720 Transmission

[Greg Trame]

I am preparing to work on my 720 transmission and have a few questions. There was a whining noise coming from the first reduction housing,so we removed it,and found the problem. After removing the first reduction and PTO gear there was a lot of play on the input shaft. The bearings are shot. My question is how big of a job is this? Can we slide that shaft out the side or do the shift rails and forks have to come out first. We have the service manual, but I wanted to know if anyone had any tricks. Any advice is appreciated.

 

[Hayrack]

I fixed both of mine last spring. The whole unit with the bearings comes out of the transmission case. There is a double nut holding the shaft in the bearings that can work loose. Both of my 720's were loose. They didn't make a whining noise like you described though. They both "clunked" loud enough I thought I had a tooth missing or a bad gear when I ran something on the pto. I just tightened up the bearings on them and reset the backlash and put it back together. Both have worked perfect ever since.. I did buy a spare parts unit before I tore into mine so if you need parts I can maybe help. Email is open.

 

[Hayrack]

Guess I should have read this a little better first... or just went to bed!!! Are you talking about the pto imput or the main transmission input shaft?

 

[Greg Trame]

I am referring to the main input shaft into the transmission.

 

[Hugh McKinney]

Can a 70 have the same problem? My 70 doesn't make much noise from the first reduction housing, unless I run something on the PTO. The 70 has a different arrangement transmission than the 720, of course, but is the nut you mentioned that got loose, also come on the 70? Thanks, Hugh

 

[Hayrack]

I believe so Hugh... I would have to check the parts books to be sure though.

 

[Hayrack]

Greg, The shaft your talking about is supported on the outer end by a ball type bearing mounted in the reduction cover and the shaft is held tight castle nut and key. They will always feel loose and have some play with the reduction cover removed. If you want to be sure I would reinstall the reduction cover with the gears first reduction gears removed and see if there is still play.