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Old 11-03-2019, 07:55 PM   #1
Fresh Air Inspector
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Default AW70 / AW70L Transmission Questions

Hello All,

I'm about to swap a low mileage 1988 AW70 from a 760T into a high mileage 1994 940 that has a AW70L. So, two questions;

1. Can I use the 'lock-up torque converter' from the AW70L in the AW70? If so, any points to take into consideration?

2. I would like to use the AW70L bell housing as it has the cast in opening for the crank position sensor. Can the bell housing be removed without removing the oil pump? If so, any points / recommendations to take into consideration?

As always, any and all feedback is appreciated.
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Old 11-03-2019, 08:09 PM   #2
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760t has aw71. If you 940 is na, it will have an aw71l, aw71 if its turbo. The torque converters don't interchange between non lock up and lock up transmissions. The aw71 from the 760t might have the cut out already but not sure on that one. If the bell housing has to be removed, there are 2 large o rings that should be changed. One is for the pump and one is for the bell housing. I have part numbers somewhere. You need to buy genuine Volvo o rings, do not try to cheap out.
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Old 11-04-2019, 09:15 AM   #3
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Hello white855T,

Woke up this morning and went 'oh s....', should have said AW71 for both. Thanks for catching my error. :-)

The 1988 bell housing does not have the cut out so I will have to use the one from the 1994. Appreciate the clarity regarding the torque converters, didn't realise that the turbos did not have the lock-up - interesting.

If you come across the part numbers for the two O-rings it would be appreciated.
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Old 11-04-2019, 03:44 PM   #4
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You can cut out and file the CPS notch in the older bell housing. Not as strong as the later housing with the factory cutout, but OK for my needs (click pics for full size):

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Old 11-06-2019, 06:33 PM   #5
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Hello bobxyz,

Thanks for the insight. Nice piece of machine work on the crank position sensor bracket. I'll use your option as a 'plan B'. I'm always a little leery of cutting away a reinforcement in a casting. I'm probably being anal. :-)

Hello All,

I've done some further research on the situation and found the following;

1. The AW70L or AW71L (lock-up torque converter), was not used in the Canadian or American market turbo models. However they were installed in the European models. The logic for this is the turbo boost response (quick) versus the torque converter lock-up disengagement response (slow). The lower highway speeds in Canada / US put too much strain on the lock-up circuit. The higher highway speeds in Europe did not this create problem. Interesting.

2. As already mentioned by 'white855T' the 'lock-up' (type L) and 'non lock-up' torque converters are NOT interchangeable. Why, because this is not the only difference, the valve bodies are also different. So, if you want a 'lock-up' torque converter, buy an AW-70L or AW71L.

Hope it helps.
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Old 11-07-2019, 04:29 PM   #6
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if you're not going to drag ass on the interstate, the later aw71L lockup transmissions work fine in turbo cars, however as has been noted, the converters are *not* interchangeable between lockup and non-lockup transmissions.

If you want to go with a lockup transmission you should source a 71L from a later model 940 NA, the 70L transmission is not the same and will not hold up in a turbo application (neither will an aw70 for that matter). As far as the notch for the crank sensor.. you're highly unlikely to split the bellhousing before the transmission internally lets go from power, so I wouldn't give a second thought to cutting out a notch for the crank sensor.. I've done it a couple of times in fact, and not nearly as nice as the above, and not had any negative results later. The transmissions may not have been long-lived, but that was for reasons other than the notch lol
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Old 11-07-2019, 04:39 PM   #7
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Canada got AW71L in 940Turbo 1993?-1995 or 1992-1995 I forget. We didn't. Pity.

Biggest complaint using the 71L from a late N/A 940 is just how horribly slow the converter stall is.
I'd always look for one from a 16V and 4.10 gears to go with to make it tolerable on the highway with the 4-cylinder.

Towing in 3rd with AW-7x with 4.10s if the car tows won't be much fun at interstate speeds.
Can't put any load on the AW7x OD, lockup only available in OD (can't tow in 3rd locked up).

Regardless, notching the bellhousing and using the AW-71 from the 760T in the 940 shouldn't be a problem, but non-lockup & lockup converters don't swap/interchange, as stated.

IIRC the converter housing swaps lockup or not, re-centering the pump and re-sealing the bolt heads takes a little doing, but far from "difficult" imo.

I'd sooner do that carefully and replace the pump o-rings...IIRC the pump & its bolts can stay and you can swap converter housing only from your late AW71L onto the AW71 just fine.
Converter & pump different, but I don't remember the housings being incompatible.
Replaced a bunch of those stupid o-rings taking housings on and off, as well as couple damaged pumps.
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Old 11-07-2019, 04:51 PM   #8
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housing is the same from a bolt pattern/fit perspective, wouldn't take it off vs notching though. if you pull the housing off (assuming you can, pumps get rusty and crusty and make life difficult) without removing the pump and OD unit, you risk scoring up the housing and damaging the large o-rings. if you pull the housing/pump/od unit, you risk a number of parts falling out and further FOD introduction to the transmission (as well as potentially unseating C1 and other issues).

if you seal things up decently well around the input shaft and pump, you spend about 5 minutes notching it out and hose it off to remove metal/dust/etc, aand then you're done and re-installing the transmission.
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Old 11-07-2019, 05:21 PM   #9
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^Hm, those o-rings are almost always shrunken to the point that when the car's shut off there'll be a lake under if if the car/trans sits any length of time up here.
Not sure if it's unique to our climate or what, but any time they come out the converter housing comes off and it gets those 2 o-rings if unknown/suspect/any evidence of a leak there.
Not much fun to change, and if it weren't such a frequent issue I'd be much happier leaving the converter housing alone/not removing it.
But as a maintenance issue I'm almost always having to remove them to change the o-rings and IIRC all 4-cyl AW7x housings are compatible, so I'm there anyway, might as well swap the housing if notched housing or sealed housing is required (this is just swapping/recombining them between cars, no idea for going faster).

IIRC the pump/OD/C1/C0 mess all stays bolted up tight with the sealant/gooped bolts undisturbed, but getting the housing off without scoring it up does take a little doing. Usually coordinated use of penitrating oil and 2 deadblow mallets simultaneously on each side.
Pump faces don't tend to be especially rusty up here.
Too cold for the air to hold much moisture?
No salt air inland?
No road salt?
Just gravel/snow/slush/rain?
Leaky engines/cars keeping that stuff in a cloud of oil?
Low UV days/super low sunlight intensity/cold nights/little moisture coming up from the ground
IDK?

All said, if you're really sure it isn't leaking from those 2 o-rings, I'd notch it too! .
The notching isn't likely to be an issue for strength/cause other problems in any meaningful way
Disturbing less makes sense by default.
But weighed against installing a trans & having a lake of oil under it on every shutoff due to 2 cheap seals/parts only accessible with it out & those o-rings typically being very hard/shrunken to the point that on cool down they fail to seal and the converter draining/filling the pan above the gasket on level ground makes for a giant leak on most overnight.
Rarely observed one that's corroded/totally dry., will take your word for it.

Last edited by Kjets On a Plane; 11-07-2019 at 05:49 PM..
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Old 11-08-2019, 10:13 AM   #10
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no salt here, but we have buckets of humidity year-round. the pumps are just cast iron, I've never seen one that wasn't rusty and crusty unless it had a converter seal leak at a very early age lol

I've never had those two big o-rings leak, if it was that much of a maintenance concern I think I'd be inclined to augment the sealing with a thin bead of rtv between the case pieces.. it's just a gravity leak area. but if they shrunk, I could see how that'd make a mess.
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Old 11-08-2019, 04:53 PM   #11
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Hello All,

Great input. :-)

Question - you talk about 2 o-rings but I only see one. An oil seal where the torque converter slides into the pump housing (item 6 in the link below), and a large o-ring for the pump housing (item 33). Where is the 'second' o-ring?

I assume replacing the oil seal (item 6) along with the rear crankshaft oil seal is standard practice with any transmission swap that doesn't include changing the bell housing?

https://www.volvopartswebstore.com/s...rimLevel=24652

Based on your feedback I will go with the 'notching' of the bell housing.
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Old 12-03-2019, 04:25 PM   #12
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Hello All,

Thought an update would be helpful for those faced with the same challenge.

In the end I swapped the '94 AW71L bell housing (w/crank sensor cut out), for the '88 AW71 bell housing (no crank sensor cut out). The time and expertise is not that much; ~45 minutes, basic tools, soft touch and CLEANLINESS!

You will require 3 Volvo parts (thanks to white855T for providing);

1239673 - pump housing to planetary gear housing O-ring
1340096 - oil seal for torque converter flange
6814812 - bell housing to transmission case O-ring

Make sure you THOROUGHLY clean the area around the pump housing bolts before removing them. Same story for the joint between the bell housing and the transmission case. Removing the bell housing from the planetary gear housing is a delicate operation as it is a VERY tight fit and wants to take the gear housing with it. Gentle tapping with a plastic / fiberglass or nylon hammer around the perimeter of the bell housing should see it start to move forward. Having someone or something keep the pump / planetary gear housing in place will save you the frustration of trying to line-up and reinstall the planetary gear housing.

Install the torque converter oil seal before installing the pump housing along with its new O-ring. Easier to do when it is apart. Take note as to where the original oil seal sits in the housing before installing the new one to ensure it will sit in the correct location. Don't forget to remove the old and add new Silicone sealant to the pump housing bolts as required. Some of the tapped holes are exposed to ATF. Torque all bolts to spec. Go to;

http://www.volvotips.com/

On the right side of the page are the available service manuals. Go to the drive train section for the correct torque specifications.

Check the bell housing and planetary gear housing for any dirt or debris. Clean thoroughly with brake clean and a link free cloth. Install the new bell housing O-ring and thoroughly lubricate the planetary gear housing - it is a VERY tight fit and sliding it back on requires all the assistance you can give it.

Ensure the bell housing is square to the transmission case as well as lined up with the bolt holes before trying to slide it on. Tapping with a hammer is risky as you can not easily control if the housing remains square to the transmission case. We found that setting the bell housing on a piece of plywood on a concrete floor, having one person lower the transmission case onto the bell housing while the other ensures everything is aligned, works well. You can then use the weight of the transmission to drive it into the bell housing. Only lift it up a few centimeters before letting it hit the plywood squarely. Have your helper monitor movement - the force required when 'hitting the floor' will be dictated by the amount of bell housing movement. Go slowly and carefully - the bell housing will seat eventually. As it approaches the transmission case, keep checking the bolt hole alignment and make corrections as required. In my case we had to do some 'GENTLE crowbar leveraging and hammer tapping' to fine tune the bolt hole alignment. Torque all bolts to spec - see link above for where to find this info.

After installing the '88 AW71 and filling with fresh ATF (I prefer Dexron IIIH [final version of this ATF type]), I took the 940 for a 70km test drive. Despite only knowing the mileage and no service history of the AW71 (188K km), it proved to work exceptionally well, smooth but firm shifts, no unwanted noises and no leaks. Definitive improvement over the original (~350K km). Not having a lock-up torque converter will take some getting used to but I recently swapped the 4.10 rear axle for a 3.73 so the increase in highway RPM will be minimal.

Hope it helps. If you have any questions, please let me know,
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