Let's talk about DCCD's!
 

Okay, after winning PAX in Eric's car on Saturday, and then only scraping together a 3rd place SM finish on Sunday in my own car, I realize I need two major things to get more competitive: suspension, and a working Center Diff controller.

Now the suspension, I got a pretty good idea where I'm going. But the DCCD is a bit of a mystery.

I've got a factory '04 DCCD controller, the 3 G-sensors, the 2 switches, and a mess of wiring. Unfortunately, after doing some more research I'm finding out I may not be able to wire the DCCD controller up to my '02 WRX!

It looks like the DCCD controller needs these inputs:

TPS, ABS duty cycle, foot brake switch, parking brake switch, wheel speed sensors, yaw sensor, lateral-g sensors, volume control (DCCD dial), rear diff temperature. (And the '06 DCCD added a steering angle sensor.)

Now, I believe that I've got all the sensors on that list... some are the factory '02 WRX bits (TPS, ABS, wheel speed sensors) so I don't know how compatible they are w/ what the '04 DCCD controller is expecting. Other (yaw/g-sensors) I've got in a box along w/ the DCCD controller itself... but installing at least one of the g-sensors may mean compatibility issues w/ my '02 ABS controller! Ugh!

So it looks like it would be possible to wire up the DCCD controller, but it's going to take an ass-load of splicing and running miles of wire to tap into everything. Plus there are all sorts of potential conflicts between the ECU, ABS, and DCCD. Not to mention, I'd still need to source an '04 instrument panel if I want the DCCD display, and those things run around $500.

So, in an effort to find an alternative, I checked out the Neetronics programable DCCD controller:

http://www.neetronics.com/neet/senso...troller-2.html

It allows manual adjustment of the DCCD duty cycle, as well as the ability to pre-program DCCD percentages for certain situations like low speeds, foot brake engaged, full throttle engaged, and e-brake engaged. While it's certainly not as sophisticated as the factory DCCD controller that takes into account wheel speeds and g-loads, it does add the ability to customize the differential program to match the driver, much like they do in the rally cars. Plus the control itself is *much* easier to install, and costs less than the '04 instrument panel!

So, can anyone give me a reason why I shouldn't ditch the factory DCCD controller for this aftermarket one? Can anyone point me to someone that's actually successfully swapped a factory controller into a car like mine that never had a DCCD before? Are there any more alternatives out there for controlling the DCCD?

It looks like that aftermarket controller is the way to go... As in the other thread, I found that the g-sensors are different between DCCD and non-DCCD cars, and the controller won't recognise the "other" signal. It really just sounds like WAY too much work to use all of the factory components, and retain other things like ABS!

I wouldn't want to drive a car that fast with no ABS...

I agree, ABS is something I really like. I don't get into it much since I try to threshold brake above ABS lockup because I have better brake feel w/o the pump strobing. But it's a money saver since the only way I'll flat spot my tires is if I spin.

No, not that I'm aware of, and I'm not sure. Most guys running the 6MT's are running the cheaper non-DCCD trannies out of the Foresters.

Honestly, while it reperesents a small additional investment, I think it's going to pay off in the long run in terms of installation and the time it will take to work out all the bugs.

i think the gm(gm started it it didn't they?) engineer that came up with traction control that applies the brakes when there is different wheel speeds needs to be shot.

1st, utilizing the existing ABS system as an electronic control for mechanical differentials is genius... not only is it dirt cheap to add to cars, it also works extremely well.

2nd, what does that have to do with active center differential controllers?

I revisited the wiring diagrams for the DCCD, and this time dug a little deeper into the integration with other systems.

It looks like I will have to get an STi ABS controller, because I need at least 4 outputs from it to talk to the DCCD. Someone on NASIOC said they were able to swap just the controller and things started working... so it seems like the STi ABS controller is compatible with the WRX ABS pumps. Switching to the STi ABS controller may also have other benefits, because my car is covered by the ABS controller recall that I'm not eligible to recieve because of my StopTechs. :roll: The STi controller would probably have a more appropriate program for my car.

In addition to the ABS, I'd also have to tap into the ECU wiring to steal the TPS signal.

What looks good is that I think there's only one latteral g-sensor that I need for the DCCD. I think the other g-sensor I have is simply the one the STI uses for the ABS, i.e. it's not actually part of the DCCD system. So I can just leave my longitudinal ABS g-sensor right where it is, and simply add the lateral g-sensor for the DCCD.

I just need to figure out how expensive the '04 STi ABS controller is. Something tells me it'll cost more than the Neetronic DCCD controller. :lol:

I thought the 04 STi had a lateral G sensor and the 05 had a Yaw rate sensor instead.



I'd go with the aftermarket controller. Trying to figure out if signals are incompatable without some inside knowledge sucks teh c0ck. Plus the ability to customize how your Diff reacts would seem to fit your use of the car better.

The '05 added a yaw rate sensor. The '06 goes even further and adds a steering angle sensor. :cool:

I'm on the waiting list for one of the Neetronics controllers.

Wow, those crazy Canadians! I just talked to Andy (the guy behind Neetronics), he had someone cancel their order, so he's got one unit in stock. It's shipping out today, I may have it as soon as tomorrow or Friday!

The only thing that sucks is that the exchange rate to CAD kinda kicks my ass a bit these days.

i'm not saying it doesn't work well, or that its not cost efficient. i would just rather add traction than take it away.

sorry, it doesn't have much to do with the denter diff.

How is making the wheels not spin "taking traction away"? Just because you're using the brakes to allow the diffs to channel power to the non-slipping wheels doesn't mean you're wasting traction.

Yeah. Drifeshaft power to wheel - brake torque to wheel = reduced torque to ground. It's an excellent way of creating traction control considering the alternative is throttle reduction. :(

Well, I finished wiring in the new controller tonight and took the car for a test drive.

All I can say is, this is what the car's been missing. I have so much more grip now, it's retarded. In fact, the front end is grabbing so much more under braking and acceleration, I'm going to have to loosen the suspension back up a ton... I'll probably have to toss the 450 springs back on the front of the car instead of the 550's. And maybe even go back to the big rear swaybar.

One interesting side effect is that I've got the DCCD set to 35% lock under breaking, which increases the braking load on the motor significantly... so now when I'm braking hard from speed, the engine backfires like 7 times in a row... :lol: Coming off the freeway exit, I swear the car sounds like it's got an old school anti-lag system, and it must spit a long-ass stream of fire. :lol:

Holy crap. nice job.

So this is the stock controller for transmission you have?

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Fucking badass. I'm so pleased to know the car is finally coming together the way you envisioned, hell and high water notwithstanding :D

This I can't wait to see...badass... :cool:

Good news dude, I'm glad you got this figured out, now you should hopefully be on the pace at the next autocross.

So, the front end is gripping more now and it's oversteering? The changes you're describing would typically make a car oversteer more, not less.

I noticed my car did that on the way to the Natomas meet. I just thought it was my giant injectors and mediocre tune. It sounded lovely though.

I'm not talking about handling grip, I'm talking about getting more power through the front wheels, which makes it act like a FWD car and adds a ton of understeer. Instead of rotating under power like a RWD car, it wants to push under power. Same deal under braking with the center diff linking the front to rear wheels.

Since the car was rediculously loose under power after all the motor work, I had to tighten it way up. Now I can simply adjust the center diff to higher lock up and dial out the oversteer, which means I can free up the car's suspension the way it was before the tranny swap.

I gotcha.