2007 3.0r-b JDM DCCD Swap

[RX25SE]

Thanks for the info!
What's it like through the gears around town?

Not a problem!

Well, you just convinced me to go DCCD when my current box gives issues.

Thanks!

[nvmylh]

Hey Jezza I noticed on sautrday that you had some braided hoses running under your front crash bar, any info on what those were for?

[Turbo Lag]

Hey Jezza I noticed on sautrday that you had some braided hoses running under your front crash bar, any info on what those were for?

99% sure lines for the oil cooler he's set up.

[JezzaH6]

Hey Jezza I noticed on sautrday that you had some braided hoses running under your front crash bar, any info on what those were for?

TurboLag is correct! Have seen oil hit 130+ on track and that makes me uncomfortable. Aftermarket sumps for an EZ aren't really a thing, and the stock oil capacity is a lot anyway. The cooler itself is mounted in front of the passenger front wheel behind the fog-light surround, and the surround itself has been modified to allow for airflow. The oil comes from a thermostatic sandwich plate, and now sits at 80ish on highway, and I have seen it go as high as 109c on a particularly steep mountain run. On the same mountain in the past it would be easily 115-118, so given its only a small cooler I'm pretty happy with the results!

Trying to find time to do a write up for it but BigBadBenny wants the electronics side of this gearbox swap first

[bigBADbenny]

You are just kicking this outta the park!

I’d be doing same in your shoes, lol.
No wait, you can help me with mine!

[nvmylh]

Ah ok, from the photos I thought you had a standard style mishimoto sandwich plate, no thermostatic business going on? 130 is pretty hot!

[JezzaH6]

Trying to find the time to do a write-up for the oil cooler as I think it's not a terrible thing to have fitted to these cars. Oil temps are definitely something worth watching especially for these engines that are really picky on oil quality. Oil temperatures would be a bare minimum to watch, but low oil pressure is ultimately what kills them so watching that isn't a bad idea too.

I was running a standard mishimoto sandwich plate just to run the sensors, but after watching oil temperatures for about 12 months through many different situations I decided it was worth adding a cooler to the system too. Now I'm running a different mishimoto sandwich plate with thermostatically-controlled oil cooler ports, running to a 10 row plate-and-fin style cooler.

Pre-cooler install I had seen oil temps anywhere from 65-68c cruising on the freeway (which is way too cold and happened when I was running a GT thermostat), up to 135c+ on track which is way too hot. Now with an upgraded radiator, the stock 82c coolant thermostat and a 72c thermostat in the sandwich plate the oil sits around 85-90c on the highway, and on the last track day the oil stayed locked in around 125c, which is a win in my book! Next oil change I an going to swap the sandwich plate thermostat to a higher temperature one to try and bring the oil temps up a bit on the highway.

[Yowie]

Next oil change I an going to swap the sandwich plate thermostat to a higher temperature one to try and bring the oil temps up a bit on the highway.

Alternatively, if the oil cooler is practically reachable you could attach/detach a full or partial airflow block-off plate depending on whether you are going for a freeway cruise or going to a track day.

Probably not a better solution than a goldilocks oil thermostat, but it's another club in your bag.

[JezzaH6]

Next oil change I an going to swap the sandwich plate thermostat to a higher temperature one to try and bring the oil temps up a bit on the highway.

Alternatively, if the oil cooler is practically reachable you could attach/detach a full or partial airflow block-off plate depending on whether you are going for a freeway cruise or going to a track day.

Probably not a better solution than a goldilocks oil thermostat, but it's another club in your bag.

That's also something I'm working on. The cooler is behind the passenger fog light surround so is somewhat accessible. AS my oil temp and pressure gauges are DIY ones running on a way-overkill microcontroller I am working on an actively-controlled cover for the cooler itself, which will block and unblock airflow when necessary. Main problem at the moment is having it not melt when really pushing it

[JezzaH6]

Well I’ve had the electronics and interior control aspects of my DCCD swap in the car and working for the last 6 or so weeks, and finally have the time to write up my experiences with it!

I was really worried about this aspect of the DCCD swap, as my car is a 07 3.0R-B, which is a CAN-BUS equipped vehicle. This, theoretically anyway, makes accessing sensors, especially the vehicle wheel speed sensors, a lot more difficult.

I chose to use a SpiiderPlus DCCD controller, made by DCCDPro in the US. While this is not a cheap option there were a few good reasons why I chose this. Firstly, it appears to be at least somewhat of a community developed and tuned controller, and they are active on forums especially in the States. After receiving my unit and tearing it down (because of course I would) I definitely got the impression of a more ‘hobbyist’ type product, which I can totally get behind.


DCCD controller, GRB SI drive and DCCD Switch Panel


Torn-down SpiiderPlus DCCD Controller

Secondly, the SpiiderPlus itself has a neat party trick- it uses a co-processor. This allows it to set DCCD output levels based on the inputs from an accelerometer, gyroscope, throttle position sensor and, most importantly, wheel speed sensors. It doesn’t use a map of outputs for different surfaces, rather it has access to enough real-time data to algorithmically determine the optimum DCCD setting, up to a simple-to-input user selectable threshold.

By having access to the wheel speed sensor data this controller, thanks to its additional processing power compared to other controllers on the market, can determine wheel slip. This allows it to dynamically adjust the DCCD output mid-corner the moment it starts to see understeer, but not have the centre diff locked as you’re entering a corner. This should help maintain good steering feel and feedback at the moment of turn in by allowing slip through the centre diff, but then control that slip as the car starts to understeer.

To the best of my knowledge this is the only way to get the DCCD to behave like it does in a WRX STi, short of a full loom swap allowing you to use the factory controller, and should be able to unlock the potential that most other controllers leave on the table.

After driving with it enabled to different thresholds for the last 6 weeks I can say with 100% certainty this is exactly what it does. I am very happy to say that the good turn-in characteristics of my car have been maintained, and whilst you can still get understeer if you do something stupid, it is both significantly reduced and easier to recover from.



I wanted to have my DCCD install be something unique and seamlessly integrated into the car- basically I wanted to ensure my ‘normie’ mates couldn’t tell I’d actually done anything. To do this I wanted to integrate the DCCD and SI drive control panel from a GRB WRX STi into my centre console. As far as I have been able to find this hasn’t been done to a post-facelift 3.0R-B before, so definitely cool.

The shape of the GRB control panel is completely different to that of the Liberty SI drive panel, so I had to cut a new mounting hole for it. I ended up tracking down a second centre console, and had been working on this part of the project for a few weeks before the DCCD transmission swap itself. The console itself was measured up and I designed a 3D printable bracket, that was glued into the centre console to hold the GRB control panel in place and at the right height. This means the control panel clips in exactly as it would in the WRX, and should allow me to replace the panel if I have to.







From there it was a matter of getting the SI drive functionality working. The two different SI drive panels are completely different, so I had to reverse engineer the PCB layout and determine how the switch panels operated in order to get the GRB one to talk nicely to my Liberty. Prepare for some more technical posts!

[JezzaH6]

The stock Liberty SI drive knob communicates to the ECU by a 3 wire interface, but luckily for me it is neither CAN or Serial, but rather a simple voltage-threshold based communication scheme, with a ground, a VCC (not 12v, seems to be an arbitrary one generated somewhere else) and a signal, and a 4th wire for illumination. The signal wire was pulled to ground, but when you select an option on the switch it connects the signal wire to that VCC rail via another resistor. This creates a voltage divider and sends a voltage down the signal wire at a value depending on the option selected with the switch.





Luckily Subaru decided to reuse this control sequence with the GRB SI drive system, so once I worked that out it was a simple process to determine the correct wires to make the system work as it was supposed to. As I had a spare SI drive controller from the Liberty centre console I harvested its connector, and soldered it to the correct spots on the GRB panel’s PCB. I also chose to remove the illumination LED from the DCCD Auto/Manual button and replace it with an RGB LED. This will be so that when I change the DCCD controller mode using that switch the button will change colour to indicate this!



For whatever reason Subaru didn’t use a voltage-threshold communication system for the DCCD controls, instead breaking out every switch contact to the wiring loom. This made it a lot easier for me, but no idea why they’d not either send that data over CAN or at the very least save some wires and use a similar threshold communication scheme.

It was here that I ran into my first major issue. While on DCCDPro’s website they say the SpiiderPlus supports MY08+ OEM SI Drive Controls free of charge, it turns out you still have to spec that at the time of purchase. Let that be a lesson for anyone silly enough to follow this build!

As I had already started hacking the centre console to fit the GRB control panel, I needed a simple solution. So I had the switch panel, with the DCCD increase, decrease and man/auto momentary buttons, and the DCCD controller which is expecting a momentary switch input for the manual/auto mode switching, but is expecting a variable 0-5v input for adjusting the DCCD threshold level.

My fix for this is a little bit janky, but also allows for extra adjustability, as well as many different programming and input options. I made a module that sits in between the control panel, monitoring for button presses, and converting those to a servo output. This servo turns the potentiometer that came with the controller via a calculated gear ratio.

Probably not the most elegant solution, but this does have a few advantages. Firstly it allows a memory function, so when I turn the car on and off it will remember the last-used setting. It also allows for more control over the value of each individual setting. The main thing though is it should allow me in the future to integrate it into my OLED and Arduino based sensor logging system, displaying the DCCD set point and output, and logging it alongside other sensors I’ve added.



After getting this working as it should it was time to start working on the wiring for the GRB control panel. This now has a total of 3 looms; one for the SI drive, one for the DCCD buttons and one for the LED bar graph that came with the controller. To mount this I cut a hole in the GRB panel and epoxied it in. I also adjusted the value of the LED dropper resistors to help dim these otherwise bright LED’s.



With all of the control systems working it was time to get the controller in the car. Firstly the controller has an external gyroscope and accelerator, mounted in a small box, which needs to be mounted as close to the centre of mass of the car as possible. Since I have previously corner balanced the car I knew this point would be about 200mm in front of the ‘B’ pillars. The sensor package had a connector installed in its wiring loom to ensure I can remove the controller in the future, and the sensor itself was epoxied into position on top of the transmission tunnel.



As I had already run a dedicated power line from the battery into the interior along side the centre diff wiring, I used a relay and switched power from the stereo to ensure the controller turns off when the car turns off. DCCDPro specifically states that their unit requires a clean source of power to avoid interference on the wheel speed sensor wiring. The centre diff supposedly can draw up to 10 amps momentarily, so this wire was fused to 15A.

The controller also requires access to the throttle position sensor, so the ecu was uncovered and the correct wire found thanks to the FSM. A handbrake connection is not essential to the DCCD functionality, but it does mean if I ever decide to do something stupid with the handbrake while driving I don’t risk damaging the centre diff. Connectors were added to all wiring to ensure I can remove the controller in the future if I ever need to- definitely something worth remembering!

At this stage the wheel speed sensor inputs on the DCCD controller were shorted together by a removable connector- this disabled the wheel slip detection functionality as I wasn’t ready to tackle that challenge yet. I also had to remove the rear air vent duct as this didn't fit over the sensor. I ended up blocking the duct that leads to the centre console as when I go on track I tend to have heater blowing on full speed to help aid in engine cooling, and I didn't want to melt anything in the console.



With all the main wiring run the controller could be installed and the functionality tested. A test drive went really well- the system reacted to throttle, steering and braking inputs and the adjustment system worked perfectly. Testing on both asphalt and gravel roads the system felt really good and I could feel the car reacting differently under different situations.



I had previously removed the stock GPS unit and CD drive, and I mounted the controller and my DIY adjuster-module to one of the stamped metal pieces previously used to hold the CD drive. Wiring for the adjustment switches, as well as the bar graph display and the sensor package were bundled together and ran through the dash and under the centre console. The controller was mounted in such a way that I can access the programming port without having to pull the dash apart.

[JezzaH6]

After quite a few hectic months of work, uni, lockdowns and life getting in the way, as well as the car running into more problems than it normally does, I’ve finally got the time to write up my experiences with getting the wheel slip detection working the SpiiderPlus- the whole reason I chose it in the first place. This has been hooked up for the past 3ish months, and I’m happy to say modifying the quite sensitive ABS system has lead to zero issues with ABS or VSC performance, and no abs-related CEL.

This is not down to luck- not even a little bit. A lot of research went into ensuring there would be a minimal impact to the ABS system with my little hacking endeavours. Research looking into why previous attempts at hacking into the wheel speed sensors seems to suggest ripple on the lines can approach or exceed the values delivered by the wheel speed sensors themselves. Magneto-restrictive wheel speed sensors (active wheel speed sensors) output a square wave signal, passing between 0.94v (low) and 1.29V (high), at a frequency set by both the number of teeth on the tone wheel and the wheel speed.


Lots of data at the ready!

The raw wheel speed sensor data required by the SpiiderPlus is really easy to access. The data is fed into the VSC control computer, which is conveniently located right on the back of the ABS pump. The part I think others have run into issues with in the past is the ABS pump’s physical location in the engine bay versus a logical location for the DCCD controller (under the dash where I put it). The ABS pump’s location means any cables added to the wheel speed sensor wiring will have to run past the drivers side coil packs, alongside the engine bay loom and close to the ECU wiring. Any of these could have easily enough emitted EMF to completely drown out the relatively small wheel speed sensor pulses, and thus confuse the VSC controller and triggering a CEL/ABS light.

EMF is easy to mitigate, however, and my theory was with adequate shielding, and using proper twisted pairs to carry the data I wanted I could ensure the minimal amount of induced current, even though the leads I would be adding would be over 2m long. This was the cable I bought for this purpose: https://au.rs-online.com/web/p/twisted- ... le/0393028.

After removing the battery and leaving the car to sit for a while, I removed the connector from the abs pump and unravelled the loom tubing over the VSC loom. This confirmed at least one of my suspicions- the speed sensor wiring consists of twisted pairs from the sensors themselves to the VSC computer.

The wiring diagram I had made it trivial to find the correct wires in the VSC loom. The SpiiderPlus is only capable of reading two speed sensors, and they recommend you pick the axle that is more prone to slippage. At the end of the day my car is still mostly street driven, and understeer is much more likely with the way I have the car setup, so I chose to wire the controller to both front wheel speed sensors. This allows the controller to measure small differences in the front wheel speeds, which is likely to happen as understeer occurs, and reduce the lock ratio of the centre diff, thus reducing the power load on the front wheels and allowing them to regain traction.

As the VSC computer is not something you want to damage, I took a lot of precautions before doing any wiring on the car. My garage has some nice steel supporting columns that are sunk about 1m into the ground, and are not located anywhere near the house earthing electrode. To this column I grounded the chassis of the car, and I grounded both myself, my soldering iron and the tip of my hot air gun to the cars chassis. This will prevent any of the surfaces from having any form of potential difference, and prevent a static discharge event from damaging anything expensive. Obviously I left the VSC connector disconnected as well, to ensure there was absolutely no possibility of damage.

The shielded, twisted pair cable was then soldered to each of the front wheel speed sensor wires. The left hand sensor is connected to the white and black twisted pair, which corresponds to the same wiring colours on the SpiiderPlus. The right hand sensor is connected to the Green/Black and Green/Orange twisted pair, where Green/Black connects to the white wire of the second input on the controller, and the Green/Orange connects to the black wire on the controller.

I staggered the connection points on each of the twisted pairs- this is just to end up with a neater finish, and allowed me to re-twist the wires back together after soldering. All the solder joints were protected with hot-glue-embedded heatshrink tubing to ensure the connections are waterproof. After connecting long lengths of wire to both sensors, I wrapped the VSC loom in electrical tape, reset it into the loom tubing, and then wrapped all of that in another layer of electrical tape; just to try and ensure there is no possibility of moisture finding its way into the loom.

Enough writing- more photos!


Close up of wiring, before re-twisting


One wheel speed sensor wired up

Figuring overkill is underrated, I then twisted the two cables that I added into one twisted pair. After running over the twisted cables with the heat gun to hold their shape, the two cables were wrapped in a copper-braided EMI shielding mesh, to add another layer of protection. This EMI shielded braid was connected to the chassis close to the ABS pump.


Both sensors wired up


Twisted pair of shielded twisted pairs

From here a run of loom tubing was measured out and cut from the ABS pump to the grommet I wanted to run the wheel speed sensor cables through. The shielded cables were then pushed through this loom tubing, and the whole thing wrapped end-to-end in more electrical tape, once again to try and minimise the chance of moisture entering. This is how I have done any and all wiring I have added under the bonnet.


All loomed up

The cable was then routed through the engine bay, keeping it away from anything sharp or hot, and along the back of the firewall to the grommet, securing it with many cable ties along the way for a nice factory look. If you weren’t really familiar with the engine bay wiring of these cars you would be hard pressed to even notice it was there!


Good luck finding that wiring- even though you know its there!

After passing through the grommet the cables could finally be cut to length and connectors added. I used JST locking connectors, which aren’t the best from an EMI standpoint, but with proper mechanical locking (and the fact that I had them on hand), and the fact that they are inside the car and away from the more electrically noisy components I figured they would be fine. The internal shield of each wheel speed sensor cable was connected also to the chassis through this connector, but this time close to the controller. This creates a fully double shielded cable path, from the ABS pump to the DCCD controller, and seems to work really well!

From there it was just a matter of connecting my laptop to the controller, and activating the correct wheel slip detection mode using DCCDPro’s included software!

[JezzaH6]

My Thoughts

I have been asked a few times now whether or not this whole process is worth the massive amount of effort, and I am in two minds about this. The effects of DCCD have been noticeable on track; not huge, but it does allow me to get on the throttle slightly earlier without inducing understeer. I picked up about 12km/h by the end of the main straight of Winton; but I am not a racing driver and I hesitate to call that a win- especially as I had changed other things as well.


I've had a lot of fun playing around with the new setup!

On the street though, where the surface is less predictable, the effect is a lot bigger. It gives a level of confidence that is hard to convey in words. My favourite comment after letting another member who knows what he’s doing drive it was ‘it masks the terrible chassis and suspension setup of these cars and lets you actually drive it like an AWD car’. Getting power down through the corners is a lot smoother and the level of grip mid and late corner offered by this setup is hard to believe by someone who knows how limited these chassis are (and how heavy).

As the controller is only able to adjust the power distribution, it only does something when you are actually on the throttle. If you are prone to coasting through corners a DCCD swap is definitely not for you. It forces you to get your braking points perfect, and if you drive it fast without taking this fact into account you can easily exceed off-throttle grip and it becomes very unforgiving.

The benefits of the advanced controller are obvious when it’s turned to the manual mode- where you just set the level of lock on the centre diff, ignoring the accelerometer, gyroscope and wheel slip detection. With the diff set to full manual lock turn-in feels noticeably worse as the driveline binds up. Corner exit in manual or automatic feels very similar.

In the automatic mode, set in it’s most aggressive setting, good turn-in is maintained as the controller keeps the centre diff open until it detects either a higher lateral acceleration or wheel slip.

Gravel is another fun experience when running DCCD, especially with the AD08’s. In it’s most aggressive automatic mode you can feel the car really struggling for grip, adjusting the centre diff as the front wheels lost and regained traction. It’s a really hard feeling to describe if haven’t experienced it before; but it makes accelerating, braking and cornering on loose surfaces significantly faster than if I had the controller turned off.

I would not recommend it if you haven’t already done everything else you can to try and find grip with your car. Running Shockworks, brembos, poly bushes, chassis bracing, light wheels and good tyres gives the car the best possible chance of having DCCD be advantageous, and even then if you’re not in tune with the car you are unlikely to notice the effects unless you really know what you are looking for. Mates who daily other vehicles were not able to notice the difference while they were driving, but did notice it passenger-ing while I was pushing it.

In saying that the install and setup process was a lot of fun! The experience of changing a gearbox was one I wanted to have, and as an engineering student the process of getting the wheel slip working, as well as the console modification and the general wiring was a really interesting challenge. In all I can say I have been pleasantly surprised with how much of an effect the swap has actually made- I was expecting, given the gearbox is intended for the much lighter and more powerful WRX, much less noticeable of an effect, and I am very happy I put in the effort for an install I can say I’m very pleased with.

[Yowie]

Epic work & write-up!

[bigBADbenny]

Superb!
Did the project contribute to your qualification/studies?

Is front wheel speed delta the most common input for the Spiider Pro?

Are you a little tempted to make a 4 channel slip aggregator?