4 years and 15,000 miles ago I built an E4OD and swapped it into my 1979 F350 pickup truck in place of the stock C6. After the initial build I did have trouble after 800 miles when it split the neck and stripped out the splines from the aluminum OD carrier. I replaced that with a steel one and I found no other problems inside of the transmission. Since that time the transmission has been working great but last week I had it go out again. I was accelerating from a stop and when I got up to about 50mph it stopped pulling suddenly. There was no noise or anything. It felt like you were pulling it with a rope and that rope just snapped. No forward, no reverse, nothing so I knew it had to be something that broke right in the front of the transmission. I was thinking maybe the OD sprag, converter that sort of thing.

I managed to tow it home and get it inside and then yesterday I pulled it out of the truck. When I took it apart everything looks perfect. There's nothing in the pan, clutches, gears and sprags all look great but the shaft that goes from the overdrive to the forward clutch drum was snapped off cleanly. When I looked around on line I couldn't find any pictures showing this happening. I just wonder if it was a fluke. This is behind a 460 engine that makes about 525lbs/ft torque. No turbos or power adders. 4.10 gears.

Broken E4OD center shaft.

When I built this transmission I did a lot of upgrades including going to a roller style center support. The bolts were all tight when I took it apart and it looks fine. Bushings in the direct drum look like new so I don't think that there's an alignment problem. Have you ever broken one?

 

I have built many of those and I have never seen that failure, I would just inspect the unit and replace the shaft and put it back together.

 

If this problem isn't wide spread it might be just a fluke, a part failing due quality issues not typical to that part.

 

Today I did some more inspection and I got together a list of parts that I'm going to need to get the transmission put back together again and I came across something.

There's a roller bearing that goes between the end of the center support snout and the front of the forward clutch drum. I can see where that bearing wore into the end of the snout pretty significantly, I haven't measure it but probably .030-.050. It is possible that maybe I had that bearing in backwards when I put it together or some time or another it wasn't rolling correctly. I washed out the bearing and it seems to turn ok but I'm going to get a set of new ones this time around. I'm thinking that after it wore away at the end of the center support snout it started bearing on the shaft that broke in a way that it wasn't designed to handle and over time it cracked and eventually failed.

Probably the result of my assembly mistake.

 

I have 3 e4od/4r100 apart in my basement. I seen nothing in them that looked like ur pic. The foward drum is splined not with a shaft bcuz that s what the input splines to if I'm not mistaken there are c6 drums that appear to be direct fit into an e4od/4r100 but they use a thrust washer not a Torrington bearing did u build it with some c6 parts? And some of those bearing have a indexing lip and that makes the directional. Hope I helped

 

This is the shaft that comes out of the overdrive section, sticks through the center support and then drives the forward clutch drum. I changed this shaft when I built the transmission because my core was older and didn't have the roller bearing center support. The forward drum is an early E4OD 4 clutch plate one with the full length splines. I can't see where it did any damage what so ever to that drum either but I'm going to look it over some more now that most of my parts have arrived.

My center support did have some wear marks where it had been working against the case. Bolts were tight. I just wonder if that can move around and get a little bit out of alignment and that causes it to load the shaft that broke too heavily??

 

The truck is all back together again and the transmission is working well. Hopefully it'll stay together for a long time with no more parts breakage. I did do some upgrades while I had it apart; my trans had the 3 gear planet in low reverse and I put in a 4 pinion one that I had on hand. I had reused the sprags and roller clutch from my core when I originally built the transmission so I went ahead and replaced the OD with the motorhome/superduty roller clutch, went to a 45 element intermediate sprag and I also put in a new plastic caged low gear roller clutch.

The center support had a little bit of wear where it contacts the case so I went to the setup where it is trimmed down and a snap ring is put in the case.