 am

This is an example control map for a WRX's DCCD center electric diff.
Similar power split maps couple be implemented if the GT4's viscous center was replaced with a haldex (or similar ) electronic clutch:

Image

Another advantage would be handbrake (e-brake) detachment.
No more loading up a front wheel when applying the handbrake to initiate a slide :)
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby st185-sainz » Wed Dec 18, 2013 7:03 am

Hey guys,

I only had a quick overview on your posts and just wanted to clarify a statement of using an EVO gearbox or centre diff - EVO 5 for example has the same visco rating than my uprated unit!
The guy who did my Celica Visco does also rebuild all our EVO units for rallying...

mario
Mario,
ST205 blue: completely stock
ST185CS (white): white - gravel/snow spec, dog box, TRD clutch, uprated turbo, lightened flywheel, uprated actuator, cold air intake, ST182 cams, walbro pump, batt relocation, forgies, programmable ECU (dyno), ...
User avatar
st185-sainz
Club Member
 
Posts: 191
Joined: Sun Aug 08, 2004 2:28 pm
Location: Austria

Re: Variable F/R torque split (to 50/50) idea

Postby athousandleaves » Fri Dec 20, 2013 2:36 am

Just from glossing over the OP's original idea it sounds much like the V-Flex AWD system installed in the ST215G/matrix/voltz but electronically controllable.

http://toyota-club.net/files/faq/04-01- ... 15-eng.htm

Might be worth working with those parts before you step into the world of Audi...

-edit-

Also the SV25 Camry with automatic transmission featured a clutch type center diff instead of the viscous coupler... Perhaps this unit could be modified to offer a different split to the front or rear and be electro-hydraulically controlled as well.
1992 Red GT-FOUR RC 626•1800
Image
1992 White turbo4WD
User avatar
athousandleaves
Established Member
 
Posts: 1288
Images: 0
Joined: Wed Nov 19, 2008 12:54 pm
Location: Ontario, Canada

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Fri Dec 20, 2013 3:25 am

athousandleaves wrote:Just from glossing over the OP's original idea it sounds much like the V-Flex AWD system installed in the ST215G/matrix/voltz but electronically controllable.
http://toyota-club.net/files/faq/04-01- ... 15-eng.htm
Might be worth working with those parts before you step into the world of Audi...


Interesting... i wasnt aware of the G version.
As that page says though, its a worse system than the viscous center diff we have at the moment.
Nothing from that system could be reused to do what im after.
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby athousandleaves » Fri Dec 20, 2013 5:15 am

I'm fairly sure that with the automatic Camry that the 4WD button once pressed allows the car to apportion up to 50% to the rear end when it senses a difference in wheel speed.

Its not a full 50% or nothing situation because its a clutch based unit responsible for the transfer and by engaging the 4WD it allows the car to increase/decrease the pressure on the plates until it senses that front and rear wheel speed are the same however due to how the center differential is designed I think that you only ever see about 50% power at the front even with the 4WD disengaged.

So I believe that its F50:R0-50, not exactly the F100:R0/variable ratio that you were looking at with the Audi parts. Could make for a pretty aggressive drag setup maybe?

If you wanted a different ratio like F30:R70 with the Camry parts you would have to change the center differential gearing to bias it to the rear.
Last edited by athousandleaves on Fri Dec 20, 2013 5:21 am, edited 1 time in total.
1992 Red GT-FOUR RC 626•1800
Image
1992 White turbo4WD
User avatar
athousandleaves
Established Member
 
Posts: 1288
Images: 0
Joined: Wed Nov 19, 2008 12:54 pm
Location: Ontario, Canada

Re: Variable F/R torque split (to 50/50) idea

Postby MWP » Fri Dec 20, 2013 5:20 am

athousandleaves wrote:I'm fairly sure that with the automatic Camry that the 4WD button once pressed allows the car to apportion up to 50% to the rear end when it senses a difference in wheel speed.

Its not a full 50% or nothing situation because its a clutch based unit responsible for the transfer and by engaging the 4WD it allows the car to increase/decrease the pressure on the plates until it senses that front and rear wheel speed are the same however due to how the center differential is designed I think that you only ever see about 50% power at the front even with the 4WD disengaged.

So I believe that its F50:R0-50, not exactly the F100:R0/variable ratio that you were looking at with the Audi parts. Could make for a pretty aggressive drag setup maybe?


I think you are getting yourself confused here.
You cant have 50% of power sent to the front, and none sent to the rear. If thats the case, where does the remaining 50% go? ;)

Front % split + Rear % split always = 100%.
My collection of GT4 documentation: http://gt4.mwp.id.au
Daily: Celica GT4 ST185 (~170kw/atw)
Project: Toyota RA28 '77 Celica (1UZ-FE powered)
Chairman of the SA Classic Celica Club.
MWP
Established Member
 
Posts: 1599
Joined: Mon Jun 01, 2009 11:02 am
Location: Adelaide, South Australia

Re: Variable F/R torque split (to 50/50) idea

Postby athousandleaves » Fri Dec 20, 2013 5:23 am

The other 50% is sent into the transfer case and the parts just spin aimlessly. They specifically tell you in the manual to never drive with the 4WD button disengaged unless its being towed.

Edited my last post after you saw it too...

The car was no faster accelerating with the button off or on...
1992 Red GT-FOUR RC 626•1800
Image
1992 White turbo4WD
User avatar
athousandleaves
Established Member
 
Posts: 1288
Images: 0
Joined: Wed Nov 19, 2008 12:54 pm
Location: Ontario, Canada

PreviousNext

Return to Drivetrain Central

Who is online

Users browsing this forum: No registered users and 2 guests