AW71 vs AW71L

Getting ready to do my first turbo swap. I'll probably have a million questions for the group. First up is transmission related. I'm using the driveline from a 1991 940SE Wagon. it's got a aw71 with a trans cooler plumbed in front of the radiator and IC. Do you guys carry that over to the 240? If not what do you use as a trans cooler? Also:

- When I disconnected the driveshaft some trans fluid came out of the tail piece. Like not the seal area but from inside the area where the flange hits the shaft. Is that normal?

- I was expecting to have a aw71L coming out of 91 940SE, but it sounds like the L wasn't offered on turbos. Is that correct? I'm going off the label on the side of the case that just says AW 30-71

- I can probably search around on here for this, but I picked the SE as the donor car because it has the locking diff. But when I spin on rear wheel, the other wheel spins in the opposite direction. on LSD cars I've had (BMW's), you can tell it's a LSD because both wheels spin the same direction. Is there any other way to tell if this car has the locker (G80?)

Thanks!

-Regarding the fluid coming out of the tailshaft housing: that's normal for fluid to come out- the seal rides on the machined part of the yoke to keep fluid in.

-AW71L I think was only offered on 16v cars? I think? They never put a 71L behind a turbo so the spool up at highway speed would be better and wouldn't bog down

-Most effective way to tell it just pop of the rear gear cover. The G80, being a spring/governor/lock unit, requires almost a "jerk" to engage it.

vwbusman66 said:

-AW71L I think was only offered on 16v cars? I think? They never put a 71L behind a turbo so the spool up at highway speed would be better and wouldn't bog down

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Not sure what engineering rationale was behind lockout/no lockout aside from allowing torque converter float in overdrive on a turbo car, in order to preserve the function of overdrive. I have a '91 turbo with a 71, and a '93 non-turbo (8 valve) with a 71L. Lockout likely also improves highway cruising fuel efficiency.

Awesome thanks guys. What about the trans cooler? On my na 240 I'm always boiling my trans fluid. That's on a aw70. Id like to add a cooler to the FT setup. I can just see if it will fit when I put it all together but just trying to plan ahead to reduce downtime during the swap

The lockout clutch isn't super strong, so all sorts of part-throttle boost in lockup would probably damage it eventually. I swapped an AW71L into my 244, from a canadian 940 NA, and it was HORRIBLE with the turbo engine. I had a 3.54 (1030) rear end, and swapped to a 3.73 (1031), and that didn't help at all. Most of the L cars had a 4.10 rear end IIRC, to compensate for anemic highway cruising. It seriously felt like a dog, and cruised below 2000 RPM at 60kph (hwy limit here). I was constantly on the throttle to keep it cruising in the sweet spot, and my fuel economy didn't improve at all. The throttle plate was shut too much in order to maintain cruising speed with the 3.54 and 3.73 gears.

Ah right on. I was looking fwd to perhaps some better mpgs but your experience confirms why they didnt put the L in turbo cars.

My experiences might differ slightly to yours, if you're able to cruise higher than 60mph, lol. That's our hwy limit up here, and our 'rural' road limit is 50mph, which was even worse for the lockup. I'd be popping in and out of 'lockup', while trying to hold speed. At 70+mph there might be gains, but anything slower than that would be pretty awkward.

Good point. I regularly push my NA 240 at 80-90mph, which often leads to a fine mist of ATF on my back window. That's why I'm trying to make sure my +t swap is all tidy.

AW71L isn't terrible. I run mine through Oaktown quite frequently.... Yes, you can tell when lockup is engaged, but it's not a big deal. Picked up like 1mpg, still using my stock 1030 rear end on my 740T

1mpg... Alright not stressing on the lack of the L then. I'm off 40th/Market, turn some tight ones next time you're passing through I'll hear you running.

getouttamyway said:

What about the trans cooler? On my na 240 I'm always boiling my trans fluid. That's on a aw70. Id like to add a cooler to the FT setup. I can just see if it will fit when I put it all together but just trying to plan ahead to reduce downtime during the swap

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Many people have added trans fluid coolers to 240s. The 740 Turbos got them stock but otherwise they were an accessory for a 240/740, mostly for towing or hot climate. A little bit of everything has been done it seems. Some people use just the in-radiator cooler, some use both with no thermostat, some use only an external cooler, some people use both with a thermostat. Doesn't seem like one setup melts aw-71s more than any other, so do what you like.
Since you have the 740 cooler you can just drill some holes and mount it to the 240 in the same location ahead of the radiator it is in the 740, and then drill some more holes to pass the lines through the metal core support and around to the radiator lines. That's basically what Volvo did for the 240 accessory, but with flexible hoses instead of the hard lines the 740 got. I'm working on that right now in a 260 and not sure if I'll use the 740 lines or have to create some custom ones. With the less wide radiator of a 240 it looks like the 740 hard lines will work with no changes.
Only after typing this did I realize I'm not sure if the 1991 940 setup is the same as the 89 740T cooler, but I bet it is.

The accessory 240 transmission fluid cooler that was available had a thermostat on the outlet from radiator to transmission that bypassed the external cooler when the fluid was cool. Seems like lots of aftermarket units are available that do the same if you want it. I'm still deciding which I will do depending on how I have to route my lines.

The 740 cooler is a nice unit, but if you are already cooking fluid in your other car you may want to just buy a big setrab unit and mount it anywhere with some custom lines. Below the bumper in the ducts from the air dam is popular.

Right on. I'll see if I can fit the 940 unit in the 240. It sounds like it's possible from your post.

I also never really paid attention to the quality of ATF, I usually just use cheap stuff but I'll see if other products have a higher boiling point like performance brake fluids do.

Our '93 240+T falls on its face once the torque converter kicks in at 50 mph. 2K rpm makes for no power even with a tiny 13c.
Im really wishing I would have used a regular 71 instead of the locker.

Wren said:

Our '93 240+T falls on its face once the torque converter kicks in at 50 mph. 2K rpm makes for no power even with a tiny 13c.
Im really wishing I would have used a regular 71 instead of the locker.

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Need to make more go powahh! Or, just get the trans to downshift.

Wren said:

Our '93 240+T falls on its face once the torque converter kicks in at 50 mph. 2K rpm makes for no power even with a tiny 13c.
Im really wishing I would have used a regular 71 instead of the locker.

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^
This. They understand the pain.

yall drive too damn slow