I had to let the washer run for 2 days 24 hours a day! before ALL traces of the blasting were removed. I would switch rotation if the flow many times a day. Fine blasting residue just kept coming out of the pores of the rough casting surface of the inside of the drum.
I guarantee that 95% or better of the conversions performed, that drum was not properly cleaned AND no DIYer will ever get its properly clean with Brake Kleen or whatever.
Failure to remove ALL TRACES of that media will result in premature wear and ir transmission failure.

 

I found the picture of the two different drums. One is a gasoline engine spec drum. The other is a 7.3 spec drum. The difference between the two is the height of the retaining groove. This is because the gas spec uses 4 discs. The 7.3 spec uses 5.
I am disappointed in the photo. I should have checked it after I took it. I will post a top edge down to the top of the retaking groove caliper reading.
I will post the part number for the Borg Warner 45 element sprag.
Havd fun boys. Live right. Say your prayers. Stock up on blood pressure medicine and Valium to deal with the parts acquisition.
The earliest drum style will require a thrust washer at the end of the inner hub. Later models that were also sprag design had a shorter inner hub that did not use that thrust washer sowatch out for that as well when looking around for the drum.
I will post pictures of the differences there as well.

 

Hi Nick ,I'm over in the UK and am having a good old time of rebuilding this thing 2001 7.3 f250 lariat,my transmission was not shifting into 3rd easily and with a bang , its a mech diode box , we stripped it,mech diode broken ,found a great guy really helpful over your side of the pond with a good used 5 clutch drum with sprag and outer clutches and 4 tab thrust washer the apply plate was a different thickness so he sent me that as well ,so transmission thoroughly cleaned all that good stuff and reassembled with all new seals and gaskets, fresh oil we fitted the thinner apply plate as it seemed to go better with the drum spacing ,all looked well, now its back in the truck and this SOB will not go into 3rd gear and above for love nor money , am I likely to be missing something really obvious at this point ,it's taken me an age to get to this point any help massively appreciated

 

Ok… In the above photo is a gas spec and a diesel spec drum. It’s a lousy photo showing the inner clutch disc retaining groove height difference and I will get that measurement for you BUT it does show the difference between the oldest style of drum that takes a thrust washer at the end of the inner hub NOTE the 4 grooves for the thrust washer. Newer style has a shorter inner hub and does not use a thrust washer there. Both new and old style are sprag design, gas and diesel BUT it must be the 5 disc height retaking groove 7.3 spec VS the 4 disc height retaining groove spec gas spec drum.

 

I love reading all of this. It has completely convinced me NOT to try rebuilding my trans myself when it's time.

 

Oh that would be a huge mistake letting somebody else do it. You would be floored by the hack procedures, lack of procedures performed, ect. By all of the self proclaimed expert shops and the same with the shops that post videoed on YouTube. I’ve seen them ALL. Frickin horrible!! It ranges from playing Russian Roulette to just putting a shotgun in your own mouth if somebody like those put their paws on your transmission.
Do not do it Greg. When the day comes I will be here for you brother. I walk you through each and every step and tell you what to and what not to get. I’ll tell you have to rectify engineering flaws and what is ok and not to change.

 

Curious Nick, I take it you're not a fan of the 4r100 though you're doing an admirable job with the rebuild and explanations, is there an alternative direct bolt in replacement?

 

They are fine once squared away.

 

There isn't a direct bolt in replacement. With a lot of time and money other transmissions could be adapted, but it will not be easy or cheap.

 

Nick is no longer on this site.

The mechanical diode caused a problem going into second gear, not third gear. Something else is causing the third gear problem.

Have you read the codes in the PCM? That's always the best place to start the diagnosis.

 

Hi thanks for replying ,have p0782 shift from 2 to 3 shift error , I also have an Idm code P1316 that after going in to do the buzz test is showing related to a bad connection injector 5 when wobbled goes away so that will be the harness ,my concern is that after doing the direct drum conversion I now have the problem ,new solenoid block fitted also

 

If you had a solenoid problem you would have a code that says so. But you don't, so it is almost certainly NOT a solenoid problem.

It could be a sticking 2-3 shift valve, or something wrong in the direct clutch, such as a leaking seal. Does reverse work normally? That also uses the direct clutch.

 

Apologies I meant to put in the text that reverse works fine ,I'm worried that when I have replaced the mechanical diode with the direct drum that I have missed a step somewhere ,I could find out very little about actually swapping the drums and if there was anything else that needed changing bar the clutches, drum and sprag itself ,we kind of had to use a bit of engineering logic to use the apply plate that goes with the sprag drum , all the shift valves did seem OK but I'm kind of with you unless we have a wiring issue or bad connection somewhere

 

If you have a wiring issue you'll have a code for a wiring issue. With only a code for a missed shift it is almost certain that the problem is something mechanical inside the transmission.

 

Well ,that leads me back to my first question ,are there any other steps that are in the conversion from mechanical diode to direct drum other than drum,sprag and outer clutches , which apply plate should I have used ,

 

I don't know the details of that conversion to be able to help with your question.

 

This is THE sprag to buy to replace the mechanical diode. It is the best brand. There are junk ones out there. This part number is a 45 element model. It is the strongest model. The pre/post 2001 sprags were 34 element and not as strong as this 45 element bad boy.