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AWD gearbox into a true 4WD?
Posted: Tue Oct 13, 2009 8:59 pm
by twilightprotege
does this
convert an awd gearbox into fwd, rwd and 4wd?
found it here:
http://www.possumbourne.co.nz/trans_diff_parts.html
has anyone used it or know more about it??? (although it says 6MT i'm sure i've seen it for 5MT too) ... or ... i've seen guys just installing a switch for the electronically controlled centre diff in the later gearboxes - is that just the easier way to go???
Posted: Tue Oct 13, 2009 10:18 pm
by daza
twilightprotege wrote:does this
convert an awd gearbox into fwd, rwd and 4wd?
No,
It converts an awd gearbox into fwd, rwd
OR 4wd.
It's not selectable, you install the part for which configuration you want.
twilightprotege wrote:
or ... i've seen guys just installing a switch for the electronically controlled centre diff in the later gearboxes - is that just the easier way to go???
I don't think anyones actually tried putting a DCCD center in a dual range box yet, be cool if it worked though.
Daza.
Posted: Tue Oct 13, 2009 11:42 pm
by Kappage
If it was selectable id be all over this like white on rice!
Posted: Wed Oct 14, 2009 7:04 am
by Jeff
Daza i have looked into DCCD into a dual range box and the problem is you can't use your DCCD while you have a wheel in the air so it would be useless for offroading
Posted: Wed Oct 14, 2009 8:12 am
by vincentvega
Jeff wrote:Daza i have looked into DCCD into a dual range box and the problem is you can't use your DCCD while you have a wheel in the air so it would be useless for offroading
what makes you think that?
thats like saying you can't use a VTD auto while a wheel is in the air? Mine does this regularly, and well
Posted: Wed Oct 14, 2009 10:25 am
by Jeff
Just going by the version 3/4 jdm STi owners manual
Posted: Wed Oct 14, 2009 10:35 am
by Outback bloke
What does it say?
Posted: Wed Oct 14, 2009 3:37 pm
by __JC__
Translated from JDM instructions - check out the warnings toward the end.
"DO NOT use the DCCD while any of the wheels are in mid air"
DRIVER'S CONTROL CENTER DIFF
The intent of this mechanism is to adjust the diff lock ratio of the LSD (limited slip differential) as necessary.
Adjusting the dial to "diff free" (indicator: green, empty square, empty triangle) under normal driving conditions, and "diff lock" (bright orange solid triangle) on gravel, snow, in the rain, is effective (probably means suggested). By setting the diff lock ratio as necessary, depending on the various roads and running conditions, unrivaled driving mobility will be demonstrated.
WARNING!
This is not an all purpose vehicle. DO NOT overestimate its abilities. Please use appropriate discretion and drive at safe speeds where there are sudden braking, sudden turns, sudden curbs, snowy roads, slippery roads, etc.
USING THE CONTROL DIAL
The dial is located next to the handbrake lever, rotating it fully forward is diff free, rotating it fully backward is diff lock. You can continuously change the diff lock ratio using the settings in between.
DIFF FREE: No front and rear LSD (Front to rear power distribution=36:64)
DIFF LOCK: The front and rear have an almost direct connection. (Front to rear power distribution=front/rear load distribution)
INDICATOR (ON THE METER DISPLAY)
The diff lock ratio is displayed at one of six settings, as it is linked to the control dial. The upper lighted block (orange solid triangle) indicates a greater direct connection.
The true lock ratio can be continuously changed.
ADVICE
• The indicator is the criterion.
• Regardless of what the dial settings are, LOCK will illuminate for one second after the key is turned to the on position.
• At night, while your driving lights are on, the display may appear to go dark for a moment, but this is normal.
CANCELLATION OF DIFFLOCK
Even if the DCCD is set to LOCK (orange), by pulling the hand brake lever, it will automatically go to DIFF FREE, moving all power to the rear wheels. (linked to the brake warning light) However, the indicator will not change.
Once you release the hand brake lever, the DCCD will return to its proper setting.
TIGHT CORNER BRAKING PHENOMENON (makes more sense once you read the following)
When the indicator is orange while driving on dry tarmac/asphalt, corners, and even reverse parking, due to the rotational difference between the front and rear wheels, there are cases where heavy vibration and noise may occur during braking.
Though this is not out of the ordinary, and to resolve this "problem", you can simply either set the DCCD to DIFF FREE or pull the hand brake enough so that the brake warning light illuminates.
While you may feel a light "shock" when using the control dial during quick acceleration and tight cornering, due to the movement of the center diff, this is normal.
WARNING!
• DO NOT use the DCCD while any of the wheels are in mid air.
• Set the DCCD to DIFF FREE while the car is stopped.
• Set the DCCD to DIFF FREE while the car is being pulled or towed. The car can only be towed/pulled either by rope or on a rollback. DO NOT pull or tow the car on only its front or rear wheels.
• ALWAYS set the DCCD to DIFF FREE when using the emergency spare tire. Change or fix the tire as soon as possible.
• When the center diff requires repair (control unit, disconnected wires, shorted wires, voltage issues, etc.) the DCCD reverts back to DIFF FREE and the indicator (at which you last had it set) should flash at 1 second intervals. Please go to your nearest Subaru dealer immediately. Once a problem arises, even if the unit regains power, it will not reset itself until the engine key is set to the off position.
Posted: Wed Oct 14, 2009 5:44 pm
by Outback bloke
So I wonder what the rally boys did then. They are forever getting wheels off the ground.
Posted: Wed Oct 14, 2009 6:06 pm
by Gannon
I think it means not to jack up one end of the car and try to drive, much the same for any LSD. As the car may lurch foward
Posted: Wed Oct 14, 2009 7:31 pm
by Jeff
Thanks Jake that is exactly what i was referring to
Posted: Wed Oct 14, 2009 8:12 pm
by twilightprotege
daza wrote:No,
It converts an awd gearbox into fwd, rwd OR 4wd.
It's not selectable, you install the part for which configuration you want.
fairy nuff - i just figured because it said "oil pump drive" that means it can be changed???
Posted: Fri Oct 16, 2009 9:42 am
by spike
ok from a rally forum
i posed the4 same question
My feeling is that it would be in there for Subaru to cover themselves.
The DCCD in lock mode or near lock mode works for a rally car, when one or more wheels are momentarily off the ground but not necessarily for off-roading where you pick one wheel up slowly and expect full drive going to the others (as per an air locker or normal dual-range 4WD etc.)
I would expect that using the normal DCCD to try and lock the centre diff for serious off-roading would potentially damage it, and Subaru wish to avoid warranty claims in that situation.
Those PBMS parts would be to simply turn a 6-speed DCCD box into a full-time locked-centre 4WD, which isn't really ideal for rallying.
Just my thoughts, and I'm happy to be proven wrong.
Well, if you install one of these, then you are guaranteed at least two wheels will be driving at any time. So if you hang the front left off the road it will spin, and one/both of the rears will still have drive.
It will most likely understeer a lot more, the drivetrain will wind up on tarmac, etc etc.
Alex.
About 9 volts is all you can run on a six speed dccd center diff. At that it shows 50% torque split at the wheels, but with a good PWRC engine , it cant hold the dccd locked at peak torque.
im not sure as i havent got the time to understand the system but this may help
Posted: Fri Oct 16, 2009 11:57 am
by vincentvega
basically its the same as any other limited slip differential. It can only hang on to so much torque.
That said.. an NA engine would have trouble producing enough torque to bother a DCCD center in my opinion.
Posted: Fri Oct 16, 2009 8:51 pm
by AlpineRaven
vincentvega wrote:basically its the same as any other limited slip differential. It can only hang on to so much torque.
That said.. an NA engine would have trouble producing enough torque to bother a DCCD center in my opinion.
That what I thought earlier..
Cheers
AP