I have a E350 chassis motorhome. It's a 92 with the 7.5 460 and E4OD. The trans was rebuilt by previous owner and I have the Repair Order. Standard rebuild with solenoid pack, center support upgrade and OD snap ring. It has 27,000 miles since the rebuild. It has always worked fine until last Friday. We went to the race track and stopped at the gate to pay. When I went to pull out it wouldn't move. It was like the trans was in reverse and drive at the same time like my race truck with the trans brake on. I started to shift it from reverse to drive and gunning it some as I was in a bit of a panic. It gave a loud bang ( I thought the driveshaft blew off) . After that I have Reverse but no forward gears. Engine just revs in any forward gear. I got it towed home and have dropped the pan. It looks like new, red fluid, no odor and no debris. I'm posting because I can't find anyone that seems to have had this happen. I could see maybe something inside broke but have no idea what made it lock up in the first place. Just wanting to see if anyone experienced anything like this or heard of it. Thanks

 

The only way that can happen is if the forward and reverse clutches were on at the same time. That should never happen. The bang apparently was when the forward clutch broke.

Take the trans out, tear it down, and fix what broke.

 

Thanks for the reply. I have resigned myself that it will have to come out. I'm also figuring on tackling it myself. I'm retired from auto repair mostly body but have built several TH350s for drag racing. I know this is more complex but I have the tools. Local shop won't warrantee bench work anyway and I don't want to have it towed again plus the additional labor. I use this to tow my race trailer so it sees whatever the 460 can put out. I did add a larger, stacked plate oil cooler , installed the cooler bypass and replaced the 5/16 lines with 3/8. I also use the OD button on hills so it doesn't hunt in and out.

If I go through it are there any other upgrades I should do ? I'm told steel planetary would be a good idea. Would it be worthwhile to get a later trans like a 95 or 96 as a core ? I did find a 95/96 460 4WD trans. Someone said the cases are the same just have to use my output and ext hsg. I know there were many changes with these units but don't really know what to look for.

 

I wanted to update this since I got it torn down. What happed was the aluminum forward planet carrier melted/welded itself to the hub. Only thing I can think of is something happened to cause it not to get enough lube or just overloaded. So that locked up the trans. When I continued to force it, the splines stripped out of the aluminum carrier thus no forward gears. I had to use a large slide hammer with a hook to get the planet off the output shaft. After I separated the planet from the ring gear,the 4 pinions seem in good shape as does the rest of the trans.

 

I can't stand the use of stinking soft aluminum in any automatic transmission, yes even the stator in the torque converter. There should be absolutely nothing on or in the transmission made from aluminum. In the old days there was very little use of it in automatic transmissions.
Aluminum distorts under load, especially the cast parts like the cases. Aluminum has much lower tensile strength than steel, and will wear out easily or not take the load, like the spines you mentioned. When used as a valve body or coated valves they wear easily.

 

Actually I don't fault the aluminum completely. I found something else since I last posted. The previous shop into this trans installed a Sonaxx 1 piece rear bushing. However they did not follow the installation instructions to locktite and stake it in place. I noticed it had slid forward into the case about 1/4" and when I went to drive it out, it fell out with a light tap. So I'm thinking it may have also turned. This would restrict or completely block off the lube going into the output shaft at the rear. The forward planet is the last thing at the nose of the output to get lube from that passage in the case. Even if it was a steel one as I installed now, it would also fail without lube.

 

If you enjoy getting sub 10mpg due to the rotating mass and friction losses involved with an all-steel automatic transmission, more power to you. I'll pass.

 

Steel is not going to cause friction losses, you would use normal bushings and bearings in the steel parts. Rotating mass at constant rpm, the heavier the better since the inertia helps. Gosh there was talk in the past about powering vehicles with heavy inertia wheels.
Maybe aluminum crankshafts should now be the thing, since all that rotating mass and friction is so bad (it is for high rpm change rate). The reason for the use of aluminum has zero to do with what you mentioned, it is all about the $ for the manufacture that is not past on to us the consumer.
Aluminum is easy to machine, easy to cast, less heat involved etc. it is not used because of some fabulous mechanical or physical advantage over steel, it is all about how to make the product cheaper and faster, not better. Its not like the old days when quality mattered, just look at some of the junk some tool manufactures put out these days. There is only one brand of american made vise grips available, yes the foreign made ones work and sometimes last, but how often is the savings past on to us?
In the end I'd rather have top quality drive train components and less fluff in the cab, the weight of all the plush crap they add to a pickup now, get rid of some of that to make up for the extra weight of a good transmission or engine, simple logic.