Yes I have search and read threads for hours and hours mostly following Marks threads. I cannot find an answer to my problem so I am resorting to this post.

2000 Ford Excursion 7.3 4wd.

Trans was rebuilt about 30k miles/3 years ago with some of the below mods.
MTS RV torque converter for towing.
Line pressure booster
New solenoids and stage 2 valve bodies from MTS.
Updated sprag
Spiral lock ring update.
McLeod clutch and rebuild kit.

Yesterday I was accelerating pretty hard up a hill and while in gear there was a pop and what seemed like the truck went to neutral. I coasted to a stop and found I had no gears, no forward, no reverse. Park would still hold the truck in place. Transfer case and rear still good.

Today I pulled the pan, found clean clear pink fluid, filter still in place and nothing out of sorts.
Shift linkage spot on. No issues.
I then pulled the trans, flex plate perfect, no signs of issues.
Torque converter pulled found no wear signs and it was installed correctly. Splines inside of torque converter all good. Placing the input shaft inside the torque converter reveals some resistance to rotation, assuming not sheared off or broken internals.
Input shaft is in one piece, no spline issues.
Pulled pump, seems ok, opened pump and inspected gear, looks good nothing worn or cracked.
Pulled next section to inspect intermediate shaft, no issues.
Basket inside intermediate shaft section(sorry don't know the proper name) appears good no broken gears etc.
Output shaft seems to have resistance to turning does not "feel" broken.

I made one critical mistake before I pulled the trans and that was I did not check for line pressure, so I don't know if I had it.

My questions for Mark or whoever is an expert is the following:

1. Based on what I have torn down and not found could this show the torque converter may have completely failed somehow?
2. I don't have the tool to compress the section of the internals needed to put back together(I could build one), is there anything beyond the intermediate shaft that could cause no movement and is it worth going deeper?
3. Is it possible for the line pressure regulator valve in the pump to get stuck open while driving resulting in a loss of pressure, enough to cause a neutral situation?
4. Is there a good method to test or inspect the regulating valve to see if it has failed open?
5. Is there anything else I should be considering perhaps on the valve bodies?

I don't want to start throwing parts at this trans, it seems like a waste of time. If there is anything else I should inspect I would like to know.

 

Have you separated the transmission and transfer case to rule it out? Can't really think of a scenario where park would still work but I'm no expert. Wouldn't even call myself a novice. Just throwing things out, might trigger an idea for you or someone else.

 

First off kudos on an excellent post with sufficient details for us to make some educated guesses. Too often people post on here with "Something broke. Help!!"

Secondly, I think you are on the right path suspecting the intermediate shaft. This is exactly what happened to my 4R100 and it's a BTS. It was during moderate acceleration (although others on here think what I call moderate is considered insane everywhere else) when I heard a pop and lost all drive in all directions. Both input and output shafts seemed to behave normally. Parking pawl worked. I shipped mine back to BTS for repair.

 

I can't say that is impossible, but it is not likely.
You HAVE to go deeper, you haven't found what broke. And something did break.
Once again, I can't say that is impossible. But it is unlikely. The way to test if the regulator has failed open is to look at the valve and see if it is stuck.
No. The valve body didn't cause this failure.

 

Mark and others,
Thank you for the responses. I'm heading to the shop to keep pulling it apart. I'll just build a tool to compress things when I put it back together since it sounds like I'm still looking for a broken hard part. I will report back what the final find and fix was since I see a lot of these threads unanswered.

 

I found the issue, it was right in front of me but my untrained eyes missed it the first time. The splines where the intermediate shaft go into were gone, smoothed out so well I missed it. So I need to know what this is called so I can order hopefully a stronger one.

Also while I am in here should I put the line pressure back to stock? This trans bangs gears hard (which I wanted for towing) but I am thinking it may be too hard which perhaps brought me to the splines being wrecked. I have modified valve bodies as well so I know that is contributing to the shifts but perhaps lower pressure would be a better match?

Can someone identify what this part is called so I can source it? I think it maybe the forward drum?

 

Does this help?

http://www.tcsproducts.com/media/1/T...ts_Nov2012.pdf

 

No I have been looking at that already and it is hard to know where the splines are attached to. I think it is this:

https://www.dieselsite.com/4r100Adva...lutchdrum.aspx

 

$745????? Are they worth anything used?

 

Forward clutch drum. $120-$140 online or any transmission shop.

Bought two of them myself in the last month. Just don't forget new steel sealing rings.

 

I couldn't bring myself to put another weak part back in. I next day aired a billet forward clutch drum, seals, and gaskets. Honestly the cost of the billet part is cheaper than a tow when I am hauling my 40ft 11.5k trailer on the interstate 300+ miles from home.

Pulled it all apart today, cleaned and checked everything. Now the magic part will be putting it back together again. Building a tool to compress the parts for that one snap ring as we speak.