My First Build Thread, and a long time comin' Options

[Eric_Shea]

Nice build.

[76-914]

If anyone wants some good info on Subaru transmissions let me know - I found some awesome threads on 'em!


[/quote]
You got my attention. What tranny info do you have.

[skeates]

You got my attention. What tranny info do you have.

Here are some good links to get you started:

Gear ratios for various tranny codes: http://www.catherineandken.co.uk/sti/trans.html
Overview of Subaru transmissions, weaknesses, and upgrade paths: http://forums.nasioc.com/forums/showthread.php?t=665334
More gear ratio discussion: http://www.rs25.com/forums/f8/t100042-lear...tml#post1598005

It seems like all the discussion about the weak spots in the Subaru transmissions come down to two theory's. The first is that the case flexes under load because of it's split design and messes up the gear mesh. The second theory is that it is shock loading the gears which aren't quite beefy enough. It was interesting to read that many of the failures were actually 3rd and 4th gear, not first! Either way since we use it in 2 wheel drive in the 914 the transmissions would be under quite a bit less stress. Less stress because excess torque is "dispelled" by wheel spin. With two tires we don't have enough traction to apply the full torque of the engine on hard launches (unless you are running wide slicks of course). Thus it should be able to handle quite a bit more torque/HP than in an all wheel drive application. I suppose I'll find out soon enough with the EZ36!

I noticed that some of the gear ratios in the thread I listed contradict with each other, particularly on the final drive. I ended up feeling fairly confident that the Legacy GT (Turbo) box had a 3.9 final drive ratio and had slightly taller gear ratios than the WRX boxes. Since my engine should have a lot more torque than the WRX (at least at the lower RPMs) I wanted the taller gears. Plus it minimizes my RPMs while cruising on the freeway. That said, the '06 - '07 WRX's had a 3.7 final drive ratio which actually makes 4th and 5th effectively taller than the Legacy GT. However, I felt that the lower FD would add more stress to the gears...of course, I was more or less at the mercy of the dismantler in terms of what they had available. (IMG:style_emoticons/default/biggrin.gif)

Way I figure it, if you are running a 6 cylinder or turbo then you ought to be fine with almost any transmission post 2003. In 2003 they "upgraded" the gears by making them thicker. Prior to then only the WRX transmissions had the thicker gears. You are probably already aware that you also need to make sure that you are matching the slave cylinder, fly wheel and clutch (push vs. pull type), but that has been discussed here at some length in some of the other Subaru threads. I can find those links for you if you want.

Hope that helps!

[skeates]

I've been slowly making progress behind the scenes. This week was a big'n! Still gotta do the final fitment, but hell - this is the first time the car has had an engine in it in 4 years! And it's very purdy drive train if I don't say so myself:

[76-914]

(IMG:style_emoticons/default/thumb3d.gif) Congrat's, That's a major milestone.

[skeates]

So - as soon as I got the engine in it was time to take it out again! While the main engine supports/cradle were all done, I still had one more mount to fabricate which supports the front of the engine. I was actually a bit surprised to see it there when I picked up the motor since I hadn't seen it on the other Subaru engine conversions around here. Apparently at some point (maybe '08?) Subaru added a front engine mount to their engines. Honestly, I was pretty happy to see it there since the whole cantilevered engine thing never sat well with me. While the engine was out I figured I'd get all the clutch stuff sorted out too.

Front Mount:



Here's the pedal cluster all fitted up. You'll probably notice that I borrowed the design from 76-914. It works great! The only difference is that I ended up using the original clutch clevis and pin by making a very high tech metric to SAE adapter (welded an M6 bolt to a 5/16" nut). Now the only pedal left to figure out is the electronic gas pedal.








While the engine was out I figured I'd get the clutch and flywheel installed too - no sense in pulling this thing out more times than I need to. So - I ponied up for the Exedy OEM clutch & flywheel kit. The flywheel is a lightened one and at 12.5 lbs I am a little bit worried about its street-ability, but I figure that's not hard to change down the road if it becomes a problem. At this point the price was right! One thing I found interesting is that the flex plate on the automatics are attached by 14 mm hex bolts, but the flywheels for the manuals use M10 Torx bolts! Weird...



and here the engine sits ready to be installed..again...

[sixnotfour]

The front mount is awesome..good work

[Socalandy]

Awesome work, keep the progress pics coming!!!

[rick 918-S]

Glad to see in your absences you were able to get the chassis figured out. I like the Suby 6 engines.

[76-914]

Deja vu.

[abnrdo]

Nice work man! Keep it up, your giving me inspiration. What long stiffening kit did you use? Is that a ColdWater engine mount?

-Jim

[skeates]

Glad to see in your absences you were able to get the chassis figured out. I like the Suby 6 engines.

Yeah - I was really relieved to see that I hadn't royally hosed the chassis as much as it initially looked like. Now that I've got the car back on wheels and the doors on again I'm not too thrilled about the door gaps on the driver's side - but I can't remember how bad they were when I started the project (should have taken pictures). I figure though that's something that I can address when I do the final tear-down for bodywork.

[skeates]

Nice work man! Keep it up, your giving me inspiration. What long stiffening kit did you use? Is that a ColdWater engine mount?

-Jim

Thanks! The long kit is one that I purchased second hand (un-installed obviously) from someone on the board. It is one of the Engman long kits. The engine cradle is one of Ian's (Coldwater), though I'll add the caveat that is was a prototype from his initial development of this product (and therefore significantly discounted). The prototype didn't have the mounts for a 6-cyl and needed some "tweaks" for it to bolt up correctly. If you look closely you'll be able to see my additions. His current cradles are going to be a lot more polished than mine.

[skeates]

Got a few more hours in yesterday. Re-installed the engine (I'm starting to get the feeling that I'll be very good at this soon), finished drilling the holes for the front engine mount plates and even got the nutserts installed for the fuel pump.

Here's the front engine mount. Only thing left here to do is trim down excess metal and paint!



Nutserts for the fuel pump. It looks a bit messy right now on the top side since I used the extra epoxy to fill in holes left by the original fuel sender. Tonight I should be able to remove the tape I used as a backing material and sand it all down nice and smooth. I probably would have been OK welding it (It's been empty for 4+ years), but I just didn't feel like trying it alone at 11 PM without a fire extinguisher. Since the holes are all located where the gasket material covers this is more for good measure anyways. This pic really brings out the "patina" inside my gas tank!

[ruby914]

Somehow I missed a lot of your progress. The car is looking good. I think the front mount is great.
I am currently replacing my 901 with a Suby transmission. I am looking for some sort of pitch mount replacement. There is not a lot of room at the aft firewall, about 1.5".
I thought I could make it work but the Suby pitch mount is too long.
The front mount should solve this for you.
I don't understand how we have so many conversions built with out a pitch mount and we don't see problems. Not just with breaking motor mounts but with a jerky feeling motor. At one time I felt a lot of wheel hop in a rolling 2nd gear burnout. I don't know if this could be from the motor rocking back and forth or something else? If I come up with something before I put everything back together I hope to feel some solid improvement. If not, at least I will feel everything is locked in place better.