hamyam

thanks for the reply was told not to use it in reverse though as it would destroy the diffs, is that true ta.

Houghton

iTrader: (1)

Haven't experienced a problem with reverse during a 'competitive type event' but the same 'clonking' applies for slower manoeuvres backward and forward from what I've found.

IMO if you keep the driving 'lively' it all takes care of itself. If you're in grannie mode stick with greens.

STI5300

iTrader: (4)

Just found this info. just what we need, I had asked a friend at work who is married to a Japannese guy to translate a page for me. It was a no no as she/he didn't have the technical vocab. Brilliant Brilliant. So does this mean that as the control **** is a variable resistor not a switch, if I measure its value, then buy and mount a small rotary one on the steering wheel I could lock up for starting in sprints then unlock for corners etc. as required.!!!!!!!!
Look out Subaru Sprint Championship here I come.

David_Harden

Oh mate, now were talkin' !!!

Can I book my car in with you for the mod?

Houghton

iTrader: (1)

I'd have thought it would be easier where it is rather than try to find a moving target on the steering wheel IMO

terryb

Steerng wheel mount is a great idea - have been thinking of this myself for the last few days

doug2507

iTrader: (6)

Doesnt Andy.f have a similar sort of setup on his for the 1/4 mile? Think its locked 50/50 for starts then at the press of a button reverts back to std settings. (open). I imagine this is usefull on the strip as the 50/50 lock will give a better start and switching back will reduce drag once underway....?

STI5300

iTrader: (4)

I knew that I would have at least one good idea in my lifetime, will dig out the control **** on the weekend and have a play. Maybe I should have kept my idea quiet. In reply to Houghton, the way I sprint I need both hands on the wheel as much as possible !!!!!!! Look out

tharoka

Not shure where to post but I think I may try here

My question is regarding to the new MY06 DCCD splits and operation. I'll paste (and edit) some of this questions made in other forum which where not answered.

I'm trying my best to understand not only how the AWD on the latest STi's works but where its (split) limits are.

As long as I know the 06 STi DCCD AWD system includes:

*Front helical LSD
*Center planetary differential (wich, as I understand, it is equal to an open one but with an initial split i.e. 41F/59R) + cam type LSD (wich limits the speed difference between F/R axles in order to avoid the torque 'gets lost' by one axle if this spins) + DCCD system (wich has the ability to change the behaviour of the center LSD i.e. change the % of lock in the LSD)
*Rear Mechanical Cable type LSD (translated by babelfish from the japanesse Subaru web)
*Various sensors, like Yaw senson, steering wheel-angle sensor,... governed by an ECU capable to changeing the % of lock in the centre LSD automaticaly or manualy.

So it seems that the initial torque split is 41f/59r on the auto mode, but:

1-What maximun splits can this system reach, and in what conditions? (both in auto and manual)

2-What splits corresponds to the different dccd wheel positions?

PD: Its really hard to me to believe that this has not cleared allready by any Subaru person or any subaru entusiast. Hope we can clear this...

johnfelstead

Front Helical LSD is a mechanical conventional gear LSD, not a suretrack torque sensing diff as previous newage STi's, this is a much better diff for hard driving IMHO.

Centre diff is similar to all the DCCD centre diffs in its basic design concept, it uses a variable rate plated LSD, the DCCD varies how tight the LSD is by altering the clamping force on the clutch plates in the plated LSD unit. The MY06 setup varies to the previous DCCD equipped cars by using a 1.1:1 drop gear to drive the front diff, the previous versions used a 1:1 drop gear.

The centre diff lock rate is infinately variable, each dash light is just a guide to how locked the diff is, there arn't distinct jumps from one settng to the next (think analogue rather than digital).

You could force the car to drive like a RWD car by making the centre diff act as an open diff if you get the rear wheels spinning by overcoming the rear tyres traction, this would give you a 100R/0F torque split. You could also make the car drive like a FWD car by locking the rear wheels on the handbrake whilst keeping the throttle floored, this would give you a 0R/100F torque split, something i wouldnt advise you try!

Rear diff is a conventional plated LSD.

tharoka

Hi namesake !

So you state that when the centre diff is in manual mode at the open position, it departs from a 41:59 and depending of the surface grip conditions it can vary from 100:0 to 0:100?

And if it happens this way, will not we be continously losing traction from one axle as soon as some grip is lost in one axle (like in a front drive car with an open diff, once it losts traction in one of the front wheels)?

And finally, is the auto mode capable of controling a 100:0 to 0:100 torque split in order to keep the cars direction where he determinates the car should go?

johnfelstead

It requires some severe inputs or a very low grip surface to make the car drive the front or rear axles exclusively. Stick the back wheels on ice for example, and with the diff in manual mode and fully unlocked, just the rear wheels will spin and you wont go anywhere. You can also force this to happen by powersliding the car or doing donuts, as soon as you reduce the engine torque, the rear tyres will grip and torque will be transfered to the front again.

yes, but losing traction takes a lot of effort in practice in most circumstances, you have to have the tyres on both sides of the car on that axle losing traction because the axles LSD is going to be active. In manual mode on a slippy road you can light up just the rear tyres, especially if you are using some poor wet weather tyres, this is how a lot of classic TypeR versions were written off, when you lose the AWD traction its an instantaneous change in handling charicteristics which will catch out a less than capable driver.

No, auto mode never allows the torque split to be any less than 41f/59r.

dynamix

iTrader: (3)

thanks for your numerous undoubted words of wisdom John

been experimenting wiht the dccd-a in mine and fully manual does feel more like a rwd car than an awd car. I know this is such a variable beastie but is it best to wind it back a bit from fully unlocked to provide us lesser mortals with a more forgively driving behaviour from the car?

johnfelstead

I usually drove with the centre diff fully open, unless i was on a wet road with standing water, or the road was unusually greasy, where i would wind a small amount of lock in. This was mainly to improve the braking rather than power on traction, as it helped even out the brake load accross all four tyres by utilising the LSD's (i didnt have ABS).

I always used good quality tyres, i tried a set of P1 Pirellis once and that made the car almost undrivable on a greasy road, with those i would use more lock unless i wanted to exit every corner with full oposite lock on, which is fun unless you want to go fast.

To be safe it would help to run a small amount of diff lock if it's not dry, if you arnt particularly experienced or have slow reactions to power oversteer. In the dry it's unlikely you will break traction, unless you hit some diesel and were hard on the power.

dynamix

iTrader: (3)

thanks John - as i thought

u gotta love these babies - the engineering is fantastic

tharoka

As my (may be old-fashioned LOL) English/Spanish dictionary says, namesake=persons with the same name, i.e. my name is Jon also.

Thanks again for your answers.

OK, so finally I have an answer I was looking for; the lower split limit in auto mode id 41f/59r. But what is the highest split auto mode limit?

dynamix

iTrader: (3)

pretty sure that this is 50/50

tharoka

It sounds like it has sense, but then would not this be a disadvantage vs. the MY05 DCCD system since (35/65~50/50) is a wider range than 06's (41/59~50/50)?

I have read around the web that the MY06 system allows a GREATER action range than the previous years. Is this matter what gets me confussed. Added to this, some magazines stated the MY06 DCCD can reach 80:20 splits... ence all my confusion and questions... I want to find where the misinformation is and/or where the split limits where.

dynamix

iTrader: (3)

in manual mode there is infinite adjustment as per john's posts above.

johnfelstead

No, thats not the context of what i say, i didnt make it clear enough. By infinate i mean the manual adjustment is an analogue potentiometer, which isnt giving specific steps which you might consider is being aplied by the limited number of dash lights.

The amount of adjustment is always between the max and min lock rates of 50/50 and 41/59, unless you force the wheels to break traction at one end of the car.

P.S. My name is john, not jon.

marcymarc555

Sorry but this may be a stupid question.
I have read this topic 3 or 4 times now and there is something i am not clear about.

Someone earlier in the thread said "can the diff be changed while stationary" and the reply was yes. But this must only be the case when the handbrake is pulled up til the warning light is on...... Yes??
The translated hand book says put the diff in open lock when stopped, so what happens when you stop for a few seconds only while giving way etc when in a diff lock position, surly your not ment to click your hand brake up EVERY TIME you stop... and surly everytime you stop you shouldnt have move your diff switch back to open diff (unless stoping to stay stopted)because thats what handbrake sensor is for.

The more i read about dccd the more i keep getting the vibe its a bit of a hinderance/bind really. In no other car practice have i ever known a reason to take your hands of the steering wheel as much in fast road/rally/competition as the dccd requires. except F1 where the drivers change parameters with finger and thumb.

When i had my type r v5 two years ago i never once used the diff switch i was to scared as i thought i would break it .. what a lump i am

I used to feel as if the car was really crap at handling this must have been because i never made use of the diffy poos Id dab the breaks and the backend would skip out that really annoyed me .

What kind of setting/how many clicks do you guys use on a b road thrash , surly not in the open diff position???

dynamix

iTrader: (3)

depends on the road conditions really:

totally dry and warm = totally free diff
moist roads = one indicator light up
wet roads - i tend to leave on Auto to be honest as it does a pretty good job for me in the 06 STi.

if you are driving an 06 spec car with the DCCD-A then you cant go far wrong with the auto setting IMO at least until you get used to the way the car handles with that. I used the Auto setting at Snetterton on Sunday and it did a great job on a mixture of track conditions.

jonjo

Is using the DCCD on the 1/4 mile strip in my V4 type-r a good idea then or not?? Im confused

If so which setting should be used for most effective launch??

Joe.....

johnfelstead

NO, you can alter the diff settings at any time, when stationary, doing 0.5MPH, doing 150MPH, whatever.

This subject isnt complicated in practice, i can see it's not coming accross well in written explanations though. Would people be interested in me setting up a "how to drive a DCCD equipped car" training course?

Andy S.

Yes, you could practise your training on me John!
Just got an 04 JDM Sti with DCCD. full to the rear is fun in the snow

marcymarc555

Two words John...YES PLEASE

tath

One thing i found wrong with my STI RA was when in open it was nasty and twitchy if you weren't extra careful with the power. It would oversteer at slightest provocation and, frankly, i thought it was pretty ****. I later found out the geometry was MILES out, rear thrust angle was out, rear camber was slightly positive and the tyres were of a ridiculously hard compound.

It's now 100x better after a geom setup and some decent rubber. So i'd caution anyone who isn't happy with DCCD to check these things first... DCCD cars are a lot more sensitive to sloppy geom than a normal one

dynamix

iTrader: (3)

is that a real offer John?

if so - sounds good to me

johnfelstead

OK, i'll work on getting something practical setup.

Chip

Nice one John

Chip