AW4 no reverse

I recently rebuilt my AW4 and 4.0L. The engine is running like a top but the tranny is having problems with reverse. I disconnected the linkage and played with it by hand to no avail. It doesn't even try to grab. It goes into drive and runs fwd fine. (With the exception that the transfer case doesn't know if it wants to be 2 or 4 wheel... pretty sure that's a linkage issue). I went ahead and pulled the tranny with the intention to dismantle it again and see if I found where I messed it up. I was just sitting here at work thinking about having to tear into it again when I remembered that I never adjusted the reverse band. So the question is...
If the reverse band is too loose, will it keep it from going into reverse??? It makes sense to me but it is always nice to get a second (or third, or more) opinion.

The band used in the aw4 transmission is called the second coast brake band. It's function is to lock the direct clutch drum from turning clockwise or counter clockwise. It is not used in reverse. The held components in reverse gear are 1.) Overdrive direct clutch 2.) Direct clutch 3.) First reverse brake. Since all of your forward gear ranges are operating this rules out that your clutches are holding more or less. The culprit most likely is the valve body, make sure your checkballs are in there correct location and check the passages in your valvebody steel seperator plate & plate gaskets with a light to check for blocked pasages. Checkball locations differ from transmission year. I hope this helps. ::

Thanks alot! I'll rip into it tomorrow. Not too excited about it but at least I might not have to tear into the internals again. Talk about a bunch of busted knuckles! I have 3 more hours at work though. Anymore ideas of what to check?

I went ahead and pulled the tranny and dropped the valve body. Everyone I've spoken to (including Tito!) say that it sounds like a valve body problem. I verified that all of the check balls were installed correctly and the actuation of the valves. Everything checked out ok. The manual says that there should be a couple check balls that are steel. Mine only had rubber when I took them out and the rebuild kit only had rubber also. I assume that this is merely a tech pub issue and reinstalled rubber. I did verify that they are the proper diameter. As I was verifing the gaskets, I realized that I had originally swapped the upper and lower. I am wondering if that might fix my issue or if it is probably something else. The way the gaskets fit, having them installed in opposite positions would allow for the migration of tranny fluid from several of the channels.

The transmission is back in the Jeep. Still have the same problem. Park works perfect. Neutral and reverse go forward slowly. The other positions go forward. I haven't taken it on the road to see if it shifts gears in drive yet. Everything has been done in my driveway on jackstands. Any ideas? What else in the valve body could it be?

Solenoid 2 could be stuck in the ON position.

Have you checked the pressure yet?

Nope. Haven't found a gauge yet.
Once I put it back on the ground it won't even go forward. Negative progress.

mahanja said:

Nope. Haven't found a gauge yet.
Once I put it back on the ground it won't even go forward. Negative progress.

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Unplug the TCU and see what happens, you should be able to shift the gears manualy, less any 2nd.

I got it to go fwd. I forgot to take the transfer case out of neutral. Whoops.
Then I finally took it to a great tranny shop here in town. Let me know if anyone wants their #. Really great.
It ends up that it was actually one of the seals on the first/reverse brake. The valve body and everything else works fine. It ended up costing a bit more than I was initially planning on but I wasn't going to pull the tranny out again! Thanks everyone!

Not to hijack the thread, but I am having a similar problem. My Jeep seems like it is not taking off in 1st gear, as it will stay in the same, doggish gear from take off to about 45-MPH. If I shift it into 1-2 manually, it will stay the same, until I slow down, and then the torque converter will lock up very suddenly. What do you think, same problems, valves, solinoids, etc. I am pulling my hair out trying to fix it. THANKS!

kj139 said:

Not to hijack the thread, but I am having a similar problem. My Jeep seems like it is not taking off in 1st gear, as it will stay in the same, doggish gear from take off to about 45-MPH. If I shift it into 1-2 manually, it will stay the same, until I slow down, and then the torque converter will lock up very suddenly. What do you think, same problems, valves, solinoids, etc. I am pulling my hair out trying to fix it. THANKS!

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First thing is to disconnect the trany control box under the dash.

No wait first thing is what year and Model.?

1988. I have disconnected the TCU and let it reset and installed a new TPS. I also disconnected the starter relay and ran a "bump" switch and cleaned the NSS. Still not taking off in first.

mahanja said:

I went ahead and pulled the tranny and dropped the valve body. Everyone I've spoken to (including Tito!) say that it sounds like a valve body problem. I verified that all of the check balls were installed correctly and the actuation of the valves. Everything checked out ok. The manual says that there should be a couple check balls that are steel. Mine only had rubber when I took them out and the rebuild kit only had rubber also. I assume that this is merely a tech pub issue and reinstalled rubber. I did verify that they are the proper diameter. As I was verifing the gaskets, I realized that I had originally swapped the upper and lower. I am wondering if that might fix my issue or if it is probably something else. The way the gaskets fit, having them installed in opposite positions would allow for the migration of tranny fluid from several of the channels.

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I am no transmission expert by any stretch of the imagination.
My opinion is that the gaskets matter a lot. I've seen some and I believe that the wrong gaskets could open or close passages they shouldn't.
I'd install them where they belong if I had problems.

KJ139 - same problem here. Can only pull away in first if i select 1/2 manually. I've not got very far with solving it yet though. Replaced fluid and filter and I have a spare TCU but want to check fault codes first.

Steve.

Stevemedlock said:

KJ139 - same problem here. Can only pull away in first if i select 1/2 manually. I've not got very far with solving it yet though. Replaced fluid and filter and I have a spare TCU but want to check fault codes first.

Steve.

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That sounds like an entirely different problem than his.

Yours sounds like a blown TCU fuse, or bad TCU.

I finally took mine to a reputible tranny shop here in town. They did an awesome job. They found everything was installed correctly but a rubber seal was cut during the installation of the first/reverse brake, keeping it from maintaining pressure. Sucks. Works great now though! A word of advice to anyone wanting to do all the work themselves: Don't waste your time with AW4s! It would have been worth every penny to pull the tranny myself and paid the $1100 to have it rebuilt ($425 of which was parts) to have saved all the time. This ain't no freakin' 3-speed C4! Thanks for the help!!!

$1,100 !!!!!!!!!!
That's more than I paid for 3 of my jeeps!!!!!

I won't ask if they used vaseline!

And that was with you pulling it?

Did that price include the aprts you installed first?

I bought the rebuild kit. I pulled it. I rebuilt it. I installed it. It didn't work. I pulled it again. I dismantled it. I didn't find anything wrong with it. I reinstalled it. It didn't work. I pulled it again. I went through the valve body and checked the operation of everything with low pressure air. I reinstalled it. It still didn't work. I finally took it to the tranny shop. They pulled the valve body. Checked it with low pressure air. Everything checked good. Reinstalled the valve body. Still didn't work. They pulled the tranny. Dismantled it. Found the cut ring. Replaced the ring. Went through the entire tranny. Reassembled the tranny. Reinstalled it. Finally got it working. Find me a rebuilt AW4 for under $1500. The cheapest I found was $1800. The only junkyard around that had an AW4 wanted $500. With 125k miles. I had one tranny shop quote me $2900 to rebuild mine. Way out of line. I got so friggin fed up with pulling the tranny that it was worth every penny to have it done. And it is nice to know that the engine and tranny are fresh rebuilds since it is my wife's jeep and I want to ensure it remains reliable. Reliable Jeep. Kinda funny. Both were a pain in the dick but it is done.