I was taking off my transmisson cover on my D-4 7U..serial no 6041.. to get at my steering clutches...I use a pry bar to break it loose from the frame(it was stuck pretty tight).I was surprise to find that someone earlier had taken this cover off and busted it into two peieces right where the clutch housing and the transmisson housing meet..was I surprised.. I had not notice it when I bought the cat..but I am rookie cat buyer..someone had used caulk etc to seal it up...did a pretty good job as there was no water in either compartment and it sat outside for ten years..so I got to looking to see how this could happen(after I took my transmisson cover off in two pieces..one was light and one was real heavy) I reviewed the removal procdure in the manual..step by step...hadnt missed anything, or did I...got to looking at the front piece and how it set on the tractor and notice the cover set under the pony pinion and that if you didnt have the pony pinion engaged to the flywheel before you pull the cover it will pinch and cause the you to have a two piece transmisson cover...you cant pull the cover back first..cause of the steering clutchs...you have to lift the back straight up at first to clear them then pull back..I cant figure why the manual never said anything about this..I mean if the guy before me hadnt done it ,,I probably would have.. as I was using the same manual..any one else had this happen...or am I just lucky.

This is pretty common on these machines. Actually these covers are cut apart in two pieces intensionally. This makes getting at the drive clutch quite a bit easier. Are you sure it was broken or did someone saw it in half with a saws all or band saw. If you look around on this site there is some pretty good information on how to do it and why it is done.
As far as slipping it under the pinion I am not sure but I bet someone else on here would know the answer to that.

thanks for the reply..Yeah..i did notice that in the manual the later tractors did have the split covers...but this one was broken....has uneven and jagged edge. Might be able to get by with it as is..guess its been broken for a while..my machine shop says he can weld it up for $150..I know this cat has the bath tube chassis...so the cover is just a cover or does it add strength to the frame chassis..thanks

Leave it broken! It saves a lot of trouble when you need to get into the clutch. It just needs the silicone on it. Yours probably seals better than those that are cut with a saw. Someone may have been in too much of a hurry to spend the time sawing it and figured out how to snap it instead.

Welding such a large piece would most likely leave it a bit warped and probably crack again if you tighten it down to seal properly around the edge.

okay..after reading the last couple of replys to my post...I went out into the dark with the flashlight..put the two pieces togther... well it was not broken, just a cut that wasnt the best..I guess that what happens when you havent got alot of experience working on cats..sorry guys..I am just rookie:(

Caterpillar issued precise instructions on how to saw the D4 transmission cover into two pieces, in the July 23, 1952 issue of the Caterpillar Service magazine. This issue showed the new, factory two piece transmission cover, initially .. and then went on to explain how earlier tractors could have the cover sawed into two pieces.
The new two piece cover appeared on tractor S/No's, 6U7364 and 7U16998 onwards ..

As always, many owners without access to a big bandsaw, and working with limited tools and limited ability, would have sawed the cover on earlier tractors, in two, in any manner they could achieve. Some would have been a success, some would have been pretty rough. Fortunately, Silicone sealant is Gods gift to Caterpillar true believers ..

The relevant article .. www.antiquecaterpillar.net/ACF_v2/showthread.php?t=12826

Bernie has done a fairly good job of splitting his D4 cover with a sawzall and angle grinder.
I think the cut he achieved is quite satisfactory and serviceable, considering the tools he used. It's a difficult cut, but once split, the access is improved no end.

Bernies D4 cover split .. www.antiquecaterpillar.net/ACF_v2/showth...2&highlight=D4+cover