Ford 850 5 speed trans repair -help

[GlenIdaho]

Well, the saga continues with my 850. Was out putting some time on the motor and working out the bugs after a rather lengthy and extensive rebuild when 3rd gear decided it had had enough. Haven't been into it yet but I think the teeth on 3rd gear and the coupler have had it. It won't stay in third gear even on flat ground. It comes out when power is applied. So, it looks like I'm going to have to split the tractor again and repair the trans. I didn't go into the trans when I did the rebuild because it had no problems other than intermitent 3rd gear issue. The detents and springs were severely worn so I hoped new ones would do the trick. After the rebuild it was solid even on hills. Then there was some trouble getting it into third and I must have knocked some teeth off. I now wished I would have opened up the trans when I had it split. Looks like I'll be doing some repainting too after I get it back together. I have to remove the fel so I'm going to build an A-frame to lift it off in one piece. Looks like another good winter project. I'm in the process now of learning more about the 5 speed and would appreciate any suggestions about the tear down and rebuild. Anything I should look for besides obvious wear, broken teeth etc? How difficult is this job? I've done an old Ford 3 speed, but nothing else. Any sources of specs for measuring wear tolerances?

I've read previous posts in the archives and thought Zane's fix may be a good one to pursue. I know awhtx has replaced 3rd in one of his tractors. So with all the expertise out there any help is greatly appreciated.
 

[fordtractorpro]

I have several complete 5 speed transmissons.
500.00 for complete 5 speed.
 

[awhtx]

Glen,
Yes, I had the same problem with 3rd gear in my 861D and I tore it down and replaced the 3rd/Rev sliding coupler which is part number 43 in the "5 speed transmission gears" subsection in the NH diagrams. There are 3 of these couplers in the transmission and they are all the same part. I got a good used one from Alexander's in Texas. The only worn teeth in my trans were in the coupler- the teeth on the gear were still good.
I also did Zane's mod to the shift rail while I had it apart.
Send me an e-mail if you need any moral support while you do the work.
Alan