[Erik]

I posted this on agtalk but didnt get a response so it was suggested that I try here. A leak has developed out of the front driveshaft yoke on our 4800 transmission. I got it partially disassembled today and discovered that there was some play where the yoke attaches to the transmission output shaft. The castle nut holding it on is loose however the cotter pin is still in place so it could not have turned off. Could there be something wrong internally in the transmission that allowed the shaft to come forward slightly and cause this to be loose? Also how does the yoke seal to the shaft? does the yoke have an oring in it?

 

[20advance]

I do not know what to tell you about the play. I do know that behind the nut and washer is a o-ring that keeps the oil in the case. I my service manual is at the shop, or I could tell you more.

20advance

 

[flatfoot]

First, I have no experience with a failure on bottom shaft!

I would check end play of shaft and I am quessing here, if it is more than say 15 thou you may have a problem.

Bearings are adjusted with shims under caps, not with nut on yoke. Rear bearing must be adjusted first and then front bearing can be adjusted. There is 3 timkin bearings on that bottom shaft!

There is a o-ring under washer shown in your pic.

Nut is to be torque to 175ft-lbs

I hope onionfarmer or others adds there thoughts.

I will try and scan cross section of tran and that might help.

 

[flatfoot]

Cross section of lower part of tran

 

[onionfarmer]

This happens not a big deal. Yes there is a O ring under the washer and with time the yoke can get loose and then it leaks. The yoke has nothing to do with the pre load on the bearing on the out put shaft. If the seal needs to be replaced make sure you carefully take off the plate and keep all the plastic shims put it back just like before. AND torque the nuts. Get a new O ring tighten the nut there is a torque can't remember the spec. You are suppose to run it up to torque and go to the next hole for the cotter pin.

 

[onionfarmer]

Happy Thanksgiving to all . I will have all the kids and most important grand kids with us this year . The grand kids are keeping grandpa busy that's ok

 

[Erik]

Thanks for all the replies! So the fact that the yoke is loose with the cotter pin still in the nut doesn't concern you? If so that's a big relief, I was getting worried the transmission would have to be pulled!

 

[onionfarmer]

Just get it tight it will be fine . The thing to always check is the transmission filter on the right side. It is a suction filter any problems will show up in side the filter take a good look every time you change it

 

[albertabuck]

Just get it tight it will be fine .

Have never worked on one of these, so my comments are based on experiences with similar arrangements. If I am completely missing something, my apologies in advance.

As long as there is no wear on the splines creating movement, then yes I would totally agree. Otherwise simply tightening the nut is not going to make all the problems go away, if the flange is loose on splines, won't be long and things be all floppy and leaking again.

On most driveline setups like this, the flange or yoke is always softer than the shaft and is the one that wears. And while it might be a few hundred bucks to replace, it is often the cheaper alternative then to continuing to operate it with things loose and moving. I recently had a similar issue on the front output flange on my Versy 875. Front flange in question is no longer available. Shaft was perfectly within spec. As there was about 3/16in of splines not being used, we machined off that much off rear of flange to engage the full splines by allowing it to slide on further. There was wear at the rear of the flange which would make it tip, as in it was looser at the rear than the front. Bored out 1/2in of the splines in the flange at rear and pressed in a machined interference fit bushing which now holds the rear of the flange precisely in place. Then torqued down the nut and everything is all good. Had to do some adjusting to the brake caliper to compensate for the repositioning of the brake disc, but otherwise nothing else changed.

Not sure if such a fix would work here, nor availability of parts for Massey. Versatile uses a large coarse spline, not so sure such a fix would work as well if splines are fine

 

[flatfoot]

Thanks for all the replies! So the fact that the yoke is loose with the cotter pin still in the nut doesn't concern you? If so that's a big relief, I was getting worried the transmission would have to be pulled!

Definitely check splines and if you can tighten things back up with a new yoke - great. So far as far as I know MF has been great about supplying parts for these tractors - just price might scare you sometimes.

For your own peace of mind, I would check end play on this shaft since you have gone this far. You can probably replace seal without removing cap, but if you have excessive end play and wanted to check output bearing, by removing cap you should be able to remove bearing cone ( if is tight and you can't, that is good) to inspect and check and see if bearing cup is snug on shaft. As onionfarmer stated be carefull of plastic shims!!

If you do check endplay, I would like to know what you have.

 

[Erik]

Il check the end play while its apart, the seal seems fine (its bone dry on the back side of the yoke) all the oil was coming out through the splines. Il definitely cut open the suction filter too. Its always better to catch things early before it causes more damage that's for sure! Thanks for everyones input!