5091 Tranny.. several Issues

[Anglo Traction 761]

Well, I knew I had to split the case on this, mainly due to a leaking gasket. Just as well I did. Doing this for the first time, my hesitation allowed me to just take it a bit at a time after reading the Manual a few times.

Having split the Case, the first thing that required a 'Second Glance' was that the Reverse Idler gear was wearing a small circular groove in the Running Face that it's shaft fits into. It was a 'Burred' edge on the Idler gear where it meshes with another. ....it had been put back upside down with the Flange upwards.

(see arrow on left of picture).

I wanted to dismantle the Diff, as I needed to check it and measure the R/H Axle shaft for possible replacement. Before I started, I had studied the Pinion Ends that show on each end of the Diff Case. Some have 'X's stamped and others are Centre Drilled, obviously for machining etc. However the pattern to these were not symetrical , which made me wonder (see highlighted area on Right of Pic) ...... Sure enough, when I opened the Diff, I find 3 Pinions driving the Left hand side Axle and 5 driving the R/h side !!!.

It must have been used like this for some time, but fortunately there are no 'Ill Effects' on Bearings, Gears etc, but I imagine there were unequal forces applied to the Left Axle with only 3 pinions.

Anyway, I have resolved these problems, cleaned Burrs of Rev Idler using an Arkensas Whetstone and placed the pinions the way they should be.

Oh, and I've got to replace the Plug in the Ball/Spring Dentent Hole, because it had been drilled through and leaked Oil, but I can make that easily enough.

Now the questions -

The Diff Bolts are only 5/16" dia Grade '8' with Locknuts and no Washers (1974 Model). The Diff Cases are drilled 5/16" for these ok, but the Crown/Diff Gear is drilled 3/8" dia ?. I know they went to 3/8" bolts in March 75, but is it adviseable to modify this one to 3/8" ?.

I visualise these undersize 5/16" bolts slopping back and forth when torque is applied to it in Fwd drive then in Reverse and I don't like that idea.

I am able to machine and harden some 'Sleeves' that will fit over the Bolts and in the Bolt Holes of the Diff Gear, rather than try and obtain the correct new bolts.

Secondly. Are there any other likely problems I should look for with regard to the Reverse Idler fault ?.

Needless to say, apart from evidence of some P/Owner Gear Cruching, the Tranny Gears,Shafts and Bearings are ok, Oil was clean and only small spots of Condensation rust on inner case.

Any advise will be greatly appreciated.

[stevasaurus 23,521]

I like your ideas and I think you will be OK. Question: Are you sure the reverse idle gear was upside down? The bevel side of the gear should be up I believe or you will have trouble shifting into reverse. Check the manual again and see what it says.

Other then that, I think you are good to go. :ychain:

[TT-(Moderator) 1,169]

@ Steve:

He's saying that the shoulder (step) of the gear should be installed against the "bottom" case half - which will put the beveled end of the teeth at the "top".

As far as the through-bolts on the differential are concerned.......

Either fit them with new locking nuts, apply thread-locker, or both - and torque them to the proper specification and I don't think there will be a problem with the end caps moving on the ring gear.

More failures are caused by a nut loosening / falling off which allows the through-bolt to work out of the differential and catch inside the case. Once that happens, it usually causes big problems.

Worst-case scenario (pun intended) :

[clintonnut 127]

MMM tasty!

$2.00 worth of good locknuts can save you a whole tranny! Who would've guessed!

Charlie

[Anglo Traction 761]

Steve/Terry, Thanks for your responses, advice and clarifying my mis-use of the word 'Flange' iso 'Shoulder'. The Reverse Idler was found 'Shoulder Up' and is now Down.

I won't make any changes to the 'Bolt Fit' and I have New 'Nylock' S/Steel Nuts to replace the old ones. Especially as the Unit (& Tractor) has been 'Bodged' by someone with 'Iffy Standards' in the past.

What I will do is rotate the Diff gear against the Bolts/Nuts when they are in and 'Finger Tight' so that the 'Forward' drive force transmits through the Gear, Bolts, Diff cases and pinions, giving it no chance to move. Reverse force is more gentle, so less chance of movement in that direction.

The nuts will also have Threadlock applied and Torqued to 28ft lbs.

Hopefully, this will avoid the destructive result in Terry's picture !.....wow, what a way for someone to drain the Oil !.

I will have a Shaft Keyway repair job (R/H side) due to a Bodged Sloppy fit of the Hub Keyway (junked). Otherwise it's a good condition Shaft and I have good Hubs now to go on them.

There seems to be a trend with R/H Axle keyway/Bearing and Seal wear, I have seen this on 4 W/H Tractors... I wonder if it is a common wear fault ? .

Thanks. Regards.

[stevasaurus 23,521]

Thought that was what was going on...just wanted to clarify. Nice pictures TT. :ychain: