DCCD Operation During Handbrake Turn?
09 February 2005, 08:20 PM
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DCCD Operation During Handbrake Turn?
Hiya
A question's arisen on another forum - does the STi's centre diff 'disconnect' the rear wheels when the handbrake is used, during a handbrake turn for example?
Cheers,
Ru'
A question's arisen on another forum - does the STi's centre diff 'disconnect' the rear wheels when the handbrake is used, during a handbrake turn for example?
Cheers,
Ru'
09 February 2005, 09:06 PM
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I'm not totally sure about the handbrake turn bit, but for sure if the diff is wound up (whereby it tightens right up if you are doing a low speed tight turning manouveaur with the diff locked) then pulling the hand brake up suddenly releases the diff.
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10 February 2005, 07:24 AM
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Easy Andy, you side-swipe the horse/cyclist 
Actually, I wasn't aware that any stock DCCD diff'ed Subaru paid any attention to the foot brake?
Would be nice to confirm re. the hand brake too.
Richard
Actually, I wasn't aware that any stock DCCD diff'ed Subaru paid any attention to the foot brake?
Would be nice to confirm re. the hand brake too.
Richard
10 February 2005, 03:14 PM
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So does that mean that if you pull a handbrake turn and keep the power on, the front wheels will pull you around?
I'm thinking of this for the hairpin at Croft rather than the Maccy D's car park
Steve
I'm thinking of this for the hairpin at Croft rather than the Maccy D's car park
Steve
10 February 2005, 03:44 PM
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Steve,
Careful You need to treat a DCCD car the same as a RWD car 
With the diff fully open you still have 66% going to the rear diff. Not sure I'd like to try that FWD trick on a DCCD car.
Richard,
The DCCD goes to fully open when the handbrake is applied (you just need to get the light on the dash, not have it braking), this helps if you've got the diff locked and your in a slow turn to stop any transmission windup.
I'm guessing that Harvey has had his modified to fully lock the diff when he brakes as it does make a big difference (brings the rear brakes into play and makes it harder to lock the front tyres, no abs), but only when braking in a straight line.
Or you can get the GEMS controller (only about £450 fitted+mapped).
Dave.
Careful
You need to treat a DCCD car the same as a RWD car With the diff fully open you still have 66% going to the rear diff. Not sure I'd like to try that FWD trick on a DCCD car.Richard,
The DCCD goes to fully open when the handbrake is applied (you just need to get the light on the dash, not have it braking), this helps if you've got the diff locked and your in a slow turn to stop any transmission windup.
I'm guessing that Harvey has had his modified to fully lock the diff when he brakes as it does make a big difference (brings the rear brakes into play and makes it harder to lock the front tyres, no abs), but only when braking in a straight line.
Or you can get the GEMS controller (only about £450 fitted+mapped).
Dave.
10 February 2005, 09:24 PM
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Originally Posted by Steve Sherwen
I'm thinking of this for the hairpin at Croft
you'll scrub a massive amount of speed off, and it ain't very mechanically sympathetic
10 February 2005, 10:10 PM
#13
it doesnt disconnect the diff which is what cars like the WRC Toyota's did, it opens the centre diff locking plates, so you end up with an open centre diff. Ideally you want to be depresing the clutch as you lock the rear wheels or you will put a lot of load into the centre diff, but if you dont care about the stress you could lock the rears up and power the front wheels at the same time.
10 February 2005, 11:17 PM
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Actually this is very intersting, does the TEG centre diff ECU have some sort of sensor on the brake pedal to measure how much braking effort is used to lock the centre diff ? ..... cause otherwise I can't imagine how the car would behave if you use some left foot braking .
Carlos
.Carlos
Last edited by carlos_hiraoka; 10 February 2005 at 11:39 PM.
11 February 2005, 11:58 AM
#17
It is similar to the Town End Garage system but not exactly the same.
I can map any configuration I want with the separate diff ECU and my lap top. There are five switch positions, 1 is fully locked, 5 is fully open. The handbrake releases the diff via a separate switch, not the dash light switch/sensor. (Ithink)
It was installed by Tristan Pye and we ran into problems with the hardware and soft ware and were able to resolve most issues after input from Bob Rawle. Thanks again Bob for your in depth knowledge and application of a nimble mind.
The system is still to be perfected as we are not getting a true rpm signal.
Under hard braking the diffs are locked but I will have to check on how that is adjusted and at what level of lock. Cornering and braking in normal road driving has not been a problem but I will do some more vigerous experiments to explore what happens but the diff lock is only evident on hard braking so it is adjustable by some means.
Left foot braking, which as far as I am concerned is not required for road driving, is still possible and I assume that the diff ECU takes a signal from the TPS so any throttle takes precedence over locking.
Hand brake turns. Just like I had with a 16V 2.0 Astra flying machine.
Hand brake locking the rear axle driving the front axle, possible, spectacular on wet grass but probably not advisable as John says.
Tristan is rallying in Wales so I will ask the questions on Monday.
Off to find somewhere to hard brake and corner.......................
I can map any configuration I want with the separate diff ECU and my lap top. There are five switch positions, 1 is fully locked, 5 is fully open. The handbrake releases the diff via a separate switch, not the dash light switch/sensor. (Ithink)
It was installed by Tristan Pye and we ran into problems with the hardware and soft ware and were able to resolve most issues after input from Bob Rawle. Thanks again Bob for your in depth knowledge and application of a nimble mind.
The system is still to be perfected as we are not getting a true rpm signal.
Under hard braking the diffs are locked but I will have to check on how that is adjusted and at what level of lock. Cornering and braking in normal road driving has not been a problem but I will do some more vigerous experiments to explore what happens but the diff lock is only evident on hard braking so it is adjustable by some means.
Left foot braking, which as far as I am concerned is not required for road driving, is still possible and I assume that the diff ECU takes a signal from the TPS so any throttle takes precedence over locking.
Hand brake turns. Just like I had with a 16V 2.0 Astra flying machine.
Hand brake locking the rear axle driving the front axle, possible, spectacular on wet grass but probably not advisable as John says.
Tristan is rallying in Wales so I will ask the questions on Monday.
Off to find somewhere to hard brake and corner.......................
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