CIS Subaru

Does anyone know where I could buy an external center diff? Or, have any ideas for "making" one? I'm building my '80 Hatch into a street racer of sorts (autocross?), and I'd like to eventually put a FT4wd or AWD 5spd into it for better power distribution. Since the FT4wd trannies are a little hard to get, I wondered about the possibility of creating FT4wd by adding a center diff to a PT4wd tranny? I'll probably stumble onto a FT4wd box and use that, but I'd like to explore this possibility. So far, my only idea has been to modify and mount a Justy rear diff sideways... Not too practical, but it could work. (I could weld one of the side gears to the carrier and remove the pinion gear completely, then cut the front housing down and cap it off.) Just dreaming here, all thoughts are welcome.

After looking around on the net, it appears that the general consensus is: FT4wd usually refers to systems with an open center diff. AWD usually refers to systems with some sort of lsd center diff. Systems that are primarily 2wd, and activate the other 2 wheels only when slippage occurs at a primary drive wheel are called either FT4wd or AWD depending on who you ask. Subaru AWD is vastly different between Autos and 5spds. At least in gen 1 Legacy models, the auto tranny AWD system was of the 2wd until AWD is needed variety. (Hence the 90/10 torque split). On these models, it is nearly impossible to spin a rear wheel when neither front wheel is slipping. 5spd models were true AWD all the time. So I guess it's a judgement call as to whether the EA82 auto FT4wd was really AWD or not.

oops, nevermind

So what you're saying is that you agree with me that the EA82 FT4wd auto cars could rightfully be called AWD?

I ran into this same issue with my spider intake. Does your distributor have 1 or 2 vacuum lines? Mine had 2. You should be able to get away with plugging off the "retard" line, and connecting the advance line directly to the base of the throttle body. I had some other issues that resulted in my current use of a 1-line disty, but I don't think this should be necessary for you.

As Mick said, your binding is front-to-back, so you will need a device that allows front-to-back speed variation. Any type of rear differential is only going to affect side-to-side speed variation in the rear. A viscous coupling sounds like a good plan, and probably alot of work. It could be positioned anywhere between the tranny and the rear diff, so you could choose whatever location seems best.

The diff lock cannot be the answer. The WRX STi models have center diff locks, and some Audi Quattros had locks for both center and rear diffs. I've never heard anyone refer to these cars as anything but AWD.

I thought that center diff=AWD? As not to hijack this thread, I'm starting a new one on this topic: http://www.ultimatesubaru.org/usmb/forum/showthread.php?s=&threadid=12957

I believe I've seen this posted before, but my search did not find it. What is the technical difference between FT4wd and AWD (not limited to the world of Subarus)? I have been told in another thread that the EA82 4EAT FT4wd tranny is NOT considered an AWD tranny. WHY NOT?? After all, there are many varieties of AWD. Even the current Subaru AWD trannies are radically different between Auto and 5spd versions. I know that the EA82/ER27 FT4wd 5spd trannies had open center diffs, so I can see why these might not be considered AWD by some people. I was under the impression that the 4EAT FT4wd tranny operated in a very similar way to the later EJ AWD trannies. In what way is this not true?

If you want to put the EFI pump under the hood, I suggest getting a "surge tank" from a VW Fox. In the following picture, it is labled as a "fuel resevoir": http://usmb.net/repair/cis/Fuel%20Pump%20Assembly%20Diagram.JPG You would be connecting it just as the labels indicate. I tend to agree with the others here that you might be best off just putting the EFI pump in place of the original one. Subaru MPFI doesn't run anywhere close to the 80psi that CIS uses, so you should be fine if you just replace the rubber sections with fuel-injection hose from a parts store. Either way should work fine, so it's really just a question of which one seems best to you.

If your car has the 4-spd auto (and I expect it does), then it really IS AWD (full-time 4wd). '88 was the first year for that transmission.

OOPS!! I just realized that I was talking about the dual-carb EA81. I don't know if the dual-carb EA71 is any different from the normal one.

I can't tell from the serial#, but I can tell you what to physically look for. From the pics I've seen on the net (If I can find 'em I'll email them to you), the dual-carb engines had the intake and exhaust valves in the EA82 positions. This means that the intake valves are directly under the intake port in the head, while the exhaust valves are at the front and rear of the head. If you look at a normal EA71 or EA81 head, you can see where the intake runners continue from the intake ports out to the valves. On the dual carb version, these runners don't exist. Also, the exhaust ports on the dual-carb heads are oval and have a thin divider splitting them. Because the exhaust ports are separated by that divider, it was possible to build a true header for these engines (I have a pic of this somewhere too). I'll be quite jealous if this is a true dual-carb engine. (heck, I'm already jealous of the manifold alone). Congrats.

John, I've had front wiper issues before with Soobs that have not moved in a long time. It seems that the motors "seize" from lack of use. I just turn the switch on (high) and move the wipers by hand. As soon as they "break" loose, they continue to work just fine. If this is not your problem, you'll need to check for power at the wiper motor and troubleshoot from there.

Brian, I agree with whoever it was that said you'd be okay by just eliminating the turbo and swapping in the NA pistons. The boost/vacuum sensor swap also sounds reasonable, except that I don't remember any sort of pressure sensor on my '85 MPFI car. You'll probably need to make a custom intake duct to go from the MAF to the throttle body, but that's no big deal. I have an MPFI non-turbo "elbow" from an '85 that fits to the throttle body if you need it. It'd be a shame to cut the turbo one. The way I look at this is: a turbo car does not always have boost, and most turbo cars will still run (poorly) with a seized turbo, SO I see no reason for this car to have any problems running with no turbo and 10:1 compression AND I fully support your decision to try this. I don't know if you've thought of this, but you'll have a knock sensing ignition too! (unless the disty curve doesn't work out and you have to swap in a NA disty.)

If it's carbed, it's probably not really a GL-10. Does it have all of the GL-10 options? -Digital Dash -Trip Computer -Cloth Headliner -Height Adjustable Driver's Seat -Rear Head Rests -Gravel Guards on Rear Doors (<- this one is key) Sounds to me like maybe someone put a GL-10 badge on a GL, but '85 was a weird year.

Miles, that sounds like a great solution if it works. Where would that leave the vac advance pointing? (sorry for stomping on your thread, Noah)

My first Subaru ('85 GL-10) would not run without the oil cap!

Thanks. I'll have to take a look at this. Maybe I can work around it? (maybe put the manifold on backwards?)

Pencil me in. Looks like a 12-13 hr. drive, so scheduling is an issue. If I can make it, I'll drive the CIS Wagon. It's got a mangled fender, and my formerly imaculate engine is now pretty filthy, but it's probably still the most interesting car I own.

What engine are you trying to put the EA82 manifold on? The High-Po EA81? How exactly does it not fit? I was planning to use an EA82 carb on one of my EA81 projects, so I'm very curious.

Check ebay. I'm pretty sure I saw some there recently.

http://www.airflowperformance.com/airframe.htm I bet it's pretty pricey, but I found the non-electronic nature of it interesting. I emailed them, but I can't really justify throwing out the $10 for their catalog right now.

It's an '80 or '81 (same thing). My '80 EA81 Hatch (square headlights) has that very same grill. My '81 DL Hardtop (round lights) has the same shape, but a smaller badge. The later model EA71/EA81 cars that had individual round or square lights had different grills and corner lights than these early ones and different from each other. (naturally, the dual-rect. light models had their own grills)

I've heard that EA71 heads fit on EA81 blocks, so I'd assume that the reverse would also be true. If that is the case, one should be able to put EA81T heads on an EA71 block in order to add fuel-injection and a turbo. Why? Well, the EA71 has a shorter stroke and thus will rev up quicker than an EA81. I believe that this would be a nice quality for a turbo engine. As a bonus, this engine would likely get better gas mileage too. Miles, you're just a little off about the "fat case" engines. There were actually 3 major versions of the EA71 in the USA. The '70s version has the funky external water pump. The "fat case" models look much more like an EA81. I believe that these were introduced in 1980 with the EA81, but they may have actually shown up in '78 or '79 (I'm not at home right now, so I'm working from memory). In 1984, a third EA71 variation appeared. These late models use the same bellhousing shape as the EA81, as well as the same valves. I've heard that there was yet another version available overseas that had hydraulic lifters.