Brendan's STi 6MT Swap

No one wants an ungreased shaft. It could cause chaffing.

The new yoke for the driveshaft finally came in today. I picked it up from the driveshaft shop today and brought it home. I just measured all the crucial measurements and will return it to the shop tomorrow. Should have the new driveshaft by the end of next week.

 

Sorry for the delays guys. I am trying my best to get this all done, but it is an expensive, timely, and tricky process.

^^^ Your money and your car...no apologies to us.

Yea, we're just excited/happy you are even tackling this project

 

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^Exactly! This may be the best addition to the 5th gen forum yet. It definitely opens up our possibilities for more power.

Picked up the new driveshaft today. I posted a pic of the old versus new below. I did a test fit and it fits perfect( insert inappropriate joke here). So Hopefully I will get time to get everything back together this weekend and will be driving by Monday. Cross your fingers guys.

So I Got everything buttoned up today. I had to modify the exhaust hanger that bolts from the trans to the exhaust as it did not bolt up correctly. Also for some reason the PW intercooler is now farther forward than it used to be. I am guessing the mounting point on the transmission is in a bit different spot, about 20mm forward. Since that is the case, the scoop that goes down to it hits it too early and now the hood will not close. Easy to fix, but just another mod.

 

However, I started the car up and it ran perfectly. I ran the car through all of the gears and all seems to be OK. I will put the wheels on tomorrow and do a test drive, but it looks like everything is going to be good.

Well fellas I had a bit of a hiccup today. Remember a while back when I said that the rear axles were stretched as far as they would go and may not work. Well I took it out for a drive and as soon as I hit third gear the rear axles popped right out of the diff. Fortunately, I was close to home so I was able to tow it home with my lawn mower. So now I need to pull the rear diff out again and see what I can do with the axles. I never checked if our shafts will mate up to the spec b inner. I suspect not, but that will be the first thing I check. Anyway, its not done yet, but its real close. Everything else worked real good. Trans shifted smooth and the center diff is working just right. Sorry guys, but we will just have to wait a bit more.

Don't apologize man! You're breaking new ground here, and we're all excited no matter how long it takes to do it right.

Thanks, I appreciate the support. On a side note. Here is a pic of the engine bay all finished with the new CP. Also I just pulled one of the rear axles and am disassembling it as we speak to see how it compares with our factory one. Will update later.

Ok so we have the same problem as all other wrx to sti axles. The inners will not fit on our shafts. Now it looks like I am going to need to lengthen the funky axles I created. Not optimal, but I believe I can make it work. Unfortunately, our cars are wider. SO even if I went with STI hubs this problem would still be there. I will find out more tomorrow and let you all know what I find out.

I'm sure you've checked but, would maybe the 2015+ axles work? I wasn't sure what year you are using. The 2015 seems pretty similar to ours in terms of size.

I'm sure you've checked but, would maybe the 2015+ axles work? I wasn't sure what year you are using. The 2015 seems pretty similar to ours in terms of size.

 

The problem would remain the same, since the axle is probably the same part as our platform currently has, it wont fit into the rear diff or the cups from the spec b axles.

Love what your doing and all, but where is the pic of you towing your GT with the lawnmower?

 

 

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So I went all over San Diego today figuring out a solution to my problem. I finally ended up at Moore performance(machine shop in SD not the blast plate people). He said that he can make me custom cv shafts no problem. So that is the route I am going. I am going to bring him one of each of the shafts and he is going to build me some custom axles that should work perfect. Edited June 13, 2017 by BBPeik

So I just was cleaning up the shafts before I take them in tomorrow to have the new one made. I figured I would post a pic of the two side by side so you guys could see the difference. The top one is the spec b axle and ours is the bottom. I need one with our length and the spec b spline count on the inner. Ours is 32mm longer than the spec b one.

So far, are the axles the only thing you've had to have custom fabricated? I know you've had to modify a few things to address mounting issues, but I don't recall having to special order anything up until this point, right?

Correct. If you keep the r160 you can use the axles but you will have to re gear the diff to 3.90 and get a posi

 

edit: driveshaft was custom too

Edited June 14, 2017 by BBPeik

You have a 1:1 center diff not 1.1:1?

 

3.545 rear diffs are as common as dirt.

Yes. Mine is a 1/1 ratio. I used an 05 transmission.

In the interest of originality and ease of replacement parts, couldn't we just swap our carrier to a 3.9 ring and pinion with an LSD? Even if it is more expensive wouldn't it save a lot of trouble in finding parts in the end?

Yes you can, or you could source an jdm r160. I found a few that were 3.9. Like fahr_side said though. If you go with one of the 1.1/1 transmissions then you can go 3.54 which is an easier find.

Or you might find a 1.1:1 transfer gear easier to source than a 3.9:1 ring gear and pinion.

Just read this entire thread and I've got my popcorn waiting for more to be posted. BBPeik good luck with the axles I can't wait to see this thing drive.

Just putting it out there, but did you look into an automatic driveshaft before going custom? I've done the sti 6 spd swap on my 3rd gen and 4th gen, and each time people told me to go custom ds, but I've just used an auto driveshaft of the same chassis and everything lined up perfectly.

 

Looks good so far!