Thanks for mentioning the little screen mine was just floating around. My snap ring is intact no issues that i can detect but I'm not getting overdrive. Was hoping i had a broken snap ring like everyone else. Shifts fine out of over drive any ideas before i put it back together?

 

Great Writeup!!!

I am just curious if anyone knows the reason "Why" the Servo Clip Breaks?

My "Guess" is that if towing a trailer and driving with the Overdrive ON that when the transmission is shifting back and forth from Overdrive to 3rd and back, over and over again while pulling a heavy load that the Sevo is probably banging/Slamming into the Sevo Clip much harder that it would normally under normal, driving conditions, non towing conditions?

And also if the truck is run really hard/racing all the time in Overdrive?

My truck has 212,000 miles and shifts just fine right now (4R70W Transmission). I will be using this forum page if my transmission ever loses overdrive!!

 

This is my first post, but i have an 05 that lost overdrive. I dropped the valve body and cleaned out all of the c-clip. I reassembled and filled with MerconV. I had no drive or reverse, pulled it all again and I inspected the separator plate and found a crack from the 2-3 accumulator. I could see on the plate where the gasket wasn't sealing so i replaced it with new gaskets thinking that was my problem and STILL no drive or reverse. I've dropped the valve body a few times to check everything and can not find the problem.
Is the fill procedure on this trans really that touchy or did i screw something up? I've even check my line pressure and it's at 0psi, nothing. Checked the filter every time as well and still nothing. It drove before with just the overdrive issues, but now can't even get it to move.

Please somebody with some knowledge set me in the right direction.

 

Best you start a new thread for this issue.

 

I realize this is a very old thread and there may not be anyone still active here, so this is a long shot. I have the 4R75E, same issue as OP. No 3rd or 4th but can get 3rd back when I turn off O/D. Just bought the truck and drove home 1.5 hours no issue. Fixing various issues and test drove about 5-10 miles when the issues started. So no idea what the behavior was before it broke. Tore into it yesterday and found the small e-clip on the O/D cylinder was broken, but just laying on top of the valve body. Sweet- no pieces inside. Still tore apart the valve body and made sure everything moved. Apparently didn't do a perfect job as putting it all back together and- still the same issue. Replaced the e-clip with a 3/8" clip as it seemed to fit and an M10 wasn't available anywhere in town. So on the off chance anyone in here is still active:
1- Seems like the O/D band can't have disengaged if the smaller e-clip broke as the piston never left the bore. I did not replace it.
2- If I understand correctly, the real reason for the symptoms is the piece of metal in the valve body, not the actual breaking of the snap ring- at least when it's the larger one. Unclear what the smaller one breaking does by itself. So presumably I have some small piece of something unrelated in the valve body now?
3- can the O/D piston itself be seized/broken? I've found a few posts showing that had to be replaced. Will it do the same issues if that's the case? I didn't pull the piston for fear of the band engagement issue, which I now understand better and have no qualms about.

Current plan: tear it all back apart. Replace the valve body gaskets and check *****. (EOAZ-7E195-B for the ***** from Ford) THOROUGHLY clean the valve body, especially the O/D valve. Replace the O/D piston and snap ring there since I already bought it and they're known to break over time anyway so may as well.

Anyone have any other ideas? Every single thing I find points to this being the issue for my symptoms. Even the local transmission shop said it sounded like my snap ring broke. I'm giving it one more shot and then taking it in to them. This was supposed to be a backup/cheap truck for me that I got for $3k, so not really wanting to spend another $1-2k at a shop.

 

Been a while , but I will tell you that with my truck the first successful fix of the snap ring lasted a few years and then I again lost 4th. And I just said left it that way for another couple of years since I was at a loss as to what this could be - was assuming the new ring did did not snap. Didn't do a lot of long distance highway driving, and no harm was done apart from melting a few more sq yds of ice cap. Just a though if this indeed a back up truck.

 

thanks. That's what I'm finding- that since I technically still have 3rd, it really isn't terrible, but I'd really rather not run 80 down the interstate in 3rd and blow the engine. I did order a new piston entirely though so that I make sure it replaces with the correct snap ring instead of just what Advance had laying around. Also thinking the o-ring on the piston may have flown off when the smaller snap ring broke- that much pressure right there as it displaced only the smaller piston...? Going to give it one more go then may just say screw it for awhile. my last truck I put 2k miles on in 6 years. If I get 4th back, I will literally never put enough miles on it to break it again.

 

This is a great resource for the OD issues we all seem to be experiencing... Here is what I found when I pulled by valve body and only could find 7 of the check *****.. One of the check ***** wore small enough to get stuck in the opening in the valve body cover itself. See picks below. I am in the process of reassembling and hope it resolves my issue!


stuck ball has red circle around it

stuck ball has red circle around it

one ball is much smaller than the others

 

F150 with 4r75e

Long story short... direct drum teeth damage. No OD at all. Snap ring and e ring ok, no damage, band looks ok. Change drum and clutch disks. OD servo pin with orings installed. Take the truck for a ride. BAM! no OD. Omg. In the heat of the moment I floored with frustration and bum OD works. Seems the OD only works when I'm in rage xdd. But if I drive like a normal human being OD won't work. Any suggestion?

Thanks in advance.