An Automatic Transmission Question for PhyrraM

[Oppenheimer]

If you can get a 'really old 2WD Subie trans' then use it - it's almost exactly the same basic transmission.
I wouldn't bother with removing it from one trans and installing it on another.

Except the old trans is old, and worn out. The donor trans is potentially low enough miles to use without rebuilding.

Will the 2WD cover fit the mentioned Legacy trans that uses paddle shifters?

[PhyrraM]

I've driven the 5EAT Legacy. Yes, it has paddle shifters. No, they are not worth using. Very slow to respond, much more waiting than fun.

Also, keep in mind that many WRXs (all?) came with the VTD automatic - which does not have the "always connected" FWD and would require a conversion sleeve similiar to the 5 speed manual. Most of the non-WRX automatics have the proper automatic (called Torque-on-Demand for many years).

[Aloha818]

Now that a few have received their kits and builds underway, any new observations on using an auto? I will be using an auto and eventually a modified version with paddle shifters. FFR is NOT supporting an auto, per email received today.

BTW, my 818 completion date is 8/31, this week YEA!

[Xusia]

Have you already bought your donor? If not, you might consider buying a newer Subaru with an EZ series H6. Those all come with automatic transmissions, AND most seem to have the manual drive mode - which looks like it would be very easy to adapt to paddle shifters.

There would be some issues, for sure: wiring harness, speedo sensor, some parts not compatible, etc.

[Aloha818]

Have you already bought your donor? If not, you might consider buying a newer Subaru with an EZ series H6. Those all come with automatic transmissions, AND most seem to have the manual drive mode - which looks like it would be very easy to adapt to paddle shifters.

There would be some issues, for sure: wiring harness, speedo sensor, some parts not compatible, etc.

Yes I have! Being in Hawaii the options for donors on island are about zero. I have a 2000 2.2l that I am adding a TD04 turbo to. Light boost, 7psi. Should be good for about 210 hp.

Transportation to Hawaii will take about three weeks, so when it gets here I can verify how much of the tail section to cut off. Then weld on a plate to block off. I guess I need to keep enough of the tail section for the bearing supports.

[PhyrraM]

Since your donor is a 2000, I would look for a '90-'95 FWD 4 speed automatic (Impreza or Legacy). There would be no need to modify the transmission and the electrics are likely close enough to be DIY with a little effort.

I would also *guess*, based on pictures, that a factory FWD transmission will fit the 818 without requiring rear bumber bodywork.

[Clif]

How much power do you think the automatics can handle?

[65 Cobra Dude]

Guys,

I pick up my kit on 9/16 and am using an 04 WRX with auto tranny. FFR asked me to make sure and document what needs to be done to make it work. I'll let you know what I find out and will be keeping a close look here as I am Subaru stupid.

Henry

[StatGSR]

How much power do you think the automatics can handle?

All of it if built right. All the fastest high horse power Subaru run automatics.

[Aloha818]

Guys,

I pick up my kit on 9/16 and am using an 04 WRX with auto tranny. FFR asked me to make sure and document what needs to be done to make it work. I'll let you know what I find out and will be keeping a close look here as I am Subaru stupid.

Henry

Have you picked up yet? Mine has made it across the Pacific and it should get to my shop today. The first item to check out is the auto trans fitment.

[Aloha818]

No one has followed up with actual information on installing an auto yet. There has been about 36ea 818's delivered so far, I guess everyone else is sticking with a stick?

I received my kit a couple weeks ago, missing the hardware, so I'm jumping around on the build. Yesterday I started on the engine install.

While I had it in the air I dropped the pan and changed the filter and gasket;
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With the engine on the mounts and the trans pan sitting on the frame;
image.jpg

This shows how much of the rear needs to be cut off to fit the body;
image.jpg

New rear trans mount will need to be fabricated, one to keep the rear section as low as possible, two because the mount location is on the section to be removed. The engine, even with the trans sitting on the frame, tips the engine slightly forward. I'm not sure if this is a problem yet. If it is then the rear frame section will need to be modified.
image.jpg

How often does the trans need to be serviced? If maintenance or service is required the trans will have to be removed or the frame will have to be modified to gain access to the pan.

So later today I plan on pulling off the tailpiece and see if its possible to just cut off what is in the way, keep enough material to support the bearing that needs to stay and fabricate a blank off plate.

Anyone with any helpful info?

Does anyone know if its possible to lock the solenoid in its operated position without having to supply voltage via the FWD fuse? I was thinking it would be better to lock permanently so as to not have to worry about the solenoid burning up. Then if needed, add a resistor to the supply voltage to trick the ECU into thinking the solenoid is still in place.

I know others are interested in using the 4EAT, so jump in with answers, I can be the guinea pig.

[Goldwing]

I can't answer the solenoid bit, but here's the maintenance page I saved for reference to answer your maintenance frequency question. Until weather mods are made, I can see many 818s in the north needing maintenance for time not miles.
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[riptide motorsport]

thanks for trying the auto.............................its the way I want to go.

[Aloha818]

I am not an expert, barely a shad tree mechanic, so my choice of part names, functions, and if this will work are just my observations.

Maybe too simple?

It looks to me like I just need to cut off the tailpiece section of the output shaft at the arrow in this pic;
image.jpg

Then cut off the tailpiece housing at the arrow in this pic, which looks like it is short enough to clear the frame/bumper location;
image.jpg

In the first pic, just before the arrow, you can see two O rings about 3/4" apart. I assume this is to minimize oil escaping to the rear of the tailpiece. In between the two O rings, in the housing, is what looks like an oil feed. So this area of the output shaft needs to stay, but beyond that looks like it can go.

Here is a pic of inside the tailpiece housing;
image.jpgimage.jpg

So I can see what others have posted, that you have to keep the tail shaft bearing support, and then I also think you have to keep enough of the shaft and housing for the oil supply. Also, just beyond the location that the two O rings sit in, in the tailpiece, is a small hole in the bottom. Below the hole is an opening. I believe this is to let any oil that gets past the last O ring to be able to drain back into the front section of the tailpiece/transmission. So enough of the tailpiece housing must remain to keep this function.

Then only a small "plug" would be needed to cap the end of the tailpiece housing opening to keep oil from leaking out.

Not sure about the height though. With the transmission pan sitting on the frame the engine is tipped forward some, the center of the side driveshaft output is about 5" above the frame below it, anyone that has installed an engine with the 5-speed care to measure what your dimension is at this location?;
image.jpg

Also, the height of the tailpiece housing, at the proposed cut line, is about 11" above the frame. I have not tried the rear bumper, but the flat area in this location is about 10" before it steps inward. It looks like I can cut some of the top "fin" off of the tailpiece to clear, and/or, I'm thinking that the crossbracing under trans has got to go to allow the engine/trans to sit more level, allow acces to the trans pan, and clear the bumper.

I guess I will start off with just keeping a fuse in the FWD location to keep it in FWD mode only.

[65 Cobra Dude]

Aloha,

Got your PM as well. I gave up trying to put the auto in because I could not figure out a way to not have to cut the body for the extra length of the auto. I had the FFR boys measure from the center of the CV hole on the tranny to the fiberglass body and they said it was 25 inches. I could not figure out how to keep the auto working and drop off the couple of inches needed to get it to fit without body mods. I bought a used 5 speed tranny and new clutch, pressure plate and throw out bearing and they are mounted to the motor and in the car now.

Henry

[RM1SepEx]

I am not an expert, barely a shad tree mechanic, so my choice of part names, functions, and if this will work are just my observations.

Maybe too simple?

It looks to me like I just need to cut off the tailpiece section of the output shaft at the arrow in this pic;
image.jpg

How is this entire section attached? It appears to be similar to the center diff and output assy that we remove on the std trans. I would see if this entire assy could be removed and you could make a flat cover of some sort. Anyone have an exploded view of the auto transmission?

[PhyrraM]

http://www.northursalia.com/techdocs...ssion/4eat.pdf

While the pictures are small, pay attention to the parts related to the section labeled "MPT". The two pictures labeled "Reduction shaft seals" and "MPT power flow" show that the front axle is always powered and the rear axle (the part to remove) is only powered by the clutch - which is deactivated by the fuse.

*IF* you can determine that the shaft/gear behind the clutch is supported by a bearing (not relying on that last bearing) then you can just remove the clutch as a whole.

[RM1SepEx]

It looks to me like you could remove the whole shebang!... I'd investigate.

[Aloha818]

http://www.northursalia.com/techdocs...ssion/4eat.pdf

While the pictures are small, pay attention to the parts related to the section labeled "MPT". The two pictures labeled "Reduction shaft seals" and "MPT power flow" show that the front axle is always powered and the rear axle (the part to remove) is only powered by the clutch - which is deactivated by the fuse.

*IF* you can determine that the shaft/gear behind the clutch is supported by a bearing (not relying on that last bearing) then you can just remove the clutch as a whole.

It looks to me like you could remove the whole shebang!... I'd investigate.

Thanks guys for commenting!

My opinion, for what it's worth, is that physically the output shaft/clutch could be removed. The clutches on one end are supported by the main shaft and the back end of the output shaft has its own bearing in the tailpiece housing.

Inside bearing support in tailpiece housing.
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Just under the Hula Girls chin is the bearing
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Inside view of the clutch and the main shaft
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So if the clutch/output shaft is removed I believe the bearing support in the tail housing would not be required. However, it is my opinion that the outside portion of the clutch housing is part of the speed input to the transmission control unit.
There is a sensor that reads this housing;
image.jpg

There is also a oil feed that sends oil from the trans to the tailpiece section. So if the clutch/tail shaft and housing is removed I think, again my opinion, that it will change the oil pressure and/or I would need to try and cap it.

So without any knowledge that my plan will actually work, I jumped right in and did it. I cut the tail section and output shaft as I had marked and posted yesterday.

Here is the clutch/output shaft wrapped up and ready to cut;
image.jpg

I cut the tail section, cleaned it up and painted it like I did the rest of the trans with aluminum paint. The camera doesn't show easily but what looks like empty space just beyond the cut in shaft opening is actually the cut section of the output shaft. It is cut short of the housing by around a half inch. You can see the small hole just in from the cut that let's the oil that gets past the seals on the shaft to drain back into the trans. Both of these cut locations I think are critical, the shaft being a little short allows access to the drain hole and keeps both oil seals, and the location on the housing keeps the strengthening rib. Now I just need to fabricate a sheet metal cover plate to keep the oil from draining out. Should be no pressure here since the oil just drains back into the trans.
image.jpg

Since this cut location gets the trans short enough to fit the 818 bumper, does not change, modify, restrict any of the bearings, seals, sensors, and oil flow, I can't see why this isn't the perfect solution! Another bonus is no extra parts/cost!
image.jpg

So besides the cover plate, all I need is to put the fuse in to keep it in "FWD".

Comments welcome!

[nubie]

Thanks guys for commenting!

My opinion, for what it's worth, is that physically the output shaft/clutch could be removed. The clutches on one end are supported by the main shaft and the back end of the output shaft has its own bearing in the tailpiece housing.

I can't say if it is possible, but it looks like you could possibly find an open bearing, perhaps with inner race, that would fit in the 2WD tailcap and run on the end of the AWD shaft. Supporting the part that currently has needle bearings and goes inside the clutch pack. It might be necessary to remove (break or cut off) the basket on the top shaft gear (I have seen one that broke off on its own, should be doable). It would take access to a FWD tailcap to see if it is possible. That would only require a 2WD or custom back plate and another bearing mechanically. The ideal way to do it would be to pull the top shaft out and swap in the 2WD top shaft. There is a warning that the gears are a matched set and should be changed together. If there are readily available junkyards it might be possible to obtain all these pieces relatively inexpensively.

So besides the cover plate, all I need is to put the fuse in to keep it in "FWD".

Comments welcome!

I don't know if you gain anything with the FWD fuse, it will just full power the soleniod to "dis-engage" the clutch. You could just leave it, with no output shaft the drag of the fluid will be spinning the clutch pack non-stop anyway. I wonder if that rear sensor is a slip sensor for the rear wheels to determine if lock up is desired. I would just leave out the FWD fuse, minimal if any gains.

Another option is leaving the trans in full lock up AWD by unplugging the solenoid and using a proper resistor to mimic the resistance of the coil so there won't be any code from it missing. Also no real point, except simplification if you swap to a FWD top shaft.

The gears connecting the top and bottom shaft transfer power full time to the front diff, whatever previously powered the rear wheels doesn't matter, and will likely spin along with the top shaft no matter what you do with the FWD fuse or disconnecting the solenoid.

I like your cut, that is a perfect spot to make a flat plate cover. I think there are a lot of Auto donors out there and going auto is probably a simple choice for a lot of reasons (no clutch line and one less shift cable being good reasons). Watching this thread with interest.

[Xusia]

Could you just remove the clutch components of the center differential (they look like a motorcycle clutch)? That would leave the housing with race bearing intact (for support), but the RWD components would not spin.

[PhyrraM]

After looking at the pictures, I think what you did was perfect.

The FWD axle will get 100% power no matter what the RWD output does. It could spin or stay stationary without any effect on the front. You don't even need to use the FWD fuse now. Because the clutch drum has very low inertia, even if the clutch pack engages the amount of torque "taken away" from the front will be next to nothing.

Even if the computer sees a speed differential between the front sensor (on the ring gear IIRC) and the rear sensor (pictured), it will engage the clutchpack and the (now load-less) clutch drum will spin up instantly. The changes should be invisible to both the driver and the computer.

Nice job.

[Xusia]

It does look like a really nice job. It kinda cracks me up that you call yourself a shade tree mechanic! Your work thus far looks excellent!

[Aloha818]

Thanks PhyttaM, Xusia, Nubie, and RM1SepEx for your time to reply and comments!

AZPete replied to the question about the distance from frame to the center of the side driveshafts in my build thread, his pic is from a 2006 5MT in 818S;
image.jpg

This is almost exactly what I have with the trans pan sitting directly on the frame. So I guess I'm going to leave the frame under the trans pan intact. When the trans mount bushings arrive (for a BMW) I will build the height to be about 1/4" space, then raise as needed to keep the pan from contacting the frame under load. I also plan on adding adding a brace to the top of the engine to keep it stable.

[RM1SepEx]

That distance doesn't really matter, the CV joint can deal with any misalignment easily

[Aloha818]

That distance doesn't really matter, the CV joint can deal with any misalignment easily

Dan thanks for commenting.

I believe that the CV joint can handle some misalignment, as that is its purpose to move with the suspension travel. My main question in asking the measurement from a 5-speed transaxle is for a point of reference, as is my cast the engine assembly looks like it is too far tipped forward. The output shaft location is somewhat close to center and the engine mounts are just a little forward. My guess is that for every inch the rear of the trans is high the output shaft height will be about 1/4" high.

I set the bumper on to check orientation. Looks pretty good, but higher that what I've seen as the tail location on the 5-speeds;
image.jpg

Since I want as much room over the rear of the trans for exhaust and maybe a little storage, and then I'm concerned about the tilt of the engine and access to the trans pan, Im going to go ahead and rework the 1" square bracing under the trans and let the rear drop down about an 1 1/4".

I'll update as I make the changes.

[riptide motorsport]

Nice avatar, shaaawing................

[Aloha818]

Nice avatar, shaaawing................

Thanks! Gotta show Hawaiian Spirit right?

Today I finished modifying the rear section of the frame for the auto. For better or worse I felt that access to the pan and getting the engine/trans a little more level was more important that the cross bracing I had to remove;

image.jpgimage.jpg

Then I welded in another 1" tube between the rear lower control arms, and flipped the existing rear trans mount plate, I'm hoping enough steel to make up for what I removed. I'm not a great, or even good welder, but good enough to get it done. Then primed and painted;

image.jpgimage.jpg

I made a rear transmission mount from a piece of 1" angle and a new pair of transmission mounts that are for a BMW;

image.jpg

The bottom of the trans pan is now about 1/2" above the bottom of the frame;

image.jpg

And the center of the side driveshaft location is still close to 5", which is about the same as the 5-speed;

image.jpg

And now the engine sits a little more level and the trans pan is fully accessible and the trans mounts should help stabilize the rear and still minimize vibration;

image.jpg

[Wayne Presley]

I'm no so sure I would have taken the bracing out which supports the rear suspension when you could take off the rear mount and tilt the motor forward enough to remove the pan. You can remove the trans in less than an hour if needed, even on a completed car.

[Aloha818]

I'm no so sure I would have taken the bracing out which supports the rear suspension when you could take off the rear mount and tilt the motor forward enough to remove the pan. You can remove the trans in less than an hour if needed, even on a completed car.

Wayne, thanks for commenting. I should have mentioned I am adding a solid steel plate, bolted/removable from the bottom, to take the place of the cross bracing. Also, besides making the trans pan accessible, I needed to drop the rear of the trans into the area of the cross bracing and have room for the trans mounts.

[Wayne Presley]

Wayne, thanks for commenting. I should have mentioned I am adding a solid steel plate, bolted/removable from the bottom, to take the place of the cross bracing. Also, besides making the trans pan accessible, I needed to drop the rear of the trans into the area of the cross bracing and have room for the trans mounts.

I'd bolt in 8 per side and you are going to need to put sleeves in the tubes to keep the bolts from crushing the tubes. All and all I think it would be easier to have kept the X brace for the number of times the trans pan will need to be removed.

[Aloha818]

It's taken me a little time to get here, but I can report that a 4EAT auto will fit in the 818.

I took my first test drive today. I'm in a city environment so I can't really get up to highway speeds until I have it registered. I did get up to 45 mph with no issues.

Since the stock shifter cable will obviously not reach I bought a PCS Push Button Shifter. Works perfectly.

[Wayne Presley]

Does the ECU control the shifts or is the trans self contained?

[Bob_n_Cincy]

Does the ECU control the shifts or is the trans self contained?

The TCM in the 06 does all the shifting. This is out of the 06 manual.
tcm.jpg
tcm2.jpg
tcm3.jpg

[Aloha818]

Does the ECU control the shifts or is the trans self contained?

Wayne, I'm using the stock 2000 ECU and stock 2000 TCU. The PCS push button shifter just moves the stock linkage location from driver input/selection.

[Aloha818]

Since its been about two years (can't believe it's been that long ago) and I have more experience with my build using the 4eat, I thought I should give an update.

My previous comments about the mechanical modifications remain unchanged. Both the engine and the transmission were both operating on their stock ECU/TCU's.

After my first build completion and driving in October 2015 the trans ran and shifted as you would expect in a stock Subaru. After my first days of actual driving I made a list of things I wanted to change and put the car back in my shop and went back to work. I did not have any changes related to the trans on the list.

What was on my list was a complete rewire of the car including the engine harness, to get rid of all the Subaru harnesses and starts fresh with a generic harness from Painless and the harness from Haltech to go with the new ECU.

During my rewiring stage I asked advice from Level 10, PCS (Powertrain Control Solutions), IPT trans, and lots of reading on several forums about how to control the 4eat with an aftermarket ECU. All said it either couldn't be done, and/or they didn't offer control solutions. My local tech, John, from Hawaii Performance disagreed. He said for me to use the stock TCU, feed it power, ground, brake light and TPS inputs and it would work. I also have the front wheel drive "fuse" connected and the dropping resistor connected.

I've driven the car now about a hundred miles, at least 10 WOT from stop through all four gears, and 3 hours on the dyno with 9 full pulls. No hiccups yet. Shifts smooth and predictable in stop and go traffic, and snaps through the gears at WOT, even got a little bark from first to second.

It is a little different sound than manual shifting with turbo's, no unspooling/spooling at each gear change.

My first SCCA event will be April 3rd. I'll update again sometime after that with more observations.

[turbomacncheese]

Glad to hear this is working out. I'm looking at an auto build for my daily driver, and traffic on the 101 outside Phoenix is just...stupid. I'd really love to hear more about your experience, and any performance measurements you have.

Thanks.

[JB91710]

The Porsche 917/10 Can Am Car Replica I built has a 2007 Tribeca EZ30 and the Sport Shift 5eat. Actually, it has two EZ30 engines but that's another wiring/management nightmare. I have heard about the fuse business and hope that works. I was wondering if all that stuff in the back of the transmission can be removed and a plate attached to cover the end. I also wonder, will some kind of retainer be necessary to hold other guts in place.

Transfer GearsB.jpg20160604_102915B.jpg20160604_102946B.jpg011B.jpg021B.jpg

[maclonchas]

Aloha818,

I know it has been a while since you posted on this thread, but I was wondering if you have any pictures of the back plate you made for the 4AT. I followed all your steps in the thread, but this was the only picture missing.

Thanks


Bill

Since its been about two years (can't believe it's been that long ago) and I have more experience with my build using the 4eat, I thought I should give an update.

My previous comments about the mechanical modifications remain unchanged. Both the engine and the transmission were both operating on their stock ECU/TCU's.

After my first build completion and driving in October 2015 the trans ran and shifted as you would expect in a stock Subaru. After my first days of actual driving I made a list of things I wanted to change and put the car back in my shop and went back to work. I did not have any changes related to the trans on the list.

What was on my list was a complete rewire of the car including the engine harness, to get rid of all the Subaru harnesses and starts fresh with a generic harness from Painless and the harness from Haltech to go with the new ECU.

During my rewiring stage I asked advice from Level 10, PCS (Powertrain Control Solutions), IPT trans, and lots of reading on several forums about how to control the 4eat with an aftermarket ECU. All said it either couldn't be done, and/or they didn't offer control solutions. My local tech, John, from Hawaii Performance disagreed. He said for me to use the stock TCU, feed it power, ground, brake light and TPS inputs and it would work. I also have the front wheel drive "fuse" connected and the dropping resistor connected.

I've driven the car now about a hundred miles, at least 10 WOT from stop through all four gears, and 3 hours on the dyno with 9 full pulls. No hiccups yet. Shifts smooth and predictable in stop and go traffic, and snaps through the gears at WOT, even got a little bark from first to second.

It is a little different sound than manual shifting with turbo's, no unspooling/spooling at each gear change.

My first SCCA event will be April 3rd. I'll update again sometime after that with more observations.