- Location
- MilkyWay Galaxy
Would those pistons be in the valve body? I just realized I could probably swap valve bodies between the two AW4s a lot easier that swapping the entire AW4.
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87 AW4 1 st gear is slipping bad now
- Thread starter Ecomike
- Start date
no, the valve body sends fluid pressure to push on the pistons, which in turn engage or disengage the bands to engage or disengage the different gear sets.
When it starts to leak past those pistons you're tearing the trans apart to get at them, so might as well do the compete rebuild because you'll be there.
A good picture on the how stuff works page.
http://www.howstuffworks.com/automatic-transmission10.htm
3rd picture down is what you're looking for.
- Location
- MilkyWay Galaxy
Tested the bare solenoids, got 13.0, 14.0 and 15.0 ohms, on solenoids #2, 1 and 3 respectively. I have not checked the wires or TCU voltage yet.
I tightened up the hold down screw on the throttle cable on the side of the AW4, which was literally about to fall out. Can't help but wonder if that was the problem? As I recall it has some control of over fluid pressure? The bolt had unscrewed about 1/2" and was hanging on by a thread or two. Question is would that have affected the throttle cable travel distance? If yes, would have caused, or added to the problem?
I tightened up the hold down screw on the throttle cable on the side of the AW4, which was literally about to fall out. Can't help but wonder if that was the problem? As I recall it has some control of over fluid pressure? The bolt had unscrewed about 1/2" and was hanging on by a thread or two. Question is would that have affected the throttle cable travel distance? If yes, would have caused, or added to the problem?
joe_peters
NAXJA Forum User
- Location
- Grants Pass, OryGun
Well, it does effect pressure so I would be interested in what it would do after being tightened.
Only way to tell for sure is to button it up and fill it up--might be a lot of work without a "happy ending."
Only way to tell for sure is to button it up and fill it up--might be a lot of work without a "happy ending."
- Location
- MilkyWay Galaxy
I had the dirty filter too, and black greasy muck in the pan bottom, dirty fluid after TransX flushed and cleaned things. But the Reverse still worked fine, so yes, it might not work. I am still temped to look at swapping the valve bodies, and then trying it, before moving on to a complete swap or repair. And I guess I still don't know if the TCU or wiring had a problem yet, till I refill it and run it.
I doubt I will swap the entire thing or pull it and rebuild it with out at least one re test.
- Location
- MilkyWay Galaxy
I have forgotten the various spline count variations, etc, is that off of a 4x4? Is that what the 21 spline count tells me?
I may be wrong but the AW4 manual makes it look like I could use a blow off gun to force the pistons out with just the valve body off? But another friend of mine (who has rebuilt an occasional auto tranny here and there of the years) told me today that the clutch packs also an o'ring piston which maybe be worn and leaking. I will do some manual reading this weekend. I have also decided to live test the solenoids with a battery to make sure they actually work, and not seized up mechanically.
You can force the pistons out maybe with air, you can for sure test the actuation with compressed air.
The clutch pack O ring is what I was talking about earlier, and is what you see here:
The pistons that can be moved/forced with air are the ones that move the bands here:
Early 4WD AW4's had a 21 spline output, somewhere in mid 89 they changed it to a 23 spline output like the 5 spds. I've no idea what 2wd ones had.
The clutch pack O ring is what I was talking about earlier, and is what you see here:
The pistons that can be moved/forced with air are the ones that move the bands here:
Early 4WD AW4's had a 21 spline output, somewhere in mid 89 they changed it to a 23 spline output like the 5 spds. I've no idea what 2wd ones had.
- Location
- Rainy side of Washington
2wd ones all had 27 spline outputs to match the slip yoke, from what I heard back from a guy who asked if he could just cut the shaft down a bit.
RCP Phx
NAXJA Forum User
- Location
- Phoenix,Az
Yes,a total tear-down would be required for a 4wd conversion.It is easy and cheap to do though.
- Location
- MilkyWay Galaxy
"Early 4WD AW4's had a 21 spline output, somewhere in mid 89 they changed it to a 23 spline output like the 5 spds. I've no idea what 2wd ones had."
Thanks!
That sounds like one of the things I recall hearing a while back. So there is 21, 23 and 27 spline scattered through out the landscape, and 2WD/4WD shaft length, rear housing length difference. And if true it would limit me to using a 4WD from 87-88 it sounds like, with out worrying about other issues. IIRC there was a switch in the Transfer case, that had to do with the switch from 21 to 23 spline count on the 4WD AW4 output shaft.
Thanks for the pictures and break down on which piston O'rings....
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So help me play devils advocate here. But first a question. Does the fluid pressure (high pressure) engage the clutch, or does it dis-engage the clutch by over coming some sort of spring pressure?
(2) The one consistent thing I would see the last 3 winters was that on cold start up, and only the first early morning cold start up, the car would not move in forward, 3 or 1-2, until the engine and tranny fluid (through the radiator), would warm up the T-fluid some. After that I had no problems all day long. Then once the car began moving forward (like a valve suddenly opened or closed, shifted) it would work perfectly, all gears, all day. And the reverse always worked immediately, never had any trouble with it, never had to warm it up. The last 3 summers, I never had any problems! Only the cold winter mornings.
Now, the T-fluid should have a higher viscosity when cold, and lower when hot, and an o'ring seal leak should leak more with low viscosity hot fluid than cold, high viscosity fluid I think? Unless T-Fluid is one of those special non-Newtonian fluids that increases viscosity as it warms up or shears? And this link says it is not Thixotropic:
http://en.wikipedia.org/wiki/Thixotropy
"Clutch-type automatic transmissions do not use fluids with thixotropic properties. The oil in automatic transmissions is used solely for hydraulic actuation and there are no thixotropic properties used in the process of gear change or actuation of clutch packs"
So if the piston cup leak is the source of my problem, would it not be worse in hot weather, than in cold? Trans-X additive (which I had used lately) typically swells the seals a little to help them seal better, but also dissolves varnish (that might have been helping the seal), and at first thins the T-fluid a little. But some of the Trans-X is volatile, and eventually evaporates.
I am leaning towards a sticking valve, that is sticking when the fluid is cold and sticky, varnish build up sort of problem, or one of the things I am already fixing, like the throttle cable hold down screw being loose enough to nearly fall off, or a sticking solenoid (which I will tests for next), or some other temperature related issue that started out not working just when cold.
Now, changing thoughts here, if the piston o'ring seal in the clutch was the problem, then adding Lucas Tranny additive, the supper thick version, might increase the viscosity, and help the o'ring seal? But I would think cold viscous T fluid would do that do too, which counters the problem history of the last 3 winters?
Reminder, we have a 1996 company XJ automatic that was slipping (or something that resembled slipping), that stopped slipping after Lucas T-fluid (the one that is designed to help stop leaks and stop slipping), was added months ago.
I think I may need to check my TPS too, just to be sure it has not been screwing with me, since I have yet to check it with out the TCU attached. I made that mistake for a long time once before, and discovered what I thought was Tranny problem was a TPS with a funky ground and a funky output just on the TCU side. Be interesting to know it the TPS-TCU side output is used in reverse, or just in forward? HMMM?
Lastly, a reminder that reverse was still working perfectly, before I dropped the pan.
Thanks!
That sounds like one of the things I recall hearing a while back. So there is 21, 23 and 27 spline scattered through out the landscape, and 2WD/4WD shaft length, rear housing length difference. And if true it would limit me to using a 4WD from 87-88 it sounds like, with out worrying about other issues. IIRC there was a switch in the Transfer case, that had to do with the switch from 21 to 23 spline count on the 4WD AW4 output shaft.
Thanks for the pictures and break down on which piston O'rings....
--------------------------
So help me play devils advocate here. But first a question. Does the fluid pressure (high pressure) engage the clutch, or does it dis-engage the clutch by over coming some sort of spring pressure?
(2) The one consistent thing I would see the last 3 winters was that on cold start up, and only the first early morning cold start up, the car would not move in forward, 3 or 1-2, until the engine and tranny fluid (through the radiator), would warm up the T-fluid some. After that I had no problems all day long. Then once the car began moving forward (like a valve suddenly opened or closed, shifted) it would work perfectly, all gears, all day. And the reverse always worked immediately, never had any trouble with it, never had to warm it up. The last 3 summers, I never had any problems! Only the cold winter mornings.
Now, the T-fluid should have a higher viscosity when cold, and lower when hot, and an o'ring seal leak should leak more with low viscosity hot fluid than cold, high viscosity fluid I think? Unless T-Fluid is one of those special non-Newtonian fluids that increases viscosity as it warms up or shears? And this link says it is not Thixotropic:
http://en.wikipedia.org/wiki/Thixotropy
"Clutch-type automatic transmissions do not use fluids with thixotropic properties. The oil in automatic transmissions is used solely for hydraulic actuation and there are no thixotropic properties used in the process of gear change or actuation of clutch packs"
So if the piston cup leak is the source of my problem, would it not be worse in hot weather, than in cold? Trans-X additive (which I had used lately) typically swells the seals a little to help them seal better, but also dissolves varnish (that might have been helping the seal), and at first thins the T-fluid a little. But some of the Trans-X is volatile, and eventually evaporates.
I am leaning towards a sticking valve, that is sticking when the fluid is cold and sticky, varnish build up sort of problem, or one of the things I am already fixing, like the throttle cable hold down screw being loose enough to nearly fall off, or a sticking solenoid (which I will tests for next), or some other temperature related issue that started out not working just when cold.
Now, changing thoughts here, if the piston o'ring seal in the clutch was the problem, then adding Lucas Tranny additive, the supper thick version, might increase the viscosity, and help the o'ring seal? But I would think cold viscous T fluid would do that do too, which counters the problem history of the last 3 winters?
Reminder, we have a 1996 company XJ automatic that was slipping (or something that resembled slipping), that stopped slipping after Lucas T-fluid (the one that is designed to help stop leaks and stop slipping), was added months ago.
I think I may need to check my TPS too, just to be sure it has not been screwing with me, since I have yet to check it with out the TCU attached. I made that mistake for a long time once before, and discovered what I thought was Tranny problem was a TPS with a funky ground and a funky output just on the TCU side. Be interesting to know it the TPS-TCU side output is used in reverse, or just in forward? HMMM?
Lastly, a reminder that reverse was still working perfectly, before I dropped the pan.
Last edited:
- Location
- Rainy side of Washington
If anything the 21 to 23 change was mid 90 or 90-91. I know of multiple people who had 21 spline trannies in their '90s.
- Location
- MilkyWay Galaxy
I checked the spare transmission I have and it is 21 spline, from a 4X4, Model number 30--40LE, SN 88GR-50873 from the nameplate on the side. Needs a good bath on the outside. Has the TC and flex plate with it.
Also found a OBD-1 (about 1994) vintage XJ, 4X4 for sale next to my shop. Asking $1700, Hmm.
Not sure my Renix jeeps would like that idea. I looked at Grand Cher. 2 years ago and my 87 Wagoneer overheated while I was looking it over for 5 minutes (idling in the summer heat with the AC on).
So it looks like I have the right AW4 to do a swap, if it comes to that.
Also found a OBD-1 (about 1994) vintage XJ, 4X4 for sale next to my shop. Asking $1700, Hmm.
Not sure my Renix jeeps would like that idea. I looked at Grand Cher. 2 years ago and my 87 Wagoneer overheated while I was looking it over for 5 minutes (idling in the summer heat with the AC on).
So it looks like I have the right AW4 to do a swap, if it comes to that.
maybe, hard to say wtf AMC was doing towards the end of their life.
You can use a later model trans, just get the t-case that mates to it. You'll have to swap some sensors and such to get along with the TCU in the renix, and you'll have to swap your speedo gear stuff over if it's got an electronic speedo output.
- Location
- Rainy side of Washington
Long as it's a 95 or earlier, go for it. If it is a 96 or later you will have to swap rear driveshafts as well and will be more vibration prone.
91 and later do have the electronic VSS, but I'm fairly certain the cable driven one bolts right in.
91 and later do have the electronic VSS, but I'm fairly certain the cable driven one bolts right in.
if it doesn't bolt in you can swap the mainshaft from your 21 spline input T-case to the 23 spine input t-case, along with the rear half of the case.
- Location
- MilkyWay Galaxy
CPS and Flex plate changed in 1991 due the change from Renix to Chry.
yes, but the torque converter didn't, so just swap over the renix plexplate and CPS over to the HO trans. It all bolts up, Chryco didn't change any hard parts, just electronics.
- Location
- MilkyWay Galaxy
Well I have run out of options short of pulling the AW4 and repairing it, or swapping it.
I found some really good deals on rebuild kits. An Ebay seller that is wholesale transmissions parts!!!
http://stores.ebay.com/Winners-Choi..._i.html?_nkw=aw4&submit=Search&_sid=922740691
$69 to $200 for simple oring and seals kits to master overhaul kits.
Next I need to think about a new torque converter while I have it apart, if they are not too $$$$$!
I found some really good deals on rebuild kits. An Ebay seller that is wholesale transmissions parts!!!
http://stores.ebay.com/Winners-Choi..._i.html?_nkw=aw4&submit=Search&_sid=922740691
$69 to $200 for simple oring and seals kits to master overhaul kits.
Next I need to think about a new torque converter while I have it apart, if they are not too $$$$$!
- Location
- Rainy side of Washington
Not sure anyone makes them new these days. I paid about 160 for a reman from transtar iirc, if you buy from them make sure you ask for extra packing material as I and several others have had converters shipped with no packing at all, just bouncing around in the box. I got lucky and mine was fine, some guy on pirate did not and the pilot snout on his was worn down to a point.
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