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Brendan's STi 6MT Swap


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So now it is advice time. I am doing the rear diff soon. I was planning on going with spec b axles, but apparently they are impossible to source. Any other ideas on making a hybrid axle. I have read a bunch of threads, but thought you guys might have some fresh ideas.

I went around and around on this for ages and the options were basically mixing the GRB inner CV joints 28492AG010 with my WRX axles or as you say ordering the rare-as-unicorn-poop Spec B axles. In the end I decided to put an LSD into a 3.545 R160 and see if I broke it. So far so good. Light and cheap. There is someone out there doing very beefy aftermarket half-shafts but of course it's a bit spendy.

Edited by fahr_side
Gear ratio incorrect
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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I looked at doing an LSD in my r160, but they are not exactly cheap. I also tried to get a hold of super dave for some of his custom races to make hybrids, but his email does not work anymore. I have a buddy of mine that is a machinist looking into making some of the races for me. I think my options boil down to your suggestion with the limited slip or perhaps my buddy could make the custom races. Any suggestions on an lsd that is decent but does not break the bank either?
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If the driveshaft problem were simpler I'd have used a stock R180 and been very happy with the helical diff. Instead, I was very lucky and got hold of a used R160 Suretrac. There's usually someone out there who bought a clutch type LSD and found he can't live with it.
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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That is the direction I am going to have to go. My only dilemma is do I do a gear swap on my diff or get a used diff that is already 3.90 which is a hard find. Will any r160 3.90 bolt into my diff? Or can I get a JDM r160 suretrac and change the gears in that? Any idea where to get gears other than Subaru? Edited by BBPeik
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Sorry, I typed the wrong gear ratio. I have a 1.1:1 trans so I needed a 3.545 rear diff. Open R160s as common as dirt. Suretrac... I'm not aware of any USDM cars getting those. Edited by fahr_side
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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I'm also pretty sure you have the smaller R160 case like other Legacy models and not the larger ones found on WRX models. I know Cusco have a unique LSD kit for the BR9 and I've seen them fitted to EDM cars.
Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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So I need a little help from those that are good at wiring. So I will be installing teh DCCD controller this weekend and there is one wire I am confused on. It is designed for cars with a manual ebrake. One of teh wires is supposed to be hooked up to the wire that grounds when the ebrake is engaged. This is real simple on a manual brake but ours is a bit more confusing. I looked at the diagram and on the ebrake switch I think it is wire 1. Would some of you guys mind referencing the fsm and confirm this for me. Also here are the installation links for the controller as well.

 

Thanks a lot

 

https://dccdpro.com/main/wp-content/downloads/DCCDPro%20UNI.pdf

https://dccdpro.com/main/wp-content/downloads/Spiider%20Wiring%20Diagram.html

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It almost sounds like that feature is so that the center diff completely disengages when that wire is receiving current. On our cars you wouldn't need it because our parking brake is not a hand brake and cannot be utilized when trying to rotate the car during rallying type driving activities.
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It almost sounds like that feature is so that the center diff completely disengages when that wire is receiving current. On our cars you wouldn't need it because our parking brake is not a hand brake and cannot be utilized when trying to rotate the car during rallying type driving activities.

That's exactly the purpose of the brown wire, it's the handbrake turn signal. In a handbrake turn you want the center diff open to minimize binding and let the car rotate. As you can't do mad skids with the silly electric parking brake you don't need to hook this up. All you need are the blue wire to the TPS input, the black and white wires to the DCCD harness, red for ignition-switched 12v power and green to ground. Done.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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If it is meant to protect the diff in case of hoon lever engagement, but you still want to hook it up, this thread may give you some inspiration: http://legacygt.com/forums/showthread.php/disabling-safety-features-nav-system-180080.html

 

I haven't done the mod myself, but the fact that you give a random pin a path to ground to trick the head unit into thinking the parking brake is set means that when you set the brake, the BIU gives some pin on the head unit a path to ground.

 

If you have a multimeter with a continuity setting, backprobe (stick a paperclip in the back of the connector) the terminal of your choice with one end and touch the other to ground, and see if you get continuity when you engage the brake and lose it when you disengage. Looking at the vacation pics, it might be the blue wire (see Rutchard's link in post #2), since that one goes to the BIU. If you don't have nav, there's a blue wire coming out of position 12 (I think it's the only blue wire, too) on the big, not-quite-rectangular connector (i26, if you're looking at wiring > audio system) that goes to the same pin on the BIU, so I'd try that test on that pin. If you find a winner, vampire tap into that wire, hook it up to the DCCD, and rest assured that if you ever have to engage the e-brake while you're moving, at least you won't roast your center diff when you lock up the rear axle.

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Well I just found that answer reading the faq on their website. I guess I should have done that first. Live and learn I guess.

Does your controller have a handbrake input allowing the diff to open when the handbrake is pulled?

All models of our controller’s feature an optional handbrake cutout wire, but for the most part it isn’t necessary. It is simply a crutch for the lesser semi-auto controllers in order to do low speed driving in parking lots and for handbrake turns. Both of which are not a problem in auto mode with my controllers. If you do not wish to use it please tape it up and isolate it from accidental grounding. Grounding the handbrake wire will simply stop output from the controller temporarily until the wire is not grounded anymore.

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If it is meant to protect the diff in case of hoon lever engagement, but you still want to hook it up, this thread may give you some inspiration: http://legacygt.com/forums/showthread.php/disabling-safety-features-nav-system-180080.html

 

I haven't done the mod myself, but the fact that you give a random pin a path to ground to trick the head unit into thinking the parking brake is set means that when you set the brake, the BIU gives some pin on the head unit a path to ground.

 

If you have a multimeter with a continuity setting, backprobe (stick a paperclip in the back of the connector) the terminal of your choice with one end and touch the other to ground, and see if you get continuity when you engage the brake and lose it when you disengage. Looking at the vacation pics, it might be the blue wire (see Rutchard's link in post #2), since that one goes to the BIU. If you don't have nav, there's a blue wire coming out of position 12 (I think it's the only blue wire, too) on the big, not-quite-rectangular connector (i26, if you're looking at wiring > audio system) that goes to the same pin on the BIU, so I'd try that test on that pin. If you find a winner, vampire tap into that wire, hook it up to the DCCD, and rest assured that if you ever have to engage the e-brake while you're moving, at least you won't roast your center diff when you lock up the rear axle.

You are right on all points, but it's just not important. It's not like the center diff defaults to fully locked when there's no signal from the parking brake. It does whatever the control knob is set to do in manual mode and in auto mode will be close to full open if you're out of the throttle or going in a straight line. You also can't drive off with the parking brake engaged. Spiider's own instructions make it plain the brown wire can be left unconnected if you're not setting out to do handbrake turns.

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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Lucky guess on my part I guess. [emoji41]

Even a broken clock is right twice a day.

 

;)

Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs.
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Looks like my new diff and spec b axles shipped today. Should have them Friday. All that is left is install the rear diff and axles, have the driveshaft shortened, and hook up the dccd controller. I was going to do that last weekend, but as some of you know my weekend was a little screwed up. Hopefully this weekend is better.
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