It's an AW71 party in my garage. Rebuild or JY?

Vehicle is a '90 740 Turbo. Currently I have two AW71s, one is in-car and one is on the floor. Both have issues.

Transmission #1: Is in the car, has the accumulator mod done to it... but it has issues. Overdrive is shot. It's not the solenoid/wiring, it's not the kickdown cable. It does shift into overdrive. However, it will slip out of OD and back into 3rd with even slight power. It can't even maintain 55mph on level road without dropping into 3rd. Has had issues with OD since I bought the car.

After the accumulator mod, more issues showed up... but only when the trans is warm. When warm, the car will creep forward in neutral just like you are in drive. Reverse is even worse; the car won't move in reverse without lots more power than necessary... sometimes I get into boost in reverse . And, when letting off the accelerator in revers the car immediately stops. It's quite like trying to reverse with the parking brake on. I am still DDing it lately and it's been fine, but I know it's a ticking time bomb... (I do have another car!)


Transmission #2: is on the floor, in pieces, from an '87 240 I believe. As far as I know, the transmission was good until I attempted to do the accumulator mod on it and one of the valve body gaskets disintegrated on me (the original idea was to mod this one, then do a trans swap. After I broke it, we did the mod in-car at don beyer on the lift).

So, my question: Should I buy the $80 RockAuto.com rebuild kit and try to rebuild the trans on my floor? Or, should I go pull another one from the JY and try my luck there? I have the service manual that was posted online, so I think I could rebuild it myself.... but I'm not sure if it is worth the hassle.

And... NO, I don't have any problems with a missing third pedal. There is a holset in my future and I don't want to have to go through the hassle of putting a T5 in a 740.

tl;dr: Rebuild aw71 myself or pull one from the junkyard? T5/manual trans not an option.

EDIT: more to the point, does anyone want to share their experience with rebuilding the AW71? Is there anything that can be done to make it more awesome than the accumulator mod?

Personally a 93+ AW71 with the upgraded tailshaft with the accumulator mod is your best bet. Already proven to hold 300+whp daily driven and hold for low 12's.

You could rebuilt it but if you were to I would use the High end friction material to help it hold and last longer. I have a stack of old hipo friction material here I would sell for cheap, I also have another trans with built guts in it also. I am tempted to build one strong one out of the two but I am just saving up and throwing away the $ on a 200r4 for my power goals.

Check out kennys threads on the aw71, a lot can be done but in the end holding more than 350-400whp might be the limit of the transmission.

Personally a 93+ AW71 with the upgraded tailshaft with the accumulator mod is your best bet. Already proven to hold 300+whp daily driven and hold for low 12's.

You could rebuilt it but if you were to I would use the High end friction material to help it hold and last longer. I have a stack of old hipo friction material here I would sell for cheap, I also have another trans with built guts in it also. I am tempted to build one strong one out of the two but I am just saving up and throwing away the $ on a 200r4 for my power goals.

Check out kennys threads on the aw71, a lot can be done but in the end holding more than 350-400whp might be the limit of the transmission.

Oh and sounds like transmission #1 has something wrong with the Valve body (I had the same issue with an old one and fixed it with another VB), find a working one and swap it on. Use a razor blade and remove all of the stock gasket if you do not want to take it apart and remove the entire thing as it is 100% not needed.

Sad thing to note but I am on AW71 #7, none of them killed from two much power, each had it's own stupid issues that caused it to be replaced and the sad thing is two of them were built transmissions but one of them was built wrong(the one I paid $1200 for) and because of that it died in 20k miles. Either way I know a little about them.

thelostartof said:

Oh and sounds like transmission #1 has something wrong with the Valve body (I had the same issue with an old one and fixed it with another VB), find a working one and swap it on. Use a razor blade and remove all of the stock gasket if you do not want to take it apart and remove the entire thing as it is 100% not needed.

Sad thing to note but I am on AW71 #7, none of them killed from two much power, each had it's own stupid issues that caused it to be replaced and the sad thing is two of them were built transmissions but one of them was built wrong(the one I paid $1200 for) and because of that it died in 20k miles. Either way I know a little about them.

Click to expand...

Wait... the valve body gaskets aren't needed??? The paper thin ish? In theory I could scrape the one I cracked and use that valve body?

Thanks for the good info. Also, is the high friction material a pain to install? I guess if you are rebuilding a trans then pain is relative...

beepee said:

Wait... the valve body gaskets aren't needed??? The paper thin ish? In theory I could scrape the one I cracked and use that valve body?

Thanks for the good info. Also, is the high friction material a pain to install? I guess if you are rebuilding a trans then pain is relative...

Click to expand...

IIRC you need a small press, maybe a drill press would work, to compress the clutch pack spring to get the snap ring out then remove the friction/steel plates.

I have a rebuild manual for that trans and can send it to you.

I am by no means an AW** expert but:

What is it about having a correctly built tranmission and torque converter is not worth the hassle?
Too many good engine combinations are held back by a misbehaving transmission.

Flushing and installing JY cores are a crap shoot at best. JY cores still need to be dissassembled and inspected if expected to deliver reliable and dependable service.

Rebuilding an AW71 is totally possible for someone who is mechanically inclined. If you are good at puzzles you should be able to rebuild an AW71.

A successful and lasting AW71 build is more than just replacing friction material clutches and steels with more aggressive material.

There are O rings, bushings, check balls and seals that should also be changed. There are also a few special tools that are necessary to complete the rebuild. What about air testing the transmission for proper movement?

The accumulator modification is recommended if you intend to drive your car with higher power output. you can vary the length of the rods in the accumulator to achieve a compromise between shock shifting and smooth engagement.

I agree with Mike (TLAO) a properly built AW71 should be able to withstand 300RWHP on a DD basis.

A model specific rebuild manual is a must. Read and understand the process before starting.

As a sidenote: I rebuilt my AW** and put over 100K miles on a rebuild with the accumulator mod. So far no problems. Also recommended is a torque converter rebuild. The clutch plate in the converter also wears out.

Just something to think about.

89740GLT

Well, that settles it. Sounds like I should really give the rebuild a go.

I have the large A43D PDF that's been passed around a few times. Going to sit down and give it a good once-through this afternoon and make sure I feel confident with the steps involved.

I don't have a spare TC, so I may see if I can grab one from somewhere.

If everything makes sense to me, I'll go out and pick up a torque wrench and some other bits "soon".

Will keep this updated. Thanks for the helpful info!

FYI the other trans is from 81 240 turbo - not 87.

I think the torque converter is still on the floor in the garage, but I did promise to send it to knox for sooper high stall converter cores.

Having rebuilt an AW71, my advice is this:

If your motivation is anything other than intellectual curiosity, don't do it.

It takes a long time and there is a decent chance that afterwords the transmission is still screwed up or you find out the root cause and in the end need another transmission anyway.

Those $80 kits only contain basic wear items that might repair a slipping transmission or one that shifts lazy.

There are so many 'real' wear items that are not included in those kits. As one example: one-way bearings.

You need no special tools except compressed air, a large vice, a helping 2nd hand, and a clean workspace. I ended up filling like 4 or 5 dish basins with parts to keep things organized.

Good luck with whatever you choose.

-Dana

SteveMD said:

IIRC you need a small press, maybe a drill press would work, to compress the clutch pack spring to get the snap ring out then remove the friction/steel plates.

I have a rebuild manual for that trans and can send it to you.

Click to expand...

im in the middle of rebuilding mine. could i get a copy of the manual???
pm me. thanks

SteveMD said:

IIRC you need a small press, maybe a drill press would work, to compress the clutch pack spring to get the snap ring out then remove the friction/steel plates.
I have a rebuild manual for that trans and can send it to you.

Click to expand...

drill press for the clutch pack spring? you don't need anything like that, a good pick will get the clutch pack snap rings out without any drama. The apply piston snap rings are another story but you have to have the frictions and steels out before doing anything with them. the one at the very back of the case is a real pleasure to work with. A welder and some mild steel will allow one to build the stuff required to compress the pistons.

beepee said:

Well, that settles it. Sounds like I should really give the rebuild a go.

I have the large A43D PDF that's been passed around a few times. Going to sit down and give it a good once-through this afternoon and make sure I feel confident with the steps involved.

I don't have a spare TC, so I may see if I can grab one from somewhere.

If everything makes sense to me, I'll go out and pick up a torque wrench and some other bits "soon".

Will keep this updated. Thanks for the helpful info!

Click to expand...

good luck. even when it's 'right' there's a lot that can go wrong, so take your time. shouldn't need any sprags or needle bearings, but if you have two identical transmissions, you can rob parts off one for the other.

oh and while you're in there, go get yourself a c2 hub and the center support brake cluster from a d50, holds more clutches at one of the weakest points in the box.

Ok, I'm scared. Guy at work knows someone local who rebuilds outta his home..

I have a very strong feeling that I will get impatient and eff this up... and I am NOT willing to do this twice.

Does anyone on the board build up AW71s? For $$?

just don't get impatient. take your time.