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AW71 rebuild

googe said:


Does this seem like a probable cause to the tranny not upshifting?

I received new seals from Volvo but they are made from plastic (teflon?). I'll assemble the tranny and give it a shot?
Click to expand...

I changed all the o-rings (not B3) to new ones, changed the seal rings to Volvo plastic ones, exchanged my worn center support to one with less wear, did my best to align the center support and C2 AND put that little throttle valve to correct place -> the result is that the gear box is now upshifting perfectly. Thank you all for your help.

The next thing to figure out is the extremely rough engagement to R, D, 1 and 2 from P or N. I have modded the accumulators but is it too much?
 
tomasss said:
I am rebuilding the aw71 just now. The trans has 200k miles on it, and the clutches are in the half of life (thickness of new 2.3mm, minimum thickness 2.1mm, measured thickness 2.15 - 2.2mm). There are 23 of these plates in the transmission, and all are good. According to the complexity of the disassemble process for taking clutches out, I would recommend you just the rebuild of the valvebody. Yes, that is reasonable, rubber balls inside wears out and make the shifting bad.
Click to expand...
After complete dissasembly/assembly job I have done today with aw71, I have to quote my own words to correct myself.
All the clutches were in the half of the life, or better.
All the rubber o-rings on accumulators & clutch packs were in beautiful condition.
Plastic shims also like new.
What was damaged was steel oil rings on the output shaft, it was extremely thin and half of the ring was missing. Other oil rings were also worn, but nothing missing.

When I was in this job, I replaced everything - clutches, rubber seals, steel oil rings.
Now I i'm dissasembling the valve body - will post results later.
 
googe said:
I changed all the o-rings (not B3) to new ones, changed the seal rings to Volvo plastic ones, exchanged my worn center support to one with less wear, did my best to align the center support and C2 AND put that little throttle valve to correct place -> the result is that the gear box is now upshifting perfectly. Thank you all for your help.

The next thing to figure out is the extremely rough engagement to R, D, 1 and 2 from P or N. I have modded the accumulators but is it too much?
Click to expand...

sometimes after the accumulator mod they 'bang' into d, and usually reverse (reverse is a special kinda gear in most autos. my th350 with the manual valve body felt like it was dominating the world when you went from park to reverse). I'd wager you're stuck with this behavior.
 
tomasss said:
After complete dissasembly/assembly job I have done today with aw71, I have to quote my own words to correct myself.
All the clutches were in the half of the life, or better.
All the rubber o-rings on accumulators & clutch packs were in beautiful condition.
Plastic shims also like new.
What was damaged was steel oil rings on the output shaft, it was extremely thin and half of the ring was missing. Other oil rings were also worn, but nothing missing.

When I was in this job, I replaced everything - clutches, rubber seals, steel oil rings.
Now I i'm dissasembling the valve body - will post results later.
Click to expand...

yeah. I raided a toyota in the junkyard yesterday, all of the plastics, copper thrust washers, needle bearings, etc all looked perfect. I didn't measure the clutches (wasn't what I was after, but I did take them with me as spares), typically if they're not discolored they're not going to be out of spec. I think about the only things that wear out with any regularity in these boxes are the lip seals in the drums, and the steel sealing rings on the shafts. wonder if we could come up with some teflon rings from a domestic transmission, those apparently hold up better in higher load situations.

if you were inclined, you could probably dig up a selective thicker steel to bring the clearance in the clutch packs back to the snug end of the spectrum; however for a racing type situation some people believe it's better to have a little more space in there so stuff doesn't drag. this would be especially worth considering if you're rocking a higher rpm setup. The cutback valve and governor circuit would also be something to look at in that instance because they work together to bleed off pressure at higher rpm's and that kinda works against what we'd want.
 
Just finished the rebuild of the valvebody. All plastic balls were worn from 5.5mm to something like 5.3mm or so. So very little change from new. I changed them when I had dissasembled the valvebody, but next time I know I don't have to do that. By the way the balls are not rubber, but hard plastic, seems to me as very resistant.
Next time/next trans, I will do just the oil rings, input/output rubber bushing and metal extension housing bushing...
 
I have a question to these who have already disassembled the aw70/71. In the front overdrive clutch pack, there is one ceramic clutch between two metal plates, secured by thin lock ring.
overdrive_clutch.png

When I mount the metal and ceramic plates, and trying to secure them by the metal ring, I've found that after securing, the ceramic clutch is not able to move freely anymore. Is it ok? Because in all other cases (front clutch, rear clutch, brake clutch) the metal ring just secures the plates in place, but allow them to rotate.
 
check your clearances on the new friction. the rule of thumb is .010 (inch) per friction, but since that's a single you might shoot for .015. Also, if you take the two thick steels out you can normally put two or three standard frictions/steels in there (if you feel so inclined. this is not normally a problem area but other heavier duty versions of this transmission have two or three c0 clutches)
 
check your clearances on the new friction. the rule of thumb is .010 (inch) per friction, but since that's a single you might shoot for .015. Also, if you take the two thick steels out you can normally put two or three standard frictions/steels in there (if you feel so inclined. this is not normally a problem area but other heavier duty versions of this transmission have two or three c0 clutches)
 
The thickness of the old friction plate was ~2.1mm, so the new one is 2.3mm. What I am afraid of is, if I mixed the steel plate with some other, so now I have some thicker one in the front of overdrive.
The only question is - should the friction plate move freely when securing ring is installed?
 
not the whole stack per-se, once you get a bunch of those things in there it can get more difficult to turn the output shaft/input shaft, but it shouldn't be impossible and it shouldn't be extremely difficult. on an individual basis, you should be able to spin the friction with a pick or a screw driver with almost no resistance at all (save for the weight of the steels on top of it, which is additive in C1 and C2). Again, the rule of thumb is .010 (inches) clearance per friction/steel combo, unapplied.
 
Ok. In all other packs, I am able to turn with the friction discs without any problem. I just thought that this one works somehow different. But how it works was so unclear to me that I luckily asked here :nod:
It would be fun to find which two thick steels I had mixed :roll:
 
mm couldn't tell ya. there's a bunch of different sized steels floating around in these transmissions. they're not like a th350 or 400 where you get a standard size, some under-sized ones if you need them, and varying thickness pressure plates. I haven't quite figured out the reason for the snap rings in the drums though on the 71. there's also one in C1 (or maybe that's C2. whatever). seems like they would limit travel and lead to wear :shrug:
 
mm couldn't tell ya. there's a bunch of different sized steels floating around in these transmissions. they're not like a th350 or 400 where you get a standard size, some under-sized ones if you need them, and varying thickness pressure plates. I haven't quite figured out the reason for the snap rings in the drums though on the 71. there's also one in C1 (or maybe that's C2. whatever). seems like they would limit travel and lead to wear :shrug:
 
So I've completely dissasembled the trans again today. Now I am 100% sure that I didn't mixed the steel plates, because there is only one type of thick steel plates (~4mm) that fits in the front overdrive clutch pack. So, I called a buddy that already reconditioned some automatics, and understand how it works.
Problem is that the Volvo bulletin doesn't cover all versions of aw71 (I've already noticed it when I was comparing the valvebody diagrams with mine valvebody). So, scheme with the clutches is not accurate in my case.
The first steel clutch disc is not designed to be in contact with the friction disc - it is not flat, but it is designed to be springy - it is ?saggy? in the center diameter (sorry for my english). So, the correct sequence is: spring steel disc -> steel clutch disc -> friction disc (2.3mm wide} -> thin secure ring (1.4mm wide) around the friction disc (securing the steel clutch disc} -> steel disc with the tooth extension -> wide secure ring.
So, I had correct 6 parts, but wrongly assembled. When we assembled it this way, friction disc can moove freely, and the whole set make sense even to me :)
 
my gearbox now sounds like its a box of bees when its cold.
when it warms up the noise goes away.

im guessing, the noise is the pump. is there any sources on new pumps??
 
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